Heavy rainfall in parts of south east Africa over the last 2 weeks has resulted in flooding in Zimbabwe, Malawi and Mozambique.
As reported earlier this week, as many as 10 people have died in flooding in Zimbabwe. According to media reports, 6 people have been killed in Malawi and as many as 9 people have died as a result of recent severe weather in Mozambique. Heavy rainfall has also been reported in Madagascar and Zambia although no flooding has as yet been reported.
Change in Monsoon – Rainfall 150% Higher Than Normal
According to a report (pdf) on Africa Hazards Outlook by NOAA’s Climate Prediction Center, the heavy rainfall is a result of a change of the southern Africa Monsoon. The report says:
“Since late December, the character of the southern Africa monsoon has shifted considerably, as several regions of southeastern Africa continue to experience a significant increase in rains and available ground moisture. This increase has helped both alleviate and completely offset seasonal moisture deficits associated with a poor/delayed start of the monsoon during November and December.”
The report goes on to say that areas of south east Africa have seen rainfall amounts 150% higher than normal.
“During the last 30 days, analysis of rainfall anomaly tendency shows the greatest positive changes (>100mm) have occurred throughout southern Zambia, Zimbabwe, Malawi, Mozambique and western Madagascar. It is these areas that are now experiencing approximately 150 percent of their normal precipitation for the season.”
Further Rain and Flooding Expected
NOAA predicts further heavy rainfall over the coming days, and possibly for the rest of January. This makes the possibility of more flooding highly likely, in particular as river levels are already high.
“These torrential rains not only reportedly triggered flooding in central Zimbabwe during the last week, but are also expected to elevate the risk for downstream inundation along the Zambezi, Save, Buzi, Pungwe, and Limpopo Rivers in Mozambique.”
Cahora Bassa Dam
Such heavy rainfall in this area invariably focuses attention on the Cahora Bassa dam. Mozambique’s Disaster Management Technical Council (CTGC) say that the reservoir still has plenty of storage capacity, and so Hidroelectrica de Cahora Bassa (HCB), the company that operates the dam, is currently only discharging 2,500 cubic metres a second.
But if the current scenario persists, HCB may be obliged to increase the discharges in order to guarantee the safety and integrity of the dam itself. Increased discharges from Cahora Bassa will inevitably increase the threat of flooding on the lower Zambezi.
A dambreach would prove disastrous for communities downstream of the dam. The flood wave would reach Tete (with a population of more than 150,000) just 10 hours after the breach.
See the report by Marc Hartman of HKV Consultants for an animation of the potential flood resulting from a dambreach in the Cahora Bassa dam.
Yesterday 134 mm of rain fell was recorded in 24 hours in Nampula, Mozambique. Severe weather has been affecting Nampula Province for the last 2 weeks and 9 people have been reported as killed in Nacala city. The deaths were thought to have been caused by lightning strikes and by the collapse of a wall during a thunderstorm.
According to a statement made by Mozambique government’s Disaster Management Technical Council (CTGC), around 2,500 houses have been damaged or destroyed in the floods and rainstorms since late December 2014. Almost 10,000 families have been affected, with Maputo province and city are thought to be some of the worst affected areas.
@HeraldZimbabwe @ZBCNewsonline Floods at Moatize Bridge,Tete Moza delaying traffic Malawi to Zim and RSA by 4hrs pic.twitter.com/IoDDrjO7ZX
— jairzinho (@Gairezi) January 7, 2015
At least 10 people have died in the floods in Zimbabwe. The latest assessment from the Zimbabwe Red Cross says that over 160 houses have been destroyed. Other media reports says this total should be closer to 2,000. Assessment work is still being carried out by the Red cross and Zimbabwe authorities.
Six people have been reported as killed in recent flooding in Malawi – four in Mangochi, two in Zomba. Further deaths are likely, according to Paul Chiunguzeni, Commissioner for Disaster Management Affairs, who spoke to Anadolu News Agency.
World Bulletin report that at least 500 families have been displaced by the floods, which have destroyed houses and crops.