Washington, DC — - Although another tropical storm seems likely to dump more heavy rainfall into Mozambique on Monday, according to weather experts at the National Oceanic and Atmospheric Administration, it's not just more water from the sky that is causing water worries.
Down river from the high plateaus of neighboring South Africa and Zimbabwe, Mozambique can be described as "a large flood plain," says Vernon Kousky, research meteorologist at the NOAA Climate Mediation Center just outside of Washington, D.C. "The highland areas are receiving very high rainfall and are loaded with water that has not yet washed downstream into Mozambique."
Carefully controlled releases of water from the huge Cariba and Cahora dams on the Zambezi River to ease some of the buildup are being planned. The Cariba is already filled to the brim and though the Cahora downstream from it still has room, a number of calculations have to be made, says Curt Barrett, chief of technology transfer in the Office of Technology at the National Weather Service. "What is the potential damage to infrastructure should we begin releasing water? What is the risk of failure? We have to do 'dam break' analysis with hydraulic models considering a worse-case scenario. We're looking at the effect of rains that have come and rains that will come."
The National Weather Service now thinks the storm that has hammered Mozambique is part of a pattern that will continue to effect the southern Africa nation through March and perhaps through April. "It's intensified by La Nina and its activity and effects over the Pacific," says Wassila Thiaw who coordinates the Africa Desk at NOAA.
While NOAA experts are modeling hydraulic scenarios in a race against time that promises more rainfall, Mozambique officials are gathering topographic maps and other data that NOAA hopes to use for modeling. The agency will finish its first analysis of water-release parameters by early next week.
"It's tough to get," says Barrett, who anticipates NOAA hydrologists are also watch the rising Save and Limpopo Rivers which drain directly into the Indian Ocean. "This is where a large percentage of the population is and where there has already been a great deal of flooding," says Barrett.
