The Vaal River System remains in a strong position as South Africa heads towards the summer rainfall season, but the Department of Water and Sanitation (DWS) is keeping a close eye on the potential effects of El Niño.
The Integrated Vaal River System (IVRS) is currently 98.2% full, unchanged from the previous week, giving Gauteng and surrounding areas a significant water reserve ahead of potentially more challenging weather conditions.
The department said the possibility of El Niño developing during the summer could bring below-normal rainfall and hotter, drier conditions to parts of Southern Africa.
Such conditions could place additional pressure on water resources by reducing river flows and catchment runoff, while higher temperatures could increase evaporation and water demand.
The department said climate variability and climate change were also contributing to increasingly unpredictable weather patterns, including prolonged dry spells, changing rainfall distribution and higher temperatures.
Despite the potential risks, the Vaal system is entering the period with healthy storage levels.
Vaal Dam, which supplies Gauteng and surrounding areas, is at 101.0%, down slightly from 101.5% last week.
DWS said the decline reflected normal water-resource management, including the balancing of inflows, releases and demand. Grootdraai Dam remains at 96.9%, while Sterkfontein Dam is unchanged at 98.8%.
Bloemhof Dam increased from 108.0% to 109.8%, remaining significantly above its defined full supply level. DWS said storage above 100% requires careful operational management and controlled releases where necessary to maintain appropriate reservoir levels and dam safety.
The Lesotho Highlands Water Project is also contributing to the system's strong position. Mohale Dam increased slightly from 101.7% to 101.8%, while Katse Dam declined from 82.5% to 81.9%.
The department said the current levels provide an important buffer should drier conditions develop over the coming months.
However, the department cautioned that strong dam levels should not lead to complacency.
“Every effort to prevent water losses, reduce wastage and promote the efficient use of available water remains essential,” DWS said.
The department said it would continue monitoring reservoir levels, rainfall, catchment conditions, inflows, releases, water demand and seasonal climate forecasts.
El Niño can influence Southern African weather patterns and increase the risk of drier conditions in some areas. If reduced rainfall persists alongside higher temperatures and evaporation, water resources could come under increasing pressure over time.
The department said the potential influence of El Niño therefore reinforced the need for sustained water conservation and demand management.
The department added that it remained ready to implement appropriate water-resource management measures if necessary to protect supplies and maintain the resilience of the Vaal River System. – SAnews.gov.za
