No sluice gates were opened on any day of the week.
The Vaal Dam wall is seen during a period of heavy rains, 3 January 2021. Picture: Michel Bega
Vaal Dam was 100% full as of Friday, 4 September.
While the dam remained at a high level, this marked a drop from the same week last year, when it stood at 106.7%, according to the Department of Water and Sanitation (DWS).
Vaal Dam levels fluctuate through the week
Vaal Dam’s storage opened the week at 100.63% on Monday, before decreasing to 100.38% on Tuesday, according to the weekly hydrological report compiled on behalf of Rand Water and DWS.
Storage decreased further to 100.35% on Wednesday, then rose slightly to 100.41% on Thursday, before dropping to 100% by Friday.
The weekly average storage was recorded at 100.35%, with a high of 100.63% and a low of 100%.
Inflow declines steadily across the week
Inflow into the dam decreased every day of the week, the report showed.
Monday recorded an inflow of 43.7m³/s, which decreased to 39.3m³/s on Tuesday.
Inflow decreased again to 38 m3/s on Wednesday, before increasing slightly to 42.6m³/s on Thursday.
Friday recorded the lowest inflow of the week at 25.7m³/s, a sharp decrease from the previous day. The weekly average inflow stood at 37.9m³/s.
Discharge from Vaal Dam remained constant at 16.8m³/s every day from Monday to Friday, the data indicated. No sluice gates were opened on any day of the week.
Vaal Barrage levels and discharge hold steady
The Vaal Barrage recorded a consistent level of 7.5 metres from Monday through Friday, according to the report.
Discharge at the barrage also remained unchanged throughout the week at 22.6m³/s.
Water temperature at the barrage increased from 12.6°C on Monday to 16.4°C on Tuesday.
It then decreased to 15.6°C on Wednesday, before rising again to 16.4°C on Thursday. Friday recorded a slight decrease to 16.2°C.
The weekly average temperature was 15.4°C.
The report noted that not all abstraction and evaporation losses from Vaal Dam were reflected in the figures, and cautioned that weekend data remained unverified pending confirmation.
