by Tigere Chagutah – SANF 08 No 06
Southern Africa has been warned to brace for more and heavier rains as the peak of the rainfall season approaches.
The rainfall season in most of southern Africa stretches from October to March with a peak in late February.
A forecast for the period January to March 2008 issued by the SADC Drought Monitoring Centre warns of heavy rainfall across most parts of mainland SADC and Madagascar.
Mauritius is expected to receive normal to above normal rainfall during the same period.
Already, continuous heavy rains that began in December 2007 have led to flooding in parts of the region, claiming lives, and destroying property and infrastructure.
According to preliminary figures released by national disaster authorities the number of people affected by rains and floods since October 2007 in southern Africa currently stands at more than 190,000.
In particular, Malawi, Mozambique, Tanzania, Zambia and Zimbabwe have been the most affected.
In Malawi more than 60,000 people have been affected mainly through damage of property and crops. The damage stretched into southern Tanzania.
About 95,000 people have been evacuated and resettled on higher ground in Mozambique while in Zambia about 17,000 have been affected with 1,900 in temporary accommodation while the rest are in host families.
In Zimbabwe about 15,000 have lost their homes, crops and property to the floods.
Significant incidents of flooding have also been reported in Lesotho (4,000 affected) and Swaziland (2,500 affected).
In Madagascar, tropical cyclone Fame developed in the Mozambican channel at the end of January and moved across the island causing widespread damage and severe flooding while 550 people were left without shelter.
Meanwhile, warnings have been issued of the possibility of flooding in the flood prone Caprivi area in northern Namibia due to the heavy rains that have been falling in that area and upstream of the Zambezi River in Zambia and Angola.
This season’s La Niña induced rains have brought some of the “heaviest rains in living memory” in most countries in the region with Zimbabwe recording its highest ever rainfall for the months of October, November and December (OND).
Records at the Department of Meteorological Services in Zimbabwe show that OND rainfall in 2007 averaged 453.4 mm. The wettest season to date was 1924/1925 with an average of 413.8 mm for the same period.
“The La Niña phenomenon is the opposite of the more common El Niño effect associated with recent droughts in the region” says Amos Makarau, climate expert and Director of Zimbabwe’s Meteorological Services Department.
The La Niña phenomenon is characterised by a cooling of sea surface temperatures in the equatorial pacific and has significant impacts on rainfall patterns in the whole world, causing very heavy rains in southern Africa.
“Unlike the El Niño effect which is more periodical, occurring every four to five years, La Niña events are less frequent, irregular and when they occur their impacts can be quite significant,” warned Makarau.
Makarau urged national authorities to stay on alert and prepare for further flooding as these conditions are expected to persist until April.
Meanwhile, the SADC Disaster Emergency Response Team says the likelihood of continued intense rainfall upstream of the Zambezi River has renewed the threat of extensive floods downstream as river levels continue to rise rapidly.
Water levels at Kariba and Cahora Bassa dams, which usually act as buffers, preventing flooding in the Zambezi valley continue to rise sharply.
Water is currently entering Lake Cahora Bassa at 10,000 cubic metres per second, double the rate that is being discharged by the dam.
The Zambezi River Authority (ZRA) – a body set up by the governments of Zambia and Zimbabwe to manage Kariba Dam – opened one spillway gate at Kariba dam on 11 February 2008 in order to minimise structural damage to the dam wall.
The Authority warns that if the heavy rains persist as is forecast, “more gates may be opened as necessary without further notice”.
Cahora Bassa is currently less than 65 percent full and has the capacity to accommodate the sudden inflow if one floodgate is opened at Kariba.
However, officials from the Mozambican National Disaster Management Institute warn that if two or more floodgates are opened a series of small towns in the Zambezi Valley thus far unaffected might be inundated.
The action by ZRA is in accordance with the Standing Operating Procedures for Kariba Dam.
Under an agreement with Mozambique, any decision to open the Kariba floodgates must be announced at least seven days in advance, which was duly done by ZRA.
During a recent visit to Mozambique on a fact finding mission to assess the impact of floods in the region, SADC Executive Secretary Tomáz Salomão emphasised that the only way to minimise the impact of floods is through the improvement of communication and warning systems between the governments of countries that share river basins.
Salomão said that it is important for countries upstream and downstream of major regional rivers to exchange information in order to plan joint action as agreed in the SADC Revised Protocol on Shared Watercourses.
