Increasing water demand due to population growth, economic expansion and the need for development puts a strain on the supply capacity of the Vaal River catchment in South Africa. Climate change presents additional challenges in the catchment which supports the country's economic hub, more than 30% of its population and over 70% of its maize production. This study evaluates the influence of climate change on current and future intra-annual water availability and demand using a multi-tiered approach where climate scenarios, hydrological modelling and socio-economic considerations were applied. Results shows exacerbated water supply challenges for the future. Temperature increases of between 0.07 and 5 °C and precipitation reductions ranging from 0.4 to 30% for Representative Concentration Pathways (RCPs) 4.5 and 8.5, respectively, are also predicted by the end of the century. The highest monthly average streamflow reductions (8–10%) are predicted for the summer months beyond 2040. Water Evaluation and Planning (WEAP) simulations project an increase in future water requirements, gaps in future water assurance and highlight limitations in existing management strategies. The study recommends a combination of adaptation plans, climatic/non-climatic stressor monitoring, wastewater-reuse, conservation, demand management and inter-basin transfers to reduce future uncertainty in monthly water sustainability.

Understanding the impact of climate change on agricultural nonpoint source (NPS) pollution is crucial for developing effective adaptation strategies and reducing vulnerabilities where such challenges exist. This study evaluated the impact of precipitation and temperature variations on Total Inorganic Nitrogen (TIN), Total Inorganic Phosphorus (TIP), and sediment loads in the Sand River Catchment (SRC) using the Soil and Water Assessment Tool plus (SWAT+). One-way analysis of variance (ANOVA) was used to determine the significance (p < 0.05) of the relationships (R²) between precipitation and temperature on sediment, TIN, and TIP loads in the SRC. SWAT+ calibration and validation demonstrated that the statistical indices (NSE and R² ≥ 0.72; −17.30 ≤ PBIAS ≤ 14.74) fell within an acceptable range. Results indicated a significant influence of average monthly precipitation (p < 0.0001) and temperature (p ≤ 0.004) on sediment, TIN, and TIP loads. In addition, a decrease in average annual precipitation led to a decline in sediment, TIN, and TIP loads (R² ≥ 0.55), with the average annual temperature increasing in the same period (R² ≤ 0.23). This study confirms that climate change contributes to agricultural NPS pollution in the SRC and highlights the need to employ suitable adaptation strategies for pollution control in the catchment.

The water unavailability crisis in South Africa significantly contributes to socio-economic challenges affecting some of its underdeveloped former homeland areas. Limpopo province, which is predominantly rural, is nuanced by these challenges. The province is characterised by limited surface and groundwater resources, unevenly distributed, already overallocated and overused with limited scope for further development. At the same time, the province desperately needs high impact development to improve the socio-economic conditions of its communities. Water is the key resource required for those development initiatives to materialize. This study evaluates the water resources yield across the Limpopo District Municipalities. The mapping of the province’s water yield patterns across the five districts provides an insight into the extent of its water challenges and the cascading effects of this on developmental potentials of the province. The Pitman and Water Resources Yield Models were employed to achieve this. The total historical firm yield was estimated at 160.20, 39.84, 72.24, 125.79 and 120.96 Mm³/a for Vhembe, Capricorn, Waterberg, Mopani and Sekhukhune districts respectively. This study provides an insight into approaches that could be deployed by the districts to determine local water resources availability to support planned developmental projects while ensuring sustainable provision of water services to their communities.