2 FEBRUARY 1984 - 38 YEARS AGO
SEVERE TROPICAL STORM DOMOINA
Severe Tropical Storm Domoina in 1984 caused 100-year floods in South Africa and record rainfall in Swaziland.
While Domoina was moving through South Africa, it drew an area of moisture from the northeast, which produced heavy rainfall that peaked at 950 mm between Richards Bay and Sodwana Bay.
Totals of over 700 mm were reported along the upper Umfolozi, Mkuze, Pongola and middle Usutu and Komati rivers, and along the upper and lower Ingwavuma river. Precipitation spread as far south as Durban, but did not penetrate far into the center of the country. An area of about 107,000 km2 received 370 mm of rainfall.
Along the Umfolozi River, a discharge rate of 16,000 m³/s was recorded, which was three times the rate of a 100-year flood. The river avulsed, or changed its course, near where it met with the Msunduzi River. High rains in the mountains caused the largest flood to date along the Pongola River. The floodplain downstream of the Pongolapoort Dam was inundated to where the Pongola met the Ututu River, which filled many pans – dry lakes - in the region. Along 29 river locations in eastern South Africa, river heights were estimated to have been 1 in 50 year events. The river flooding moved sediment along many banks, and in one location the sediment reached 10 km in length. Due to the widespread flooding and the remoteness of the worst affected areas, there were minimal measurements on the river flow along the Pongola, although above the Pongolapoort Dam, levels reached 13,000 m³/s, which were 18 times higher than the previous record highest.
There had been a planned release of water from the Pongolapoort Dam in March 1984 to provide adequate water to the floodplain, but Domoina prevented this from occurring. The dam had its highest hydrology on January 31 and reached 87% of its capacity. Waters from the dam were released on February 2 to prevent the dam from exceeding capacity. With the future threat of Cyclone Imboa, dam levels continued to drop until returning to normal by February 16, despite requests to hold the water to prevent further crop damage.
Near the South Africa border with Swaziland, flooding stranded about 80,000 people on tribal lands. One road in the country was converted into a makeshift landing strip to allow helicopters and planes to drop off emergency supplies. A period of heavy rain flooded the Umfolozi River, which destroyed a rail bridge near Mtubatuba and a bridge crossing highway N2. The floods were so strong that they washed a boat from Lake St. Lucia to a point 16 km away.
At the lake, the floods washed away a dredge and severely damaged a nearly-finished canal from the lake to the Umfolozi River. Widespread crop damage occurred along the Umfolozi river plains after being covered by up to 1 m of sediment. The South African Weather Bureau considered Domoina as the "first tropical cyclone in recent history to have caused flooding and extensive damage." Nationwide, the storm caused 60 deaths and damaged the properties of 500,000 people, causing R100 million (1984 ZAR, $70 million 1984 USD).
While Domoina was moving through South Africa, it drew an area of moisture from the northeast, which produced heavy rainfall that peaked at 950 mm (37 in) between Richards Bay and Sodwana Bay. Totals of over 700 mm were reported along the upper Umfolozi, Mkuze, Pongola and middle Usutu and Komati rivers, and along the upper and lower Ingwavuma river. Precipitation spread as far south as Durban, but did not penetrate far into the center of the country. An area of about 107,000 km2 received 370 mm of rainfall.
Along the Umfolozi River, a discharge rate of 16,000 m³/s was recorded, which was three times the rate of a 100-year flood. The river avulsed, or changed its course, near where it met with the Msunduzi River.
High rains in the mountains caused the largest flood to date along the Pongola River. The floodplain downstream of the Pongolapoort Dam was inundated to where the Pongola met the Ututu River, which filled many pans – dry lakes – in the region. Along 29 river locations in eastern South Africa, river heights were estimated to have been 1 in 50 year events. The river flooding moved sediment along many banks, and in one location the sediment reached 10 km in length. Due to the widespread flooding and the remoteness of the worst affected areas, there were minimal measurements on the river flow along the Pongola, although above the Pongolapoort dam, levels reached 13,000 m³/s, which were 18 times higher than the previous record highest.
There had been a planned release of water from the Pongolapoort Dam in March 1984 to provide adequate water to the floodplain, but Domoina prevented this from occurring. The dam had its highest hydrology on January 31 and reached 87% of its capacity. Waters from the dam were released on February 2 to prevent the dam from exceeding capacity. With the future threat of Cyclone Imboa, dam levels continued to drop until returning to normal by February 16, despite requests to hold the water to prevent further crop damage.
Near the South Africa border with Swaziland, flooding stranded about 80,000 people on tribal lands. One road in the country was converted into a makeshift landing strip to allow helicopters and planes to drop off emergency supplies. A period of heavy rain flooded the Umfolozi River, which destroyed a rail bridge near Mtubatuba and a bridge crossing highway N2. The floods were so strong that they washed a boat from Lake St. Lucia to a point 16 km away. At the lake, the floods washed away a dredge and severely damaged a nearly-finished canal from the lake to the Umfolozi River. Widespread crop damage occurred along the Umfolozi river plains after being covered by up to 1 m of sediment.
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