Assessment of groundwater resource in the Tsineng area, Northern Cape: a geophysical survey perspective
| dc.contributor.advisor | Fourie, F. | |
| dc.contributor.author | Mokgatle, Tumelo | |
| dc.date.accessioned | 2017-03-15T06:23:45Z | |
| dc.date.available | 2017-03-15T06:23:45Z | |
| dc.date.issued | 2016-07 | |
| dc.description.abstract | English: In this study the groundwater resource the in Tsineng area, Northern Cape was assessed in terms of the volumes of water that may be sustainably abstracted from the aquifer system, and the quality of the available groundwater. A strong emphasis was placed on the use of airborne and ground geophysical techniques to gain a better understanding of the geological and geohydrological conditions in the study area. The airborne geophysical technique employed during the current investigation was the time-domain electromagnetic method (using the SkyTEM system), while ground geophysical surveys employed the gravity, magnetic, frequency-domain electromagnetic and electrical resistivity tomography methods. The geophysical techniques were used to provide information on physical changes in the subsurface conditions that may be related to the presence of geological structures associated with potential groundwater resources. The results of all the geophysical methods used were collated and correlated to the local geology to make an informed decision during the selection of drilling targets for the installation of production boreholes. From the TDEM data, information on the subsurface distribution of resistivities was obtained. Well-defined resistivity anomalies correlated well with the known presence of two prominent fault zones. Furthermore, resistivity anomalies were also identified at the locations of mapped dolerite dykes known to intersect the study area. The ground geophysical investigations were conducted across preliminary targets defined from the airborne TDEM data. The ground geophysical investigations confirmed the presence of the structures identified from the TDEM data. Based on the results of the geophysical investigations and the known local geological conditions, drilling targets were selected at positions deemed promising for the installation of successful production boreholes. A total of 78 exploration boreholes were drilled during the current investigations. Sixty of these boreholes had water strikes and were thus considered successful. A combined total blow-yield of 409 l/s was measured in the successful boreholes. Forty of the drilled boreholes had blow-yields in excess of 2 l/s. These boreholes were selected for aquifer hydraulic tests to assess the hydraulic parameters of the intersected aquifer systems. From the estimated hydraulic parameters, sustainable yields were determined for the tested boreholes. The total estimated sustainable yield from the boreholes was more than 7 500 m3/day. Water samples from the 40 high-yielding boreholes were submitted for chemical analyses. The results of the analyses showed that the water in the study area is generally of very good quality, suitable for human consumption. It is therefore concluded that groundwater may be successfully used to augment the municipal water supply in the Tsineng area. The results of the current research demonstrate that the use of geophysical techniques could greatly contribute to an understanding of the geological and geohydrological conditions in a study area, which could in turn lead to a higher success rate during groundwater exploration programmes. Keywords: Geophysical Afrikaans: In hierdiestudie is die grondwaterbronne in die Tsineng-area in die Noord-Kaap Provinsiegeëvalueer in terme van die volumes water wat volhoubaaronttrekkan word vanuit die akwifeersisteem, asook die kwalitiet van die beskikbaregrondwater. ‘nSterkklem is geplaas op die gebruik van geofisiesetegnieke om ‘n beterinsig in die geologieseengeohidrologiesetoestande van die studie-area teverkry. Die lug-geofisiesetegniek wat gebruik is gedurende die huidigeondersoek was die tyd-domeinelektromagnetiesemetode (die SkyTEM-sisteem is gebruik), terwyl die grondgeofisieseopnames die gravitasie-, magnetiese-, frekwensie-domeinelektromagnetiese-enelektrieseweerstandtomografie-metodesgebruik het. Die geofisiesetegnieke is gebruik om inligtingtebekomoor die fisieseveranderingeondergronds wat verband mag hou met die teenwoordigheid van geologiesestrukturegeassosieer met potensiëlegrondwaterbronne. Die resultate van al die geofisiesemetodes is gesamentlikbeskouengekorreleer met die plaaslikegeologieomingeligtebesluitete neem tydens die seleksie van boorteikensvir die installering van produksieboorgate. Vanaf die TDEM data is inligtingoor die ondergrondseverspreiding van soortlikeweerstandeverkry. Goed-gedefinieerdeweerstands-anomalië het goedooreengestem met die bekendeteenwoordigheid van twee prominenteverskuiwingsones. Verder is weerstands-anomaliëookgeïdentifiseer by die posisiesvan bekendedolerietgange wat die studie-area deurkruis.Die grondgeofisieseondersoeke is gedoenoorvoorlopigeteikens, soosgedefinieervanaf die TDEM-data.Die grondgeofisieseondersoekehet die teenwoordigheidbevestig van die strukture wat vanaf die TDEM-data geïdentifiseer is. Vanaf die resultate van die geofisieseondersoeke, asook die bekendeplaaslike geologiesetoestande, is boorteikensgekies op plekke wat as belowendbeskou is vir die installering van suksesvolle produksie boorgate. ‘n Totaal van 78 eksplorasie boorgate is geboortydens die huidigeondersoeke.Sestig van hierdieboorgate het water getrefen is gevolglik as suksesvolbeskou.‘n Gekombineerde total eblaaslewering van 409 l/sis gemeet in die suksesvolleboorgate.Veertig van die boorgate het blaaslewerings van meer as 2 l/s gehad. Hierdieboorgate is gekiesvirhidrouliesetoetsing van die akwifeerom die hidrouliese parameters van die akwifeer-sisteemtebepaal. Vanaf die geskattehidrouliese parameters, is volhoubareleweringsvir die getoetsteboorgatebepaal. Die total egeskattevolhoubarelewering van die boorgate was meer as 7 500 m3/day. Watermonsters van die 40 hoë-leweringboorgate is ingedienvirchemieseanalises. Die resultate van die chemieseanalises het getoondat die water in die studie-area oor de algemeen van baiegoeiekwaliteit is, geskikvirmenslikegebruik. Die water kandussuksesvolgebruik word om die munisipalewatertoevoer in die Tsineng-area aantevul. Die resultate van die huidigeondersoek toon dat die gebruik van geofisiesetegniekegrootlikskanbydra tot die begrip van die geologieseengeohidrologiesetoestande in ‘n studie-area, wat weerkan lei tot ‘n hoërsukseskoersgedurendegrondwatereksplorasieprogramme | en_ZA |
| dc.description.sponsorship | Department of Water and Sanitation | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11660/5816 | |
| dc.language.iso | en | en_ZA |
| dc.publisher | University of the Free State | en_ZA |
| dc.rights.holder | University of the Free State | en_ZA |
| dc.subject | Geophysical techniques | en_ZA |
| dc.subject | Groundwater exploration | en_ZA |
| dc.subject | Groundwater resource assessment | en_ZA |
| dc.subject | SkyTEM | en_ZA |
| dc.subject | Aquifer parameters | en_ZA |
| dc.subject | Borehole sustainable yield | en_ZA |
| dc.subject | Water quality | en_ZA |
| dc.subject | Water-supply -- Management | en_ZA |
| dc.subject | Aquifers | en_ZA |
| dc.subject | Boring -- South Africa -- Northern Cape | en_ZA |
| dc.subject | Water well drilling | en_ZA |
| dc.subject | Dissertation (M.Sc. (Institute for Groundwater Studies))--University of the Free State, 2016 | en_ZA |
| dc.title | Assessment of groundwater resource in the Tsineng area, Northern Cape: a geophysical survey perspective | en_ZA |
| dc.type | Dissertation | en_ZA |