A research report submitted to the Faculty of Science school of Geosciences in partial fulfillment of the requirements for the degree of Masters of Science in Hydrogeology. Johannesburg, June 2017. / The Masama Sandstone Aquifer is located in a semi-arid region of south-eastern Botswana where there are no perennial rivers. Groundwater is the main source of water supply for the communities. Historically many water drilling programs have been carried out in this area and the hydrogeological system has been conceptualized. An integrated approach coupling environmental isotopes, radioisotopes and multivariate statistical analysis of the hydrochemical variables was employed to study the origin, age, recharge conditions, rock-water interaction and the hydrological link between the aquifer and geological structures. The major ions in this area are Na+, Ca2+, Mg2+ and HCO-3. Groundwater in the Masama area fall in the transition from a Na-HCO-3 –type through Ca-Na-HCO-3 to Ca-Mg-HCO-3 -type waters from the western to the eastern part of the area. The water types are as a result of cation exchange, carbonate dissolution and rock-weathering processes. The δ18O and δ2H values vary spatially depending on the source of moisture, rainfall season, geology, topography and groundwater circulation depth. Deep circulating groundwaters are isotopically depleted whilst shallow circulating groundwaters are isotopically enriched with respect to winter rain. Low tritium values < 0.8TU and 14C values < 80pmc testifies for recharge. Recent rainfall amount in the area is not sufficient enough to make a profound replenishment in the aquifer. Tritium, 14C and Chloride Mass Balance helped in identifying recharge location and hydrologic connections between structures and the sandstone aquifer elucidating that recharge zones are in the NE and NW of the study area. High recharge rates occur in the north-eastern part and the Makhujwane fault act as a conduit for groundwater recharge. This study provides a better understanding of the aquifer and the information contained herein can be incorporated into future works for sustainable use of the groundwater resource. / XL2017

A research report submitted to the Faculty of Science, in partial fulfilment of the requirements for the degree of Master of Science in Hydrogeology, School of Geosciences, University of the Witwatersrand. Johannesburg, June 2017. / Groundwater is a principal source of water for many semi-arid countries, including Botswana and South Africa. This is especially true for the rural communities within these regions that lie on the periphery of local water scheme pipelines and make direct use of groundwater. The Ramotswa transboundary aquifer, which supplies local communities and nearby cities with fresh groundwater, is a highly productive and unique karst sequence shared by South Africa and Botswana. The objective of the study was to contribute to the available hydrogeological data by means of evaluating groundwater flow, nitrate pollution and the median recession index and master recession curve for the aquifer. The interpreted airborne geophysical data revealed the presence of collapsed features in the northeastern area corresponding to the karst morphology. A piezometric map of the area shows the groundwater flow is towards the north-northeast, which is supported by salinity increase across the study area. Increased nitrate concentrations were identified in areas with increased rainfall, shallow groundwater and a mature karst system. Only 3% of the 36 sample sites had nitrate concentrations exceeding the WHO guideline limit of 50 mg/l. This was attributed to the legacy of unlined pit latrines in karstified areas. Pollution is entirely anthropogenic and generally from non-point sources. A median recession index computed by RECESS program from the Dinokana spring discharge data was 295.7 days per log cycle and the generated master recession curve’s gentle slope alludes to massive storage potential within the karst compartment. The results of the study can alert stakeholders alike of the health risk of direct consumption of the groundwater without pretreatment. Establishing an understanding of the nitrate pollution sources and groundwater flow direction, and estimating the recession index provides informed groundwater pollution and vulnerability management options. This can improve the aquifer resource assessment and the livelihoods of local communities in the face of increasing climate change. / XL2017

Water resources management practice has undergone changes in management approaches and principles over time. It was previously characterised by what scholars refer to as the hydraulic mission where ‘extreme engineering’ was the order of the day (Allan, 2003). As Radif (1999) argues, water resources managers and policy makers were initially driven to manage and supply water to people for its direct use / these included drinking, growing food, and providing power for domestic and industrial use. This modus operandi continued until the end of the 1970s. Over two decades later, this focus is still prevalent in many countries in southern Africa including Botswana. As Swatuk and Rahm (2004) state, “augmenting supply is a continuing focus of government activity”. The National Water Master Plan (NWMP) is the current policy document guiding water resources management in Botswana and it focuses on supply-side interventions in response to increasing water demand. According to SMEC et al. (1991), the consulting company that conducted the NWMP study, “the investigation and studies... indicated the need for the continuing development of water supplies throughout Botswana over the next 30 years”. Based on these observations, government has developed significant human and technical capacity in exploiting both surface and groundwater resources (Swatuk and Rahm, 2004).

Water resources management practice has undergone changes in management approaches and principles over time. It was previously characterised by what scholars refer to as the hydraulic mission where ‘extreme engineering’ was the order of the day (Allan, 2003). As Radif (1999) argues, water resources managers and policy makers were initially driven to manage and supply water to people for its direct use / these included drinking, growing food, and providing power for domestic and industrial use. This modus operandi continued until the end of the 1970s. Over two decades later, this focus is still prevalent in many countries in southern Africa including Botswana. As Swatuk and Rahm (2004) state, “augmenting supply is a continuing focus of government activity”. The National Water Master Plan (NWMP) is the current policy document guiding water resources management in Botswana and it focuses on supply-side interventions in response to increasing water demand. According to SMEC et al. (1991), the consulting company that conducted the NWMP study, “the investigation and studies... indicated the need for the continuing development of water supplies throughout Botswana over the next 30 years”. Based on these observations, government has developed significant human and technical capacity in exploiting both surface and groundwater resources (Swatuk and Rahm, 2004).