Groundwater governance provisions and arrangements in South Africa were studied at national level and at local level for a highly productive aquifer, the Botleng Dolomite Aquifer. Technical, legal, institutional and operational governance provisions were found to be reasonable at the national level but weak with regards to cross-sector policy coordination. At the local level, basic technical provisions such as hydrogeological maps and aquifer delineation with classified typology are in place but other governance provisions such as institutional capacity, provisions to control groundwater abstraction and pollution, cross-sector policy coordination and the implementation of a groundwater management action plan are weak or non-existent. Adaptation measures to climate change are not yet fully considered in planning. Only at the national level a groundwater strategy and artificial-recharge strategy has been developed but awaits implementation. Most critical management measures are considered, namely:• The integration of the National Groundwater Strategy (NGS) into the various water-related strategies • Strengthening of the groundwater regulatory environment • Strengthening of the institutional capacity Keywords: groundwater, governance, dolomite, South Africa Background and methodology

Increased use and protection of groundwater resources are seen as possible solutions to mitigating water scarcity in arid and semi-arid regions. The DRASTIC index method is one of the most commonly used approaches to assess groundwater vulnerability to pollution. However, this method has been criticized in the past due to its subjectivity as well as the failure to account for some important hydrogeological characteristics (e.g. multi-layer vadose zone and preferential flow) and specific properties of contaminants (e.g. sorption and decay). These problems were addressed in this study with the objective of improving the DRASTIC method for assessment of groundwater vulnerability to generic aqueous-phase contaminants. Literature data and laboratory measurements were used in order to define categories and weighing factors for hydrogeological characteristics and specific contaminant properties. The new DRASTIC method developed in this study provides an improved categorization of the impact of the vadose zone, which accounts for the following factors: multi-layer vadose zone, based on site-specific conceptual models; hydraulic properties of the unsaturated zone (flow mechanism, drainage and travel time); and specific chemical properties (sorption and decay). The information was packaged in a user-friendly format for rating groundwater vulnerability. The method can be used for applications in site-specific environmental impact assessments for new developments, for regional groundwater vulnerability assessment as well as in integrated water resources management.

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Understanding fluid flow and solute transport within the vadose (unsaturated) zone is an essential prerequisite for protection of groundwater from contaminant sources occurring overland. Preferential flow paths in the vadose zone pose a significant problem because they are potential avenues for rapid transport of chemicals from contamination sources to the water table. The objectives of this study were i) to test the adequacy of a model, namely MACRO 5.0, in simulating bimodal water flow and generic contaminant transport in the vadose zone, and ii) to run a sensitivity analysis with MACRO 5.0 in order to determine which input parameters are the most relevant in describing the effects of preferential water flow, solute transport and exchange between macropores and matrix. Two case studies were investigated, the first at a landfill site overlying sandy unconfined aquifer (Coastal Park, Cape Town), and the second at an industrial site overlying cracking clayey soil and fractured rocks (Secunda, Mpumalanga Province). For the Coastal Park site, simulations of soil water content and leaching of a mobile tracer were compared to monitored soil water contents and chloride concentrations in groundwater. For the Secunda site, simulations of soil water content and concentrations of boron and fluoride originating from effluent irrigation were compared to soil profile measurements. In both cases, the MACRO 5.0 model predictions agreed well with measurements, appropriate input calibration data were used. The sensitivity analysis indicated that soil water properties related to preferential flow (hydraulic conductivity at the boundary between macropores and matrix, soil water content and tension, and diffusion pathlength) have influence on simulation results. Similarly, the solute balance is mostly influenced by degradation rate coefficients (both in solid and liquid phases), sorption distribution coefficients and solute concentrations.