Impact of climate change on groundwater potential and recharge in the drought prone Runde catchment of Zimbabwe

Abstract

Groundwater provides critical freshwater supplies for most rural communities living in drought-prone areas. Such is the case for Runde catchment in Zimbabwe, whose rural communities depend on groundwater. Climate change and increased variability pose a threat to water availability by affecting groundwater potential and recharge, but the full extent of the threat is not well understood. Thus, the main objective of this study was to assess the impact of climate change on groundwater potential and recharge in the catchment. The groundwater potential mapping was performed using a spatially weighted overlay method with inputs: soil type, geology, land use, observed precipitation, topographic wetness index and elevation. This mapping produced a groundwater potential index, classified into groundwater potential zones and cross-validated with borehole yield data, r=0.63 and n=62. The groundwater potential validation showed 1.6 and 4.8% of the total boreholes were in the high (>7 L/s) to very high (4–7 L/s) while 43.5 and 50.1% moderate (1–4 L/s), and low (<1 L/s) groundwater potential zones respectively. The simulated precipitation increased by 23% for 2020–2080. Climate change impacts decreased average groundwater potential by 30.8% (13,062.90 km2) low, 5.8% (2433.25 km2) moderate and increased by 34.8% (14,707 km2) high by 1.8% (789.15 km2) very high groundwater potential. For sustainable groundwater management, a holistic approach informs climate change adaptation and mitigation policies. HIGHLIGHTS Assess groundwater potential of Runde catchment in Zimbabwe.; Map groundwater recharge of Runde catchment.; Analyse CORDEX downscaled climate variables for Runde rain gauge stations.; Project the impact of climate change on groundwater potential and recharge of Runde catchment, Zimbabwe.;

Keywords

• gis
• precipitation
• simulated rainfall
• validation
• wetness index