A methodology for groundwater management in dolomitic terrains with the Schoonspruit compartment as pilot area

English: The thesis proposed to use the principle of prior conceptual model explanation (PCME) by LeGrand & Rosen, 2000, as base to develop a technical methodology towards groundwater management in dolomitic terrains, with the development of a groundwater management tool. The Schoonspruit Dolomitic Compartment was used as case study to evaluate the aquifer with current information, test the developed methodology on and develop a technical groundwater management tool. A phased approach was adopted with a geohydrological assessment of the study area as phase 1 and the development of a technical methodology and the development of the groundwater management tool as phase 2. The aim of the geohydrological assessment was the use of the PCME approach, basic geohydrological principles and previous studies to evaluate the current status of the aquifer. This was done with a description of current information and an evaluation of new information and data. The Schoonspruit Dolomitic Compartment is a dolomitic aquifer situated to the North and Northwest of the town Ventersdorp in the Northwest Province, South Africa. The compartment has been named after the Schoonspruit Eye, which is dependent on the compartment for flow. The Schoonspruit Eye, in turn, is the sole reason why the Schoonspruit has a constant flow and provides a municipality and two surface water irrigation boards with surface water all year round. Several water users abstract groundwater from the compartment impacting on the flow of the Schoonspruit Eye. With the proclamation of The National Water Act, Act 36 of 1998, groundwater was seen as a resource that needed management and, although very little information existed in most cases, Regional Offices of the DW AF, had to start taking decisions, based on sound scientific principles, as to allocable volwnes from the groundwater resources. The Schoonspruit dolomitic regime were defined, aquifer characteristics determined, groundwater quality quantified and recharge/rainfall relationships of groundwater levels and spring flow determined with the saturated volume fluctuation (SVF), moving average (MA) and cumulative rainfall departure (CRD) methods. Two zones were identified as groundwater management units in the compartment and groundwater balances for the two zones defined. The spring flow simulation equation was determined for use in all simulations related to the drainage area of the Schoonspruit Eye. The aim of the technical methodology was to provide a technical framework, which could easily be extrapolated and applied to other dolomitic areas. The methodology distinguished between essential and supplementary information needed for groundwater management in dolomitic areas. A flowchart was developed, as blueprint, when assessing dolomitic areas for the purpose of groundwater management, an overview given with regard to the legal and institutional principles that should be applied in such areas, a detailed description given with regard to the geotechnical controls that govern the groundwater flow and characteristics in dolomitic areas and the basic principles governing the development of a groundwater management tool outlined, with input and output parameters defined. The aim of the groundwater management tool was to provide a first order technical tool, which is practical and workable, for use by the Water User Association in determining allocable volumes. Input and output parameters used were proven to be sufficient for defming quantity and quality issues in the Schoonspruit Dolomitic Compartment. Allocable volumes can be determined for the 2 zones and the Schoonspruit Eye flow simulated, with the MA method, using predicative rainfall data and the drinking water quality classes were introduced, as part of an early warning system, where drinking water quality is of concern.