Sustainable Resource Management:WESTERN CAPE WATER SITUATION | MAY 2010
Situation as at 31 May 2010
| Dam | Capacity | 1 Dec 08 | 1 May 10 | 31 May 2010 | Increase (+) from 1 May '10 | |||
| Storage | % | Storage | % | Storage | % | Mcm | ||
| Steenbras Upper | 31.7 | 31 | 99% | 20 | 63% | 21 | 65% | 1 |
| Steenbras Lower |
33.5 | 32 | 94% | 13 | 39% | 18 | 52% | 5 |
| Wemmershoek | 58.6 | 54 | 92% | 24 | 41% | 36 | 61% | 12 |
| Voëlvlei | 165.4 | 162 | 98% | 96 | 58% | 113 | 68% | 17 |
| Theewaterskloof | 480.2 | 480 | 100% | 313 | 65% | 380 | 79% | 67 |
| Berg River Dam | 130 | 129 | 99% | 103 | 79% | 130 | 100% | 27 |
| Total including BRD | 899.4 | 888 | 99% | 568 | 63% | 697 | 77.5% | 129 |
Over the last week, the rainfall at the Steenbras, Voelvlei and Theewaterskloof Dams was 43.9, 28 and 17.6 mm respectively. The gross system storage increased from 685 to 697 million m3 (77.5 %), bringing the total increase since the 1st May to 129 million m3. The increase in storage was not as much as expected because the heavier rainfall occurred in the southern areas.
According to the South African Weather Service (SAWS), there is a slight chance of light rain on Thursday and Friday. The Norwegian Meteorological Institute Forecast, which extends to 9th June, shows no significant rainfall after Friday.Situation as at 17 May 2010
| Dam | Capacity | 1 Dec 08 | 1 May 09 | 17 May 2010 | Increase (+) from 1 May '09 | |||
| Storage | % | Storage | % | Storage | % | Mcm | ||
| Steenbras Upper | 31.7 | 31 | 99% | 27 | 85% | 22 | 69% | 2 |
| Steenbras Lower |
33.5 | 32 | 94% | 14 | 40% | 17 | 52% | 4 |
| Wemmershoek | 58.6 | 54 | 92% | 22 | 38% | 35 | 60% | 11 |
| Voëlvlei | 165.4 | 162 | 98% | 96 | 58% | 103 | 62% | 7 |
| Theewaterskloof | 480.2 | 480 | 100% | 333 | 69% | 374 | 78% | 61 |
| Berg River Dam | 130 | 129 | 99% | 81 | 62% | 130 | 100% | 27 |
| Total including BRD | 899.4 | 888 | 99% | 572 | 64% | 681 | 75.7% | 113 |
Over the last week, the rainfall at the Theewaterskloof, Voelvlei, Steenbras and Wemmershoek Dams was 6.9, 59, 71.8 and 78.8 mm respectively. The gross system storage increased from 608 to 681 million m3 (75.7 %). Since the start of May, the storage has increased by about 113 million m3.
According to the South African Weather Service (SAWS), there will no further rain for the following week. The Norwegian Meteorological Institute Forecast, which extends to 26th May, shows a chance of rain for Tuesday and Wednesday (25th and 26th) of next week.
Situation as at 10 May 2010
| Dam | Capacity | 1 Dec 08 | 1 May 09 | 10 May 2010 | Increase (+) from 1 May '09 | |||
| Storage | % | Storage | % | Storage | % | Mcm | ||
| Steenbras Upper | 31.7 | 31 | 99% | 27 | 85% | 21 | 66% | -6 |
| Steenbras Lower |
33.5 | 32 | 94% | 14 | 40% | 14 | 41% | 0 |
| Wemmershoek | 58.6 | 54 | 92% | 22 | 38% | 27 | 46% | 5 |
| Voëlvlei | 165.4 | 162 | 98% | 96 | 58% | 95 | 58% | 0 |
| Theewaterskloof | 480.2 | 480 | 100% | 333 | 69% | 335 | 70% | 2 |
| Berg River Dam | 130 | 129 | 99% | 81 | 62% | 117 | 89.7% | 36 |
| Total including BRD | 899.4 | 888 | 99% | 572 | 64% | 608 | 67.6% | 36 |
Over the last week the gross system storage increased from 565 to 608 million m3 (66 %). The storage in the Berg River Dam has increased by about 10% to 89.7%. For environmental reasons an annual “flood” release will normally be made from the Berg River Dam, but to help minimize the risk of the Berg River Dam spilling excessively, water will be transferred to Theewaterskloof Dam. During the past week, the rainfall at the Theewaterskloof, Voelvlei, Steenbras and Wemmershoek Dams was 25, 87, 88 and 136 mm respectively.
According to the South African Weather Service (SAWS), the current rainfall will clear by Wednesday. However, more rainfall can be expected on Thursday / Friday and it may be heavier (10 to 40 mm) in the South-Western areas of the Western Cape (Cape Town and Grabouw). The Norwegian Meteorological Institute Forecast, which extends to 19th May, shows no further rain expected from Saturday.
Situation as at 3 May 2010
| Dam | Capacity | 1 Dec 08 | 1 May 09 | 3 May 2010 | Increase (+) from 1 May '09 | |||
| Storage | % | Storage | % | Storage | % | Mcm | ||
| Steenbras Upper | 31.7 | 31 | 99% | 27 | 85% | 19 | 61% | -7 |
| Steenbras Lower |
33.5 | 32 | 94% | 14 | 40% | 13 | 37% | -1 |
| Wemmershoek | 58.6 | 54 | 92% | 22 | 38% | 24 | 40% | 1 |
| Voëlvlei | 165.4 | 162 | 98% | 96 | 58% | 95 | 57% | -1 |
| Theewaterskloof | 480.2 | 480 | 100% | 333 | 69% | 312 | 65% | -21 |
| Berg River Dam | 130 | 129 | 99% | 81 | 62% | 103 | 79% | 22 |
| Total including BRD | 899.4 | 888 | 99% | 572 | 64% | 565 | 62.8% | -7 |
Over the last week, the gross system storage dropped from 576 to 565 million m3 (62.8%). Of the major dams, only Theewaterskloof Dam received rainfall (8.7 mm) this past week.
Rain is predicted from Tuesday to Thursday of this week, with heavier falls (exceeding 10mm) in the Western areas of the Western Cape, such as Cape Town and Grabouw. The Norwegian Meteorological Institute Forecast, which extends to 12th May, shows further rain from Sunday evening until Tuesday next week (9th to 11th May).