MANAGING THE IMPACT OF IRRIGATION ON THE 
TOSCA-MOLOPO GROUNDWATER RESOURCE 
 
 
 
by 
 
 
 
 
GABRIËL STEPHANUS DU TOIT VAN DYK 
 
 
 
Thesis submitted in the fulfillment of the requirements for the degree of 
 
 
 
MASTER OF SCIENCE 
 
 
 
In the Faculty of Natural and Agricultural Sciences, 
Department of Geo-hydrology 
University of the Free State 
Bloemfontein, South Africa 
 
 
 
May 2005 
 
 
 
Supervisor: Prof. G.J. van Tonder 
ACKNOWLEDGEMENTS 
 
The contributions and support of the following persons and institutions towards this 
investigation and report are gratefully appreciated and acknowledged: 
 
• All water users from the Tosca Molopo aquifer for their concerns regarding 
sustainability of the resource and access to their property for observations. 
Also the agricultural institutions that addressed the water issues through 
their structures. 
 
• The Tosca Molopo water user association pilot committee in particular the 
chairman and vice-chairman Mr. Gert Stoltz and Lennox Louw, through 
whom most communication took place. 
 
• Me. Erika de Villiers in her capacity as social consultant for her efforts in 
drafting the Constitution of the Tosca Molopo Water Users Association. 
 
• All Department Water Affairs and Forestry internal members of the Pilot 
Tosca Molopo groundwater committee where strategies where formulated 
as possible solutions in the Tosca Molopo area. Also the staff from divisions 
responsible for implementation of these strategies. 
 
• Mr. Johan Wentzel and Me. Linda Godfrey from the RDM office for 
completion of the reserve for this area. 
 
• The staff from the DWAF Northern Cape region Geohydrology section for 
the bi-annual water level and abstraction monitoring. 
 
• The DWAF Pretoria Geophysical team for the Geophysical investigations 
and borehole siting and use of their data. 
 
• The DWAF WARMS office for assistance in verifying and communicating 
water rights with users. 
 
• Me. Liezel Ferris from DWAF GIS section for GIS analysis and maps. 
 
• DWAF Geomatics for surveying of irrigation areas. 
 
• Professor Gerrit van Tonder and Dr. Ingrid Dennis from IGS UFS for 
guidance and evaluation of work and documentation of results for this thesis. 
 
• Mr Siep Talma from CSIR Environmentek Quaternary Dating Research Unit 
for Groundwater Isotope results and recommendations towards use of data. 
 
 
 
 
 ii 
SUMMARY 
 
From 1990 to 2000 rapid development of irrigation from groundwater resources in dolomite 
aquifers took place in the Tosca Molopo area. This abstraction lead to water levels 
declining 10 to 20m regionally and up to 60m proximate to intensive irrigation. The purpose 
of this study was to investigate the impact of irrigation on the resource and initiate actions 
to manage the resource. This thesis reports on the qualification and quantification of the 
impact, determination of water use and regulating use to ensure sustainable future use. 
The Tosca Molopo area is located in South Africa proximate to the Botswana border. The 
area of interest is characterized by a flat topography. From the watershed in the west at 
1210 m the elevation gradually decline to 1070 m in the east over a distance of 60 km. A 
number of non-perennial rivers drain the area, and although insignificant as surface water 
resources they play a major role in groundwater recharge. 
A low annual rainfall, varying from 399 mm in the east to 385 mm in the west, characterizes 
the study area. Evaporation in the area is high at between 2050 – 2250 mm/a (WRC, 1994) 
with only a small percentage of rainwater available to recharge groundwater. 
Two distinctive aquifers namely a primary aquifer formed by fine-grained sediments of the 
Kalahari Group and fractured/ carstified dolomites of the Ghaap Plato formation contribute 
to the system. The general flow is from the SW to the NE with the Molopo River the base 
of drainage. From the observed water level reaction the sediments contribute largely 
towards the storage of the aquifer system with the fractures of the dolomite contributing to 
high yielding flow. 
The MODFLOW PMWIN 5.1.7 (Chiang 2000) software was used to construct a 2-layer 
finite difference flow model. The model covering 80 km east west and 50 km north south or 
4000 km2 was divided into cells of 0.5 X 0.5 km generating 100 rows and 160 columns. 
Based on the conceptual model provision was made for 2 layers namely the 
unconsolidated primary aquifer and the underlying fractured dolomite with its aquifer 
characteristics. 
The first layer ranges from an elevation of 1160 mamsl at a depth of 10 m in the southwest. 
To the northeast it range from an elevation of 1080 mamsl to a depth 960 mamsl or a 
thickness exceeding 120 m. The base of the sediments is the top of the fractured dolomite 
aquifer with its base at 900 mamsl. 
Of the number of dolerite dykes intruded into the dolomite the Grassbank and 
Quarreefontein dykes (both 15 m thick) are the most influential on the groundwater flow. 
Both these dykes act as no-flow boundaries of the Neumann (impervious) type impeding 
 iii 
flow from the south and west of the area. Towards the east the Quarreefontein dyke does 
not seem to be a no-flow boundary as the water level information indicate connection with 
the dolomite to the south. The surface and groundwater shed formed by the Banded Iron 
Formation of the Waterberge forms the boundary to the west. The combination of both a 
geological contact and watershed is a leaking boundary. The Molopo River forms the 
eastern boundary. 
Recharge to the aquifer was determined with the chloride mass balance method with 
groundwater sample analysis and the Cl rain content 0.8mg/l. Recharge zones as 
determined from this chloride analysis were used for the model. Recharge in each zone 
was based on seasonal recharge for the winter (ranging from 0.5% or 0.4 mm to 3% or 1.5 
mm) and summer (ranging from 0.5% or 1.6 mm to 3% or 8.3 mm) depending on the 
precipitation. 
Groundwater is the sole source of water for both agricultural and domestic requirements. 
As irrigation use is responsible for 99.5 % of the total use no domestic and stock watering 
abstraction was considered. Irrigation abstraction was calculated from the registration 
areas, field observations and reports from users. The volume was then averaged over a 
six-month period (182.5 days) according to crop cultivated to obtain the daily abstraction 
from the aquifer. 
The calibrated model was used to test the following 10-year future scenarios of abstraction 
and recharge in order to assist in decisions regarding management of abstraction from the 
aquifer system. 
Scenario 1 was with average precipitation and recharge at the current high abstraction rate 
of 16.1 Mm3/a. This scenario was not acceptable due to the regional water level declines of 
20 to 30m and 60 to 110 m water level declines proximate to irrigation. 
Scenario 2 was with was with average precipitation and recharge at the restricted 
abstraction at 11.1 Mm3/a. This scenario would result in regional water level declines of 10 
to 20m and 30 to 60m proximate to irrigation. With strong abstraction control this scenario 
with controllable water level declines was acceptable. 
Scenario 3 was similar to scenario 2, but with 20 % less than normal precipitation. The 
water level declines that will result with this scenario were similar to scenario 1, but it was 
expected that below normal precipitation would be the exception. 
The 4th scenario tested was if normal precipitation prevailed and all irrigation abstraction 
was stopped. The regional water level would recover fully after 10 years with only 10 m still 
to recover proximate to heavily irrigated areas. 
 iv 
The model demonstrated that rates as specified by scenario 2 can be sustainable 
abstracted from the system at average recharge and that these abstractions would still be 
sustainable at 20 % less than average recharge as in scenario 3. Management of 
abstraction of the aquifer was consequently structured to ensure that abstraction would not 
exceed the sustainable yield of 11.1 M m3/a. 
Based on the evaluation and modeling of the resource the regulating and management of 
abstraction was addressed within the legal framework provided by the National Water Act 
(NWA) to obtain sustainable, equitable and fare dispensation of water use. 
Only water use exercised before Oct 1998 is recognized as existing water use. Potentially 
unauthorized users were identified with the use of satellite images. These water users 
were given the opportunity to proof that they are authorized users through a 
communication process and to submit supporting evidence. Users who could not submit 
satisfactory evidence were directed to scale their use down to authorized use by a specific 
time (summer 2003). These water users appealed to the water tribunal against the ruling of 
the water use authority, but the tribunal ruled in favor of the water use authority. 
In line with equitable access, application from new users were still processed with only 60 
m3/ha of property owned authorized in accordance with General Authorization as 
prescribed by regulations of the NWA. 
With these actions the resource was still over allocated with water use still not within the 
accepted sustainable abstraction. Therefore it was decided that regulations would be 
implemented to enforce users to restrict their water use to 60 % of authorized water rights. 
The NWA makes provision for local management structures to be established to manage 
their local water use. Such a Water User Association (WUA) was established in the Tosca 
area and would on the long term enhance the capabilities for water use management.  
The resource is currently over allocated. It is recommended that the irrigation water use be 
restricted with 40% of authorized water rights.  
The water rights are not fairly allocated. Although the above actions are aimed at 
normalizing the critical damage to the resource and eminent conflict in the area compulsory 
licensing would be the long-term solution in this area. Compulsory licensing is aimed at 
sustainable and equitable allocation of water rights. 
The WUA should ensure that all users comply to abstraction control measures and water 
level monitoring  the boreholes in the monitoring network would indicate if the resource 
would stabilize and recover to within sustainable use. 
 v 
TABLE OF CONTENTS 
 
1. INTRODUCTION .............................................................................................. 1 
2. PHYSIOGRAPHICAL DESCRIPTION .............................................................. 3 
2.1.  Location ..................................................................................................... 3 
2.2.  Topography and drainage .......................................................................... 4 
2.3.  Climate and precipitation ........................................................................... 5 
2.4. Soil and vegetation .................................................................................... 6 
2.5. Land use .................................................................................................... 7 
2.6. Water use .................................................................................................. 7 
3. GEOLOGY ........................................................................................................ 9 
3.1. Regional Geology ...................................................................................... 9 
3.2. Local Geology ............................................................................................ 9 
3.3. Structural Geology ................................................................................... 10 
4. HYDROGEOLOGY ......................................................................................... 12 
4.1. Aquifer yield ............................................................................................. 12 
4.2. Resource units ......................................................................................... 13 
4.3. Groundwater levels .................................................................................. 14 
4.3.1. Resource Unit 1 ................................................................................ 15 
4.3.2. Resource Unit 2 ................................................................................ 15 
4.3.2. Resource Unit 3 ................................................................................ 15 
4.3.3. The primary sandy aquifer of Kalahari layers ................................... 15 
4.4. Groundwater quality................................................................................. 17 
5. WATER BALANCE ............................................................................................ 20 
5.1. Groundwater recharge ............................................................................. 20 
5.1.1. Indirect deductions from maps and recharge tools ........................... 20 
5.1.2. Chloride Mass Balance (CMB) as a chemical tracer method ............ 20 
5.1.3. Stable and radioactive isotopes recharge determination methods ... 24 
5.1.4. Cumulative rainfall departure (CRD). ................................................ 28 
5.1.5. Saturated Volume Fluctuation (SVF). ............................................... 28 
5.1.5. Recharge summarized ..................................................................... 29 
5.2. Reserve determination ............................................................................. 29 
6. GROUNDWATER FLOW MODELLING (GM)................................................. 32 
6.1. Conceptual model .................................................................................... 32 
6.2. Model design and discretisation .............................................................. 33 
6.3. Aquifer boundaries................................................................................... 34 
6.4. Geophysical investigation to confirm dolerite dykes ................................ 35 
6.5. Drilling of boreholes to confirm water level elevation difference. ............. 35 
6.6. Aquifer parameters .................................................................................. 37 
6.7. Model calibration-steady state ................................................................. 38 
6.8. Hydrolic head interpolation ...................................................................... 41 
6.9. Aquifer recharge ...................................................................................... 42 
6.10. Abstraction from the aquifer ................................................................. 44 
6.11. Initial Hydraulic heads .......................................................................... 46 
6.12. Stress periods and time steps .............................................................. 46 
6.13. Model calibration-transient state .......................................................... 46 
6.14. Scenario predictions............................................................................. 48 
6.14.1. Scenario 1 (High abstraction with average precipitation) .................... 48 
6.14.2. Scenario 2 (Restricted abstraction [–40%] with average precipitation) 51 
 vi 
6.14.3. Scenario 3 (Restricted abstraction [–40%] with below average [–20%] 
precipitation) ................................................................................................... 53 
6.14.4. Scenario 4 (No abstraction with average precipitation) ....................... 55 
6.15. Scenario predictions summarized ........................................................ 57 
6.16. Limitations of the model ....................................................................... 57 
7. REGULATION OF WATER USE .................................................................... 58 
7.1. Water use conflict and its economic implications. .................................... 58 
7.2. Water use authorization ........................................................................... 60 
7.2.1. Termination of reserved water use rights. ............................................. 60 
7.2.2. Termination of unauthorized water use. ................................................ 61 
7.2.3. Consideration and authorization of new water use................................ 63 
7.3. Effect of NWA water use authorization on water use. .............................. 64 
7.4. Implementation restriction on authorized water use. ................................ 64 
7.5. Termination of general authorization. ...................................................... 67 
8. ESTABLISHMENT OF A WATER USER ASSOCIATION ............................... 68 
9. WATER USE ENFORCEMENT ......................................................................... 70 
10. CONCLUSION ............................................................................................ 72 
11. RECOMMENDATIONS ............................................................................... 74 
11.1. Local water management structure ........................................................... 74 
11.2. Abstraction control ..................................................................................... 74 
11.3. Water resource monitoring network ........................................................... 74 
11.4. Recalibration of the model ......................................................................... 75 
11.5. New irrigation water use authorization ....................................................... 75 
11.6. Risk of declining water levels .................................................................... 75 
12. REFERENCES ............................................................................................ 76 
LIST OF APPENDICES ......................................................................................... 77 
Appendix 1 The Tosca Molopo area. ................................................................... 78 
Appendix 2 Aquifer tests...................................................................................... 79 
G39684 .............................................................................................................. 79 
G39669 .............................................................................................................. 80 
G39691 .............................................................................................................. 81 
G39693 .............................................................................................................. 82 
Appendix 3 Magnetic profile across dykes to confirm presence and position. ..... 83 
Appendix 4 Monitoring boreholes and water level records .................................. 89 
Appendix 5 Ground water level elevation maps. ................................................. 92 
Appendix 6 Groundwater elevation difference contour maps. ............................. 94 
Appendix 7 Satellite Images from February 1999 and March 2002 used to identify 
areas developed after Oct 1998. ............................................................................ 96 
Appendix 8 Schedule of authorized users and volume as in April 2004. ............. 99 
Appendix 9 Survey of irrigation areas. ............................................................... 102 
Appendix 10 Example abstraction control by means of an agreement between the 
responsible authority and user and reporting by the user to the responsible 
authority. (Afrikaans) ............................................................................................ 105 
Appendix 11 Proposed water level monitoring network. ...................................... 106 
Appendix 12 Locality of proposed water level monitoring network. ..................... 107 
Appendix 13 Draft of publication to effect water restrictions. ............................... 109 
Appendix 14 Establishment of the Tosca/ Molopo WUA as published in the 
Government Gazette 16 July 2004. ...................................................................... 110 
Appendix 15 Articles and letters published in general papers and magazines. ... 112 
 vii 
LIST OF FIGURES 
 
Figure 1. Location of the study area; (a) as located in the Lower Vaal Water 
management area and (b) showing major centers, roads, dry river beds, 
irrigation areas and surface elevation contours (mamsl). .................................. 3 
Figure 2. Precipitation as measured at rainfall stations Pomfret and Vergelegen. 6 
Figure 3. Graphical illustration of crops irrigated. .................................................. 7 
Figure 4. Geology of the Tosca area with the major economical centers, roads, 
dry riverbeds, irrigation areas (blue circles) and surface elevation contours 
(mamsl). The resource units RU1, RU2, RU3 is divided by the red dot line. ..... 9 
Figure 5. Regional geology of the Tosca area taken from SUB-KALAHARI 
GEOLOGICAL MAP by IG HADDON 2001. .................................................... 11 
Figure 6. Yield frequency of boreholes in the a) Ghaap dolomite and b) Kalahari 
sediments groups. .......................................................................................... 12 
Figure 7. Groundwater level elevation contours (mamsl) (1977 (a) left and 1990 
(b) right). ......................................................................................................... 14 
Figure 8. Groundwater level reaction in borehole G39793 in response to 
abstraction and recharge. ............................................................................... 16 
Figure 9. Piper diagram of groundwater quality of the Molopo dolomite aquifer. . 17 
Figure 10. G39682 Grassbank groundwater variation in selected chemical 
substances ...................................................................................................... 19 
Figure 11. Areas of highest recharge, based on Cl values for existing boreholes. 
(Godfrey 2002) ................................................................................................ 23 
Figure 12. Scatter plot of δD (o/oo) vs δ18O (o/oo) data. ............................................ 27 
Figure 13. Molopo dolomite aquifer area. .......................................................... 30 
Figure 14. Conceptual model of the Tosca Molopo aquifer indicating the major 
boundaries, aquifer units and historic water levels.......................................... 32 
Figure 15. Arial extend of the Tosca Molopo groundwater model with abstraction 
cells (red) (50X80 km) ..................................................................................... 33 
Figure 16. Observed versus simulated hydrolic data ......................................... 38 
Figure 17. Spatial extend of transmissivity and storativity zones in layer 1. ...... 39 
Figure 18. Spatial extend of tranmissivity and storativity in layer 2. ................... 40 
Figure 19. Groundwater versus surface elevation. ............................................ 41 
Figure 20. Recharge zones in the Tosca Molopo aquifer with Zone 1 light blue, 
Zone 2 dark grey, Zone 3 light grey and Zone 4 dark green. .......................... 42 
Figure 21. Correlation between observed (dotted line) and modeled water levels 
(solid lines) for the 20 stress periods representing winter 1994 (year 0-10) to 
winter 2004 (year 0). Water level elevation on vertical scale with the days on 
the horizontal scale. ........................................................................................ 46 
Figure 22. Selected draw down maps (meter below initial heads) results from 
transient state calibration of the model. The six 2 year periods pre-ceding the 
winter of 2004 were used. ............................................................................... 47 
Figure 23.  Estimated surface area irrigated for each half year in the Tosca Molopo 
aquifer. ............................................................................................................ 48 
Figure 24. Correlation between observed (dotted line) and modeled water levels 
(solid lines) for the 40 stress periods representing 1994 to 2014 for Scenario 1 
conditions. Water level elevation on vertical scale with the days on the 
horizontal scale. .............................................................................................. 49 
Figure 25. Selected stress periode draw down (meter below initial heads) results 
from Scenario 3 of the model. ......................................................................... 50 
 viii 
Figure 26. Correlation between observed (dotted line) and modeled water levels 
(solid lines) for the 40 stress periods representing 1994 to 2014 for Scenario 2 
conditions. Water level elevation on vertical scale with the days on the 
horizontal scale. .............................................................................................. 51 
Figure 27. Selected stress periode draw down (meter below initial heads) results 
from Scenario 2 of the model. ......................................................................... 52 
Figure 28. Correlation between observed (dotted line) and modeled water levels 
(solid lines) for the 40 stress periods representing 1994 to 2014 for Scenario 3 
conditions. Water level elevation on vertical scale with the days on the 
horizontal scale. .............................................................................................. 53 
Figure 29. Selected stress periode draw down (meter below initial heads) results 
from Scenario 3 of the model. ......................................................................... 54 
Figure 30. Correlation between observed (dotted line) and modeled water levels 
(solid lines) for the 40 stress periods representing 1994 to 2014 for Scenario 4 
conditions. Water level elevation on vertical scale with the days on the 
horizontal scale. .............................................................................................. 55 
Figure 31. Selected stress periode draw down (meter below initial heads) results 
from Scenario 4 of the model. ......................................................................... 56 
Figure 32. Roles and responsibilities of the different water institutions. ................. 69 
Figure 33. Risk areas based on water level declination data over the area. .......... 75 
 
 ix 
LIST OF TABLES 
 
Table 1. Action and reactions following the problems experienced at Tosca: ...... 1 
Table 2. Increase in irrigation areas and volumes. ............................................... 8 
Table 3. Stratigraphy and litho logical explanation. .............................................. 9 
Table 4. Groundwater qualities for Resource Units 1-3. (Godfrey 2002) ............ 17 
Table 5. Calculated recharge figures as a percentage of MAP from deductions 
and recharge tools. ......................................................................................... 20 
Table 6. Assumptions when using the CMB method in the Tosca Molopo dolomite 
aquifer. ............................................................................................................ 21 
Table 7. Recharge figures as calculated by different values of Cl in precipitation. 
The harmonic mean at Cl precipitation of 1.5% of MAP or 5.7 mm /a is 
representative. ................................................................................................ 21 
Table 8. Calculated recharge figures using CMB in different resource units. ..... 23 
Table 9. Results of age determination from selected boreholes as from 
Duvenhage and Meyer, (1991). ...................................................................... 24 
Table 10. Analysis of boreholes sampled during 1998 by CSIR (Talma). .............. 25 
Table 11. Recalculated Mean residence times (MRT) of groundwater. .................. 26 
Table 12. Isotope analysis from selected boreholes and precipitation in the study 
area. ............................................................................................................... 27 
Table 13. Determination of the groundwater component of the Reserve. ......... 29 
Table 14. Present Status Category and Desired Management Class ............... 30 
Table 15. Representative boreholes across the aquifer to indicate water level 
movement. ...................................................................................................... 31 
Table 16. Borehole information of drilled boreholes (Oct 2003 to March 2004) to 
confirm aquifer boundaries. ............................................................................ 36 
Table 17. Calculated transmissivity, storativity and yield values from controlled 
aquifer tests. ................................................................................................... 37 
Table 18. Transmissivity and storativity in zones of layer 1. ............................. 39 
Table 19. Transmissivity and storativity in zones of layer 2. ............................. 40 
Table 20. Recharge to the different zones as calculated from the summer and 
winter precipitation (182 days) in m3/day. ....................................................... 43 
Table 21. (Next page) Estimated water abstraction from the aquifer for each 
half-year m3/day. ............................................................................................. 44 
Table 22. Scenario predictions and management decision from the groundwater 
model. ............................................................................................................. 57 
Table 23. Estimated potential income form irrigation of the crops in the Tosca 
area compared to stock. ................................................................................. 59 
Table 24. Suggested actions against users following section 35 verification. ........ 62 
Table 25. General authorization on license applications and its effect. .................. 63 
Table 26. Authorized user with registered volume and the volume restricted. ....... 65 
Table 27. Water users exceeding water entitlement during 04/05 season. ............ 70 
 
 x 
 
LIST OF PLATES 
 
Plate 1. The Molopo River as seen from the farm Blackheath after precipitation in 
November 2001 and the same river after drought in November 2004. .............. 4 
Plate 2. A spring on the farm Nokani where groundwater well out in reaction to the 
barrier created by the Quarreefontein dyke. On the other side groundwater 
levels are deeper than 10 m below surface and further north they decline to 85 
m below surface. ............................................................................................. 35 
Plate 3. Abstraction points on 2 farms from the same fracture complex separated 
only by the farm boundaries. ........................................................................... 58 
Plate 4. Carting of water and re-drilling of a dried up borehole on the farm 
Quarreefontein after the water level declined an estimated 60 m due to 
proximate irrigation abstraction. ...................................................................... 60 
Plate 5. Removal of pump equipment from borehole. ............................................ 71 
Plate 6. Sealed borehole to enforce compliance. ................................................... 71 
 
 xi 
1. INTRODUCTION 
 
During the later half of the decade 1990 rapid development of irrigation from groundwater 
resources in dolomite aquifers took place in the Tosca Molopo area. Abstractions from these 
resources lead to significant decline in water levels. The purpose of this study was to 
investigate the impact of irrigation on the resource and managing the resource. This thesis is 
to report on the resource status in terms of use, impact and sustainable potential. The 
strategies and activities aimed at qualification, quantification of the impact, determination and 
regulating of the water use and assurance of sustainable future use are discussed.  The 
activities included: 
 
• Physiograpical description of the aquifer and associated structures. 
 
• Determination of the extent of irrigation and estimation of volumes irrigated. 
 
• Analysis of spatial and temporal variation in groundwater levels and qualities. 
 
• Determine mechanism and estimate recharge to the aquifer. 
 
• Numerical groundwater flow modeling aimed at testing of abstraction scenarios and 
management options for the resource. 
 
• Creation of management structures and capacitating of the users of the resource. 
 
• Regulation of the resource by implementation of the NWA. 
 
 
Table 1. Action and reactions following the problems experienced at Tosca: 
Date Event Comment 
1990 Exploration and assessment of the resource by CSIR contracted by Classify the resource as high yielding 
DWAF with limited potential due to low recharge 
1993 First concerns voiced by individuals in the community (Letter to Explanation of local nature of abstraction 
Minister) 
1994 Information session with community regarding the implications of Divided community and with no legal 
the NWA mechanism due to private ownership of 
groundwater 
1996 First estimation of extend of irrigation in the area (surface irrigated, No investigation regarding the status of 
volume abstracted) the resource 
2000 Registration of water use At meeting interest to establish Water 
User association 
2001 Jan Establish pilot steering committee for WUA establishment Was an initiative of the Local Farmers 
union 
2001 Unified voice of concerns by individuals and groupings in the Commitment from DWAF to address the 
community (Letters to Minister) problem in cooperation with the users. 
2001 First monitoring of groundwater levels to establish status of Measure approximately 10 to 20 m 
April resource regional water level decline and 60 m 
local 
2001 Aug Discuss depleted status of resource with water users Status of resource alarming with regional 
de-watering evident 
2001 Larger community expressing concern regarding the resource Commitment from DWAF to address the 
 1 
Sept unified (Number of letters of concern) problem in cooperation with the users. 
2002 Jan Number of meetings to establish the WUA Wide interest and cries for progress to 
to June manage the resource 
2002 Jun Completed report on the potential of the resource by CSIR Estimated that the resource is over 
allocated by more than 100 % 
2002 Aug Land GPS survey of irrigated areas by Geomatics When checked with office GIS it was 
found to correlate 90 to 100 % with GPS 
survey. 
2002 Aug Complete verification process of users by Satellite images 15 Potentially unauthorized users 
identified 
2002 Oct  Commence with Section 35 process  15 Potentially unauthorized users 
requested to motivate their legality. 8 
produce info to indicate that they should 
be authorized 
2002 Aug Geophysical investigation to confirm aquifer boundaries Boundaries confirmed with slight spatial 
corrections to be made 
2002 Dec Submit draft WUA constitution for approval to head office Numerous requests followed and 
proposed required needs for approval to 
be met 
2003 Jan  Directives issued against 7 illegal users To stop or reduce irrigation activities by 
March 2003 
2003 Mar Field inspections and communication confirm limited co-operation. Will have to enforce directives 
2003 Mar Discuss and get user cooperation to implement a 40 % restrictions Mixed reactions to intended restrictions 
on legal water use 
2003 Sep Commence with implementation of restrictions on voluntary basis Authorized users reluctant to comply 
2003 Sep Commence with exploration drilling to confirm boundaries and Boundaries confirmed 
extend monitoring network 
2003 Sep Confirm cooperation of unauthorized 7 users, only 3 users Commence with civil prosecution of these 
contravening directives issues against them 3 users 
2003 Oct Three users charges with using water unauthorized from the Tosca Charged through SAPD. SAPD does not 
Molopo aquifer seem interested to prosecute 
2004 Feb Meeting with water users to discuss alterations to the WUA draft Users in agreement with model. Users 
constitution, CMA establishment and discuss projections from the questioning how new use was authorized 
groundwater model. All new water use applications tabled and their 
authorization discussed. 
2004 Mar Publication of revised General Authorizations whereby no GA In father all irrigation use to be licensed 
applicable to catchments of the Tosca Molopo aquifer 
2004 Jun Approval of the WUA by the minister Publication of establishment in the 
Government Gazette 
2004 Sep Approval for water restrictions To be published in Government Gazette 
2004 Oct Publication of 40% water restrictions in Government Gazette  
2004 Dec Establishment meeting and election of WUA management Committee expressing need for DWAF 
committee assistance irt directives, crop planning, 
financial, capacity 
2004 Dec On request from WUA DWAF issue 6 directives for unauthorised  
use 
2005 Mar 6 monthly water level and use monitoring. Inspections reveal that 2 Region and HO plan to enforce 
users complied satisfactory to directives by reducing use. conditions of directives by: Gain access 
to property, Remove pump installations 
from boreholes, seal boreholes 
2005 Apr Letters to gain access to property week of 16 May 2005 issued Resistance from non complying water 
users 
2005 May Enforce water use compliance  Compliance successfully enforced 
 
 2 
2. PHYSIOGRAPHICAL DESCRIPTION 
2.1.  Location 
The Tosca Molopo area is located on in the border between South Africa and Botswana 150 
km north of Vryburg (Figure 1). A tarred road connects Tosca to Vryburg while a network of 
secondary to tertiary roads serves the local communities transportation needs. 
(a) 
-25.70
Vergelee
-25.80
Tosca
-25.90
-25.70
-25.80
-25.90
-26.00
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40
Study area
-26.00
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 24.50 (b) 
Figure 1. Location of the study area; (a) as located in the Lower Vaal Water management area and 
(b) showing major centers, roads, dry river beds, irrigation areas and surface elevation 
contours (mamsl). 
 3 
Vryburg
2.2.  Topography and drainage 
The area of interest is characterized by a flat topography. The surface elevation contours are 
indicated in Figure 1. From the watershed in the east at 1210 m the elevation gradually 
decline to 1070 m in the west over a distance of 60 km. The only topographical features being 
the Waterberge rising 50 m above the plain to the north and a number of non-perennial 
riverbeds. These rivers are the Thlagameng, Vals, Doring, Wildebeesthoring and Molopo. 
Although insignificant as surface water resources they play a major role in groundwater 
recharge.  
 
 
Plate 1. The Molopo River as seen from the farm Blackheath after precipitation in November 2001 and the same 
river after drought in November 2004. 
 4 
The Molopo River is an ephemeral river that used to flow after heavy rainfall events, however 
the building of dams (Disaneng and recently the Setumo) upstream has impeded river flow.  
Although no official gauging station exists on the river, it is reported that before 1980 runoff 
only occurred every 2-3 years.  Since 1980 flow in this section of the Molopo River only 
occurred 5 times, after severe heavy precipitation in 1988, ’91, ’96, 2000 and 2001. Plate 1 
indicate lush grass growth in the river bed after precipitation and little plant cover after dry 
periodes. 
2.3.  Climate and precipitation 
The study area is characterised by a low annual rainfall, varying between 107 – 928 mm/a. 
The calculated average rainfall is 385 mm/a (average of Pomfret [station 0504050X] and 
Vergelegen [station 0505347 6] records). Precipitation is erratic with the standard deviation 
from the mean 153 mm/a. Approximately 85% of the rain occurs during the summer months 
of October to March. 
Evaporation in the area is high, between 2050 – 2250 mm/a (WRC, 1994).  As such only a 
small percentage of rainwater is available to recharge groundwater.  
Historical records of annual rainfall are shown in Figure 2. The precipitation since ‘99/00 
season was measured as above average at the Pomfret station. Over the same period the 
precipitation at Vergelegen was measured below the average. It is noted that precipitation 
measurements at Pomfret was automated during 1991 while hand measurements are still 
taken at Vergelegen. 
 5 
Annual Precipitation at Pomfret    JUN   
   MAY   
800
   APR   
700
   MAR   
600
500    FEB   
400    JAN   
300    DEC 
200    NOV   
100    OCT   
0    SEP   
   AUG   
Hidrological Year
   JUL   
 
Figure 2. Precipitation as measured at rainfall stations Pomfret and Vergelegen. 
2.4. Soil and vegetation 
White calcium enriched soils are predominant in the east while red-brown iron enriched soils 
occur toward the west.  
The low rainfall in the Molopo district results in semi-arid conditions, characterized by tropical 
bush and savanna types (Bushveld) vegetation. Acacia species are predominant with the 
distinctive tree species the Camel thorn (Acacia Erioloba). A number of grass species cover 
the areas between bush and tree. 
 6 
precipitation (mm)
60/61
61/62
62/63
63/64
64/65
65/66
66/67
67/68
68/69
69/70
70/71
71/72
72/73
73/74
74/75
75/76
76/77
77/78
78/79
79/80
80/81
81/82
82/83
83/84
84/85
85/86
86/87
87/88
88/89
89/90
90/91
91/92
92/93
93/94
94/95
95/96
96/97
97/98
98/99
99/00
00/01
01/02
02/03
2.5. Land use 
 
The main economic activity within the area is agriculturally based. The Tosca Vergelegen 
area was historically a stock farming area with cattle farming and more recently game 
farming. The grazing capacity of the area is reported at 10 ha per large stock unit. At 400 000 
ha the stock capacity of the area of interest is 40 000 large stock units.  
Since 1990 rapid development of irrigation transformed the socio-economic and 
environmental prospects in the area. By 2002 it was estimated from registration of irrigation, 
satellite images, surveys and reports from farmers that approximately 2000 ha were irrigated 
consuming 18.9 million m3 of water. The crops irrigated as illustrated in Figure 3 are corn 
(41%), paprika (19%), peanuts and wheat (30%) and potatoes and alfalfa (10%).  
Lucern
8%
Wheat
14%
Maize
Potatoes 41%
3%
Paprika
19%
Peanuts
15%
 
Figure 3. Graphical illustration of crops irrigated. 
2.6. Water use 
 
Groundwater is the sole source of water for both agricultural and domestic requirements.  The 
water use of stock, domestic and other activities is negligible if compared to irrigation. The 
other uses are only 0.5 % of the total use with irrigation use responsible for 99.5 % of the total 
use. As such irrigation farming has placed a considerable strain on the dolomite aquifer. 
A combination of factors led to the development of the resource for irrigation purposes. 
During 1990 the CSIR explored the resource and the resource was characterized as high 
yielding. Quality and Isotope samples taken from the water at the time did however flag the 
sustainability of the resources characterizing some of the water as fossil water.  Reacting on 
half the recommendation farmers started developing irrigation with high yields and increased 
income in mind.  
Table 2 indicates the rapid rate at which irrigation development took place. 
 7 
 
Table 2. Increase in irrigation areas and volumes. 
Year 1990 1996 2000 2001 2002 
Irrigation systems 2 22 32 40 45 
Irrigation area (ha) 100 600 1182 1495 2000 
Volume Irrigated (Mm3/a) 0.77 4.6 9.1 11.1 18.9# 
Stock watering (Mm3/a) 0.5 0.5 0.5 0.5 0.5 
Human consumption (Mm3/a) 0.5 0.5 0.5 0.5 0.5 
Total (Mm3/a) 1.8 5.6 10.1 12.1 19 
All volumes estimated at 7500m3/ha/annum. 
#Estimated after crop factors for the different crops used. 
 
Other factors contributing to the development of irrigation was the completion of the tarred 
road by 1994, the availability of electricity by 1995, the availability of high yielding pump and 
irrigation systems, unfavorable climatic and economic conditions for dry land cultivation, 
favorable prices and profit generated by crops and the knowledge to apply the technology.  
 8 
3. GEOLOGY 
3.1. Regional Geology 
The stratigraphic succession of the area is given in Table 3 (SACS, 1980).  The sub-outcrop 
geology is shown in Figure 4. Although almost the total area is covered by the Kalahari Group 
it is mapped only where its thickness exceed 15 m. 
Table 3. Stratigraphy and litho logical explanation. 
Sequence Group Formation Description 
Gordonia Red brown aeolian sand 
  Eden Calcareous sandstone and clay Kalahari Budin Red clay 
Wessels Sandstone and gravels 
Post Karoo   Dolerite dykes and sills 
 Makganyene Diamictite 
Griquatown Asbestos Hills Banded ironstone, including jaspilite and 
Griqualand West chert 
Campbell Ghaap Plateau Dolomite chert limestone Schmidtsdrift Dolomite and shale 
 Vryburg Quartzite 
Archaean   Granite 
 
D' A'
-25.70 C
RU1 Vergelee
G47610
-25.80 B' G476143 D
Tosca Legend
G476121 G47604
G4760 C Dolerite dyke-25.90 RU3 G476056G47607 RU2G47615 Kalahari sediments
G476089 Banded Ironstone 
-25.70
-25.80
-25.90
-26.00
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40
-26.00 A B Study area
Dolomite
Quartzite
Granite
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 24.50  
Figure 4. Geology of the Tosca area with the major economical centers, roads, dry riverbeds, 
irrigation areas (blue circles) and surface elevation contours (mamsl). The resource 
units RU1, RU2, RU3 is divided by the red dot line. 
3.2. Local Geology 
The full geological succession given in Table 3 is represented within the study area.  The 
Archaean granites form the basement of the area, outcropping to the south of the study area. 
The granites are overlain by quartzites of the Vryburg formation, which reach thickness of 
 9 
only tens of meters. The dolomites of the Campbell Group reach thickness of 900-1650 m 
and are a significant water bearing formation.  The dolomites are overlain in the north of the 
study area, by banded ironstone of the Asbestos Hills formation. Intruded into these rocks are 
dolerite sills and dykes. This package of rocks dips at approximately 10° into a northwesterly 
direction.  Large north-south trending faults are present within the area. 
An era of intense weathering and erosion followed the deposition of these formations, carving 
a northeast trending U-shaped valley into the dolomite. The thickness of the valley increases 
towards the Molopo River where a depth in excess of 150 meters is reached.  This valley is 
filled with sediments of the Kalahari Group.  At the base of the valley gravels and sandstones 
of the Wessels formation were deposited.  These gravels are poorly sorted and range in size 
from less than 1 mm to 25 mm.  On top of the gravels red-brown clay of the Budin formation 
were deposited, followed by fine-grained sandstone of the Eden formation.  The sequence is 
covered by red-brown Aeolian sand, which covers most of the area.  The thickness of 
Kalahari Group varies across the area from less than 15 m near the dolomite and granites 
outcrops in the west, to up to 150 m of thickness to the northeast of Vergeleë, in proximity to 
the Molopo river (Figure 4). 
Along the Molopo River and tributaries, very recent river deposits are present.  The channel 
of the Molopo River meandered within a 4 km wide band from the present channel to build up 
a riverbed deposit up to 30 m in depth.  These deposits consist of gravels of 1 to 10 mm, 
sandbars and fine-grained sand and to a lesser extend silt. 
3.3. Structural Geology 
The most prominent structural controlling event is the presence of the now generally 
accepted Morokweng Impact Structure to the south. (See Figure 5). This impact structure 
formed when a meteorite penetrated this earth’s atmosphere and crashed into the earths 
crust. As a result of this Impact structure lineament are developed radially around this 
structure. These lineaments are faults that can be intruded by dolerite material and are 
aligned NE SW in the Tosca area. The host rock is fractured and weathered along these 
faults and dolerites. Due to the nature of dolomite rock solution of rock material can lead to 
the formation of cavities. 
Although the total hard rock package dip at 10° northwest large folds could change the dip of 
rocks locally. 
 
 10 
 
Figure 5. Regional geology of the Tosca area taken from SUB-KALAHARI GEOLOGICAL MAP by 
IG HADDON 2001.  
 11 
4. HYDROGEOLOGY 
4.1. Aquifer yield 
The dolomite aquifer present in the Tosca area was characterized during the DWAF 
1:500000 mapping program. This characterization was based on data captured till 1990 
when water use in the area was limited to stock watering. From this information it is 
evident that more than 13% of successful boreholes yielded more that 5 l/s which would 
theoretically be needed for irrigation. (Figure 6) 
Since high yielding boreholes to irrigate from became the objective a number of boreholes 
were sited and drilled. Advanced geophysical technology to locate fractures in depth and 
advanced drilling technology to drill holes through carstic formations to depth was used. 
The percentage of high yielding boreholes drilled therefore increased dramatically. 
In contrast most boreholes in the Kalahari sediments yield less than 2 l/s. 
YIELD FREQUENCIES OF BOREHOLES IN THE GHAAP GROUP
(1324 BOREHOLES ANALYSED)
(888 dry boreholes ommitted)
100
90
80
70
60
50
40
30
20
10
0
0.0-0.1 0.1-0.5 0.5-2.0 2.0-5.0 >5.0
yield in l/s
a)
YIELD FREQUENCIES OF BOREHOLES IN THE KALAHARI GROUP
(1735 BOREHOLES ANALYSED)
(1081 dry boreholes ommitted)
100
90
80
70
60
50
40
30
20
10
0
0.0-0.1 0.1-0.5 0.5-2.0 2.0-5.0 >5.0
yield in l/s
b) 
Figure 6. Yield frequency of boreholes in the a) Ghaap dolomite and b) Kalahari sediments groups. 
 12 
PERCENTAGE PERCENTAGE
O rigin of groundwater in the Tosca Molopo Dolomite Aquifer. 
T here is the perception that water in this aquifer originates from the Okavango Delta, the 
K uruman spring or the Molopo spring. To date no scientific evidence could support these 
t heories and the following facts are listed to indicate why these water bodies cannot be 
c onnected to the Tosca Molopo aquifer: 
 • The Tosca Molopo Dolomite Aquifer is located at an elevation of between 1150 and 
 1000 mamsl. The Okatanga Delta is located at elevation 950 mamsl, the Kuruman 
 spring at 1410 mamsl and the Molopo spring at 1430 mamsl.  
 
 • Water from the other water bodies drain away from the Tosca Molopo aquifer with the 
 Kuruman spring draining northwest, the Okavango southwest and the Molopo spring  west. 
 
 • The Distance between this area and these water bodies is 700, 200 and 200 km 
 respectively. 
 • Numerous Geological boundaries like different rock units, faults, dykes, impermeable 
 layers (a number visible in Figure 6) transect the areas between these water bodies. 
 • The water quality is different in nature with the Tosca Molopo electrical conductivity at 
 50 to 200 mS/m, the deeper Okavango delta aquifers generally exceeding 300 mS/m, 
 and the Kuruman and Molopo springs fresh at less than 50 mS/m. 
 • The Isotope character of the water is different. 
 
 
4.2. Resource units 
Three Resource Units (RUs) are defined within the Tosca Molopo dolomite aquifer, identified 
from the observed aquifer characteristics, from drilling logs, water level response, aquifer 
tests and the presence of regional dolerite dykes, which divide the area into 3 major 
compartments (Godfrey 2002) (Figure 4).  These include: 
RU 1 – Tosca dolomite aquifer 
RU 2 – Dolomite aquifer, area of post Karoo dolerite intrusive (dyke swarms)  
RU 3 – Pomfret dolomite aquifer 
These resource units are overlain by, low yielding, Kalahari sand aquifer. It is only used 
extensively close to the Molopo River due to the good quality water available above the Budin 
clay formation. Away from the river very little groundwater is available in this formation. 
Within the three identified Resource Units (RU1-3), smaller geohydrological response units 
exist. They are typically formed by the intrusion of dolerite into the dolomite aquifer forming 
small compartments, which may act as isolated units.  Where possible, reference is made to 
these response units. 
 
 13 
4.3. Groundwater levels 
Regional water level records for 2 periods (1977 and 1990) were available to assess the 
reference conditions of the groundwater resource within the eastern part of the Molopo 
dolomite aquifer (RU1 and RU2).  During the 2 years prior to the 1974 hydro census, 
investigations in the area provided a data set of water levels (mamsl) (Figure 7(a)). 
During 1990 a similar hydro census was conducted where 351 boreholes were located 
(Duvenhage & Meyer, 1991).  Water level measurements were possible at 198 boreholes.  
The water levels in the northwest vary from 5 to 10m below surface, gradually deepening to 
50 and 60 m to the northeast at the Molopo River (Figure 7(b)). 
25.60
1180
1160
25.70
Vergelee Vergelee 1140
25.80 1120
Tosca Tosca 1100
25.90 1080
1060
26.00 1040
1020
26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 1000
 
Figure 7. Groundwater level elevation contours (mamsl) (1977 (a) left and 1990 (b) right). 
To assess how representative the water levels for 1977 and 1990 are as reference 
conditions, the precipitation for those years was compared with the average.  It is evident that 
the pre-1974 water levels were measured in a period of average to below average rainfall 
(Figure 2) while the 1990 water levels were measured following high rainfalls in 1988.   
Only minor changes in groundwater levels are evident between 1977 and 1990.  The most 
striking being elevated water levels along the Molopo River and elevated water levels along 
the dyke swarms parallel to the Quarreefontein dyke.  As such the groundwater levels in 1990 
are still considered to be unimpacted, reference conditions.  From both maps (Figure 7) the 
northeast gradient of groundwater levels towards the Molopo River is evident with the dyke 
swarms possibly impeding groundwater flow from the south and southwest. From the existing 
declined water levels it is possible to delineate the aquifer into at least 3 distinctive resource 
units. These are illustrated in Figure 4 and 11. 
 
 14 
4.3.1. Resource Unit 1 
This resource unit is the area north of the Quarreefontein dyke and east of the Grassbank 
dyke Figure (4 and 11). To date there is no evidence that this resource unit is sub divided in 
more compartments, as the water levels do not indicate that. In this area the thickness of the 
Kalahari sediments is generally more than the depth of the water level therefore effectively 
connecting the total area. Even with the declined water levels no separate compartments 
could be identified. 
4.3.2. Resource Unit 2 
This resource unit is separated from resource unit 1 by the Quarreefontein dyke to its north. 
Numerous dyke swarms intrude the dolomite of this area. The Kalahari sediments are thin at 
approximately less than 15 m with the water level below this depth. This effectively divides 
the area into numerous different compartments.  
4.3.2. Resource Unit 3 
Resource Unit 3 represents the Pomfret dolomite aquifer and overlying banded ironstone 
formation.  Groundwater is encountered within the banded ironstones, the dolomite/shale 
contact and within fractures, brecciation zones and solution cavities within the dolomites. 
The dolomite aquifer in the region of Pomfret is characterized by at least 13 compartments, 
bounded by dolerite dykes (van Dyk, 1993).  Very little information on the reference 
conditions of water levels within these compartments is available.  Different piezometric water 
levels are encountered in the three different aquifers in this RU.  Water levels in the banded 
ironstone aquifer vary between 30-60m; water levels in the dolomite/shale transition zone 
vary between 40-70m while the water levels in the dolomite aquifer vary between 10-30m 
below surface. 
As in the Tosca aquifer, the gradients of groundwater levels are towards the Molopo River, 
however the abstraction of groundwater from compartments 3 and 5 has resulted in a 
groundwater sink to the east of Pomfret. (van Dyk, 2003) 
4.3.3. The primary sandy aquifer of Kalahari layers 
This aquifer cannot be classified as a separate resource unit. It is the shallow, Kalahari 
aquifer, which overlies the Molopo dolomite aquifer.  The thickness of the Kalahari sands 
varies from less than 5 m in the southwest of the study area to as much as 150 m in the 
northeast, adjacent to the Molopo river, as indicated in Figure 4.  From the regional decline in 
the water level, abstractions from the underlying dolomites have resulted in water levels 
 15 
declining 10 to 20 m.  Boreholes, which penetrate the Budin formation into the underlying, 
Wessels gravels (high yielding) are impacted upon by changes in water levels in the 
underlying dolomite aquifer. 
The groundwater level in proximity to the Molopo River is approximately 50 mbgl. Away from 
the river water levels increase to between 70-90 mbgl. Since extensive abstraction 
commenced, the water levels in the shallow Kalahari boreholes, away from the river, 
decreased by between 10 and 20 meters. 
The use of groundwater loggers logging water level data every hour at selected boreholes 
indicated a dynamic system with water levels reacting that to daily and seasonal influences. 
The graph in Figure 8 below from borehole G39793 proximate to the Molopo for 11 months 
indicate a seasonal variation of more than 10 meters in reaction to intensive abstraction for 
irrigation. The reaction when abstraction is stopped temporary during the time when levels 
are declining regionally is visible as temporary recovery of almost 2 m. Water level reactions 
of less than 10 cm is visible. 
-60
29-Nov-01 29-Dec-01 29-Jan-02 28-Feb-02 29-Mar-02 29-Apr-02 29-May-02 29-Jun-02 29-Jul-02 29-Aug-02 29-Sep-02 29-Oct-02
-62
-64
-66
-68 Intensive irrigation Intensive irrigation 
commence w ith declining commence w ith 
-70 w aterlevels declining w aterlevels
-72
Recharge to groundw ater by 
-74 Abstraction ceeced after preceding precipitation
precipitation w ith temporary 
-76 recovery of w ater levels
Intensive irrigation ceased w ith 
-78 recovery of groundw ater level
Water level below  range of logger
-80
Time
 
Figure 8. Groundwater level reaction in borehole G39793 in response to abstraction and recharge. 
 16 
waterlevel depth (mbg)
4.4. Groundwater quality 
Groundwater quality data from the DWAF NGDB, for 316 samples is available for the study 
area.  A summary of groundwater quality per Resource Unit is given in Table 4.   
Table 4. Groundwater qualities for Resource Units 1-3. (Godfrey 2002) 
Chemical  Resource Unit  (SABS 241:1999) 
Parameter RU 1 RU 2 RU 3  Class 0 Class I  Class II 
pH  7.3 - 7.8 - 8.3 7.3 - 7.7 - 8.4 7.2 - 7.7 - 8.4  6 – 9 5 – 9.5 4 - 10 
Electrical mS/m 
Conductivity  47 - 81 - 182 75 - 115 - 304 57 - 86 - 199 
 < 70 70 - 150 150 - 370 
Calcium as Ca  mg/l 10 - 66 - 112 28 - 76 - 191 23 - 72 - 165  < 80 80-150 150-300 
Magnesium as mg/l 
Mg 28 - 57 - 87 37 - 71 - 179 26 - 55 - 131 
 < 30 30-70 70-100 
Sodium as Na mg/l 11 - 34 - 105 27 - 73 - 332 8 - 30 - 120  < 100 100-200 200-400 
Total Alkalinity mg/l 128 - 310 - 439 140 - 299 - 452 142 - 284 - 430  - - - 
Chloride as Cl mg/l 19 - 62 - 348 40 - 163 - 714 17 - 58 - 314  < 100 100-200 200-600 
Sulphate as SO4 mg/l 4 - 11 - 61 7 - 38 - 199 4 - 53 - 151  < 200 200-400 400-600 
Nitrate as NOx mg/l 0.1 - 3.5 - 29 0.2 - 12 - 75 0.1 - 2.3 - 116     
*  Values given as the 5th – median – 9th percentiles 
It is evident from this summary that the groundwater of RU1 and RU3 are very similar in 
quality, generally low in total dissolved solids, while RU2 has an elevated salt content for all 
major cat ions and anions.  More saline, higher TDS, groundwaters are therefore associated 
with the east-west dolerite dykes, as one would expect from the difference in ages of the 
groundwater (Section 5.1).  The groundwater type varies considerably throughout the area 
from a Ca, Mg-HCO3 type water to an Mg, Na-Cl type.  The dominant cat ions are however 
Mg and Ca and dominant anions, HCO3 and Cl.  All groundwater quality samples have been 
plotted on the Piper Diagram (Figure 9), and show the spatial variation in groundwater quality 
within the study area, from low TDS waters typical of recharge areas, to high TDS 
groundwater.  
  
80 80 
 
 60 60 
40 40 
Recently 
20 20 
recharged 
groundwater 
Mg SO4 
80 80 
 60 60 
 
40 40 
 
20 20 
 
 80 60 40 20 20 40 60 80 
 Ca Na HCO Cl  
Figure 9. Piper diagram of groundwater quality of the Molopo dolomite aquifer. 
 17 
Elevated concentrations of F and NO3, often associated with pollution, are present in RU2 
and RU3.  The origin of the F could be from weathering of the dolerite intrusions or from the 
proximity to the granites. The elevated NO3 in these units with their shallow water levels may 
be the result of local pollution from human and animal excreta and fertilizer application or 
naturally reduced denitrification processes. Tredoux et al. (2003) name a number of 
parameters that could influence the denitrification process. These include temperature, pH, 
organic carbon, carbon: nitrogen ratio, oxygen content and redox potential, microbal activity, 
water content of soil, permeability and porosity, anthropogenic activity (i.e. ploughing) and 
other nutrients. In this area specifically the absence of organic carbon and low soil water 
content combined with high soil permeability / porosity with high soil oxygen content could 
inhibit denitrification with rapid infiltration during recharge. Therefore it is postulated that 
recharging water rich in nitrogen reach the aquifer. 
The borehole G39682 on the farm Grassbank has been sampled regularly as part of the 
National Groundwater Monitoring Program since 1996. The borehole was sampled 12 times 
during October and April aimed at before and after precipitation. During 1995 intensive 
irrigation proximate to the borehole commenced. The variation in selected chemical 
substances is compared with the initial concentrations when the borehole was completed in 
by 1991and graphically presented in Figure 10 a, b.  
There was a significant increase in the anions SO4 and Cl with a dramatic decrease in 
(NO3+NO2). The increase in SO4 can be attributed to sulfate containing fertilizers. Although 
these fertilizers also contain nitrogen this nitrogen did not reach the groundwater. The 
enhancement of the denitrification process through ploughing the fields to release oxygen 
from the soil, higher soil water content due to irrigation, the increase of SO4 through 
fertilization presence of organic carbon through cultivation enhanced microbal activity and 
therefore denitrification. Consequent recharge water to the aquifer is therefore with of lower 
nitrogen content.  
The cationes Na and Ca also increased significantly. The Na, Ca and Cl increase can be 
attributed to evapotranspiration enrichment in the soil and infiltration of these substances 
during recharge to the aquifer. The other substances were stable compared to the initial 
concentrations and their variation seasonally. 
 
 18 
a) 
b) 
Figure 10. G39682 Grassbank groundwater variation in selected chemical substances 
 
 19 
5. WATER BALANCE 
 
5.1. Groundwater recharge 
5.1.1. Indirect deductions from maps and recharge tools 
According to Vegter (WRC, 1995b), groundwater recharge within the catchment varies from 3 
to 12 mm per annum.  Recharge software developed by the Institute for Groundwater Studies 
(IGS) (van Tonder, 2000) was used to assess recharge for each of the resource units.  The 
software makes use of three recharge methods, the Chloride method (Bredenkamp et al., 
1995), Vegter’s Recharge map (WRC, 1995b) and the Harvest Potential map (DWAF, 1996).  
The results of each of these methods are given in Table 5. 
Table 5. Calculated recharge figures as a percentage of MAP from deductions and recharge tools. 
Resource Recharge (1) 
Unit [%/a of MAP] 
[mm/a of MAP] 
Cl Method Vegter Harvest 
Potential 
RU 1 0.13 – 9.2 0.75 – 3.0 6 – 53 
6.4 - 45 3.7 – 14.7 29.5 - 260 
RU 2 0.05 – 4.0 0.75 – 3.0 6 – 53 
0.3 – 19.5 3.7 – 14.7 29.5 - 260 
RU 3 0.20 – 7.2 0.81 – 3.2 6 – 57 
9.8 – 35.3 4 – 15.7 29.5 - 279 
(1) Rainfall figures for Vergelegen (399 mm/a) have been used for RU1 and RU2, while figures from Pomfret (371 mm/a) 
have been used for RU 3.  
 
5.1.2. Chloride Mass Balance (CMB) as a chemical tracer method 
The Chloride Mass Balance (CMB) method was identified as a suitable method more 
accurate recharge figures in South Africa (Bredenkamp et al., 1995) and its applicability to the 
study area was determined. As reported by van Tonder and Bean (2003) significant seasonal 
variation in the chloride content was measured for monthly composite rainfall samples. 
A composite rainfall sample for the period Oct 2001 to February 2003 was taken on the farm 
Forres proximate to Tosca with an uPVC rainwater collector (CSIR, Weaver). When analyzed 
a Chloride content of 1.4 mg/l was reported. This content was regarded as unrealistic due to 
possible chloride content increased by PVC and silicon oil (Adams, 2004). The value of 0.8 
mg/l that is more in line with proximate studies in Botswana (GRESS1,2 Beekman et. al. 
1996) was used. A rainfall collector (DWAF van Wyk) was erected on the farm Quarreefontein 
and would collect future rainfall to determine local rainfall Cl content. 
 20 
The recharge rates were calculated by using the Chloride Mass Balance (CMB) saturated 
zone ratio where the average chloride content in precipitation to that in groundwater is 
determined.  
The total recharge is estimated by using he equation: 
RT= TD 
Clgw 
Where: 
RT = total recharge (mm/a) 
TD =total deposition (mg/m2/a) 
Clgw =Cl content in groundwater (mg/l) 
 
The fundamental basis of the CMB method is that the water mass flux crossing the plane of 
the water table can be calculated if most of the assumptions prescribed in Table 6 below are 
met (Wood, 1999 and Adams. 2004). 
Table 6. Assumptions when using the CMB method in the Tosca Molopo dolomite aquifer. 
Chloride in groundwater originates only from precipitation (no measurable chloride mass from No 
overlying, underlying or adjacent aquifers and no measured surface water percolation) 
Chloride is conservative in the system Yes 
The chloride mass flux has not changed over time Unknown 
There is no recycling or concentration of chloride within the aquifer No 
No evaporation of groundwater occurs up gradient from the groundwater sampling points Yes in 
general 
The adsorption of chloride in soils and the vegetation uptake is considered negligible Yes 
Although not all the assumptions are met with expected inaccuracies in results the CMB is 
still considered a suitable method for first approximation of recharge. The results of these 
calculations are included as Table 7.  
Table 7. Recharge figures as calculated by different values of Cl in precipitation. The harmonic mean 
at Cl precipitation of 1.5% of MAP or 5.7 mm /a is representative. 
  [Cl]gw  [Cl]p = 0.9 [Cl]p = 0.9 [Cl]p= 0.8 [Cl]p= 0.8 [Cl]p=1.0 [Cl]p=1.0 Re = P*[Cl]p / [Cl]gw   
Farm name (mg/l) Re(385 mm) Re(400) Re(385) Re(400) Re(385) Re(400) P = precipitation (mm/a)   
Albury 33 10.5 10.9 9.3 9.7 11.7 12.1 [Cl]p=concentration Cl in rainwater (mg/l) 
Ascott 155 2.2 2.3 2.0 2.1 2.5 2.6 [Cl]p=concentration Cl in groundwater (mg/l) 
Ascott 467 0.7 0.8 0.7 0.7 0.8 0.9  Re= recharge (mm/a)     
Brentwood 44 7.9 8.2 7.0 7.3 8.8 9.1    
Buttermere 464 0.7 0.8 0.7 0.7 0.8 0.9    
Blackheath 28 12.4 12.9 11.0 11.4 13.8 14.3    
Birkdale 184 1.9 2.0 1.7 1.7 2.1 2.2    
Buxton 194 1.8 1.9 1.6 1.6 2.0 2.1    
Belvidere 46 7.5 7.8 6.7 7.0 8.4 8.7    
Belvidere 288 1.2 1.3 1.1 1.1 1.3 1.4    
Bees Wood 39 8.9 9.2 7.9 8.2 9.9 10.3    
Bees Wood 171 2.0 2.1 1.8 1.9 2.3 2.3    
Brenton 87 4.0 4.1 3.5 3.7 4.4 4.6    
Birnam Wood 39 8.9 9.2 7.9 8.2 9.9 10.3    
Bradbury 193 1.8 1.9 1.6 1.7 2.0 2.1    
Clearstream 35 9.9 10.3 8.8 9.1 11.0 11.4    
 21 
Clearstream 134 2.6 2.7 2.3 2.4 2.9 3.0    
Exeter 57 6.1 6.3 5.4 5.6 6.8 7.0    
Eden 118 2.9 3.1 2.6 2.7 3.3 3.4    
Elchester 548 0.6 0.7 0.6 0.6 0.7 0.7    
Elchester 1126 0.3 0.3 0.3 0.3 0.3 0.4    
Forest hall 26 13.3 13.8 11.8 12.3 14.8 15.4    
Forres 1 43 8.1 8.4 7.2 7.4 9.0 9.3    
Forres 2 184 1.9 2.0 1.7 1.7 2.1 2.2    
Geesdrif 131 2.6 2.7 2.4 2.4 2.9 3.1    
Gannalaagte 45 7.7 8.0 6.8 7.1 8.6 8.9    
Hou moed 26 13.3 13.8 11.8 12.3 14.8 15.4    
Hurst Park 29 11.9 12.4 10.6 11.0 13.3 13.8    
Harcourt 25 13.9 14.4 12.3 12.8 15.4 16.0    
Harcourt 288 1.2 1.3 1.1 1.1 1.3 1.4    
Knysna 84 4.1 4.3 3.7 3.8 4.6 4.8    
Kokomeng 106 3.3 3.4 2.9 3.0 3.6 3.8    
Kameeldoorns 93 3.7 3.9 3.3 3.4 4.1 4.3    
Langedraai 11 31.5 32.7 28.0 29.1 35.0 36.4    
Langedraai 532 0.7 0.7 0.6 0.6 0.7 0.8    
Mositlane 139 2.5 2.6 2.2 2.3 2.8 2.9    
Mositlane 774 0.4 0.5 0.4 0.4 0.5 0.5    
Marstone 491 0.7 0.7 0.6 0.7 0.8 0.8    
Marlborough 35 9.9 10.3 8.8 9.1 11.0 11.4    
Weltevrede 251 1.4 1.4 1.2 1.3 1.5 1.6    
Navarre 67 5.2 5.4 4.6 4.8 5.7 6.0    
New Barnet 51 6.8 7.1 6.0 6.3 7.5 7.8    
Knapdaar 76 4.6 4.7 4.1 4.2 5.1 5.3    
Paddapan 1347 0.3 0.3 0.2 0.2 0.3 0.3    
Paddapan 259 1.3 1.4 1.2 1.2 1.5 1.5    
Platbosbult 77 4.5 4.7 4.0 4.2 5.0 5.2    
Quareefontein 24 14.4 15.0 12.8 13.3 16.0 16.7    
Ravensbourne 37 9.4 9.7 8.3 8.6 10.4 10.8    
Redmonds hoek 70 5.0 5.1 4.4 4.6 5.5 5.7    
Rhodes 299 1.2 1.2 1.0 1.1 1.3 1.3    
Salamanca 167 2.1 2.2 1.8 1.9 2.3 2.4    
Salamanca 338 1.0 1.1 0.9 0.9 1.1 1.2    
Stretford 120 2.9 3.0 2.6 2.7 3.2 3.3    
Sandilands 31 11.2 11.6 9.9 10.3 12.4 12.9    
Thorntwaite 97 3.6 3.7 3.2 3.3 4.0 4.1    
Thornwick 155 2.2 2.3 2.0 2.1 2.5 2.6    
Thorncroft 19 18.2 18.9 16.2 16.8 20.3 21.1    
Vogelvry 39 8.9 9.2 7.9 8.2 9.9 10.3    
Vergelegen 62 5.6 5.8 5.0 5.2 6.2 6.5    
Vergelegen 336 1.0 1.1 0.9 1.0 1.1 1.2    
West End 202 1.7 1.8 1.5 1.6 1.9 2.0    
Wakefield 133 2.6 2.7 2.3 2.4 2.9 3.0    
Westward 27 12.8 13.3 11.4 11.9 14.3 14.8    
Zandvloed 155 2.2 2.3 2.0 2.1 2.5 2.6    
Sandvloed 132 2.6 2.7 2.3 2.4 2.9 3.0    
Average 185.9 5.5 5.7 4.9 5.1 6.1 6.4    
Harmonic mean 62.9 1.9 1.9 1.7 1.7 2.1 2.2    
A spatial plot of these results highlighted areas of higher recharge, as shown in Figure 11.  
These areas coincide with existing structural features, such as lineaments, outcrop areas and 
 22 
alluvial channels, likely areas of recharge.  The proposed recharge areas also coincide well 
with existing conceptual models and understanding of the dynamics of the dolomite aquifer.  
With this method recharge is calculated to be between 0.2 to 28 mm/a of MAP in the different 
areas of the aquifer. This harmonic mean for all groundwater analyzed is 1.7mm/a. This 
corresponds to 0.1 to 7.3% of MAP and a harmonic mean of 0.4%.To be more representative 
these figures were recalculated in resource unit context and the following recharge figures 
(Table 8) were obtained for each of the Resource Units. 
Table 8. Calculated recharge figures using CMB in different resource units. 
Percentage of Boreholes 
Resource Response % Recharge 
Unit Unit 5th – Median – 95th
< or > % Recharge 
  < 1% > 1% > 2% > 5% > 10% 
(i) 0.18 – 1.06 – 4.45 41.67 58.3 33.3 0.0 0.0 
RU 1 
(ii) 0.25 – 1.41 – 4.22 38.06 61.9 33.6 2.2 0.0 
RU 2 - 0.12 – 0.51 – 2.05 81.11 17.8 5.6 0.0 0.0 
(i) 0.54 – 1.70 – 4.94 26.32 73.7 44.7 5.3 0.0 
RU 3 
(ii) 0.26 – 0.93 – 4.89 52.38 47.6 31.0 4.8 0.0 
Average  1.12      
These recharge figures correspond well with those previously reported on by Smit (1977), 
who gave recharge figures in outcrop areas of 2.2 – 3.8%.  According to Smit, no recharge to 
groundwater occurs in areas where the thickness of the Kalahari sand is greater than 15m, 
due to the high evaporation.  In areas where the Kalahari is > 15m recharge to groundwater 
varies between 0.26 – 0.8%, with an average of 0.5% (Smit, 1977). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 11. Areas of highest recharge, based on Cl values for existing boreholes. (Godfrey 2002) 
Based on the results of the Chloride recharge method, the following areas of recharge to the 
dolomite aquifer are proposed (Figure 11): 
 23 
• Recharge through geological lineaments (generally faults, and less dykes) 
• Recharge through shallow outcrop and sub outcrop of dolomite (southwestern area) 
• Recharge through banded ironstone formation (northern border of study area). 
• Recharge through the alluvial channels of the Molopo River and tributaries. 
Figure 11 indicate these areas (in red) of highest recharge values, based on groundwater 
quality of existing boreholes. As such the demarcation of these high recharge areas are 
based on the presence of existing boreholes and may actually extend further that indicated. 
5.1.3. Stable and radioactive isotopes recharge determination methods 
5.1.3.1. Carbon 14 
Through groundwater age or mean residence times deductions can be made regarding 
recharge areas, recharge rates, groundwater flow as well as the identification of non 
renewable water resources (Beekman and Selaolo, 1997). These deductions must be made 
in combination with the existing geochemical conceptual model of the groundwater system. 
This method was utilized by Duvenhage and Meyer, (1991) in the Tosca Molopo area and the 
estimated ages in Table 9 were obtained. 
Table 9. Results of age determination from selected boreholes as from Duvenhage and Meyer, 
(1991). 
DATE Description of sample point LAT LONG 
FARM BOREHOLE sampled C14 MRT 
Water strike above Budin clay 
TENNANT PRIVATE 1991     89.3±0.8 <500 formation-recent water RU1 
25.85453 23.83918 N-S fault with high yield and GRASSBANK G39682 1991 80.5±0.5 490 good quality waterRU1 
Magma dyke contact with 
THORNTWAITE G39692 1991 -25.878 24.01894 44.7±0.6 5290 dolomite in RU2 
25.88783 23.99822 Magma dyke contact with KOKOMENG G39686 1991 28.5±0.3 8880 dolomite in RU2 
Water strike in deep primary 
LANGEDRAAI G39693 1991 -25.6741 24.14435 41.1±0.6 5930 aquifer at 150 m RU1 
They concluded that significant recharge along faults and along the Molopo and other river 
beds could take place due to the age determinations of groundwater, which indicated young 
waters, i.e. more recent recharge (< 500 years) associated with faults, and older water (> 
5000 years) associated with dykes (Duvenhage and Meyer, 1991). The conceptual model of 
significant recharge along faults, riverbeds and poor recharge along dykes and isolated 
compartments is supported by these age determinations. 
The nuclear bomb testing during 1952/53 added additional radiocarbons into the atmosphere. 
Carbon dioxide (CO2) from the air is trapped in rain and the water is tagged by atmospheric 
14C. This water infiltrates and is isolated from the atmosphere. The radioactive 14C gradually 
decay. Carbon 14 ages refer to the period of time elapsed since the water moved deep 
enough into the groundwater zone to be isolated from the atmosphere. 
 24 
Radioactive decay is expressed by: 
A = A0 e-1/τ 
Where: 
A = the specific activity of 14C 
A0 = the initial activity per unit mass of sample 
t = the decay age of the carbon isotopes (years) 
τ = mean half life of 14C (8270 years) 
t = -8270 ln (A/A0 ) 
Adams (2004) cited from Schwartz (1990) that the following processes could alter the 14C 
activity of groundwater: 
• Congruent dissolution of carbonate minerals, which add dead carbon or carbon without 
14C activity to the groundwater, effectively lowering the 14C activity. 
• Incongruent dissolution of carbonate or other Ca containing minerals accompanied by 
precipitation of calcite. This process will remove 14C as calcite precipitates and if 
dolomite is the mineral dissolving add dead carbon through this process. This process 
could occur in the zone of saturation following the rapid solution of calcite to 
equilibrium with subsequent precipitation as dolomite slowly dissolves. 
• The addition of dead carbon from other sources such as the oxidation of old organic 
matter, sulphate reduction and methanogenesis can reduce the 14C activity. 
• Isotopic exchange involving CO3 and carbonate minerals could lower the 14C activity. 
This process is generally considered to have a negligible effect at normal groundwater 
temperatures. 
The factors above need to be considered in radiocarbon dating and unrealistic high ages can 
be corrected geochemical models. 
During 1998 the CSIR (Talma, 1998) took 4 samples in similar areas than 1991 and the 
results are tabled in Table 10. 
Table 10. Analysis of boreholes sampled during 1998 by CSIR (Talma). 
DATE LAT LONG 
FARM BOREHOLE sampled  C14 TRITUIM C13 O18 Deut 
GRASSBANK G39682 19980206 25.85453 23.83918 78.2±0.6 1.5±0.2 -9.1 -4.86 -37.6 
KOKOMENG G39686 19980206 25.88783 23.99822 77.7±0.5 1.3±0.2 -9.7 -4.71 -34.5 
THORNTHWAITE G39665 19980206 25.87157 23.99882   1.0±0.2   -4.21 -28.5 
THORNTHWAITE NE4 19980206 25.87268 24.00167 70.8±0.4 0.7±0.2 -9.0 -5.07 -31.8 
Calculation and re calculation of previous analysis with the discussed theory and formulas 
resulted in the ages as determined in Table 11. 
 25 
Table 11. Recalculated Mean residence times (MRT) of groundwater. 
DATE Aquifer 
FARM BOREHOLE sampled A Q MRT 
Water strike above Budin clay 
TENNANT PRIVATE 1991 89.3 0.85 <500 formation-recent water RU1 
N-S fault with high yield and good 
quality waterRU1 Water level at approx 
GRASSBANK G39682 1991 80.5 0.85 450 25 m 
Magma dyke contact with dolomite in 
THORNTWAITE G39692 1991 44.7 0.85 5315 RU1 
Magma dyke contact with dolomite in 
KOKOMENG G39686 1991 28.5 0.85 9040 RU1 
Water strike in deep primary aquifer at 
LANGEDRAAI G39693 1991 41.1 0.85 6010 150 m RU1 
N-S fault with high yield and good 
quality waterRU1. Water level at approx 
GRASSBANK G39682 19980206 78.2 0.85 6900 60 m 
Magma dyke contact with dolomite in 
KOKOMENG G39686 19980206 77.7 0.85 740 RU2 
Magma dyke contact with dolomite in 
THORNTHWAITE NE4 19980206 70.8 0.85 1510 RU1 
In the Grassbank area groundwater of older estimated age seem to have entered the fault 
fracture system and characteristics of the previously regarded younger water now reflect an 
older age. The water level also declined dramatically in the fracture system. 
In the Kokomeng area previously older water now reflects a younger signature. This drastic 
difference can not be explained. The water level declined from 11 m to 15 m and precipitation 
during 1998 and previous years was above normal. The same happened in the Thorntwaite 
area. 
In general contrast with very old and very modern water could have been averaged out by the 
more dynamic system and mixing due to abstraction. The system could have been activated 
by abstraction with modern recharged water from the recharge area mixing with the older 
water in the generally northeast draining water. 
5.1.3.2. Stable isotopes -Oxygen 18 and Deuterium 
The stable isotopes deuterium and oxygen 18 can be used to differentiate if groundwater in 
the saturated zone recharged directly (fast) or was added indirectly (delayed). Table 12 
reflect the isotope composition of groundwater from selected boreholes and a bulk rainwater 
sample with a scatter plot of these values in Figure 12. The bulk rainwater sample was 
collected over the period Oct 01 to Feb 03. Like the Cl analysis from this precipitation sample 
the deuterium and oxygen 18 analyses also seem suspect. 
 26 
Table 12. Isotope analysis from selected boreholes and precipitation in the study area. 
δ  O18  δDeut Aquifer 
FARM BOREHOLE TRITUIM C13 (o/oo) (o/oo) 
N-S fault with high yield and 
GRASSBANK G39682 1.5±0.2 -9.1 -4.86 -37.6 good quality waterRU1 
Magma dyke contact with 
KOKOMENG G39686 1.3±0.2 -9.7 -4.71 -34.5 dolomite in RU1 
Magma dyke contact with 
THORNTHWAITE G39665 1.0±0.2   -4.21 -28.5 dolomite in RU1 
Magma dyke contact with 
THORNTHWAITE NE4 0.7±0.2 -9.0 -5.07 -31.8 dolomite in RU1 
Bulk precipitation Oct 01 to 
FORRES Precipitation     -1.88 -1.4 Feb 03 
0
-5 Precipitation Bulk Oct02 toFeb03
-10
-15
-20 y = 8x + 10GMWL
-25
-30 NE4 G39665 Intermediate zone
-35 G39686 Intermediate zone
-40 G39682 Recharge zone 
-45
-50
-10 -8 -6 -4 -2 0
Gamma 18O (o/oo)
 
Figure 12. Scatter plot of δD (o/ 18 ooo) vs δ O ( /oo) data.  
The global meteoric water line (GMWL) is the solid line. The bulk precipitation sample was 
collected during the period Oct 2001 to Feb 2003. With only one precipitation analysis no 
conclusions regarding the nature and variability of the isotope content of the precipitation can 
be made. No local meteoric water line (LMWL) can be determined.  
The slope of the line through groundwater δD (o/oo) vs δ18O (o/oo) scatter plot is > 6 and the 
negative values imply that a degree of the precipitation character took place before the water 
reached the saturated zone. Visually it is evident that infiltration in this area must be 
immediate as no surface water bodies, rivers or any other structure exist that can delay 
infiltration. The only exception is the Molopo River where water would be present for a few 
weeks after precipitation, which could enhance transpiration. The other mechanism that could 
delay recharge is evapotranspiration in the unsaturated zone. This process must be active 
and is supported by groundwater δD (o/oo) vs δ18O (o/oo) character to conclude (Smit, 1977) 
 27 
Gamma D (o/oo)
that in areas where the Kalahari thickness exceeds 15m, recharge to groundwater must be 
low. 
5.1.4. Cumulative rainfall departure (CRD). 
The CRD method is based on the premises that water level fluctuations are caused by rainfall 
events. (Beekman et al. 2004, Bredenkamp 1995). Data requirements for this method are 
monthly rainfall records, matching water level records for the rainfall, borehole abstractions 
and aquifer properties (storativity) and size of recharge area. The CRD method is represented 
by the following equation: 
av1CRDi=Ri-kRav+ av1CRDi-1 
Where: 
CRDi  = accumulated rainfall departure from mean at time i  
Ri  = rainfall at time i 
K = 1 indicate natural conditions and k>1 indicate that the aquifer is being exploited 
Rav = average rainfall 
 
The absence of long enough monthly water level records over the appropriate period made it 
difficult to apply this method to determine the recharge and it is rather recommended that 
monthly water level data be gathered in efforts to refine the determined recharge estimates 
calculated from other methods. 
5.1.5. Saturated Volume Fluctuation (SVF). 
The SVF method is an inventory of input to the aquifer over a specific time period with output 
from the aquifer. The water balance is reflected in the water level reaction. This method is 
suitable for most hydro geological analysis and aquifer management applications 
(Bredenkamp et al., 1995). The formula of this saturated water balance is: 
I-Q+Re-Q=S V 
t 
Where: 
S = storativity/ specific yield 
V = saturated volume of aquifer 
I = lateral inflow 
O = lateral outflow 
Re = recharge 
Q = net discharge 
t = time 
 
The absence of long enough monthly water level records over the appropriate period made it 
difficult to apply this method to determine the recharge and it is rather recommended that 
 28 
monthly water level data be gathered in efforts to refine the determined recharge estimates 
calculated from other methods. 
5.1.5. Recharge summarized 
With the available data only the CMB could be applied with confidence. With this method 
recharge is calculated to be between 0.2 to 28 mm/a of MAP in the different areas of the 
aquifer. This harmonic mean for all groundwater analyzed is 1.7mm/a. This corresponds to 
0.1 to 7.3% of MAP and a harmonic mean of 0.4%. 
The stable isotopes deuterium and oxygen 18 indicate immediate and delayed recharge to 
the aquifer in different areas of the aquifer and carbon 14 confirm that preferred recharge in 
areas of the aquifer and probably along preferred pathways. 
The CRD and SVF methods could not be applied with certainty due to the lack of sufficient 
water level data. 
5.2. Reserve determination 
In response to pressure on the groundwater resource a preliminary intermediate reserve 
determination was done for the Pomfret Vergelegen dolomite aquifer, which includes the 
Tosca Molopo dolomite aquifer. (Godfrey 2002). The results of this reserve are included as 
Table 13 and the area of investigation as figure 13. 
The findings of this reserve determination were that the total resource unit 1 was over utilized 
and portions of resource unit 3 were over utilized. Their present category status was 
classified as F, which is very poor and modified and it is desired that with intervention this 
could be improved to C (good or moderately modified) as in Table 14. 
Table 13. Determination of the groundwater component of the Reserve. 
BOUNDARIES AND 
RECHARGE RESERVE 
TYPING Groundwater 
MAP component Baseflow Allocatable 
Total Total BHN Reserve 
Resource Aquifer %  Recharge of baseflow Required (Mm3/a) 
Area Recharge Reserve as % of 
Unit Type 2 Recharge (mm/a (Mm
3/a) (Mm3/a) by IFR 
(km ) (Mm3/a) 3 (Mm
3/a) Recharge 
) (Mm /a) 
(i) BIF/Dolo 138 1.58 0.87 
1 399 6.90 0 0 0.037 0.54 6.86 
(ii) Dolomite 863 1.75 6.02 
2 - Dolomite 624 0.69 399 1.72 1.72 0 0 0.005 0.29 1.72 
BIF/Dolo
(i) 254 2.08 1.96 
3 mite 371 10.95 0 0 0.091 0.83 10.86 
(ii) Dolomite 1478 1.64 8.99 
TOTAL      19.57 0 0 0.133 0.68 19.44 
 
 29 
Table 14. Present Status Category and Desired Management Class 
Resource Unit Present 
Desired 
Status Category Management Class 
RU 1 F C 
RU 2 B B 
RU 3 F c 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 13. Molopo dolomite aquifer area. 
 
The following recommendations from this reserve determination are listed and were pursued: 
• The current over utilization of the aquifer must be stopped immediately, so as to 
ensure the long-term sustainability of the aquifer.  This may be done by: 
o Removing all unauthorized groundwater users in the area (post 1998); 
o Reducing the current volumes of groundwater abstracted by authorized 
groundwater users through compulsory licensing; and 
o Removing unauthorized groundwater users as well as reducing volumes abstracted 
by authorized water users. 
• The actual volumes of groundwater abstracted from the aquifer for use, on a monthly 
basis must be quantified.  This may involve the installation of flow meters on all 
abstraction boreholes. 
• Continuous water level monitoring within the dolomite aquifer is essential, to assess the 
response of the aquifer to the reduction of pumping.  There are currently two boreholes 
installed, equipped with continuous water level loggers (since Oct/Nov 2001). The 
boreholes carefully selected in areas as described in table 15 with graphical presentation 
give a representative indication of water level movement. 
 30 
Table 15. Representative boreholes across the aquifer to indicate water level movement. 
Precipitation (cm 6 months)
50
G39684 RU3 Distance from 40
abstraction Recharge zone
G39667 RU2 no abstraction 30
Recharge zone 20
G39670 RU2 no abstraction 10
Intermediate Zone 0
G39663 RU1 Distance from
abstraction Intermediate zone -10 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06
G39677 RU1 Distant from abstraction -20
Intermediate zone
G39671 RU1 Distant from Abstraction -30
Intermediate zone -40
G39685 RU1 Proximate to intensive -50
abstraction Intermediate zone
G39687 RU1 Distance from -60
abstraction Intermediate zone -70
G39674 RU1 Proximate to abstraction -80
Intermediate Zone
G39693 RU1 Distance from -90
abstraction Discharge Zone -100
G39673 RU1 proximate to Time
abstraction Discharge zone
 
• Due to the conservative approach adopted in estimating the available groundwater, 
recharge values must be refined to improve upon the level of confidence for future 
evaluations.  A rainfall collector is apparently in place to obtain more accurate Cl values 
for rainfall, the results of which should be available in November 2002. 
• A quantitative 2D model for the Molopo aquifer must be created, to use as a decision 
support tool, to manage the aquifer, and assess the response of the aquifer to the reduced 
abstraction volumes. 
• Continuation of the groundwater quality-monitoring programme for the Molopo dolomite 
aquifer at strategic boreholes within the area. 
 31 
waterlevel (mbs)           Precipitation summer and 
winter  (cm)
6. GROUNDWATER FLOW MODELLING (GM) 
A model is defined as a tool designed to represent a simplified version of reality (Wang and 
Anderson, 1982). From the hydro census, geophysical investigations, drilling records, 
geology, aquifer test, water level dynamics, groundwater chemistry, groundwater isotope 
character, recharge investigations and any other relevant observations the conceptual model 
was constructed. The aquifer boundaries and parameters are the numerical components of 
this conceptual model. 
The aim of modeling groundwater flow is to predict the aquifer piezometry under various 
groundwater stress situations. The rapid and drastic piezometric level variations made GM a 
suitable tool to explain observed variations. Prediction of future variations would be extremely 
valuable. 
6.1. Conceptual model 
The area to be modeled is approximately 80 km by 50 km as depicted in Figure 15. The 2D 
dimensional features from this geological map were extended into the 3 rd dimension through 
the sections depicted by Figure 14 (positions of these sections are visible in Figure 4). 
G39684 G39685 G39687 G39693
(1990)
1200 Quarreefontein
(2001) Molopo river
1100
Kalahari sediments
(1990)
1000 (2001)
(2003)
Dolomite
900m Grassbank dyke BIF
A A'
E 10 20 30 40 50 60 70 80 kWm
G39678 G39679 G39685G39680G39677 G39670 G39671 G39687 G39672 TO2 G39673 G39693
1100 (1990)
(20K03a)lahari sedimen
BtsIF Kalahari sediments
(1990) BIF Kalahari sediments
(2003) (1990)
1000 (2003)
Quartzite
Quarreefontein dyke BIFQuarreefontein dyke Quarreefontein dyke
900 Granite Dolomite Dolomite
B B' C C' D Dolomite D'
S N S N S N  
Figure 14. Conceptual model of the Tosca Molopo aquifer indicating the major boundaries, aquifer 
units and historic water levels. 
 32 
The aquifer consists of the sediments of the Kalahari Group and dolomites of the Ghaap Plato 
formation. The spatial dimensions are approximated in the conceptual model. The basin of 
sediment deposition deepens and is also broader closer to the Molopo River. The general 
flow is from the SW to the NE at the Molopo River. From the observed water level reaction the 
sediments contribute largely towards the storage of the aquifer system with the fractures of 
the dolomite contributing to high yielding flow. 
6.2. Model design and discretisation 
The MODFLOW PMWIN (Chiang 2000) software was used to construct a flow model. A 
large-scale model covering 80 km east west and 50 km north south or 4000 km2 was 
constructed. The area was divided into cells of 0.5 X 0.5 km generating 100 rows and 160 
columns. Based on the conceptual model provision was made for 2 layers namely the 
unconsolidated primary aquifer and the underlying fractured dolomite with its aquifer 
characteristics. 
 
Figure 15. Arial extend of the Tosca Molopo groundwater model with abstraction cells (red) (50X80 
km) 
Borehole information from approximately 40 boreholes and the Kalahari formation isopagh 
map as produced by P Smit on the 1:250 000 geological map Bray was used to determine 
layer thickness. The first layer (primary aquifer of sediments) start at an elevation of 1160 
 33 
mamsl. This layer is between 1 and 10 m thick in the southwest. It thickens to the northeast 
where the thickness exceeds 120 m from an elevation of 1080 mamsl to an elevation of 960 
mamsl. The 2 nd layer (dolomite layer) lies directly beneath the first layer from an elevation of 
approximately 1159 to 900 mamsl in the southwest. To the northeast this layer wedge out to 
be present at an elevation of 1080 to 900 mamsl. 
6.3. Aquifer boundaries 
Of the number of dolerite dykes intruded into the dolomite the Grassbank and Quarriefontein 
dykes are the most influential on the groundwater flow. Plate 2 indicate and explain the 
boundary.  
The Grassbank dyke form a boundary in the west. The Grassbank dyke was interpreted to dip 
slightly to the west with a thickness of 15 m. This dykes act as no-flow boundary of the 
Neumann (impervious) type impeding flow from the west of the area. 
The Quarreefontein dyke form a boundary in the south. The Quarriefontein dyke is also 
interpreted as 15 m thick with a slight dip to the south. This dykes act as no-flow boundary of 
the Neumann (impervious) type impeding flow from the south of the area. Towards the east 
(Figure 10 Section D-D’) the Quarreefontein dyke does not seem to be a no-flow boundary as 
the water level information indicate connection with the dolomite to the south (see section 
6.4).  
The surface and groundwater shed formed by the Banded Iron Formation of the Waterberge 
forms the boundary to the west. The combination of both a geological contact and watershed 
is a leaking boundary. 
The Molopo River forms the eastern boundary. This boundary collect water from this Tosca 
Molopo aquifer as well as water from the aquifers east in Botswana. 
The total area of the model extent well beyond these boundaries. The cells on the western, 
northern and eastern rim of the model was set as fixed head cells in which initial heads will be 
kept constant. All other cells were set as specific flux cells where the hydrolic head would be 
calculated at Neumann conditions. 
 34 
 
Plate 2. A spring on the farm Nokani where groundwater well out in reaction to the barrier created by the 
Quarreefontein dyke. On the other side groundwater levels are deeper than 10 m below surface and further 
north they decline to 85 m below surface. 
6.4. Geophysical investigation to confirm dolerite dykes 
The positions of the dolerite dykes and their presence were deducted from aerial photos and 
the 1:250 000 geological map. To confirm the positions of these dykes the magnetic and 
electromagnetic geophysical method was used at investigate and select positions over the 
dykes on the farms Millbank, Quarrefontein, Ascot and Buxton. The magnetic profiles from 
line 2 (Millbank), line 3 and 4 (Quarreefontein), line 5 (Ascot) and line 6 (Buxton) are included 
in Appendix 3. As these lines indicate prominent magnetic anomalies is dyke material could 
be present. The similar anomalies over the strike of these dykes can be expected and it can 
be concluded that both dykes are present. The position of these dykes varied negligibly from 
their interpreted positions from the maps. 
6.5. Drilling of boreholes to confirm water level elevation difference. 
To confirm that these dykes form compartment/resource boundaries the boreholes listed in 
Table 16 and mapped on figure 4 were drilled to observe water level differences over these 
dykes. The boreholes were sited on the geophysical investigations reported in section 6.4. 
 35 
Table 16. Borehole information of drilled boreholes (Oct 2003 to March 2004) to confirm aquifer 
boundaries. 
Water Ec Hydrolic Cas
Bore Elevation Depth intercep Yield (mS/m Water Head ing 
hole Farm Lat Long (mamsl) (m) tion  (m) (l/s) ) level (m) (mamsl) (m) Comment 
In town, water 
provision, No 
G47604 Ascot -25.8743 23.9625 1115 102 54 2.65 336 50.70 1064 6 geophysical siting 
North of Dyke 5 m 
43,       0.2, difference over dyke, 
G47605 Ascot -25.8918 23.9616 1120 102 76 0.3 160 34.72 1085 6 Line 5 
South of Dyke 5 m 
difference over dyke, 
G47606 Ascot -25.8997 23.9625 1120 150 81 1.48 102 29.26 1091 7 Line 5 
Farm water provision, 
G47607 Quarrefontein -25.9138 23.8418 1133 150 123 0.10 61 8.37 1125 30 No Geophysical siting 
G47608 Quarrefontein -25.9438 23.8238 1150 50 7 0.88 110 3.99 1146 6 West of Dyke, Line 3  
G47609 Quarrefontein -25.9429 23.8249 1145 102 7 0.10 92 8.86 1136 7 East of Dyke, line 3                 
121,      1.6, 
G47610 Marlborough -25.8140 23.7900 1140 150 131 2.6 64   1140 37 Water provision 
G47611 Millbank -25.8686 23.7737 1145 102 0 dry   41.37 1104 6 West of Dyke, Line 2  
G47612 Millbank -25.8695 23.7730 1145 150 47 0.10 60 55.45 1090 6 East of Dyke, line 2   
G47613 Buxton -25.8089 24.2116 1082 150 67 0.10 81 54.31 1028 18 South of Dyke, Line 6 
53,        
G47614 Buxton -25.8077 24.2113 1079 150 72 0.50 79 52.50 1027 15 North of Dyke, Line 6 
102, 0.2,    
121,       2 .5,     Water provision, no 
G47615 Forres -25.9250 23.8961 1135 132 128 2.8   77.38 1058 3 geophysical siting 
Totals         1490           147   
On the farm Ascot between G47606 South and G47605 North there is a 6 m water level 
elevation difference (drop) over the Quarreefontein dyke. On the farm Buxton between 
G47613 South and G47614 North there is less than 1 m groundwater elevation difference 
(drop) over the Quarreefontein dyke. In this area impeded water movement over the 
boundary seem to take place. There is a 10 m groundwater elevation difference (drop) over 
the Grassbank dyke between G47608 west and G47609 east on the farm Quarreefontein. 
Between G47611 and G47612 over the Grassbank dyke there is a 14 m groundwater level 
elevation difference (drop).  
The groundwater elevation differences over these boundaries are significant and 
compartments as interpreted valid. With major water level declines (up to 60 m) within these 
resource units/ compartments even larger differences were expected. It can therefore not be 
excluded that there is still minor movement over these boundaries. 
 36 
6.6. Aquifer parameters 
To determine the aquifer parameters aquifer tests were conducted on 4 selected boreholes 
during October 2001. These boreholes were drilled during 1991. (Duvenhage, 1992). Two 
additional aquifer test were done by an irrigator and this information was also used. 
Aquifer tests provide information regarding the flow within the aquifer. The aquifer test 
analyses are included as Appendix 2. The results of these analyses are tabled in table 17. 
The location of these boreholes is visible in Appendix 12. 
The aquifer test data was analyzed with the Flow Characteristic (FC) (van Tonder and Xu, 
1999) software programme. The FC method use derivatives of the Cooper Jacob equation 
with respect to log (t) to estimate values for the transmissivity (T), and storativity (S) of an 
aquifer. 
Table 17. Calculated transmissivity, storativity and yield values from controlled aquifer tests. 
Bore T-late Est.  Q (l/s/ Water 
hole Lat Long [m2/d] Sl 
-
ate 24h) strike (m) 
Remark 
G36669 25.882 24.113 6.30 0.002 1.02 36,45,55,57 Carstic dolomite Layer 2 
G39684 25.949 23.826 109.59 0.002 16.70 34-40 Carstic dolomite Layer 2 
G39691 25.877 24.019 41.02 0.002 4.00 110 Carstic dolomite Layer 2 
G39693 25.674 24.144 37.92 0.005 13.00 96, 157 Primary aquifer Layer 1 
TO1 25.954 23.754 1000 0.002 22.00   Carstic dolomite Layer 2 
TO3 25.949 23.756 790 0.002 28.00   Carstic dolomite Layer 2 
The following parameter values estimated from the aquifer tests were used as initial 
parameters for the calibration of the groundwater flow model: 
• Transmissivity: As input for the primary Kalahari aquifer (layer 1) an initial value of 50 
m2/d was used as this aquifer is renowned for its low yields.  
As input for the flow model a 200 m2/d was used as an initial value for the dolomite 
(layer 2) since a number of high yielding boreholes exist in the area. 
• Storativity: The calculated value of 0.005 from borehole G39693 is used as initial 
storativity value for the primary Kalahari aquifer (layer 1). 
• The calculated value of 0.002 for the fractured dolomite is in agreement with values 
calculated and used in other similar dolomite areas for layer 2 (Pering Mine, Moseki, 
2001) 
• Aquifer thickness: The 1st layer is 1 to 10 m thick in the west and it thickens to over 150 
m in the east proximate to the Molopo river. The thickness was observed at a number 
of boreholes from where the thickness was interpolated. The thickness of the 2nd layer 
 37 
(carstic and fractured aquifer) was observed in boreholes to be from shallow in the 
west to 150 m. Its thickness was set at an elevation of 900 mamls. 
• The average porosity of the dolomite is assumed to be 0.03. 
6.7. Model calibration-steady state 
The model was run in its steady state and most of the assumptions proved valid with the 
exception of the transmissivity of the dolomite aquifer. The aquifer was subdivided in different 
zones based on the conceptual model and observations (isotope, recharge, hydrochemistry) 
and the calibration that followed produced a better fit for the scatter plot of calculated hydrolic 
heads against observed hydrolic heads (Figure 16). 
1160
1140
1120
1100
1080
1060
1040
1020
1000
1000 1020 1040 1060 1080 1100 1120 1140 1160
Observed hydrolic heads (mamsl)
 
Figure 16. Observed versus simulated hydrolic data 
The parameters are tabled in table 18 for the different zones of the aquifers in layer 1. These 
zones are spatially represented in Figure 17. 
 38 
Calculated hydrolic heads 
(mamsl)
Table 18. Transmissivity and storativity in zones of layer 1. 
Layer 1 Identification Transmissivity Storativity 
Zone color (m2/d) [  ] 
Unconsolidated sediments Yellow 17 0.005 
Thick calcrete with minor sand cover Dark Green 20 0.005 
Clay and calcrete with minor gravel Red 9 0.005 
Calcrete along riverbeds Light green 27  
Basal gravel Brown 37 0.005 
Zone associated with weathered Light Brown 9 0.005 
dolerite 
T=37 
T=27 S=0.005 
T=17 S=0.005 
S=0.005 
T=10 
S=0.005 
T=9 
S=0.005 
T=20 
S=0.005 T=9 
S=0.005 T=17 
S=0.005 
 
Figure 17. Spatial extend of transmissivity and storativity zones in layer 1. 
 
The calibrated transmissivities of between 9 and 37 m2/day are lower than the assumed value 
of 50 m2/day. This is consistent with the conceptual understanding of the primary sandy 
layers. This layer is heterogeneous with fine sand and clay material that can reduce the 
tranmissivity. 
The calibrated parameters are tabled for the different zones of the dolomite aquifers of layer 2 
in table 19. The different zones are spatially represented in Figure 18. 
 39 
Table 19. Transmissivity and storativity in zones of layer 2. 
Layer 2 Identification color Transmissivity Storativity 
Zone (m2/d) [  ] 
BIF Green/ Brown 5 0.002 
Dolomite with dolerite Blue 25 0.002 
Dolomite with chert Light Green 30 0.002 
Dolomite with chert, shale Grey 40 0.002 
and fractured BIF 
Dolomite with chert, shale Light Grey 60 0.002 
and fractured BIF high 
yielding 
Lava and diamictite Purple 10 0.002 
Dolerite Brown 2 0.002 
T=10 T=60 
S=0.002 S=0.002 
T=40 
S=0.002 
T=5 T=30 
S=0.002 S=0.002 
T=25 
T=2 S=0.002 
T=10 
S=0.002 
S=0.002 
 
Figure 18. Spatial extend of tranmissivity and storativity in layer 2. 
 
The zones in this dolomite layer are consistent with the sedimentary layers. The calibrated 
transmissivity values are significantly less than the assumed values deducted from the 
aquifer test results in table 17. In general the assumption is made that the extremely high 
transmissivity associated with production boreholes is the exception and that the total aquifer 
is less transmissive. 
 40 
6.8. Hydrolic head interpolation 
Two sets of water level data were available for the area. Smith (1977) collected water levels 
over a number of years, but the quality of the water levels is questioned by Duvenhage and 
Meyer (1991). 
A hydro census reported by Duvenhage and Meyer (1991) was done in 1990 with 351 
boreholes located. At 198 points water levels were measured and a further 28 borehole were 
drilled where water levels were available. At the time irrigation took place on the farms 
Thorntwaite and Blackheath. Although Duvenhage and Meyer reported water level declines 
on these properties the 1990 and pre 1977 water level elevation maps are similar in character 
(See figure 7). The 1990 water level data is therefore accepted as representing initial water 
levels. From this information the water levels were interpolated over the total area. Water 
levels collected by Appelcryn (1992 to 1993) were also used in the south and north. 
The correlation between measured water levels from 1991 and the topography at R2 =0.69 is 
poor due to water levels in the unconsolidated sediments. As abstraction over time increased 
there is no correlation with R2=0.05 by Aug 2003. See Figure 19. 
 
Figure 19. Groundwater versus surface elevation. 
1200.00
Apr-90
Aug-03 y = 1.691x - 799.95
2
Linear (Apr-90) R  = 0.6913
1150.00 Linear (Aug-03)
1100.00
y = 0.9889x - 55.694
R2 = 0.0508
1050.00
1000.00
950.00
950 1000 1050 1100 1150 1200
Surface Elevation (mamsl)
 
 41 
Water level elevation (mamsl)
6.9. Aquifer recharge 
The aquifer recharge as calculated by the chloride method was used for modeling purpose. 
Recharge zones as determined from this chloride analysis were used for the model. The 
recharge ranged from 0.25 mm (0.5%) average in winter and 6.6 mm (3%) average for 
summer, but different values were used depending on the precipitation at the time and the 
area. 
The spatial distribution of these zones is indicated in Figure 20 with the corresponding 
volume of recharge per day to that zone calculated in table 20. Eventually the average 
recharge used was 1,75 % of MAP or 9.7 mm/a of MAP. With the deep water table and 
observed water level reaction a delay period of 6 months was estimated. Therefore the 
summer precipitation reaches the aquifer that winter and the winter precipitation the aquifer 
the next summer. 
Zone 3 Zone 1 
R=0.5% MAP R=2% MAP 
1.9 mm/a 7.5 mm/a 
Zone 2 
R=1.5% MAP 
5.6 mm/a Average 
1.75 %/a MAP 
9.7 mm/a MAP 
Zone 4 Zone 3 
R=3% MAP R=0.5% MAP 
10.5 mm/a 1.9 mm/a 
 
Figure 20. Recharge zones in the Tosca Molopo aquifer with Zone 1 light blue, Zone 2 dark grey, 
Zone 3 light grey and Zone 4 dark green. 
 42 
Table 20. Recharge to the different zones as calculated from the summer and winter precipitation 
(182 days) in m3/day. 
 
Recharge Recharge Recharge Recharge Average 
Precipitation Precipitation Zone 1 @ Zone 2 @ Zone 3 @ Zone 4 @ 1.75% of 
@ @  2% of 1.5% of 0.5% of 3% of MAP 
Vergelegen Pomfret for 6 Vergelegen Vergelegen Vergelegen Pomfret 9.7 mm/a 
Stress for 6 months months (7.5 mm/a) (5.6 mm/a) (1.9 mm/a) (10.5 mm/a)  
Year period (mm) (mm) (m3/d) (m3/d) (m3/d) (m3/d) (m3/d) 
93/94 S 1 260.0 185.6 0.00003 0.00002 0.00001 0.00003 0.00002 
94 W 2 1.0 3.4 0.00000 0.00000 0.00000 0.00000 0.00000 
94/95 S 3 410.0 102.9 0.00004 0.00003 0.00001 0.00002 0.00003 
95 W 4 14.0 27.0 0.00000 0.00000 0.00000 0.00000 0.00000 
95/96 S 5 400.0 185.6 0.00004 0.00003 0.00001 0.00003 0.00003 
96 W 6 104.0 136.4 0.00001 0.00001 0.00000 0.00002 0.00001 
96/97 S 7 336.1 157.6 0.00004 0.00003 0.00001 0.00003 0.00002 
97 W 8 34.5 94.2 0.00000 0.00000 0.00000 0.00002 0.00001 
97/98 S 9 388.0 269.2 0.00004 0.00003 0.00001 0.00004 0.00003 
98 W 10 16.0 34.2 0.00000 0.00000 0.00000 0.00001 0.00000 
98/99 S 11 204.5 477.8 0.00002 0.00002 0.00001 0.00008 0.00003 
99 W 12 0.0 15.6 0.00000 0.00000 0.00000 0.00000 0.00000 
99/00 S 13 447.2 291.4 0.00005 0.00004 0.00001 0.00005 0.00004 
00 W 14 61.5 59.0 0.00001 0.00001 0.00000 0.00001 0.00001 
00/01 S 15 122.9 270.6 0.00001 0.00001 0.00000 0.00004 0.00002 
01 W 16 166.0 177.0 0.00002 0.00001 0.00000 0.00003 0.00002 
01/02 S 17 326.0 331.4 0.00004 0.00003 0.00001 0.00005 0.00003 
02 W 18 86.0 167.6 0.00001 0.00001 0.00000 0.00003 0.00001 
02/03 S 19 227.0 386.2 0.00002 0.00002 0.00001 0.00006 0.00003 
03 W 20 21.5 21.5 0.00000 0.00000 0.00000 0.00000 0.00000 
03/04 S 21 300.0 280.0 0.00003 0.00002 0.00001 0.00005 0.00003 
Average   373.9 349.9 0.00002 0.00002 0.00001 0.00003 0.00002 
Av W  50.5 73.6 0.000006 0.000004 0.000001 0.000012 0.000006 
Av S  316.2 275.3 0.000035 0.000026 0.000009 0.000045 0.000029 
20% W  40.36 58.872 0.000004 0.000003 0.000001 0.000010 0.000005 
20% S  252.936 220.216 0.000028 0.000021 0.000007 0.000036 0.000023 
 
 43 
6.10. Abstraction from the aquifer 
 
No domestic and stock watering abstraction was considered. Irrigation abstraction was 
calculated from the registration areas, field observations and reports from users. Table 21 
indicate the volumes abstracted by different users while figure 15 indicate the position of this 
abstraction positions as in summer 2003 when abstraction reached a peak. Through the 
registration of water use, which gave water users the opportunity to comply with the NWA 
water use volumes were obtained. These volumes were verified in the Tosca Molopo area 
and found that registered volumes were only reflecting 60 % of the actual volume abstracted. 
This was done through the field observations, water use verification and crop factor analysis. 
Abstraction was divided into summer and winter abstraction for the different crops. The 
surface area and crop type combined with the crop use factor was used to calculate total 
need to cultivate that crop. This volume needed was then averaged over a six-month 
abstraction period (182.5 days) to obtain the daily abstraction from the aquifer. Abstraction 
was assumed to be from the total cell of 500X500m. 
The growth period for different crops could not be accommodated. Paprika is wetted for up to 
8 months; maize 4 to 5 month and potatoes could be as short as 3 months. All calculations 
were averaged over six months. 
The accurate measuring of abstraction volumes for irrigation purposes in South Africa from 
groundwater resources is still a challenge to be met. In this area the estimations based on the 
above principles was the best option and the estimate abstraction volumes believed to be a 
accurate reflection. 
 
Table 21. (Next page) Estimated water abstraction from the aquifer for each half-year m3/day. 
 
 
 44 
Name Total use 60%   03_04 2003 03_02 2002 02_01 2001 01_00 2000 00_99 1999 99_98 1998 98_97 1997 97_96 1996 96_95 1995 91_90 1990 
  m3/a m3/a   sum win sum win sum win sum win sum win sum win sum win sum win sum win sum win 
J.C.C. Grobbelaar 69954 69954  383 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
A.V.H. Maree 153870 122322  670 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Avon Trust 74112 74112  406 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Eben Du Toit 74112 74112  406 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Thornwick Boerdery 81954 79172  434 0 450 0 450 0 450 0 450 0 0 0 0 0 0 0 0 0 0 0 
Tosca Trust 35382 35382  194 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
H.M. Joubert 51900 51900  284 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
M. Theron 25710 25710  1315 0 1644 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Fanie Griesel 65760 65760  360 0 1096 0 1096 0 110 0 110 0 0 0 0 0 0 0 0 0 0 0 
C.E. le Roux 0 0  0 0 2466 0 2466 0 2466 0 2466 0 0 0 0 0 0 0 0 0 0 0 
J.J. Hayward 95458 87275  478 0 2464 0 2464 0 2464 0 2464 0 0 0 0 0 0 0 0 0 0 0 
J.H. Fourie 64543 64543  354 0 493 0 493 0 493 0 0 0 0 0 0 0 0 0 0 0 0 0 
G I Rossouw 39902 39902  219 0 822 0 822 0 822 0 0 0 0 0 0 0 0 0 0 0 0 0 
P J Haasbroek 45876 45876  1027 0 4110 0 4110 0 2055 0 0 0 0 0 0 0 0 0 0 0 0 0 
W H Simmons 55063 55063  302 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
G H Stolz 66076 66076  362 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Emtron Bdy 367500 250500  1096 0 2014 0 2014 0 2014 0 2014 0 288 0 0 0 0 0 0 0 0 0 
P.W. Beyer 240000 174000  2795 1233 4192 0 4192 0 4192 0 4192 0 0 0 0 0 0 0 0 0 0 0 
Leniesdeel Trust 822500 523500  2532 0 4567 0 4507 0 4507 0 4507 0 3685 0 3685 0 3685 0 1096 0 0 0 
J.H. Fourie 290000 204000  953 0 1589 0 1589 0 1589 0 1589 0 1589 0 1589 0 1589 0 794 0 0 0 
D.B. Grobbelaar 482000 319200  1585 0 2642 0 2642 0 2642 0 2642 0 2642 0 2642 0 2642 0 2642 0 2642 0 
Rosstol Trust 585000 381000  1973 1233 1973 1233 1973 1233 1973 1233 1973 1233 1973 1233 1973 0 1602 0 1602 0 0 0 
Rosstol Trust 1725000 1065000  1726 4110 8219 1726 8219 1726 8219 1726 8219 1726 4576 1726 4576 1726 4726 0 4726 0 0 0 
C.J. Caroll 2395000 1467000  7874 0 13123 0 13123 0 13123 0 13123 0 8767 0 8767 0 4762 0 4762 0 2853 0 
W.C. Kriel 335950 231570  1104 0 1841 0 1841 0 1841 0 1841 0 1228 0 1228 0 920 0 920 0 0 0 
Clearstream Trust 585000 381000  1923 0 3205 0 3205 0 3205 0 3205 0 3205 0 3205 0 1600 0 1600 0 0 0 
Avon Trust 120000 102000  66 0 658 0 658 0 658 0 658 0 0 0 0 0 0 0 0 0 0 0 
J.H. Nieuwoudt 145000 117000  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
F. Barnard 144000 116400  638 0 789 0 789 0 789 0 789 0 789 0 789 0 789 0 789 0 0 0 
F.V.Z. Engelbrecht 440000 294000  1311 0 2411 0 2411 0 2411 0 2411 0 1311 0 1311 0 1311 0 1311 0 0 0 
J.P. van den Berg 1035000 651000  3567 740 4932 740 4932 740 4932 740 4932 740 3781 0 3781 0 284 0 284 0 0 0 
F. Barnard 487500 322500  1767 0 2671 0 2671 0 2671 0 2671 0 1254 0 1254 0 1254 0 1254 0 0 0 
S.G. Griesel 18000 18000  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Zenith Ranch (Pty. Ltd) 258300 184980  1014 0 0 0 0 0 0 0 0 0 0 0 4932 0 4932 0 4932 0 0 0 
A.C.J. Du Plessis 79800 77880  427 0 427 0 427 0 427 0 427 0 427 0 427 0 0 0 0 0 0 0 
A.M. Steyn 114000 98400  539 0 539 0 539 0 539 0 539 0 539 0 539 0 0 0 0 0 0 0 
Pretorius 77097 76258  422 0 422 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
I de Beer 66150 66150  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
I de Beer 72386 72386  0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
K. van der Heever 110121 96073  526 411 603 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
Hulp Alleen Familie 130500 108300  593 0 593 0 593 0 593 0 274 0 274 0 274 0 274 0 274 0 0 0 
M. Hamman 35000 35000  192 0 192 0 192 0 192 0 192 0 192 0 0 0 0 0 0 0 0 0 
W.H.A. Hamman 42500 42500  233 0 233 0 233 0 233 0 233 0 233 0 0 0 0 0 0 0 0 0 
P.A. Theunissen 225000 165000  904 0 1233 0 1233 0 1233 0 0 0 0 0 0 0 0 0 0 0 0 0 
F.J. Hamman 231700 169020  926 0 1270 0 1270 0 1270 0 926 0 926 0 926 0 926 0 926 0 0 0 
Centwise BK 74406 74406  408 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
E.C. Grobbelaar 682200 439320  2012 0 3738 0 3738 0 3738 0 3738 0 2407 0 2407 0 1096 0 1096 0 0 0 
P.E. Kriel 124250 104550  573 0 681 0 681 0 681 0 681 0 681 0 0 0 0 0 0 0 0 0 
Sandtrap Boerdery 525000 345000  2877 0 2877 0 2877 0 2877 0 2877 0 2877 0 0 0 0 0 0 0 0 0 
Botswana1 375000 255000  2055 0 2055 0 2055 0 2055 0 2055 0 2055 0 0 0 0 0 0 0 0 0 
Botswana2 90000 84000  493 0 493 0 493 0 493 0 493 0 493 0 0 0 0 0 0 0 0 0 
Botswana3 225000 165000  1233 0 1233 0 1233 0 1233 0 1233 0 1233 0 0 0 0 0 0 0 0 0 
Total m3/day for 
season 14755532 8883319  53531 7726 84958 3699 82228 3699 79187 3699 73922 3699 47424 2959 44305 1726 32391 0 29007 0 5495 0 
Total million m3 for year      11.18 16.91 16.18 15.68 15.68 15.13 15.13 14.17 14.17 9.33 9.19 8.63 8.40 6.23 5.91 5.29 5.29 1.00 1.00  
45 
 
6.11. Initial Hydraulic heads 
As discussed in data interpolation a representative dataset is available for 1990. Although the 
precipitation data reflect that from 1990 to 1994 below average precipitation prevailed and 
therefore recharge was limited, abstraction from the aquifer was also limited. These 1990 
initial hydraulic heads are therefore assumed to be representative for 1994. 
6.12. Stress periods and time steps 
The model parameters (transmissivity, storitivity), recharge and abstraction were used as 
input for the model. The length of each time step is 6 months (182.5 days) and each time step 
is a stress period. The period from 1993/94 summer to winter 2003 is therefore represented 
by 20 stress periods of 6 months each. Stress periods 2,4,…,20 (even) represent winter (April 
to Sept) with stress periods 1,3,…,19 (uneven) representing summer (Oct to March). 
6.13. Model calibration-transient state 
The model was run and water levels were generated at the 28 observation boreholes. The 
observed water levels were compared with the generated values. Figure 21 indicate the 
correlation between selected observed and modeled water level values.  
 
Figure 21. Correlation between observed (dotted line) and modeled water levels (solid lines) for the 20 
stress periods representing winter 1994 (year 0-10) to winter 2004 (year 0). Water level 
elevation on vertical scale with the days on the horizontal scale.  
G36667 redbrown, G36670 light grey, G36673 light green, G36677 pink, G36682 dark green, 
G36684 blue, G36693 black and G36694 orange. 
 
The model is under estimating water levels in the recharge zone by approximately 10 m. In 
the intermediate zone water level estimation is accurate within 1 to 5 m. In the discharge zone 
water levels are overestimated by approximately 10 m. 
46 
 
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-110
1. Stress periode 1 -93/94 summer (year 0-9.5) 4. Stress periode 13 –99/00 summer (year 0-3.5) 
  
2. Stress periode 5 –95/96 summer (year 0-7.5) 5. Stress periode 17 –01/02 summer (year 0-1.5) 
  
3. Stress periode 9 –97/98 summer (year 0-5.5) 6. Stress periode 19 –03/04 summer (year 0-0) 
 
Figure 22. Selected draw down maps (meter below initial heads) results from transient state calibration 
of the model. The six 2 year periods pre-ceding the winter of 2004 were used. 
 
The water level draw down maps from Figure 22 compare favorably with the observed water 
level draws down maps in Appendix 6. These maps were prepared with from observed 
measurements with Surfer contouring software package. The data extrapolation by the 
package distorts contours at the edges of these maps. The slight under estimation of draw 
down is also visible. 
 
47 
 
6.14. Scenario predictions 
With the satisfactory calibrated model scenario predictions can be made to assist in making 
decisions towards the sustainable managing of the water resource. The following scenarios 
were tested: 
6.14.1. Scenario 1 (High abstraction with average precipitation) 
• Water abstraction was estimated to be as in Table 21 (column 4- 02/03) and the 
equivalent surface area irrigated is graphically represented in Figure 23.  
Tosca abstraction 1994 to 2004
2500
2067
2001
2000 1927
1799
1500
1303
1154
1078
1000
788
706
500
188
90 90 90 90 13472 42 0 0
0
Year and season
 
Figure 23.  Estimated surface area irrigated for each half year in the Tosca Molopo aquifer. 
 
• Abstraction from 2004 to 2014 is assumed to at 2002 winter en 2002_ 2003 summer 
volumes by each user bringing the total abstraction to 16.1 M m3 annum water 
(highest volume ever to be abstracted) 
• Precipitation is assumed to be the average as calculated from the rainfall 
measurements at 50.5 mm and 73.6 mm in winter and 316.2 and 275.3 mm in summer 
at Vergelegen and Pomfret respectively. The recharge was then calculated as 
assigned to the different zones ranging from 0.25 mm (lowest) to 8.3 mm (highest) as 
in table 20. The precipitation was then allocated to the different zones (figure 20) with a 
6 months time lag as follow. 
 
 
48 
 
Area irrigated at maize (summer) and 
corn (winter) 
demand (ha)
03_04
2003
03_02
2002
02_01
2001
01_00
2000
00_99
1999
99_98
1998
98_97
1997
97_96
1996
96_95
1995
95_94
Precipitation Recharge Recharge Recharge 
@ Recharge Zone 2 @ Zone 3 @ Zone 4 @ 
Vergelegen Precipitation Zone 1 @ 2% 1.5% of 0.5% of 3% of 
Stress for 6 months @ Pomfret for of Vergelegen Vergelegen Vergelegen Pomfret 
Year  period (mm) 6 months (mm) (m/d) (m/d) (m/d) (m/d) Average 
Av W  50.5 73.6 0.000006 0.000004 0.000001 0.000012 0.000006 
Av S  316.2 275.3 0.000035 0.000026 0.000009 0.000045 0.000029 
This scenario was modeled and the piezometric heads from selected boreholes are 
graphically represented by figure 24 and the contoured water levels for selected stress 
periodes in figure 25. 
 
Figure 24. Correlation between observed (dotted line) and modeled water levels (solid lines) for the 40 
stress periods representing 1994 to 2014 for Scenario 1 conditions. Water level elevation 
on vertical scale with the days on the horizontal scale.  
Note: G36667 redbrown, G36670 light grey, G36673 light green, G36677 pink, G36682 dark 
green, G36684 blue, G36693 black and G36694 orange. 
 
With this high abstraction average precipitation scenario water levels would proceed to 
decline. 
Results: (Figures 24 and 25). 
• Water levels in resource unit 1 would decline regionally with 20 to 30 m (i.r.t. 1990 
water levels). The sink formed by this decline would spread over an area of 20 X 5 km 
and boreholes in this area are at risk to be de-watered. 
• At Grassbank water levels would decline to 110m (i.r.t. 1990 water levels) and 60 m at 
Blackheath. 
 
 
49 
 
1. Stress periode 31 -08/09summer (year 0+5.5) 3. Stress periode 39 -12/13summer (year 0+9.5) 
2. Stress periode 32 –2009 winter (year 0+6) 4. Stress periode 40 -2013winter (year 0+10) 
Legend 
50
40 Positive water level fluctuation indicating an 
30 increase in water levels i.r.t. initial (1991) 
20 water levels. 
10  
0  
-10 Zero water level fluctuation indicating an 
-20 increase in water levels i.r.t. initial (1991) 
-30 water levels. 
-40  
-50  
-60 Negative water level fluctuation indicating 
-70 an increase in water levels i.r.t. initial 
-110m (1991) water levels
 
Figure 25. Selected stress periode draw down (meter below initial heads) results from Scenario 3 of 
the model. 
 
• In resource unit 2 water levels would decline by approximately 20 m (i.r.t. 1990 water 
levels) in the Forres area and stay constant through the rest of the area. 
• In resource unit 3 water levels would decline by 10 to 20 m (i.r.t. 1990 water levels) 
proximate to the Grassbank dyke and would remain constant or decline less than 1 m 
over the rest of the area. 
50 
 
6.14.2. Scenario 2 (Restricted abstraction [–40%] with average precipitation) 
• Water abstraction for the periode 93 to 2003 is as estimated in Table 21.  
• Abstraction from 2004 to 2014 is assumed to be restricted with 40% by each user 
(column 3- 60%) with the total abstraction at summed at 11.1 M m3/annum. 
• Precipitation is assumed to be the average as calculated from the rainfall 
measurements at 50.5 mm and 73.6 mm in winter and 316.2 and 275.3 mm in summer 
at Vergelegen and Pomfret respectively. The recharge was then calculated as 
assigned to the different zones ranging from 0.25 mm (lowest) to 8.3 mm (highest) as 
in table 20. The precipitation was then allocated to the different zones (figure 20) with a 
6 months time lag as follow. 
Precipitation Recharge Recharge Recharge 
@ Recharge Zone 2 @ Zone 3 @ Zone 4 @ 
Vergelegen Precipitation Zone 1 @ 2% 1.5% of 0.5% of 3% of 
Stress for 6 months @ Pomfret for of Vergelegen Vergelegen Vergelegen Pomfret 
Year  period (mm) 6 months (mm) (m/d) (m/d) (m/d) (m/d) Average 
Av W  50.5 73.6 0.000006 0.000004 0.000001 0.000012 0.000006 
Av S  316.2 275.3 0.000035 0.000026 0.000009 0.000045 0.000029 
 
This scenario was modeled and the piezometric heads from selected boreholes are 
graphically represented by figure 26 and the contoured water levels for selected stress 
periodes in figure 27. With this lower abstraction average precipitation scenario water levels 
would stabilize. 
 
Figure 26. Correlation between observed (dotted line) and modeled water levels (solid lines) for the 40 
stress periods representing 1994 to 2014 for Scenario 2 conditions. Water level elevation 
on vertical scale with the days on the horizontal scale. 
Note: G36667 redbrown, G36670 light grey, G36673 light green, G36677 pink, G36682 dark 
green, G36684 blue, G36693 black and G36694 orange. 
51 
 
1. Stress periode 31 -08/09summer (year 0+5.5) 3. Stress periode 39 -12/13summer (year 0+9.5) 
2. Stress periode 32 –2009 winter (year 0+6) 4. Stress periode 40 -2013winter (year 0+10) 
Legend 
50
40 Positive water level fluctuation indicating an 
30 increase in water levels i.r.t. initial (1991) 
20 water levels. 
10  
0  
-10 Zero water level fluctuation indicating an 
-20 increase in water levels i.r.t. initial (1991) 
-30 water levels. 
-40  
-50  
-60 Negative water level fluctuation indicating 
-70 an increase in water levels i.r.t. initial 
-110m (1991) water levels
 
Figure 27. Selected stress periode draw down (meter below initial heads) results from Scenario 2 of 
the model. 
 
 
Results: (Figures 26 and 27). 
• Water levels in resource unit 1 would decline regionally with 20 to 30 m (i.r.t. 1990 
water levels).  
• At Grassbank water levels would decline 60m (i.r.t. 1990 water levels) and 30 m at 
Blackheath. 
• There would be a 10 m water level recovery compared to the water levels of 2004. 
• There would be a 10 m water level recovery compared to the water levels of 2004. 
• In resource unit 2 water levels would remain constant (i.r.t. 1990 water levels). 
• In resource unit 3 water Ievels would remain constant (i.r.t. 1990 water levels). 
52 
 
6.14.3. Scenario 3 (Restricted abstraction [–40%] with below average [–20%] 
precipitation) 
• Water abstraction for the periode 93 to 2003 is as estimated in Table 21.  
• Abstraction from 2004 to 2014 is assumed to be restricted with 40% by each user 
(column 3- 60%) with the total abstraction at summed at 11.1 M m3/annum. 
• Precipitation is assumed to be the at 20 % less than the average as calculated from 
the rainfall measurements at 50.5 mm and 73.6 mm in winter and 316.2 and 275.3 mm 
in summer at Vergelegen and Pomfret respectively as in Table 20. The recharge was 
then calculated as assigned to the different zones ranging from 0.2 mm (lowest) to 6.6 
mm (highest) as in table 20. The precipitation was then allocated to the different zones 
(figure 20) with a 6 months time lag as follow.The precipitation was then allocated to 
the different zones with a 6 months time lag as follow. 
Recharge Recharge Recharge 
Precipitation Precipitation Recharge Zone 2 @ Zone 3 @ Zone 4 @ 
@ Vergelegen @ Pomfret Zone 1 @ 2% 1.5% of 0.5% of 3% of 
Stress for 6 months for 6 months of Vergelegen Vergelegen Vergelegen Pomfret 
Year  period (mm) (mm) (m/d) (m/d) (m/d) (m/d) Average 
20% W  40.36 58.872 0.000004 0.000003 0.000001 0.000010 0.000005 
20% S  252.936 220.216 0.000028 0.000021 0.000007 0.000036 0.000023 
This scenario was modeled and the piezometric heads from selected boreholes are 
graphically represented by figure 28 and the contoured water levels for selected stress 
periodes in figure 29.  
 
Figure 28. Correlation between observed (dotted line) and modeled water levels (solid lines) for the 40 
stress periods representing 1994 to 2014 for Scenario 3 conditions. Water level elevation 
on vertical scale with the days on the horizontal scale. 
Note: G36667 redbrown, G36670 light grey, G36673 light green, G36677 pink, G36682 dark 
green, G36684 blue, G36693 black and G36694 orange. 
53 
 
1. Stress periode 31 -08/09summer (year 0+5.5) 3. Stress periode 39 -12/13summer (year 0+9.5) 
2. Stress periode 32 –2009 winter (year 0+6) 4. Stress periode 40 -2013winter (year 0+10) 
Legend 
50
40 Positive water level fluctuation indicating an 
30 increase in water levels i.r.t. initial (1991) 
20 water levels. 
10  
0  
-10 Zero water level fluctuation indicating an 
-20 increase in water levels i.r.t. initial (1991) 
-30 water levels. 
-40  
-50  
-60 Negative water level fluctuation indicating 
-70 an increase in water levels i.r.t. initial 
-110m (1991) water levels
 
Figure 29. Selected stress periode draw down (meter below initial heads) results from Scenario 3 of 
the model.
Results: (Figures 28 and 29) 
• Water levels in resource unit 1 would decline regionally with 10 to 20 m (i.r.t. 1990 
water levels).  
• At Grassbank water levels would decline 40 to 50m (i.r.t. 1990 water levels) and 30 m 
at Blackheath. 
• There would be a 10 m water level recovery compared to the water levels of 2004. 
• In resource unit 2 water levels would remain constant (i.r.t. 1990 water levels). 
In resource unit 3 water Ievels would remain constant (i.r.t. 1990 water levels). 
54 
 
6.14.4. Scenario 4 (No abstraction with average precipitation) 
• Water abstraction for the periode 93 to 2003 is as estimated in Table 21.  
• Abstraction from 2004 to 2014 is assumed to have stopped or 0 M m3/annum. 
• Precipitation is assumed to be the average as calculated from the rainfall 
measurements at 50.5 mm and 73.6 mm in winter and 316.2 and 275.3 mm in summer 
at Vergelegen and Pomfret respectively. The recharge was then calculated as 
assigned to the different zones ranging from 0.25 mm (lowest) to 8.3 mm (highest) as 
in table 20. The precipitation was then allocated to the different zones (figure 20) with a 
6 months time lag as follow. 
Precipitation Recharge Recharge Recharge 
@ Recharge Zone 2 @ Zone 3 @ Zone 4 @ 
Vergelegen Precipitation Zone 1 @ 2% 1.5% of 0.5% of 3% of 
Stress for 6 months @ Pomfret for of Vergelegen Vergelegen Vergelegen Pomfret 
Year  period (mm) 6 months (mm) (m/d) (m/d) (m/d) (m/d) Average 
Av W  50.5 73.6 0.000006 0.000004 0.000001 0.000012 0.000006 
Av S  316.2 275.3 0.000035 0.000026 0.000009 0.000045 0.000029 
 
 
Figure 30. Correlation between observed (dotted line) and modeled water levels (solid lines) for the 40 
stress periods representing 1994 to 2014 for Scenario 4 conditions. Water level elevation 
on vertical scale with the days on the horizontal scale. 
Note: G36667 redbrown, G36670 light grey, G36673 light green, G36677 pink, G36682 dark 
green, G36684 blue, G36693 black and G36694 orange. 
 
With this no abstraction and average precipitation scenario water levels would recover to their 
original levels (1990).  
 
55 
 
1. Stress periode 31 -08/09summer (year 0+5.5) 3. Stress periode 39 -12/13summer (year 0+9.5) 
2. Stress periode 32 –2009 winter (year 0+6) 4. Stress periode 40 -2013winter (year 0+10) 
Legend 
50
40 Positive water level fluctuation indicating an 
30 increase in water levels i.r.t. initial (1991) 
20 water levels. 
10  
0  
-10 Zero water level fluctuation indicating an 
-20 increase in water levels i.r.t. initial (1991) 
-30 water levels. 
-40  
-50  
-60 Negative water level fluctuation indicating 
-70 an increase in water levels i.r.t. initial 
-110m (1991) water levels
 
Figure 31. Selected stress periode draw down (meter below initial heads) results from Scenario 4 of 
the model.
Results: (Figures 30 and 31) 
• By 2010 water levels would have recovered substantially (i.r.t. 1990 water levels) in all 
areas and by 2014 regional water levels would have recovered fully to the levels prior 
to intensive abstraction (1990 levels) 
• Only in areas proximate to intensive abstraction Grassbank and Blackheath water 
levels would still be 10 m lower (i.r.t. 1990 water levels). 
56 
 
6.15. Scenario predictions summarized 
 
The calibrated model was used to test the following 10-year future scenarios of abstraction 
and recharge in order to assist in decisions regarding management of abstraction from the 
aquifer system. 
Table 22. Scenario predictions and management decision from the groundwater model. 
 Recharge Abstraction Water level reaction by 2014 (irt 1990 levels) Management Decision 
(mm/a) Mm3/a 
Scenario 1 0.4 - 1.5 winter 16.1 Decline regionally 20 to 30 m  Not acceptable 
1.5 - 8.3 summer Proximate to irrigation 60 to 110m declined 
Scenario 2 0.4 - 1.5 winter 11.1 Decline regionally 10 to 20 m  Acceptable with strong 
1.5 - 8.3 summer Proximate to irrigation 30 to 60m declined abstraction control. 
Scenario 3 0.2-1.2 winter 11.1 Decline regionally 20 to 30 m  Acceptable with strong 
1.2-6.7 summer Proximate to irrigation 60 to 110m declined abstraction control. 
Scenario 4 0.4 - 1.5 winter 0 Full regional water level recovery Acceptable 
1.5 - 8.3 summer Proximate to irrigation 10 m declined unconditionally 
The model demonstrated that rates as specified by scenario 2 can be sustainable abstracted 
from the system at average recharge and that these abstractions would still be sustainable at 
20 % less than average recharge as in scenario 3. Management of abstraction of the aquifer 
was consequently structured to ensure that abstraction would not exceed the sustainable 
yield of 11.1 M m3/a. 
6.16. Limitations of the model 
• Water level increase is modeled in the area north of the BIF, which could be as a result 
of declines prior to the initial heads assumed for that area. 
• In the area proximate to the Molopo River modeled water levels are lower than 
observed water levels. However these water levels recover substantially after periods 
of abstraction. 
• In the Belvedere area elevated water levels are modeled to increase contrary to 
observed declines. 
57 
 
7. REGULATION OF WATER USE 
7.1. Water use conflict and its economic implications. 
The competition for the groundwater resource and its rapid deterioration resulted in conflict 
between users. At first the environment had unlimited access to the water resource with only 
natural events like droughts impeding availability. Drilling technology evolved to make the 
resource accessible to domestic, stock watering, small scale gardening and ultimately 
irrigation. The mentioned number of factors lead to irrigation in the area impeding on both 
environmental; domestic, stock watering, small gardening and lately also basic human needs 
for municipal use.  
 
Plate 3. Abstraction points on 2 farms from the same fracture complex separated only by the farm boundaries. 
The Nash equilibrium (John Nash) popularised by the film “A beautiful mind” 2001 entails the 
best possible action for all players to arrive at the dominant strategy. The dominant strategy 
for all other users would be to pressurise and ensure that the irrigators consume less water. 
The irrigation water use developed unregulated and with large capital investment. The 
estimated capital investment by water users in terms of boreholes, pipes, electricity, pipes, 
dams, irrigation equipment was R52 million by 2002 (Estimated by Mr G. Stoltz Letter 2002). 
The estimated potential income from irrigation crops is tabled in Table 23 and compared to 
stock farming. With big capital investment and high potential income the dominant strategy for 
58 
 
irrigators would therefore be to irrigate as big possible areas to generate profit and ensure 
income on capital investment. 
Table 23. Estimated potential income form irrigation of the crops in the Tosca area compared to 
stock. 
 
Potential Input Cultivation Water cost Profit/ Loss Profit/  
 Surface yield Price Income Cost per Input Cost  Water use (@R0.36 /ha) with water Loss (R 
Crop (ha)  (T/ha) (R/T) (R/ha)      Income (R)      h  a  (R)   (R)            (m3/ha) ® cost (R)    per ha) 
1             2  3 4 (3*4) 5   (2*5) 6 7 (2*7) 8 9 (2*10) 11 (6-8-11) 12 13 
Maize         775  12.00       800       9,600     7,440,000       7,200     5,580,000       7,500     2,092,500       -232,500       -300  
Peanuts         197  3.50    3,903     13,661     2,691,119       7,000     1,379,000       7,000        496,440        815,679     4,141  
Paprika         306  2.00  10,000     20,000     6,110,000       1,500        458,250     12,000     1,319,760     4,331,990   14,180  
Potatoe           68  30.00    2,000     60,000     4,050,000     57,000     3,847,500       7,000        170,100          32,400        480  
Wheat         235  6.50    1,100       7,150     1,680,250       6,000     1,410,000       7,500        634,500       -364,250    -1,550  
Lusern           93  19.00       650     12,350     1,142,375       5,600        518,000     11,400        379,620        244,755     2,646  
Totals/ 
Average 
cultivation      1,673  12.17    3,076     37,419   23,113,744     14,050   13,192,750       8,733    5,092,920     4,828,074     2,887  
                       
cattle  400,000  0.015 10000        150   60,000,000  35  14,000,000  2.19      315,360   45,684,640        114  
            
Bekker A., (2003). Kostegids vir besproeiing in die Griekwaland Wes Kooperasie gebied. GWK Douglas. 
                                                                                                                                                                                                                                                                      
 
Comparing cattle production in the area of interest at 4000 km2 or 400 000ha one unit large 
stock can be sustained at average on 10 ha (Department Agriculture North West). Therefore 
40000 stock of which approximately 24 000 can be sold annually at R1900 per unit the 
potential income is R45.6 million from stock farming. This is profit at a low rate of R114 per ha. 
The total potential income of R23.1 million on the 1673 ha is high, but the high cultivation and 
water pumping cost reduce the net profit to only R4.8 million at an average of R2887 per ha. 
The question would be if this irrigation income utilizing 99% of the water, justifies the risk 
water loss risk (boreholes drying up) it poses to the stock industry with the potential income of 
R45.6 million annually. 
Decisions regarding water rights and authorization must therefore take into consideration all 
factors. The potential irrigation income to be generated by both all sectors of water use and 
the capital investment made by these water users to ensure their livelihood. All efforts should 
be made to ensure that the authorized use is managed appropriately not to impact negatively 
on the sectors where profits cannot justify drilling replacement holes exc. 
 
59 
 
 
Plate 4. Carting of water and re-drilling of a dried up borehole on the farm Quarreefontein after the water level 
declined an estimated 60 m due to proximate irrigation abstraction. 
7.2. Water use authorization 
The registered water use from WARMS and observed irrigation development indicate a 
surface area of 2076 ha requiring 12.2 million m3 of water. As reported the volume registered 
on WARMS seem unrealistic considering crop demand. Recalculation of the use considering 
crop demand sum to 18.1 million m3/annum. 
The reserve determination (Godfrey 2002) delineates the area into 3 resource units at 
different status of impact. It was decided that in the short term the resource rather be 
managed in as a unit, to ensure consistent actions against all users in the community 
regardless of the specific status in the resource unit. This would imply that the sustainable 
abstraction from the resource is estimated at 11.1 million m3 per annum. The aim of actions 
would therefore be to reach this volume in the short term. 
7.2.1. Termination of reserved water use rights. 
A number of users registered use not developed yet in order to reserve water rights for future 
use. The volumes registered by these users was cut back to general authorization applicable 
60 
 
in this area. This effectively reduced the potential development of registered use of 2.6 million 
m3 (or 247 ha) to 0.6 million m3 of water under general authorization. 
7.2.2. Termination of unauthorized water use. 
The section 35 processes (NWA) verification of existing lawful use was used to verify 
registered and actual water use in the area. After potential unauthorized irrigation use was 
identified from February 1999 and March 2002 satellite images (See appendix 7) the 
prescribed letters were dispatched to these users requiring them to respond by applying for 
verification of the legality of their water use. 
Their response was evaluated by the Regional Water Use Authorization Committee on the 9 
the December 2002. Table 24 is a summery of the recommendations from this committee. 
The legality of use of 15 users was questioned. Six users could supply evidence that their use 
should be considered authorized. The remaining 9 users (red) were directed to reduce their 
use with effective dates during March 2003. Following these directives 2 users supplied 
information and directives issued against them were cancelled. 
The result of this action would be a total reduction of approximately 251 ha in surface irrigated 
or 3 .7 million m3 in volume abstracted from the resource.  
61 
 
 
Table 24. Suggested actions against users following section 35 verification. 
Correct New Sat Image 
VOLUME Date Farm General Total volume permitted Sat Image Mar 2002 Remove 
Name user REG NR REG bought Farm Area Auth Irri crop factor  use RU Jan 1999 (Ha) ha Suggested actions  
M. Theron 25001514 277900 1997 Millbank 428.5 25710 50 404000 25710 1 No 50 45 Cut back to GA. Directive issued 5 Ha  
Fanie Griesel 
Trust 10082527 200000 2000 Belvidere 1096 65760 40 456000 65760 1 No 25 13 Cut back to GA. Directive issued 12 Ha  
Total use transferred from Forres. May 
Emtron Bdy 10081216 335650 1999 Grassbank 785.8057 47148 55 520500 520500 1 7 50 0 continue  
No GA in D41C, Cut back to 0. Directive 
C.E. le Roux 25007117 152100 2000 Westward Ho 1892.43 0 60 666000 0 1 No 60 60 issued.  
Cut back to GA. Terminate current 
License arrangement. Enforce directive 04/2002. 
P Haasbroek application 0 2001 Marlborough 713.6 42816 50 375000 42816 1 No 50 45 New Directive issued 5 ha  
J.J. Hayward 25008679 282900 1997 Forres 1590.975 95458 30 441000 95458 1 No 30  14 Cut back to GA. Directive issued. 16 Ha  
The use registered as GA on Blanco farm. 
J.H. Fourie 10081323 255400 1988 Hurstpark 2494.751 149685 60 440000 60240 1 40 60 0  No action  
Remove 30 ha, rest legal. Directive 
Mr. P.W. Beyer 10081234 798200 2003 Harcourt 1241.4 74484 140 1174000 439000 1 30 60  30 issued.  
Leniesdeel 
Trust (Jan 
Fourie) 10081350 655100 1995 Harcourt 620.7 37242 120 935000 777500 1 106 146  40 Remove 40 ha, rest legal. Directive issued  
Hulp Alleen Cut back to GA. Considered information. 
Familie Trust 25006010 95850 2000 Genade 471 28260 18 130500 130500 3 No 18  0 Declared as existing legal use  
P.A. Cut back to GA. Considered information. 
Theunissen 10081243 182400 1998 Nokani 293.4542 17607 30 225000 225000 3 No 30  0 Declared as existing legal use  
E.C. 
Grobbelaar 10081369 484060 1992 Robyn 2254.6 135276 66 682200 682200 3 52 52  0 All legal no action  
Mr. F.J. 
Hamman 10081314 66570 1994 Sentac   0 24 231700 231700 3 19.8 28.3  4 Remove 4 ha, rest legal  
Motivations justify planned to irrigate area, 
Mr. P.E. Kriel 10081261 89180 1999/10/01 Millbank 856.5315 51392 17.5 124250 124250 3 6 15  0 quotations supplied, no action  
Moved irrigation, Remove registered use 
Mr. F. Barnard 10081289 383750   Woodborough 1551.1 93066 50 555000 444000 NA 40 50  0 from Elchester  
  4259060 Volume Reduced  3495516 7360150 3864634T otal 192 2726.3 251H a reduced  
   Volume Reduced RU1 3384516 5411500 2026984 1 183 441 247H a reduced RU1  
   Volume Reduced RU3 little 1393650 1393650 3 118 193 4H a reduced RU3  
 62 
7.2.3. Consideration and authorization of new water use. 
Considering the depleted state of the resource new water use applications were considered with 
caution. To ensure equitable access to the resource and the depleted state of the resource it 
was decided that restricted authorization be permitted. All new water use applications were 
restricted to the general authorization applicable to each catchment. Table 25 summarize the 
volumes water users applied for and the volumes allocated. 
Table 25. General authorization on license applications and its effect. 
Area for Effect of 
Farm General Volume Suggested maize allocation 
Name Farm Catch Date Area Auth applied auth (ha) RU from RU 
G I Rossouw Harcourt D41D 10/12/2001 620.7 37242 30500 37242 5 1  
P J Haasbroek Marlborough D41D 13/01/2002 713.62 42817 750000 42817 6 1  
W H Simmons La Rochelle D41D 02/08/2002 856.53 51392 181200 51392 7 1  
G H Stolz Willarie D41D 10/06/2002 1027.85 61671 147000 61671 8 1  
D.J. Marais Rouwkoop D41C 10/3/2003 1426.8 0 85608 0 0 1  
A. van Zyl Clearstream D41D         0 0 1  
JAS Simmons Tennant D41D 3/10/2003 994 59640 45600 45600 6 1 201480 
SG Griesel Monti Piano D41D 26/11/2002 300 18000 225000 18000 2 2  
Zenith Ranch Forres D41D 10/12/2004 4305 258300 640000 258300 34 2  
Rose Kokomeng D41D 10/12/2005 1135 68100 600000 68100 9 2 344400 
Pretorius Quareefonein D41D 14/09/2001 1284.95 77097 375000 77097 10 3  
P E Kriel Millbank D41D 16/07/2002 428.15 25689 110250 0 0 3  
I de Beer Nokani D41D 05/09/2002 1029 61740 180000 61740 8 3  
I de Beer Koedoeskop D41D 05/09/2003 1126 67560 180000 67560 9 3  
K. van der Heever Deelfontein D41D 10/12/2002 1713 102780 146700 102780 14 3  
Centwise Nokani D41D 3/10/2003 1240 74406 375000 74406 10 3 383583 
                      
        17580 969192 4041358 929463 124    
 
By applying this principal the these new license applications would result in authorization of only 
977223 m3 in total or 180 ha in surface area to be irrigated.   
 63 
7.3. Effect of NWA water use authorization on water use. 
 
The net result of these water use regulation actions can be summarized as follow:  
Description Irrigation area Volume (million 
(Ha) m3/a) 
Registered irrigation surface and volume 2076 18.2 
Termination of reserved use -260 -2 
Termination of unauthorized use -451 -2.0 
New water use authorization 124 0.93 
Total irrigation areas after NWA reduction processes 1489 15.13 
The resource is still over allocated by 4 million m3 of water annually. 
7.4. Implementation restriction on authorized water use. 
The registration of use from the area was verified and use by 15 users was requested to 
motivate that they should be considered as authorized through the section 35 processes. Of 
these 15 users the use of 7 was reduced or stopped. The net result is termination of 
unauthorised use of 251 ha of irrigation or abstraction of 4 M m3/a. 
Application for new water use was from considered and use up to General Authorization was 
recommended. The net result is authorization of an additional 124 ha or 0.93 M m3/a. Therefore 
the total future use is between 15 and 16 Mm3/a. 
A model of the resource was constructed with abstraction, recharge and water levels the last 10 
years (1994 to 2004) as input. Prediction from this model indicate that the water levels would 
continue to decline at this abstraction rate of 15 to 16 Mm3/a. The resource is still over allocated 
by 40%. A restriction of 40% on authorized use is needed to reduce the abstraction from the 
resource to 11 M m3/a. The current estimated sustainable volume available from the resource is 
11 M m3/annum.  
The above scenarios were discussed with the water users and they agreed that water 
restrictions could relieve stress on the aquifer. They requested that economic viability of 
irrigation units be ensured by effecting 40% restrictions on use exceeding 10 ha or the volume of 
75 000 m3/a. 
The schedule of registered use in Table 26 indicating the volume to which each user would be 
restricted. The 40% restrictions would effectively reduce use to approximately 10 Mm3/a. 
For these restrictions to be effective and to measure the response by the aquifer these 
restrictions would have to be imposed for 5 years (to be effective as from water year April 2004 
to April 2009). These measures could be reconsidered when compulsory licensing is 
implemented. 
 64 
The restrictions would be implemented in line with Schedule 3 Section 6 of the National Water 
Act. 
A flow meter combined with a volume recorder on each borehole is installed to record the 
volume abstracted/irrigated or a bulk meter is installed to measure the total volume irrigated. 
The user would log the measurement on a monthly basis and supply this measurement on a 
monthly basis to the responsible authority. 
The responsible authority would inspect both the surface/ crop areas and the measuring device 
by August and April annually and enforce the above i.t.o. Schedule 3 section 6 items 4,5. 
The responsible authority should have the right to terminate the use of users not complying with 
restrictions or its enforcement i.t.o. Schedule 3 section 6 items 4,5. 
Table 26. Authorized user with registered volume and the volume restricted.  
Not 
 developed at date= 625983 83 
Use 
Volume exceeding Total 
Title deed Registered 75000 restricted 
Reg no: Name Farm Description number (m3/a) (m3/a) use (m3/a) 
25009473 F.V.Z. Engelbrecht Albury farm no. 171 portion no. 2 T2601/1994 398000 323000 268800 
Ascot farm no. 184 portion no. 0-remaining 
10081001 Tosca Trust extent T302/2000 187000 112000 142200 
10082527 Fanie Griesel Trust Belvidere     Farm No. 157 T63/2000 65760 0 65760 
25021949 W.H. Simmons Belvidere farm no. 157 portion no 1 T3027/2002 51393 0 51393 
Carroll Family Blackheath farm no. 90 portion no. 0-remaining 
10081225 Enterprises  extent T1802/2001 1735000 1660000 1071000 
25017213 J.H. Fourie Blanco Farm no. 173 portion no. 1 T3321/1999 64543 0 64543 
Brenton farm no. 180 portion no. 0-remaining 
10081378 J.C.C. Grobbelaar extent T1352/1979 69954 0 69954 
25007821 Avon Trust Brentwood Farm No 181 Portion 1 T4173/2000 74112 0 74112 
Brentwood farm no. 181 portion no. 0-remaining 
10081252 Eben Du Toit extent T215/1996 74112 0 74112 
10081412 J.P. van den Berg Buttermere farm no. 1017 portion no. 0 T1913/1998 1035000 960000 651000 
25007698 Clearstream Trust Clearstream  Farm No. 168  Portion No. 0 T493/2000 585000 510000 381000 
25021976 K. van der Heever Deelfontein Farm no. B215 remaining extent T857/1986 102780 27780 91668 
10081298 P.M. Fourie Elchester farm no. 174 portion no. 1 T1283/2001 144000 69000 116400 
Johan en Esta Theron 
25006831 Familie Trust Forres T489/2000 302400 227400 211440 
10081190 W.C. Kriel Forres farm no. 216 portion no. 2 T285/1989 335950 260950 231570 
25008679 J.J. Hayward Forres farm no. 216 portion no. 5 T1467/1997 95458 20458 87275 
25021280 Zenith Ranch (Pty. Ltd) Forres farm no. 216 portion no. 8 T1663/2000 258300 183300 184980 
25000310 Leamy Family Trust Forrest Hall farm no. 182 portion no. 0 T2109/2001 153870 78870 122322 
10081181 H.M. Joubert Gannalaagte farm no. 6 portion no. 0 T2667/1996 90250 15250 84150 
25017972 Hulp Alleen Familie Genade Farm 209 Portion 0 - Remaining extent   130500 55500 108300 
 65 
Grassbank Farm No. 187 Portion No. 0-
25021412 Fransua Stolz Trust Remaining extent T742/1995 1202500 1127500 751500 
10081216 Emtron Bdy Grassbank farm no. 187 portion no. 2 T1725/1999 367500 292500 250500 
Harcourt farm no. 185 portion no. 0-remaining 
  K. van der Heever extent T603/1968 37242 0 37242 
Harcourt farm no. 185 portion no. 0-remaining 
New Owner Beyer Trust extent T1466/2003 360000 285000 246000 
10081350 Leniesdeel Trust Harcourt farm no. 185 portion no. 1 T2840/1995 655100 580100 423060 
Hastings farm no. 142 portion no. 0-remaining 
25003638 M. Hamman extent T931/1988 35000 0 35000 
10081323 J.H. Fourie Hurstpark  Farm No. 170   T212/1988 440000 365000 294000 
25002675 S.G. Griesel Kokomeng farm no. 178 portion no. 2 T148/2001 18000 0 18000 
  Rose  Kokomeng    68100 0 68100 
Koodooskop farm no. 206 portion no. 0-
25021930 I de Beer remaining extent T1715/2001 67560 0 67560 
Libertas-Zand vloed farm no. 218 portion no. 1-
25004753 A.C.J. Du Plessis remaining extent T1589/1983 79800 4800 77880 
Marlborough farm no. 167 portion no. 0-
25021921 P J Haasbroek remaining extent T2010/2001 42818 0 42818 
Millbank farm no. 188 portion no. 1-remaining 
10081261 P.E. Kriel extent T635/1994 124250 49250 104550 
25001514 M. Theron Millbank farm no. 188 portion no. 2 T2209/1999 25710 0 25710 
10084865 Sandtrap Boerdery Millbank farm no. 188 portion no. 3   525000 450000 345000 
  I de Beer Nokani    67560 0 67560 
Nokani Farm No. 208  Portion No. 2-Remaining 
25018203 F.J. Hamman extent T2693/1997 15420 0 15420 
Nokani farm no. 208 portion no. 3-remaining 
10081243 P.A. Theunissen extent T1015/1988 225000 150000 165000 
25022573 Centwise BK Nokani farm no. 208 remaining extent T191/1988 85656 10656 81394 
25018196 Pretorius Quareefontein  Farm No. 212 Portion No.1 T2665/2001 77097 2097 76258 
25007028 J.H. Nieuwoudt Quareefontein farm no. 212 portion no. 2 T4582/1998 145000 70000 117000 
25021404 Fransua Stolz Trust Rhodes Farm No. 186 Portion No. 0 T1421/2000 450000 375000 300000 
Senlac farm no. 143 portion no. 0-remaining 
10081314 F.J. Hamman extent T350/1977 212800 137800 157680 
25003503 W.H.A. Hamman Stilton farm no. 189 portion no. 22  T2278/1996 127000 52000 106200 
Tennant farm no. 152 portion no. 0-remaining 
25020726 JAS Simmons extent T648/1967 45600 0 45600 
10081387 D.B. Grobbelaar Thornthwaite farm no. 179 portion no. 0 T973/1978 482000 407000 319200 
Thornwick farm no. 175 portion no. 0-remaining 
10081163 Kwagga Molopo Trust extent T2787/2002 121600 46600 102960 
10081430 A.M. Steyn Vaalboschoek Farm 227 Portion 1 T452/1995 114000 39000 98400 
25021912 G H Stolz trust Willarie 1019 portion no. 0   61671 0 61671 
10081289 F. Barnard Woodborough farm no. 159 portion no. 0 T374/1987 487500 412500 322500 
25007732 Avon Trust Woodborough farm no. 159 portion no. 1 T1115/2003 120000 45000 102000 
10081369 E.C. Grobbelaar Wynberg farm no. 165 portion no. 1 T1046/1977 612000 537000 397200 
       13451866 9942311 9474942 
 
 66 
During September 2004 the proposed restrictions were approved by the Director General and 
publication of the notice in the Government Gazette as attached in Appendix 13 would give the 
responsible authority powers to implement these restrictions. 
7.5. Termination of general authorization. 
The borders of the surface water drainage D41D and D41 C catchments transect the geological 
and aquifer borders of the Tosca Molopo dolomite aquifer. The general authorization of 60 
m3/ha/a applicable to D41D and not to D41C created problems in terms that potentially every 
landowner in the area can claim this right. It was therefore requested that this authorization be 
terminated. Termination of this General Authorization came into effect by the publication of 
REVISION OF GENERAL AUTHORISATIONS IN TERMS OF SECTION 39 OF THE 
NATIONAL WATER ACT, 1998 (ACT NO. 36 OF 1998) in the Government Gazette on 26 March 
2004. This would ensure a uniform water use authorization. 
 67 
8. ESTABLISHMENT OF A WATER USER ASSOCIATION 
 
Sandoval (2004) concluded that water management requires not only a lot of “water wisdom”, 
but also “management wisdom”. Complex problems such as groundwater misuse will never be 
properly faced with participation processes that are merely a consultative effort (Sandoval 
2004). Only a structure that is part of the problems can be committed to provide the solutions. 
The NWA (1998) provides for a suitable structure in the form of a Water Users Association. 
Water users in the community initiated the establishment of a water user association. A pilot 
committee was established during January 2001 with Mr. Gert Stoltz as chairman and Mr. 
Lennox Louw as vice chairman. There was a prominent division within the committee between 
the irrigation water users and the stock watering users. The stock watering community 
requested that the pilot committee be re-elected on the grounds that it is biased and advancing 
irrigation interest. DWAF persisted with this committee on the grounds that it did not have any 
powers in water regulation and management. The role of the pilot committee is solely to compile 
a draft constitution for the WUA to the Minister (DWAF) to establish the WUA. 
The chairman commenced with compiling this draft constitution, but with the above reservations 
DWAF decided to appoint a consultant to proceed. Me. Erika de Villiers was appointed and after 
a number of consultative meetings this draft constitution was submitted for approval by Oct 
2002. A number of improvements to the constitution followed before approval of the constitution 
by May 2004. 
After elections of a committee and submittance of a business plan the WUA will commence its 
activities. This WUA would enhance water use from the aquifer. The area of responsibility of the 
WUA is reflected in Appendix 1 and is estimated at 200 000 ha with 53 registered irrigation 
water users, a domestic bulk water supplier, approximately 200 stock water users. 
The roles and responsibilities of the different water institutions are reflected in figure 31. The 
institutional capacity is greatly enhanced in relation to the current direct interaction between 
individual water user and a national government department. This would enhance water user 
and resource protection. 
On the 16 July 2004 the Minister of Water Affairs approved the establishment of the WUA and 
Forestry with the publication of its establishment in the Government gazette as reflected in 
Appendix 14. 
 
 68 
Figure 32. Roles and responsibilities of the different water institutions. 
DWAF regional office CMA responsibility 
Kimberley responsibility  
Determine the Reserve Issue WUA with schedule of use 
Determine resource potential and users 
Register all water use Set conditions for new water use 
Verify registered water use Support WUA in intervention with 
Authorize new water use individual users 
Compile a schedule of use Enforce measures to contain water 
Determine measures to contain use use like restrictions 
 
Extend of Tosca Molopo 
operation 
 Land of ±200 000ha valued at  
±R200M 
Developed irrigation of 2000 ha 
valued ±R52M 
Stock valued ±R40M 
Monitoring network of 100 
boreholes 
Schedule of 53 registered irrigators 
Water resource with estimated 
capacity 1600 ha irrigation or 11.1 
M m3 
39 monitoring boreholes valued at 
±R1M 
Individual user Tosca Molopo WUA 
responsibility responsibility 
Clarify allocated volume and Compile a business plan 
authorization/ use conditions Communication with individual 
Plan annual water use activities to water users 
comply with all conditions associated Issue water use to individual users 
with water use consistent with schedule of users 
Establish a water-monitoring plan to Plan, police and monitor water use 
measure use, water levels, and activities of individual users 
precipitation Issue directives to individual users 
Report water use to the WUA not complying with plan 
annually Report total water use to CMA 
Payment of all water use charges Establish a resource water level 
monitoring program 
Initialize additional water resource 
studies to determine resource 
potential 
Investigate and solve individual 
water users complaints 
Contribute to new water use 
authorization 
 
 69 
9. WATER USE ENFORCEMENT 
 
At establishment the WUA indicated that cooperation of water users i.r.t. compliance would be 
problematic. This was recognized by DWAF as the past 4 years at Tosca indicated that most 
users did not believe that there would be actions to enforce compliance. By December 2004 6 
water users were identified as users exceeding there entitled volume. New directives were 
issued directing these users to cut back those crops contributing to them exceeding their entitled 
volume by January 2005. Inspections regarding their compliance to these directives in March 
2005 revealed the information tabled in table 27. 
 
Table 27. Water users exceeding water entitlement during 04/05 season. 
User Property Authorized Estimated actual 
use m3 use (SAPWAT) m3 
Centwise Nokani 203 85656 180000 
C.E. le Roux Westward Ho 0 375000 
S.C. Bosch Marlborough 42818 200000 
167 
P.W. Beyer Trust Harcourt 360000 450000 
M. Theron Millbank 25710 240000 
Fanie Griesel Trust Belvidere 65760 200000 
  579944 1645000 
 
After careful consideration and discussions with the Legal Division it was decided that there was 
confusing evidence that transfers took place in the Millbank case and that there was compliance 
in the Harcourt case with late removal of crop. Enforcement actions were conducted against the 
remaining 4 users planned at mid May 2005 when crops were at the end of irrigation with the 
least loss in income to the users in mind.  
The enforcement actions included: 
• Removal of pumps from irrigation production boreholes, 
• Sealing of irrigation production boreholes. 
• Recovery of costs of the operations from the respective water users. 
Water users entitlements were restored after payment of costs, signing and agreement with 
WUA regarding future compliance and acceptance of entitlement or agreement that existing 
legal avenues would be taken regarding entitlement. 
 70 
 
Plate 5. Removal of pump equipment from borehole.  
 
Plate 6. Sealed borehole to enforce compliance.  
 71 
10. CONCLUSION 
 
1. The Tosca Molopo aquifer is a combination of a silty primary aquifer with low yield and 
high storativity underlain with a fractured/ carstified dolomite aquifer with high yield and 
low storativity.  
2. Within the primary aquifer coarse-grained sand and gravel layers form high yielding 
zones. Areas with carstified dolomite are limited to vertical to sub vertical fault lines and 
dolerite intrusions. Development of carst is also enhanced where there are chert and 
shale layers within the dolomite. 
3. Recharge to the aquifer is low at an estimated 0.5% of the average annual precipitation. 
Along fault zones, river courses and in areas where the water level is elevated (less than 
10 m) recharge is enhanced to an estimated 8% of average precipitation. The average 
recharge to the aquifer is estimated at 2% of annual precipitation or 7.8 mm per annum. 
For GM purposes the average of 1.75% of MAP or 9.7 mm/ of MAP was used. 
4. Abstraction for irrigation purposes from the aquifer has increased over the last 10 years 
leading to declining water levels. This abstraction is unsustainable and is endangering 
primary water use (human, stock watering), the environment and the aquifer. Water levels 
have declined 10 to 20 m regionally and up to 60 m proximate to intensive irrigation. 
5. It is estimated that the potential profit from stock farming is R114 /ha. Irrigation water 
users have invested more that R52 million towards boreholes, pumps, electricity, and 
irrigation equipment. The average calculated profit for irrigation in this area with the 
current crop profile is R2887 / ha. It is calculated that a loss can be expected from wheat 
and maize cultivation whilst up to R14 000/ ha profit can be expected from paprika. 
6. The volumes of 15000 to 25000 m3/km2/a or 150 to 250 m3/ha as indicated on the 
Harvest Potential Map (Seymour and Seward 1996) cannot be harvested in this area. 
With the recharge of 7.8 mm/a the harvest Potential is rather 78 m3/ha/a. 
7. Irrigation water use is more than 99% of the water from this area. Human consumption 
and stock watering is less than 1% in this area. 
8. The 2003 high of 2067 ha or 16.1 Mm3 irrigation in this area is modeled as unsustainable. 
If this irrigation scenario is continued the water levels would decline 20 to 30 m and up to 
110 m proximate to irrigation by 2014. This would not only lead to dry boreholes and 
water shortage, aquifer depletion but also land subsidence and ultimately sinkhole 
formation 
 72 
9. If irrigation can be reduced by 40% to 1300 or 11.1 Mm3 water levels would stabilize at 
the current declined levels 2003. Limited further decline would take place even if below 
average precipitation is experienced. 
10. If irrigation use were stopped completely the water levels would recover fully by 2010 with 
only limited sinks of 10 to 20 m proximate to intensive irrigated areas. 
11. Registration and verification of water use in this area was conducted resulting in the 
reduction of use with 250 ha or 4 M m3/a. Registered water use in this area reflected only 
66% of the real volume abstracted from the aquifer. Individual users under registered and 
gross misuse of water by the majority of water users were taking place. 
12. Management of irrigation use can only be reached through a participative approach with 
a capacitated and informed structure like the WUA. Management of use and the aquifer 
should be by all users and based on the best available scientific information. 
 73 
11. RECOMMENDATIONS 
11.1. Local water management structure 
The Water Users Association needs to be established to ensure local management of the 
resource and use. It is the responsibility of DWAF to establish and capacitate the WUA. 
11.2. Abstraction control 
The responsible authority (DWAF or CMA) would issue the WUA with the allocation schedule 
(table 16). Abstraction control is the function of the WUA and specifically to ensure that all water 
use in their area of responsibility is planned and used according to the schedule. It is also their 
function to manage the water resource. 
The WUA need to compile its business plan with to reflect abstraction control, water resource 
management or other measures as prescribed. 
Abstraction can be monitored by implementing a system of firstly consultation and planning with 
each authorized user on the volume available for the water year starting in May of each year. An 
agreement should be reached to the area and crop this volume can irrigate. The water user 
must then report use to the responsible authority on a monthly basis. An example is attached as 
Appendix 11. 
The water use authorized in the area need to reduced. The water use for irrigation should be 
reduced to 40% of the authorized use for irrigation for the next 5 years from May 2004 to May 
2009. This use can be reconsidered if new information justifies that. 
11.3. Water resource monitoring network 
The effect of the abstraction on the aquifer needs to be monitored. Precipitation, water level and 
water quality, need to be monitored.  
Precipitation would be measured at the SAWS stations at Pomfret and Vergeleë. Additionally a 
rainfall collector, which would also measure the precipitation, was erected in the recharge area 
on the farm Quarrefontein. DWAF would be responsible for operation and maintenance of this 
collector. 
The water level monitoring network consists of a number of carefully selected boreholes based 
of the conceptual model and modeling results. Initially as many as possible boreholes were 
measured resulting in disturbed pumping water levels proximate to irrigation. Water level 
loggers were installed on 4 boreholes along the gradients of the system on boreholes G47608, 
G39685, G39687 and G39693 to log water levels each hour. At the other 38 boreholes water 
level measurements would be taken every six months during April and August. 
 74 
11.4. Recalibration of the model 
The current groundwater model could be enhanced with new information collected. The 
information collected above would be used to recalibrate the groundwater model every 2 year 
with new recommendations regarding abstraction to be made only after 5 years. 
11.5. New irrigation water use authorization 
No new water use should be considered for the new 5 years. Only if the water level information 
and recalibrated model suggest that the water levels recovering should new authorizations be 
considered. 
11.6. Risk of declining water levels 
There could be time delay for measures to stabilize water levels and eventually recover water 
levels.  
From the water level data it is possible to construct a map delineating areas at risk. Figure 32 
delineates the area from low risk to exceptionally high-risk areas due to water levels declining. 
The associated risks of ground subsidence, sinkhole formation and aquifer reduction could 
occur over the total area. It is more likely that these disasters would be limited to the high and 
exceptionally high-risk areas  
-25.60
Areas not classified due 
to lack of information
-25.70
Low risk areas
Expected regional water 
Vergelee level decline less that 10mWater level decline could 
be increased due to local 
abstraction
-25.80
Tosca Moderate risk areasExpected regional water 
level declines up to 25 m
-25.90 High risk areas
Expected seasonal and 
regional water level 
decline up to 50 m due 
to proximity to irrigation
Possible ground subsidance 
-26.00 and sinkhole formationExceptional High risk areas
Expected seasonal and 
regional water level decline 
exceeding 50 m due to 
proximity to irrigation
Possible ground subsidance 
-26.10 and sinkhole formation
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 24.50  
Figure 33. Risk areas based on water level declination data over the area. 
Measures to protect basic human need and other water use in these areas should be negotiated 
and the WUA should be responsible for implementation of these measures. 
 75 
12. REFERENCES 
 
1. Adams S., (2004), Groundwater recharge assessment of the basement aquifers of the central 
Namaqualand, Water Research Commission Report in preparation, WRC. 
2. Beekman H.E., Grieske A. Selaolo E.T. (1996). GRES: Groundwater Recharge studies in 
Botswana 1987- 1996. Botswana journal of earth science Vol3, Dec 1996. 
3. Bekker A., (2003). Kostegids vir besproeiing in die Griekwaland Wes Kooperasie gebied. 
GWK Douglas. 
4. Braune E., (2000). Towards comprehensive groundwater resource management in South 
Africa. IAH 2000 Conference proceedings: Groundwater Past Achievements Future 
challenges P7-17. 
5. Bredenkamp D.B., Botha, L.J. van Tonder G.J, van Rensburg H.J, (1995). Manual on 
quantative estimation of groundwater recharge and aquifer storativity. WRC TT73/95. 
6. de Villiers E., (2002),  Tosca Molopo water gebruikers vereniging, Konsep grondwet. DWAF 
internal  document. 
7. Duvenhage A.W.A., Meyer R., (1991). CSIR report EMI-C 91179, Geohydrological and 
Geophysical Investigation in the Tosca-Vergelee area, 1991. 
8. DWAF National Groundwater Database (NGDB); 
9. DWAF Regional Database (Kimberley) - data of groundwater and irrigation monitoring in the 
area during 2001 to 2003. 
10. DWAF report, GH2986.  Groundwater conditions in the Pomfret Mining Area – Molopo, 1967. 
11. Ellington R.G., Usher B.H. and van Tonder G. J., (2004) Quantification of the impact of 
irrigation on the groundwater resources underlying heavily irrigated areas, Water Research 
Commission Rep in preparation, WRC. 
12. Godfrey L, van Dyk G.S. du T., (2002). CSIR rep no ENV-P-C 2002-031, Reserve 
determination for the Pomfret_Vergelegen Dolomitic aquifer, North West Province, Part of 
catchment D41C, D, E, F.  
13. Jacobs K.L., Holway J.M., (2004). Managing for sustainability in an arid climate: lessons 
learned from 20 years of groundwater management in Arizona, USA, Hydrogeological Journal 
Volume 12 Number 1. 
14. Moseki M.C., (2001). Impact of Lead Zinc mining activities on groundwater resources in the 
Pering mine compartment, PhD Thesis, Univ Free State. 
15. National Water Act 1998, Act 36 of 1998. Republic of South Africa Government Gazette, Vol. 
398, Cape Town. 
16. Parken M., (1993). Micro Economics second edition, Addison Wesley publishing company. 
17. Sandoval R., (2004), A participatory approach to integrated aquifer management: The case of 
Guanojuato State, Mexico, Hydrogeological Journal Volume 12 Number 1. 
18. Schaffner B, Chen Y.Y.,. Kelepile T, Kinzelbach W., Carlson L and Mannathoko I., (2000). 
Scientific support for sustainable groundwater management: A modeling study in Botswana 
 76 
using environmental tracers. IAH 2000 Conference proceedings: Groundwater Past 
Achievements Future challenges P291-296. 
19. Smit, PJ., (1977).  Die Geohidrologie in the opvanggebied van die Moloporivier in the 
Noordelike Kalahari.  PhD Thesis, Univ Free State. 
20. Tredoux G., Clarke S., Cavè l., (2003). Feasibility of in situ groundwater treatment for low cost 
water supply. WRC project K5/1325,  
21. van Dyk G. S. du T., (1992). DWAF report, GH3767.  Grondwater ondersoek vir Suid-
Afrikaanse Weermag Pomfret, Distrik Vryburg. 
22. van Dyk G. S. du T., (1993). DWAF report, GH3813.  Geohydrological investigation for SADF 
Pomfret. District Vryburg, Drainage Region D410. 
23. van Tonder G.J., Bean J.A., (2003). Challenges in estimating groundwater recharge, 
Contribution paper for United Nations Educational, Scientific and Cultural organization 
(UNESCO). 
24. Wood W.W ,(1999). Use and misuse of the chloride mass balance method in estimating 
ground water recharge. Ground Water 37,1,2-3 
25. van Tonder G.J. and Xu Y, (1999). A guide for the interpretation of pumping tests and 
estimation of sustainable yields of boreholes in fractured rock aquifers. Technical report 
GH3927. Department of Water Affairs and Forestry. 
LIST OF APPENDICES 
 
 
 77 
Appendix 1 The Tosca Molopo area. 
 
 78 
Appendix 2 Aquifer tests 
G39684 
  FC-METHOD : Estimation of the  
sustainable yield of a borehole         
 
G39684         
                        Extrapolation time in years = (enter) 2 1051200 Extrapol.time in minutes   
 
                  Effective borehole radius (re)  = (enter) 51.97 51.97 Est.   re  From r(e) sheet 
 
 
              Q (l/s) from pumping test = 20.1 9.35E-05 S-late Change re 
 
  
          sa (available drawdown), sigma_s = (enter) 28         Sigma_s from risk  
 
Annual effective recharge (mm) = 0 28.00 s_available working drawdown(m) 
 t(end) and s(end) of pumping test =  540 8.96 End time and drawdown of test   
 
                   Average maximum derivative = (enter) 2.9 2.8 Estimate of average of max deriv    
 
                    Average second derivative  = (enter)   0.0 Estimate of average second deriv   
                Derivative at radial flow period = (enter) 1.89 1.86 Read from derivative graph   
  T-early[m2/d] = 168.15 Aqui. thick (m)   
T and S estimates from derivatives T-late [m2/d] = 109.59 Est.  S-late = 2.31E-03 
(To obtain correct S-value, use program RPTSOLV) S-late = 2.31E-03  S-estimate could be wrong   
          
BASIC SOLUTION         
  (Using derivatives + subjective information about boundaries)  Maximum influence of boundaries at long time   
(No values of T and S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow 
sWell (Extrapol.time) = 18.50 28.04 37.58 66.19 
Q_sust (l/s) = 30.42 20.07 14.98 8.50 
 
  Best case   Worst case 
 
Average Q_sust (l/s) = 16.70        
with standard deviation= 9.26        
 (If no information exists about boundaries skip advanced solution and go to final recommendation)   
 
 79 
 
G39669 
  FC-METHOD : Estimation of the  
sustainable yield of a borehole         
 
G36669         
                        Extrapolation time in years = (enter) 2 1051200 Extrapol.time in minutes   
 
                  Effective borehole radius (re)  = (enter) 47.79 #DIV/0! Est.   re  From r(e) sheet 
 
 
              Q (l/s) from pumping test = 5.3 2.69E-06 S-late Change re 
 
  
          sa (available drawdown), sigma_s = (enter) 30         Sigma_s from risk  
 
Annual effective recharge (mm) = 0 30.00 s_available working drawdown(m) 
 t(end) and s(end) of pumping test =  540 24.52 End time and drawdown of test   
 
                   Average maximum derivative = (enter) 15.8 15.8 Estimate of average of max deriv    
 
                    Average second derivative  = (enter) 0.0 0.0 Estimate of average second deriv   
                Derivative at radial flow period = (enter)   #NUM! Read from derivative graph   
  T-early[m2/d] = #DIV/0! Aqui. thick (m)   
T and S estimates from derivatives T-late [m2/d] = 5.30 Est.  S-late = 2.48E-03 
(To obtain correct S-value, use program RPTSOLV) S-late = 2.48E-03  S-estimate could be wrong   
          
BASIC SOLUTION         
  (Using derivatives + subjective information about boundaries)  Maximum influence of boundaries at long time   
(No values of T and S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow 
sWell (Extrapol.time) = 76.49 128.46 180.43 336.34 
Q_sust (l/s) = 2.08 1.24 0.88 0.47 
 
  Best case   Worst case 
 
Average Q_sust (l/s) = 1.02        
with standard deviation= 0.68        
 (If no information exists about boundaries skip advanced solution and go to final recommendation)   
          
 
 80 
 
G39691 
  FC-METHOD : Estimation of the  
sustainable yield of a borehole         
 
G39691         
                        Extrapolation time in years = (enter) 2 1051200 Extrapol.time in minutes   
 
                  Effective borehole radius (re)  = (enter) 46.52 46.52 Est.   re  From r(e) sheet 
 
 
              Q (l/s) from pumping test = 10 6.97E-04 S-late Change re 
 
  
          sa (available drawdown), sigma_s = (enter) 90         Sigma_s from risk  
 
Annual effective recharge (mm) = 0 90.00 s_available working drawdown(m) 
 t(end) and s(end) of pumping test =  540 23.65 End time and drawdown of test   
 
                   Average maximum derivative = (enter) 22.1 22.1 Estimate of average of max deriv    
 
                    Average second derivative  = (enter) 0.1 0.1 Estimate of average second deriv   
                Derivative at radial flow period = (enter) 4.45 4.45 Read from derivative graph   
  T-early[m2/d] = 35.53 Aqui. thick (m)   
T and S estimates from derivatives T-late [m2/d] = 7.15 Est.  S-late = 7.43E-03 
(To obtain correct S-value, use program RPTSOLV) S-late = 7.43E-03  S-estimate could be wrong   
          
BASIC SOLUTION         
  (Using derivatives + subjective information about boundaries)  Maximum influence of boundaries at long time   
(No values of T and S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow 
sWell (Extrapol.time) = 96.88 169.58 242.27 460.35 
Q_sust (l/s) = 9.29 5.31 3.71 1.96 
 
  Best case   Worst case 
 
Average Q_sust (l/s) = 4.35        
with standard deviation= 3.13        
 (If no information exists about boundaries skip advanced solution and go to final recommendation)   
          
 
 81 
 
G39693 
  FC-METHOD : Estimation of the  
sustainable yield of a borehole         
 
G39693         
                        Extrapolation time in years = (enter) 2 1051200 Extrapol.time in minutes   
 
                  Effective borehole radius (re)  = (enter) 37.13 37.13 Est.   re  From r(e) sheet 
 
 
              Q (l/s) from pumping test = 14.15 7.60E-05 S-late Change re 
 
  
          sa (available drawdown), sigma_s = (enter) 60         Sigma_s from risk  
 
Annual effective recharge (mm) = 0 60.00 s_available working drawdown(m) 
 t(end) and s(end) of pumping test =  1440 20.17 End time and drawdown of test   
 
                   Average maximum derivative = (enter) 5.9 5.9 Estimate of average of max deriv    
 
                    Average second derivative  = (enter)   0.0 Estimate of average second deriv   
                Derivative at radial flow period = (enter) 6.77 6.77 Read from derivative graph   
  T-early[m2/d] = 33.05 Aqui. thick (m)   
T and S estimates from derivatives T-late [m2/d] = 37.92 Est.  S-late = 4.95E-03 
(To obtain correct S-value, use program RPTSOLV) S-late = 4.95E-03  S-estimate could be wrong   
          
BASIC SOLUTION         
  (Using derivatives + subjective information about boundaries)  Maximum influence of boundaries at long time   
(No values of T and S are necessary) No boundaries 1 no-flow 2 no-flow Closed no-flow 
sWell (Extrapol.time) = 37.06 53.96 70.85 121.53 
Q_sust (l/s) = 22.91 15.73 11.98 6.99 
 
  Best case   Worst case 
 
Average Q_sust (l/s) = 13.18        
with standard deviation= 6.71        
 (If no information exists about boundaries skip advanced solution and go to final recommendation)   
          
 82 
Appendix 3 Magnetic profile across dykes to confirm presence and 
position. 
 
• Line 2 Millbank 
• Line 3 Quarreefontein 
• Line 4 Quarreefontein 
• Line 5 Ascot 
• Line 6 Buxton 
 
 83 
  84 
  85 
  86 
  87 
  88 
 Appendix 4 Monitoring boreholes and water level records 
Boorgat Plaasnaam Lat Long Alt Map Apr-90 Apr-01 Aug-01 Jan-02 Apr-02 Aug-02 Mar-03 Aug-03 Apr-04 
G39663 Thornthwaite 25.87782 24.0190 1100 19.65 29.82 bye 26.64 26.33 26.44 28.4 29.98   
G39664 Thornthwaite 25.8764 24.0191 1100 21.02 32.78 30.61 28.23 28.22 28.04 30.64 22.26   
G39665 Thornthwaite 25.8777 24.0190 1110 29.83 29.85 30.94 28.52 28.5 28.32 30.91 32.55   
G39666 Thornthwaite ………. ………. 1110 27.12                   ……..   
hekgeslui
G39667 Vaalboschhoek 25.97224 23.9841 1128 17.43 19.44 18.8 18.5 18.54 18.68 19.26 t   
hekgeslui
G39668 Vaalboschhoek 25.96995 23.9794 1132 18.56 20.47 19.95 19.73 19.72 19.93 20.58 t   
G39669 Marstone 25.88219 24.1134 1065 11.6 16.37 15.4 20.82 15.08 15.16 16.42 17.20   
G39670 Marstone 25.88143 24.1152 1080 17.53 22.07 21.05 15.02 20.71 20.74 22.11 22.82   
G39671 Elchester 25.84426 24.0988 1069 41.24 toe 52.95 53.78 62.23   65.05 66.60   
G39672 Belvidere 25.72285 23.9776 1079 43.02 46.43 46.05 43.81 45.2 45.98 46.94 47.40   
G39673 Blackheath 25.72102 24.2392 1086 71.2 75.99 76.09 76.11 76.19 76.22 76.59 76.70   
toegesee
G39674 Belvidere 25.72919 23.9785 1079 47.73 52.71   53.26 53.58 53.85 54.84 l   
G39675 Grassbank 25.86012 23.8237 1130 24.5 droog     Toegeval Toegeval Toegeval toegeval   
…………
G39676 …………… …. ………… 1045 28 ……….           …….   
G39677 Waterbury 25.79589 23.8077 1120 30.73 35.32 37.02 36.05 38.66 pumping Pumping 41.63   
G39678 Forres 25.98289 23.9416 1147 13.25 17.97 31.75   17.78 17.85 18.41 18.71   
G39679 Forres 25.94031 23.9343 1137 19.3 35.65 36.21 38.09 38.22 Toegeval 37.47 36.47   
Cable kabelhak
G39680 Grassbank 25.83446 23.8390 1124 23.34 toe 67.53   hakvas     vas   
G39681 Forres 25.92779 23.9254 1134 18.75 46.55 45.24 43.93 46.39 Toegeval Toegeval toegeval   
kabelhak
G39682 Grassbank 25.8532 23.8387 1130 21.64 toe ……     73.7   vas   
G39683 Forres 25.92356 23.9264 1132 22.5 42.13 42.5 42.63 42.85 42.91 43.64 43.97   
G39684 Quarreefontein 25.94892 23.8259 1161 6.6 5.87 4.73 4.47 4.77 Closed 5.93 6.67   
G39685 Forres 25.88696 23.8546 1123 25.86 68.57 65.79 71.31 73.87 72.69 83.22 86.27   
G39686 Kokomeng 25.89818 24.0077 1108 11.07 19.7 15.79 15.38 14.86 15.25 18.5 20.18   
G39687 Brentwood 25.79398 23.9755 1091 45.65 63.86 62.26 64.8 66.67 65.74 70 70.24   
G39688 Kokomeng 25.89811 24.0075 1108 11.21 19.39 15.69 15.35 14.83 15.11 18.14 19.88   
G39689 Kokomeng 25.89826 24.0078 1108 11.35 wortels toegeval toe geval Toegeval Toegeval Toegeval toegeval   
G39690 Zandvloed 25.93098 24.0429 1108 16.53 16.77 1613 14.93 13.53 13.87 15.68 17.12   
G39691 Thornthwaite 25.8767 24.0190 1100 19.38 33.01 28.41 26.66 26.39 26.46 28.49 30.30   
G39692 Thornthwaite 25.87797 24.0189 1100   29.71 bye dry 26.24 26.31 28.37 30.01   
G39693 Knapdaar 25.67413 24.1444 1079 56.9 76.95 69.97 75.82 81.58 68.67 92.04 72.98   
G39694 Thornthwaite 25.87751 24.0190 1100 19.54 29.71 28.29 bye 26.23 26.34 28.38 29.90   
kabelhak kabel Cable Cablehak kabelhak
HK1 Hurstpark 25.78151 24.0553 1056   49.48 vas hakvas hakvas vas pumping vas   
HK2 Hurstpark 25.79156 24.0565 1070   53.62 72.38 55.92 57.6   pumping Pumping   
kabel 
BH1 Blackheath 25.68436 24.2376 1078   75.49 63.88 hakvas 75.84 62.66 pumping 72.26   
BH2 Blackheath 25.68426 24.2318 1081   81.93 70 81.53 82.06 68.85 pumping 78.32   
FS1 Forres 25.93267 23.9224 1133   45.91 44.87 45.43 45.66 44.91 47.06 46.47   
FS2 Forres 25.93965 23.9311 1134   46.75 45.13 bye 47.33 45.35 48.1 47.04   
bye/pum
WD1 Westward 25.6482 24.2140 1065   65.2 55.24 bye bye 55.82 ping 60.00   
GK1 Grassbank 25.85297 23.8389 1123   71.41 69.13 78.52 bye 73.72 94.15 60.14   
GK2 Grassbank 25.84345 23.8011 1123   74.7 68.67 79.57 sealed Sealed sealed 92.44   
RS2 Rhodes 25.8754 23.8660 1123   65.93 63.98 68.5 bye 70.36 78.73 80.90   
HT1 Harcourt 25.86621 23.9029 1122   66.25 62.52 bye 74.21 68.74 bye 85.14   
BE2 Buttermere 25.7918 24.0874 1068   55.03 52.86 52.97 54 50.1 pumping 52.78   
Cable Cablehak
BE1 Buttermere 25.81397 24.1258 1078   63.13 62.25 63.56 hakvas vas cablevas 67.87   
AY Albury 25.7424 24.0587 1055   49.3 38.35 40.33 49.85 38.13 pumping 41.07   
roots 
NI1 Nokani 25.96451 23.7483 1165   15.49 12.89 14.39 13.24 12.19 block wortels   
FS1 Forres 25.91099 23.8727 1131   63.41 61.4 63.95 66.06 64.87 47.06     
VM1 Veerstriem 25.79173 23.8848 1105   48.96 54.34 64.9 73.52 50.72 86 67.09   
 89 
kabelhak Cable Cablehak kabelhak
VM2 Veerstriem 25.79118 23.8845 1105   49.62 vas 65.9 hakvas vas pumping vas   
FS3 Forres 25.92764 23.8746 1131   61 60.98 60.03 59.47 60.57 62.52 61.38   
kabelhak
WG2 Wynberg 25.83467 23.7656 1138   35.97 32.38 36.85 35.1 33.59 32.28 vas   
WG1 Wynberg 25.82842 23.7797 1135   33.53 30.3 bye 33.82 Toegeval Toegeval toegeval   
kabelhak
JP1 Jakkalskop 25.80711 23.7020 1129   47.07 47.16 48.22 49.45 49.6 48.51 vas   
Kabel Cablehak toegesee
BH3 Blackheath 25.67576 24.2401 1070     hakvas     vas sealed l   
Kabel Cablehak kabelhak
BH4 Blackheath 25.67988 24.2360 1070     hakvas   sealed vas pumping vas   
TO2 Toledo 25.81819 24.3057 1078     64,71 75.03 75.24 65.59 pumping 71.43   
kabel Cablehak kabelhak
TO1 Toledo 25.8396 24.2907 1097     82,78 hakvas 82.8 vas cablevas vas   
KD1   25.8359 24.3328 1080     69,40 75.41 79.59 69.47 pumping 80.88   
RN1 Rebon 25.83866 24.3449 1085     76,30 75.79 85.81 85.9 pumping 76.18   
NE 2 Navarre 25.79252 24.2193 1090     71,30 71.18 71.91 71.78 72.25 73.45   
NE 1 Navarre 25.7499 24.2269 1086     72,30 73.42 74.53 73.07 pumping 75.96   
NE 3 Navarre 25.78084 24.2125 1090     52,05 69.9 54.07 69.62 pumping 69.45   
SD 3 Stresfod -25.781 24.213 1080             99.02 96.15   
SD 2 Stresfod 25.89272 24.2095 1095     47,31 47.31 47.40 47.7 - 47.93   
SD 1 Stresfod 25.8983 24.1872 1095     49,00 49.02 51.31 49.37 49.47 49.54   
SD 4 Stresfod 25.8873 24.2200 1092     41,35 41.35 41.25 41.19 41.61 41.59   
ID 1 Ierland 25.90943 24.2944 1101     81,70 81.5 83.97 81.78 pumping 82.11   
ID 2 Ierland 25.9121 24.2983 1100     92,43 92.1 92.11 92.09 dry toegeval   
ID 3 Ierland 25.9107 24.2998 1100   92,00 toe geval Toegeval   Toegeval droog   
BN 1 Burton 25.88702 24.3058 1104     119,00 dry dry         
VL 1 Vogel 25.87687 24.2900 1097     75,92 75.75 75.72 76 75.86 75.80   
VL 2 Vogel 25.88806 24.2723 1082     75,53 bye 56.98 57.7 62.29 58.05   
BN 2 Burton 25.90743 24.2729 1094     61,48 bye 61.51 61.65 61.45 61.36   
BY 3 Bradbury 25.90171 24.2239 1083     41,50 41.69 41.76   43.79 42.05   
BY 2 Bradbury 25.90726 24.2085 1094     59,05 56.25 55.04   52.93 51.72   
BY 1 Bradbury 25.89989 24.2279 1096     59,29 55.42 104.2   58.17 54.14   
HT  2 Harcourt 25.87772 23.9220 1126     61,53   72.89 67.87 81.55 82.32   
HT 3 Harcourt 25.88243 23.9279 1125     61,68 Sealed sealed Sealed sealed     
kabelhak
HT 4 Harcourt 25.68008 23.9167 1125     63,68 Sealed sealed Sealed sealed vas   
kabelhak
HT 5 Harcourt 25.85905 23.9163 1124     65,13 Sealed sealed Sealed sealed vas   
QN1 Quarreefontein 25.8981 23.8365 1135     68.35   70.97 72.78 sealed 86.10   
toegesee
QN2 Quarreefontein 25.8954 23.8479 1134     68.56 68.49 71.19 72.14 sealed l   
MK1 Millbank 25.83957 23.7671 1138     35.48 38.23 36.9 35.46 41.58 37.61   
GK3 Grassbank 25.84554 23.8462 1130       78.9 85.9 73.56 94.3 90.58   
HT6 Harcourt 25.88367 23.8364 1125       68.72 sealed Sealed       
Cablehak
VE1 Vrede 25.9677 23.7902 1171       8.57 7.85 vas cablevas 11.78   
VE2 Vrede 25.9613 23.8061 1167       6.57 7.89 Bee bye 18.95   
HN1 Hulpalleen 25.9911 23.7363 1171       3.12 5.09 5.73 10.24 19.23   
QN3 Quarreefontein 25.9061 23.8933 1133       68.12 71.28 72.51 sealed 86.92   
QN4 Quarreefontein 25.89 23.8391 1133       68.98 71.6 73.18 79.85 droog   
QN5 Quarreefontein                     80.96   
hekgeslui
GE1 Gosike 25.84583 23.7333 1136       29.27 sealed   sealed t   
kabelhak
BM 1 BLENHEIM 25.7678 23.7490 1118         68.84 pumping pumping vas   
BM 2 BLENHEIM 25.7673 23.7483 1118         60.84 58.6 10.6 60.48   
DN 1 DUNCAN 25.7509 23.7210 1104         124.02 121.71 120.08 126.79   
DN 2 DUNCAN 25.7229 23.7106 1091         140.02 pumping pumping 113.15   
ST 1 SANDHURST 25.721 23.7713 1092         88.82 88.71 89.08 88.35   
EUCHRE-
EW 1 HOLLOW 25.7139 23.7174 1088         149.64   pumping 111.39   
EUCHRE-
EW 2 HOLLOW 25.7025 23.7113 1085         116.87 115.83 pumping 144.35   
EW 3 EUCHRE- 25.6807 23.7071 1078         150m   pumping kabelhak   
 90 
HOLLOW cable- vas 
short 
EUCHRE-
EW 4 HOLLOW 25.6815 23.7072 1078         108.6 108.49 108.17 107.70   
ST 2 SANDHURST 25.718 23.7875 1088         90.92 90.04 90.36 89.32   
MD 1 MILLWOOD 25.711 23.8574 1084         52.01 51.47 81 51.17   
kabelhak
SR 1 SWEETWATER 25.7133 23.8999 1072         68.85 69.61 cable vas vas   
kabelhak
SR 2 SWEETWATER 25.7162 23.8861 1080         72.72 73.28 73.76 vas   
gate 
KA 1 KYNSNA 25.7507 23.9234 1084         53.74 closed 54.75 55.11   
gate 
KA 2 KYNSNA 25.7549 23.9267 1084         53.72 closed 55.37 56.04   
MD 2 MILLWOOD 25.719 23.8243 1088         81.35 dry 50.43 80.82   
JP 2 JAKKALSKOP 25.8065 23.7015 1127         51.16 51 50.96 49.94   
kabelhak
JP 3 JAKKALSKOP 25.8078 23.7007 1128         72.02 dry pumping vas   
GK 4 GRASSBANK 25.8429 23.8017           86.45 76.71 95.13     
GK 3 GRASSBANK 25.8429 23.8017 1133           73.56 94.3     
G44407   25.6119 23.4066             132.44 132.49 132.51   
G44405   25.3146 23.4753             96.4 97.13 96.82   
G44406   25.538 23.3907             119.32 119.63 119.31   
G44408   25.6757 23.2383             139.25 139.63 139.17   
G44409 Voorstershoop 25.8301 23.0136             bee bye ………….   
NI 2 Nokani 25.9629 23.7488 1183           12.19 14.3 …………   
TT 8 Tennant -25.667 23.974 1062             56.85 ………..   
hekgeslui
GK 2 Gosike -25.829 23.715 1146             33.49 t   
MK 2 Millbank -25.841 23.762 1151             44.13 46.87   
Uenice(Millban
MK 5 k) -25.857 23.787 1161             99.13 96.86   
DE 1 Deelfontein -25.93 23.754 1175             6.89 7.81   
DE 2 Deelfontein -25.93 23.754 1170             6.78 7.59   
RK 5 Molopo River -25.727 24.284 1086             4.76 …….   
RK7 Molopo River -25.715 24.312 1089             72.76 …….   
HK 3 Hurstpark -25.791 24.056 1078             63.53 62.00   
BW 5 Birnanwood -25.742 24.059 1083             46.14 ……..   
KS 5 Kameeldoorn -25.773 24.773 1084             47.79 ……   
RP 1 Roukoop -25.636 24.115 1087             48.66 …..   
MY 1 Mcgaysfolly …… ……… ……               4.92   
MY2 Mcgaysfolly ……… . …               12.19   
MY 3 Mcgaysfolly …… ……….. ……               12.19   
Uenice(Millban
MK 6 k) ……… ……… …               40.19   
HT 7 Harcourt …… ……….. ……               70.60   
 
 91 
Appendix 5 Ground water level elevation maps. 
Groundwater elevation contour maps for pre-1974, 1990, April 2001, Aug 2001, April 2002 and April 2003 to 
indicate the flow dynamics. (Prepared with Surfer C 8.02 Oct 02 from approximately 100 monitoring 
boreholes. The April 2003 contours were prepared with the dyke fault line option which is a better 
representation. 
 
 92 
Tosca groundwater level elevation contour pre 1974 Tosca groundwater elevation contour August 2001
-25.60 -25.60
1180 1010 1180.00
1001 11001114
1160 -25.70 1010 1160.00-25.70 1033
1014
Vergelee 1140 Vergelee 1140.001012
1083 1051 1029 1019
-25.80 1120 -25.80
1082
1105 1013 1120.00110610541056 10141054
Tosca 1100 Tosca1059105911006644 107629 10509 1021 1100.001057 1092 10416014085111005337 102
-25.90 -25.90 1070 1
2008
1080 1070 111000889890 1080.00
1156 11018091
1092
1152
1060 11121115 1109 1060.00
-26.00 -26.001040 1040.00
1020 1020.00
-26.10 -26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 1000 23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 1000.00 
  
  
  
  
  
Tosca groundwater elevation contour 1990 Tosca groundwater level elevation contour April 02
-25.60 -25.60
11002255 11002255 1180
110025
1025
25 110022551025 1180
960 1025 11002255 1160
962 1025 1025 969.40 997.4210120525 919080.29.416
-25.70 1025
10120525
988 10112007 1013 1140 -25.70 968.13 11601016 1031.991003.15110025 1025
938.36 9
25 1025 950.98 1003
9.178.081006.65 1007.28
1050 11003235..80
1009.81
1050 421050 10510050
1025 10120525 1005.15 1140
101705751075107511005500
1050 Vergelee 1120 979.98 1030.26
110077515050 1030.28
1011.47
10 1075 105479.16 Vergelee
-25.80 1100 10
71750575 10170550
1025
111010001100 1100
1025
1050 1100
1035.93 1120
1025 1024.33 1012.40 1018.091075
1100 1050 101500150050 -25.80105759..985845
110 1075 1050
1050 1100
1111000
0
0 110110
T10osca110000 1075
1080
1050 1050 11110
12101.
0
.9
1
10
.18
11010100 10751050 1050 1
0046.55 1044.10 1014.201100 1050
1100
-25.90 1100 11101000 1075 1050 1060 1047.79
Tosca 1080
1125 11001100 1100 1050 1053.11 107831..657601781049.13 10459..9229
1021.28
11501125 1100 1075 1025 10 1050.751150 1050 101
61
6046
.40
.023.81 1047.60
1025.02 1060
11151025 1125 1100 1075 10170575 1040 -25.90 10641.09641.72
1093.174 1041.24 1032.4
1125 1125 1125 1075 1075 1050 10
907.89
1125 1125 1075 1075 1075 1089.11150 1125 1071.53 110087.61
5
11010075 1020 11
800789.638.4.6778 1040
1156.23
-26.00 1150 1125 1111001150 001125 1151.76116131.5195.11 11111029.281150 1100 .461129.22 1020
1150 1000 1165.91
-26.00
980 1000
-26.10 980
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 960  
 960-26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40  
  
  
  
 
Tosca groundwater elevation level contour April 2001  Tosca groundwater level elevation  contour Maart 2003
-25.60
-25.60 1180
1180 1011.34
997.15 1160
969.83 986.96
-25.70 1160
-25.70 1140
1009
1003
29.972.641037.57 1006.24 1032.0 1009.41 1003.24
1140 1024.1
66 1066.24
1013.86
Vergelee 983.92 11002298.2.6531107.4 Vergelee 11201012.21
1120 980.981019 1021 1012.47 1017.75
-25.80 -25.80107860.0449
1100
1100 1097.51 111010909556.8..747212037.87 1003.95
1012083.8585.7 Tosca 10801040.87
Tosca 1080 1044.27 1044.45 1100767191..60.53639216
1051303
57.89
.195.78 1048.58 1050.39 1019.71
-25.90 11008899.8.56 1045.5311003397.2.813
1060
1083.94 1041.07 1032.55
-25.90 1060 1152.1212 1068.48 1088.361085 1092.321098.9954.593
1155.07 1040
1040 1168.7 11111018.4.724
1128.59
1160.76 1020
1020 -26.00
1000
-26.00 1000
980
980 -26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 24.50 960  
960
-26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40   
  
 
 
 
 
 
 93 
Appendix 6 Groundwater elevation difference contour maps. 
Groundwater elevation difference contour maps to indicate how the water level declined  
 94 
Tosca groundwater level difference (April 2001 m below 1990 levels)
-25.60 20
10
-25.70
0
Vergelee
-25.80 -10
Tosca
-20
-25.90
-30
-40
-26.00
-50
-26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 -60
Tosca waterlevel difference (April 2002 m below 1990 levels)
-25.60
20
EW 4 G39693 BBHH21
-25.70 EW 2EW 1 ST 2 MD 2 MD 1DN 2 ST 1 SRS 2R 1 10GG3399667724 G39673
DN 1 K AYKAA 1 2 NE 1
BM 21 Vergelee 0
NE 3
G39687 HK2 NE 2
-25.80 JJPP  132
WGW2G1
-10
MK1 GK 3 GK3 TO1
HT1 Tosca
HT  2 G3966925314 VL 1 -20
QGNQ43N92685
G3966790
SDS 2D 4 VL 2QN1 G396886
-25.90 BY 3FS1QN3 BN 2 ID 2
FS3 GG3399668813FSF
G39684 G3
1S92679 -30
NI1 VE1VE2 GG3399666687
HN1 G39678 -40
-26.00
-50
-60
-26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40
-70
Tosca groundwater level difference (Maart 2003 m below 1990 waterlevels)
-25.60
1011.34
997.15 10
969.83 986.96
-25.70
100929.972.641037.57
10031006.24 1032.06 1009.41 1003.24
0
1024.16 1066.24
1013.86
983.92 11002298.2.653
1107.4 Vergelee -101012.21 980.98
1019 1021 1012.47 1017.75
-25.80107860.0449 -20
1097.51
111010909556.8..747212037.87 10358.7 Tosca 1003.951040.87 1028.85
1044.27 -301044.45 1100767191...0653639216
105130.3195.78 104
587..5889 1050.39 1019.71
-25.90 11008899.8.56 1045.5311003397.2.8131083.94 1041.07 1032.55
1152.1212 1068.48 1088.36
-40
1085 1092.321098.9954.593
1155.07
1168.7 11111018.4.724 -50
1128.59
1160.76
-26.00 -60
-70
-26.10
23.70 23.80 23.90 24.00 24.10 24.20 24.30 24.40 24.50 -80 
 95 
Appendix 7 Satellite Images from February 1999 and March 2002 
used to identify areas developed after Oct 1998. 
 
 
 96 
 97 
 98 
Appendix 8 Schedule of authorized users and volume as in April 2004. 
Use 
Volume exceeding Total 
Title deed Registered 75000 restricted 
Reg no: Name Farm Description number (m3/a) (m3/a) use (m3/a) 
25009473 F.V.Z. Engelbrecht Albury farm no. 171 portion no. 2 T2601/1994 264000 189000 188400 
Ascot farm no. 184 portion no. 0-remaining 
10081001 Tosca Trust extent T302/2000 187000 112000 142200 
10082527 Fanie Griesel Trust Belvidere     Farm No. 157 T63/2000 65760 0 65760 
25021949 W.H. Simmons Belvidere farm no. 157 portion no 1 T3027/2002 51393 0 51393 
Carroll Family Blackheath farm no. 90 portion no. 0-remaining 
10081225 Enterprises  extent T1802/2001 1735000 1660000 1071000 
25017213 J.H. Fourie Blanco Farm no. 173 portion no. 1 T3321/1999 64543 0 64543 
Brenton farm no. 180 portion no. 0-remaining 
10081378 J.C.C. Grobbelaar extent T1352/1979 69954 0 69954 
25007821 Avon Trust Brentwood Farm No 181 Portion 1 T4173/2000 74112 0 74112 
Brentwood farm no. 181 portion no. 0-remaining 
10081252 Eben Du Toit extent T215/1996 74112 0 74112 
10081412 J.P. van den Berg Buttermere farm no. 1017 portion no. 0 T1913/1998 1035000 960000 651000 
25007698 Clearstream Trust Clearstream  Farm No. 168  Portion No. 0 T493/2000 585000 510000 381000 
25021976 K. van der Heever Deelfontein Farm no. B215 remaining extent T857/1986 102780 27780 91668 
10081298 P.M. Fourie Elchester farm no. 174 portion no. 1 T1283/2001 112080 37080 97248 
Johan en Esta Theron 
25006831 Familie Trust Forres T489/2000 90000 15000 84000 
10081190 W.C. Kriel Forres farm no. 216 portion no. 2 T285/1989 335950 260950 231570 
25008679 J.J. Hayward Forres farm no. 216 portion no. 5 T1467/1997 95458 20458 87275 
25021280 Zenith Ranch (Pty. Ltd) Forres farm no. 216 portion no. 8 T1663/2000 258300 183300 184980 
25000310 Leamy Family Trust Forrest Hall farm no. 182 portion no. 0 T2109/2001 153870 78870 122322 
10081181 H.M. Joubert Gannalaagte farm no. 6 portion no. 0 T2667/1996 90250 15250 84150 
25017972 Hulp Alleen Familie Genade Farm 209 Portion 0 - Remaining extent   130500 55500 108300 
 99 
Grassbank Farm No. 187 Portion No. 0-
25021412 Fransua Stolz Trust Remaining extent T742/1995 1202500 1127500 751500 
10081216 Emtron Bdy Grassbank farm no. 187 portion no. 2 T1725/1999 367500 292500 250500 
Harcourt farm no. 185 portion no. 0-remaining 
  K. van der Heever extent T603/1968 37242 0 37242 
Harcourt farm no. 185 portion no. 0-remaining 
New Owner Beyer Trust extent T1466/2003 360000 285000 246000 
10081350 Leniesdeel Trust Harcourt farm no. 185 portion no. 1 T2840/1995 655100 580100 423060 
Hastings farm no. 142 portion no. 0-remaining 
25003638 M. Hamman extent T931/1988 35000 0 35000 
10081323 J.H. Fourie Hurstpark  Farm No. 170   T212/1988 255400 180400 183240 
25002675 S.G. Griesel Kokomeng farm no. 178 portion no. 2 T148/2001 18000 0 18000 
  Rose  Kokomeng    68100 0 68100 
Koodooskop farm no. 206 portion no. 0-
25021930 I de Beer remaining extent T1715/2001 67560 0 67560 
Libertas-Zand vloed farm no. 218 portion no. 1-
25004753 A.C.J. Du Plessis remaining extent T1589/1983 79800 4800 77880 
Marlborough farm no. 167 portion no. 0-
25021921 P J Haasbroek remaining extent T2010/2001 42818 0 42818 
Millbank farm no. 188 portion no. 1-remaining 
10081261 P.E. Kriel extent T635/1994 124250 49250 104550 
25001514 M. Theron Millbank farm no. 188 portion no. 2 T2209/1999 25710 0 25710 
10084865 Sandtrap Boerdery Millbank farm no. 188 portion no. 3   525000 450000 345000 
  I de Beer Nokani    67560 0 67560 
Nokani Farm No. 208  Portion No. 2-Remaining 
25018203 F.J. Hamman extent T2693/1997 15420 0 15420 
Nokani farm no. 208 portion no. 3-remaining 
10081243 P.A. Theunissen extent T1015/1988 225000 150000 165000 
25022573 Centwise BK Nokani farm no. 208 remaining extent T191/1988 74250 0 74406 
25018196 Pretorius Quareefontein  Farm No. 212 Portion No.1 T2665/2001 77097 2097 76258 
25007028 J.H. Nieuwoudt Quareefontein farm no. 212 portion no. 2 T4582/1998 145000 70000 117000 
25021404 Fransua Stolz Trust Rhodes Farm No. 186 Portion No. 0 T1421/2000 411000 336000 276600 
Senlac farm no. 143 portion no. 0-remaining 
10081314 F.J. Hamman extent T350/1977 212800 137800 157680 
25003503 W.H.A. Hamman Stilton farm no. 189 portion no. 23  T2278/1996 127000 52000 106200 
 100 
Tennant farm no. 152 portion no. 0-remaining 
25020726 JAS Simmons extent T648/1967 45600 0 45600 
10081387 D.B. Grobbelaar Thornthwaite farm no. 179 portion no. 0 T973/1978 482000 407000 319200 
Thornwick farm no. 175 portion no. 0-remaining 
10081163 Kwagga Molopo Trust extent T2787/2002 121600 46600 102960 
10081430 A.M. Steyn Vaalboschoek Farm 227 Portion 1 T452/1995 114000 39000 98400 
25021912 G H Stolz trust Willarie 1019 portion no. 0   61671 0 61671 
10081289 F. Barnard Woodborough farm no. 159 portion no. 0 T374/1987 487500 412500 322500 
25007732 Avon Trust Woodborough farm no. 159 portion no. 1 T1115/2003 120000 45000 102000 
10081369 E.C. Grobbelaar Wynberg farm no. 165 portion no. 1 T1046/1977 612000 537000 397200 
       12838540 9329735 9106802 
 
 101 
Appendix 9 Survey of irrigation areas. 
ID AREA (Ha) LANDID FARMID FARMNAME Initial Surname Type irrigation Crop 
1 4.41 T0JM00000000018900004L1 T0JM00000000018900004 HASTING H HAMMAN SPRINKEL UK 
2 2.64 T0JM00000000018900004L2 T0JM00000000018900004 HASTING H HAMMAN SPRINKEL UK 
3 8.49 T0JM00000000018900004L3 T0JM00000000018900004 HASTING H HAMMAN SPRINKEL UK 
4 6.58 T0JM00000000014300000S4 T0JM00000000014300000 SENLAC N HAMMAN SPILPUNT UK 
5 6.58 T0JM00000000014300000S3 T0JM00000000014300000 SENLAC N HAMMAN SPILPUNT KORING 
6 6.48 T0JM00000000014300000S2 T0JM00000000014300000 SENLAC N HAMMAN SPILPUNT PAPRIKA 
7 6.48 T0JM00000000014300000S1 T0JM00000000014300000 SENLAC N HAMMAN SPILPUNT KORING 
8 2.36 T0JM00000000018900001S1 T0JM00000000018900001 MILLBANK PE KRIEL SPILPUNT PAPRIKA 
9 2.36 T0JM00000000018900001S2 T0JM00000000018900001 MILLBANK PE KRIEL SPILPUNT UK 
10 2.36 T0JM00000000018900001S3 T0JM00000000018900001 MILLBANK PE KRIEL SPILPUNT UK 
11 2.36 T0JM00000000018900001S5 T0JM00000000018900001 MILLBANK PE KRIEL SPILPUNT UK 
12 2.36 T0JM00000000018900001S6 T0JM00000000018900001 MILLBANK PE KRIEL SPILPUNT UK 
13 2.36 T0JM00000000018900001S4 T0JM00000000018900001 MILLBANK PE KRIEL SPILPUNT UK 
14 72.28 T0JM00000000018800000S4 T0JM00000000018800000 MILLBANK RA PRETORUIS SPILPUNT UK 
15 20.24 T0JM00000000018800000S3 T0JM00000000018800000 MILLBANK J THERON SPILPUNT UK 
16 20.24 T0JM00000000018800000S2 T0JM00000000018800000 MILLBANK J THERON SPILPUNT UK 
17 14.15 T0JM00000000018800003S2 T0JM00000000018800003 WYNBERG N GROBBELAAR SPILPUNT UK 
18 13.73 T0JM00000000018800003S1 T0JM00000000018800003 WYNBERG N GROBBELAAR SPILPUNT PAPRIKA 
19 24.01 T0JM00000000018800003S3 T0JM00000000018800003 WYNBERG N GROBBELAAR SPILPUNT UK 
20 29.94 T0JM00000000021000001S1 T0JM00000000021000001 HULP-ALLEEN P THEUNISSEN SPILPUNT KORING 
21 12.63 T0IM00000000020900000S1 T0IM00000000020900000 KOEDOESKOP P THEUNISSEN SPILPUNT KORING 
22 51.21 T0JM00000000018800000S1 T0JM00000000018800000 MILLBANK M THERON SPILPUNT UK 
23 50.75 T0JM00000000018700000S3 T0JM00000000018700000 GRASBANK G SCHOLZ SPILPUNT PAPRIKA 
24 50.75 T0JM00000000018700000S4 T0JM00000000018700000 GRASBANK G SCHOLZ SPILPUNT UK 
25 48.99 T0JM00000000018700000S6 T0JM00000000018700000 MALBOROUGH P HAASBROEK SPILPUNT UK 
26 48.99 T0JM00000000018700000S5 T0JM00000000018700000 MALBOROUGH P HAASBROEK SPILPUNT UK 
27 50.76 T0JM00000000018700000S2 T0JM00000000018700000 GRASBANK G SCHOLZ SPILPUNT UK 
28 50.76 T0JM00000000018600000S2 T0JM00000000018600000 GRASBANK G SCHOLZ SPILPUNT UK 
29 50.76 T0JM00000000018600000S1 T0JM00000000018600000 GRASBANK G SCHOLZ SPILPUNT UK 
30 50.76 T0JM00000000018700000S1 T0JM00000000018700000 GRASBANK G SCHOLZ SPILPUNT PAPRIKA 
31 30.00 T0JM00000000021600005S2 T0JM00000000021600005 RHODES G SCHOLZ SPILPUNT UK 
32 30.00 T0JM00000000021600005S1 T0JM00000000021600005 RHODES G SCHOLZ SPILPUNT UK 
33 30.64 T0JM00000000021600004S1 T0JM00000000021600004 FORES J HAYWARD SPILPUNT UK 
34 30.64 T0JM00000000021600004S2 T0JM00000000021600004 FORES J HAYWARD SPILPUNT UK 
 102 
35 20.71 T0JM00000000018500000S2 T0JM00000000018500000 RHODES PW BEYER SPILPUNT UK 
36 20.71 T0JM00000000018500000S3 T0JM00000000018500000 RHODES PW BEYER SPILPUNT PAPRIKA 
37 20.71 T0JM00000000018500000S1 T0JM00000000018500000 RHODES PW BEYER SPILPUNT KORING 
38 22.88 T0JM00000000018500002S10 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
39 22.88 T0JM00000000018500002S9 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
40 22.88 T0JM00000000018500002S8 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
41 25.19 T0JM00000000018500002S3 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
42 25.19 T0JM00000000018500002S4 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
43 23.08 T0JM00000000018500002S7 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
44 23.08 T0JM00000000018500002S6 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
45 23.08 T0JM00000000018500002S5 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
46 10.69 T0JM00000000018500002S1 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT KORING 
47 51.56 T0JN00000000017900000S1 T0JN00000000017900000 THORNTHWAITE DB GROBBELAAR SPILPUNT KORING 
48 30.27 T0JN00000000017500000S2 T0JN00000000017500000 THORNWICK K VAN DE BERG SPILPUNT UK 
49 30.27 T0JN00000000017500000S1 T0JN00000000017500000 THORNWICK K VAN DE BERG SPILPUNT PAPRIKA 
50 30.38 T0JN00000000017200000S1 T0JN00000000017200000 BUTTERMERE K VAN DEN BERG SPILPUNT UK 
51 12.34 T0JN00000000017300000S2 T0JN00000000017300000 HURSTPARK JH FOURIE SPILPUNT KORING 
52 12.34 T0JN00000000017300000S1 T0JN00000000017300000 HURSTPARK JH FOURIE SPILPUNT UK 
53 40.24 T0JN00000000017000000S1 T0JN00000000017000000 HURSTPARK JH FOURIE SPILPUNT KORING 
54 20.18 T0JN00000000017100000S6 T0JN00000000017100000 ALBURY-SONOP FVZ ENGELBRECHT SPILPUNT GRAS 
55 20.18 T0JN00000000017100000S5 T0JN00000000017100000 ALBURY-SONOP FVZ ENGELBRECHT SPILPUNT GRAS 
56 20.18 T0JN00000000017100000S1 T0JN00000000017100000 ALBURY-SONOP FVZ ENGELBRECHT SPILPUNT GRAS 
57 20.18 T0JN00000000017100000S3 T0JN00000000017100000 ALBURY-SONOP FVZ ENGELBRECHT SPILPUNT RUS 
58 20.18 T0JN00000000017100000S2 T0JN00000000017100000 ALBURY-SONOP FVZ ENGELBRECHT SPILPUNT GRAS 
59 20.18 T0JN00000000017100000S4 T0JN00000000017100000 ALBURY-SONOP FVZ ENGELBRECHT SPILPUNT AARTAPPEL 
60 12.51 T0JM00000000018100000S1 T0JM00000000018100000 BELVEDERE SG GRIESEL SPILPUNT KORING 
61 12.51 T0JM00000000015700000S1 T0JM00000000015700000 BELVEDERE SG GRIESEL SPILPUNT UK 
62 11.22 T0JM00000000015800000S2 T0JM00000000015800000 WOODBOROUGH F BARNARD SPILPUNT UK 
63 40.35 T0JM00000000015800000S1 T0JM00000000015800000 WOODBOROUGH F BARNARD SPILPUNT UK 
64 47.67 T0JN00000000009000000S1 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT UK 
65 39.60 T0JN00000000009000000S7 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT UK 
66 39.60 T0JN00000000009000000S6 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT GRAS 
67 39.60 T0JN00000000009000000S5 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT UK 
68 39.60 T0JN00000000009000000S3 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT KORING 
69 39.60 T0JN00000000009000000S4 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT KORING 
70 47.67 T0JN00000000009000000S2 T0JN00000000009000000 BLACKHEATH CJ CAROL SPILPUNT UK 
71 2.81 T0JN00000000009000000L2 T0JN00000000009000000 BLACKHEATH CJ CAROL DROE LAND UK 
72 2.41 T0JN00000000009000000L1 T0JN00000000009000000 BLACKHEATH CJ CAROL DROE LAND UK 
 103 
73 4.77 T0JN00000000017900000L1 T0JN00000000017900000 THORNTHWAITE DB GROBBELAAR SPRINKEL KORING 
74 1.00 T0JM00000000018700000L4 T0JM00000000018700000 GRASBANK G SCHOLZ SPRINKEL GRAS 
75 1.17 T0JM00000000018700000L2 T0JM00000000018700000 GRASBANK G SCHOLZ SPRINKEL GRAS 
76 0.35 T0JM00000000018700000L1 T0JM00000000018700000 GRASBANK G SCHOLZ SPRINKEL GRAS 
77 0.85 T0JM00000000018700000L3 T0JM00000000018700000 GRASBANK G SCHOLZ SPRINKEL GRAS 
78 1.19 T0JM00000000021600005L1 T0JM00000000021600005 RHODES G SCHOLZ SPRINKEL UK 
79 3.07 T0JM00000000021600005L2 T0JM00000000021600005 RHODES G SCHOLZ SPRINKEL UK 
80 0.78 T0JM00000000018800000L1 T0JM00000000018800000 MILLBANK M THERON SPRINKEL GRAS 
81 2.33 T0JM00000000018800000L2 T0JM00000000018800000 QUARRIEFONTEIN     SPRINKEL PAPRIKA 
82 1.22 T0JM00000000014300000B1 T0JM00000000014300000 SENLAC N HAMMAN DRIP OLYFBOOM 
83 30.24 T0JM00000000101600000S3 T0JM00000000101600000 FORREST HALL D VAN ZYL SPILPUNT UK 
84 29.99 T0JM00000000101600000S2 T0JM00000000101600000 FORREST HALL D VAN ZYL SPILPUNT UK 
85 29.99 T0JM00000000101600000S1 T0JM00000000101600000 FORREST HALL D VAN ZYL SPILPUNT UK 
86 31.15 T0JN00000000000700000S1 T0JN00000000000700000 WESTWARD HO V LE ROUX SPILPUNT KORING 
87 30.49 T0JN00000000000700000S2 T0JN00000000000700000 WESTWARD HO V LE ROUX SPILPUNT KORING 
88 10.69 T0JM00000000018500002S2 T0JM00000000018500002 HARCOURT J FOURIE SPILPUNT UK 
1 1.49 T0JM00000000018100000L1 T0JM00000000018100000 BRENTWOOD E DU TIOT DRIP UK 
2 9.88 T0JM00000000018100000L1 T0JM00000000018100000 BELVEDERE SG GRIESEL SPRINKEL GRAS 
Total 1993.41        
 
 
 104 
Appendix 10 Example abstraction control by means of an agreement between the responsible 
authority and user and reporting by the user to the responsible authority. (Afrikaans) 
Gebruiker              
NAAM REG NR VOLUME PLAAS AREA AKTE ALG. TOT Mielie Grondbone Paprika @ Aartapples Koring Lusern Ander 
MAGTIG @7500 @ 7000 12000 @ 7000  @7500 @11400 @volume 
Mr. P.E. Kriel 10081261 89180 Millbank 856.5 T2667/1996 51392 17.5 3.5 14           
Volume   124250           26250 98000           
Beplan 2003/2004 Hektaar                         
gewas 
Beplan Volume                           
Verduidelik hoe u beoog om die volume wat u besproei weekliks te meet of kies uit die onderstaande :       
                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                   
                                                                                                                                                                                                                                   
1.     n Vloeimeter met ‘n outomatiese volume registreerder op elk van u produksie boorgate wat gekalibreer, verseel en ‘n verskaffers     
sertifikaat van akkuraatheid het.             
2.     ‘n Grootmaat Vloeimeter met ‘n outomatiese volume registreerder wat die volume meet wat die versamel dam of verlaat of ingaan     
of op die besproeiings toestel              
3.     ‘n Gesertifiseerde water sisteem vloei/ behoefte sertifikaat van die verskaffer van die besproeiings toestel asook ‘n uur meter wat die     
hoeveelheid ure wat besproei word registreer en /of           
‘n Gekalibreerde Eskom kilowatt-hour meter wat spesifiek registreer die ure wat die besproeiings sisteem in gebruik is.     
               
               
Vanaf weeklikse volume metings moet maandeliks teen laaste dag van die maand aangeteken word die volume besproei     
               
Maand  2003 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
Volume gebruik kubiek meter                           
Maand  2004 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
Volume gebruik kubiek meter                           
               
Verklaring deur watergebruiker: Hiermee verklaar ek dat my besproeiing beplanning gedoen is teen aanbeveelde gewas behoeftes     
binne die toegekende volume. Die werklik gepompde volumes is gemeet akkuraat soos per voorgeskryfde metode en maandeliks korrek     
aangeteken.              
               
Handtekening:              
Datum:               
 
 105 
Appendix 11 Proposed water level monitoring network. 
Borehole Farmname Lat Long Alt GPS Alt Map Equipment 
G39663 Thornthwaite -25.8778 24.01897 1116 1100 oop-bg 
G39664 Thornthwaite -25.8764 24.01911 1112 1100 00p-bg 
G39665 Thornthwaite -25.8777 24.01897 1120 1110 oop-bg 
G39667 Vaalboschhoek -25.9722 23.98411 1158 1128 oop-bg 
G39668 Vaalboschhoek -25.97 23.97935 1160 1132 oop-bg 
G39669 Marstone -25.8822 24.11341 1106 1065 oop-bg 
G39670 Marstone -25.8814 24.11524 1110 1080 oop-bg 
G39671 Elchester -25.8443 24.09883 1093 1069 mono 
G39672 Belvidere -25.7229 23.97763 1103 1079 oop-bg 
G39673 Blackheath -25.721 24.23915 1119 1086 oop-bg 
G39674 Belvidere -25.7292 23.97851 1096 1079 oop-bg 
G39675 Grassbank -25.8601 23.82374 1139 1130 oop-bg 
G39677 Waterbury -25.7959 23.80765 1153 1120 mono 
G39678 Forres -25.9829 23.94156 1172 1147 domple/p 
G39679 Forres -25.9403 23.93427 1148 1137 oop-bg 
G39680 Grassbank -25.8345 23.839 1153 1124 mono 
G39681 Forres -25.9278 23.92537 1158 1134 oop-bg 
G39682 Grassbank -25.8532 23.83869 1148 1130 mono 
G39683 Forres -25.9236 23.92636 1169 1132 oop-bg 
G39684 Quarreefontein -25.9489 23.82593 1172 1161 oop-bg 
G39685 Forres -25.887 23.85463 1145 1123 Logger 
G39686 Kokomeng -25.8982 24.00768 1136 1108 oop-bg 
G39687 Brentwood -25.794 23.9755 1130 1091 Logger 
G39688 Kokomeng -25.8981 24.00754 1132 1108 oop-bg 
G39689 Kokomeng -25.8983 24.0078 1127 1108 oop-bg 
G39690 Zandvloed -25.931 24.04289 1128 1108 w/p 
G39691 Thornthwaite -25.8767 24.01904 1133 1100 oop-bg 
G39692 Thornthwaite -25.878 24.01894 1130 1100 oop-bg 
G39693 Knapdaar -25.6741 24.14435 1103 1079 Logger 
G39694 Thornthwaite -25.8775 24.01898 1127 1100 oop-bg 
G47604 Ascot -25.8743 23.9625 1115 1115 oop-bg 
G47605 Ascot -25.8918 23.9616 1120 1120 oop-bg 
G47606 Ascot -25.8997 23.9625 1120 1120 oop-bg 
G47607 Quarrefontein -25.9138 23.8418 1133 1133 oop-bg 
G47608 Quarrefontein -25.9438 23.8238 1150 1150 Logger 
G47609 Quarrefontein -25.9429 23.8249 1145 1145 oop-bg 
G47610 Marlborough -25.7755 23.8236 1140 1140 oop-bg 
G47611 Millbank -25.8686 23.7737 1145 1145 oop-bg 
G47612 Millbank -25.8695 23.7730 1145 1145 oop-bg 
G47613 Buxton -25.8089 24.2116 1082 1082 oop-bg 
G47614 Buxton -25.8077 24.2113 1079 1079 oop-bg 
G47615 Forres -25.9250 23.8961 1135 1135 oop-bg 
 
 106 
Appendix 12 Locality of proposed water level monitoring network. 
 
 
 107 
 
 108 
Appendix 13 Draft of publication to effect water restrictions. 
 
 
 
 
 
    GOVERNMENT NOTICE 
 
 
 
NO.         
 
 
 
RESTRICTIONS ON THE TAKING OF WATER FROM THE TOSCA MOLOPO DOLOMITE 
AQUIFER. 
 
 
 
By virtue of the powers vested in me under section 63 read together with section 72 of the National 
Water Act 1998 (Act No 36 of 1998), I, Arnold Michael Muller, in my capacity as Director-General of 
the Department of Water Affairs and Forestry: 
 
 
(a) Believe that a water shortage exists in the Tosca Molopo dolomite aquifer; and 
 
(b) Limit, in terms of Item 6(1)(i) of Schedule 3 of the National Water Act, 1998, the taking 
of water from the aforementioned aquifer on the farms and for the volumes set out in 
Table 1. 
 
(c) Direct that the restriction will be applicable for the period 1 August to 31 July of any 
given year commencing from 2004, until I repeal this restriction. 
 
 
 
 
 
 
DIRECTOR-GENERAL 
DEPARTMENT OF WATER AFFFAIRS AND FORESTRY 
DATE: 
 109 
Appendix 14 Establishment of the Tosca/ Molopo WUA as published 
in the Government Gazette 16 July 2004. 
 110 
 
 111 
Appendix 15 Articles and letters published in general papers and 
magazines. 
 112 
 
 113 
 
 114 
 
 115 
 
 116 
 
 117 
 
 118 
 
 119 
 
 120 
  121 
  122 
 
 123