Water and Sanitation releases hydrological report

Localised floods are on their way, warns a hydrological report

Although the expected La Nina this summer may be weak, South Africans should prepare themselves for possible localised flooding, a report released by the Department of Water and Sanitation this week predicted.

“Given the current condition of the veld cover (vegetation) we can expect increased levels of runoff even with a weak La NiAa. The expected La NiAa is very weak and trending towards neutral. Most key atmospheric variables continue to indicate neutral ENSO conditions,” the report says.

It further warns the country of below normal rainfall and warm temperatures during spring. However, based on the seasonal outlook report by the South African Weather Services (SAWS), we have “very bleak weather prospects” this weekend as a series of cold fronts will zoom across parts of the country that will bring about a cold Sunday and some snowfalls over the south eastern parts of South Africa that will be followed by some showers.

The report says that there has been a falloff in average dam levels in all provinces with the exception of the Western Cape where levels have increased by 34.2% over the past thirteen weeks and are now at 62.1%.

On specific examples for dams and systems:

The Amathole System has six dams that are serving Buffalo City; this week it is at 81.1% compared with 81.6% last week, a decrease of 0.5%;

Cape Town Dams System with six dams that are serving mainly the City of Cape Town this week increased slightly by 0.9% to 61.1% from 60,2%. The Voelvlei Dam has increased by 2% to 67.6% from 65,6%, whilst the Clanwilliam Dam is still spilling and is at 100.6%. Water restrictions remain in place.

The Umgeni Dam system with five dams that are serving mainly eThekwini and Msunduzi in Pietermaritzburg this week stood at 45.7% compared with 46.2% last week, a decrease of 0.5%. The system was at 70.9% in the same period last year.

Hazelmere Dam is at 60.8%, a decrease of 0.3% week on week. The dam still receives water that is pumped from the uThongathi. The Nagel Dam has decreased by 1.6% to 65.9% from 67,5%, and the Midmar Dam outside Pietermaritzburg experienced a decrease of 0.1% to 46% from 46,1%.

The Algoa System which has five dams that serve the Nelson Mandela Bay Metropolitan area this week increased by 0.1% to stand at 72.3% from 72,2%.

Other KwaZulu-Natal dams which remain dangerously low are Klipfontein which is at 12.3%, Hluhluwe at 18.3% and Goedertrouw at 17.5%. The current restrictions for Goedertrouw Dam will remain at 15% for industrial, 40% for domestic and 80% for irrigation.

The Vaal River System has 14 dams that are serving mainly Gauteng, Sasol and Eskom. The system has decreased by 0.7% to 52.4% from last week’s 53.1%. The system was at 73.6% last year. The Katse Damn in Lesotho is at 44.7%, whilst the Vaal Dam decreased by 0.9% week on week to 31.6%. The Sterkfontein Dam is steady at 89.8% and the Grootdraai Dam is at 72.9%, marking a decrease of 1.4%.

While Rand Water started reducing supplies from 6 September and all metros have published their restrictions, the impact of the restrictions is not yet visible. Releases from Vaal Dam are still taking place to maintain the quality of the water in the river below the dam and down to Bloemhof Dam below 600ppm TDS. The Task Team continues to meet every Monday to monitor developments.

The Gariep Dam is at 57.9%, an increase of 0.1% and Van Der Kloof Dam stands at 62.7%, a decrease of 1.4%.

The Crocodile West system has six dams that serve mainly Tshwane, Madibeng and Rustenburg. It decreased by 1.3% to 92%.

The Bloemfontein System has four dams that serve mainly Mangaung. This week it stood at 37.3% compared with 37.7% last week, a decrease of 0.4%. The system was at 32.2% at the same time last year.

“We continue to monitor 211 dams on a weekly basis. Twelve dams are now below 10%, 61 are below 40% and 20 dams are above 100%.

Our national storage is under increasing stress and still shows a steady decline week on week. We need to continue to intensify the enforcement of restrictions to stretch our available water supplies. The drought is far from over and even with a normal season it will take a number of years for the system to stabilise.

Source: Government of South Africa.