Staff Reporter
14 June 2011
Windhoek — The Hydrological Services in the Ministry of Agriculture, Water and Forestry says due to the good rains in the Bloemfontein area of South Africa, the Lower Orange River at Noordoewer will rise to 5.80 metres by the end of this week.
The Hydrological Services indicated that there will be little or no impact to Noordoewer or the grapevines of Aussenkehr although water will flow at 2350 cubic metres per second.
It warned of high flows in the Lower Orange River for the next seven days and that the peak of the flood in the Riet River reached the Vaal River at 20:00 on Sunday with a discharge of approximately 2200 cubic metres per second.
The latest report forwarded by Brink du Plessis of Directorate of Water Affairs in South Africa shows the Modder/Riet rivers join the Vaal River just upstream of its confluence with the Orange River.
It said streams are moving fast with a flow recorded at Katlani along the Orange- Vaal River confluence with a strength of 2 700 m3/s peaked on Sunday.
The flow at Prieska peaked at 2780 cubic metres per second on Sunday while the flow at Upington recorded 2000 cubic metres per second to peak at 2700 cubic metres per second by today.
The flow at Vioolsdrift is to reach a peak of 2500 cubic metres per second this Friday while the flow at Brand Kaross is now moving at 600 cubic metres per second but will peak at 2400 metres per second on Sunday.
Meanwhile, the Hydrological Services is asking for assistance with flood monitoring in the next rainy season.
Chief hydrologist Guido van Langenhove, said although the rainy season is over and the coming rainy season may seem in the far distant future, his institution would like to appeal for possible support from interested persons later this year and next year, in particular in the flood-prone areas along Namibia’s northern and southern borders.
In a communication released by the Hydrological Services, he indicated that records of waterlevels, like gauge readings at the official monitoring sites like Rundu, may deviate at times because of electronic drift.
He pointed out that any information on rainfall and the highest flood levels this year, in particular dates and comparison with previous years, will be welcomed.
Any marked flood levels for this year or previous years that may be suitable for surveying as part of flood mapping can be forwarded to him.
He said anyone interested in taking and forwarding daily rainfall and/or river level readings in the coming year can contact his office.
Van Langenhove said the Hydrological Service will assist with the gauges and if necessary installation.
“Unfortunately, there is still no progress with the monitoring and communication systems for floods in the headwaters of the Cubango-Okavango River Basin.” The proposals of the hydrologists in this regard he said, were duly noted, but implementation was left in the middle.
“OKACOM may be the first river basin organisation in Africa to see the importance of data sharing, but the Cubango-Okavango River Basin may be the last one in this part of Africa where the principle is put in practice for sharing of flood information, leaving in particular Namibia subject to rumours and speculation about upstream floodwaves in the rainy season.
“Basin communities and other interested parties can act on the basis of sound scientific research, “rather than rumour and speculation”.
AllAfrica – All the Time
Excerpt from:
Orange River Expected to Swell