Flood levels ‘worse than 1934’

“A FREAK of nature”.

This is how both the developers of the Acacia housing scheme in Windhoek’s Dorado Park suburb and the Windhoek Municipality yesterday described the flood that ravaged newly-built houses on Friday night. As both parties washed their hands of any blame for damage to the houses, built on the banks of the Arrebbusch River, officials said the water level rose way above the flood level of Windhoek’s worst-known floods in 1934.On the damage to the Acacia houses, Director of Dannic Construction, Danie Pienaar, said human error was not the cause of 16 houses being waterlogged by the storming Arrebbusch River.”We have found that the factors [that caused the flood] were not consistent with normal flood scenarios.Nobody is to blame.The municipality can’t be blamed.We can’t be blamed.Everything was done according to regulation,” Pienaar told The Namibian yesterday after surveying the river’s course from the air.At a media briefing in Windhoek yesterday afternoon, Mayor Matheus Shikongo said while the development had become a “bone of contention” in the wake of Friday’s flooding, the City was not at fault for giving the go-ahead for the construction of houses in the immediate vicinity of the Arrebbusch River.”It is a private construction scheme.The City has very little role to play there.If we revert back to how the plans were approved, I can assure you the City Council will come out clean,” charged Shikongo.Both the City and Dannic Construction attributed the “unforeseen” flooding to the heavy rains which fell in the mountains south of the City.With more than 100 mm of rain falling in each of the two catchment areas feeding the Arrebbusch River, officials say the water level rose way above the flood level of Windhoek’s worst known floods in 1934.According to local authority legislation, development may only proceed taking into consideration the one to 50 year floodline [the magnitude of a flood expected to occur once in 50 years].City officials say the water level rose over the one-to-100 year floodline, and said it had no legal grounding to enforce constructors to adhere to this estimation.”Unfortunately it was a disaster.The provision of one to 50 wasn’t enough to safeguard life and safeguard property,” said Harold Kisting, an official from the City’s Town Planning Division.Piet du Pisani, the City’s Strategic Executive for Infrastructure, Water and Technical Services, said even if the guideline had been strictly enforced, there was no indication that the situation wouldn’t repeat itself the very next day.”There is very little that can be done [to prevent such a situation].We can just improve the conditions of our river beds and remove obstructions,” said Du Pisani.Dumping in the Arrebbusch riverbed has been singled out as the greatest controllable culprit of the Acacia area flooding.Building rubble just 500 metres upstream from the development is said to have prohibited the large volumes of water travelling down the river from flowing the entire width of its course.According to Pienaar, because of the restriction to its natural flow, the water was forced backwards against the current, causing the level to swell so much that it seeped along the sides of the river into the residential area.The bridge at the entrance of Acacia is about 3,5 metres in height.By the time the water reached this point it had swelled to about five metres and was forcing its way through the middle section of the bridge only.Large mounds of sand and other waste building material dumped in the river prevented the water from passing through the two end points of the bridge, officials said.”This bridge can hold a volume double that it took.The flood damage was not at the height of the river, but the level to which the water was pushed back.The river should be allowed to flow naturally,” said Pienaar, whose company built the bridge.The company says it will now spend between N$800 000 and N$1 million on taking the necessary precautions to prevent a repeat scenario and to repair the damage.An electric security fence which encircles the development, as well as sewerage lines which run along the river, have been totally destroyed.As both parties washed their hands of any blame for damage to the houses, built on the banks of the Arrebbusch River, officials said the water level rose way above the flood level of Windhoek’s worst-known floods in 1934. On the damage to the Acacia houses, Director of Dannic Construction, Danie Pienaar, said human error was not the cause of 16 houses being waterlogged by the storming Arrebbusch River. “We have found that the factors [that caused the flood] were not consistent with normal flood scenarios. Nobody is to blame. The municipality can’t be blamed. We can’t be blamed. Everything was done according to regulation,” Pienaar told The Namibian yesterday after surveying the river’s course from the air. At a media briefing in Windhoek yesterday afternoon, Mayor Matheus Shikongo said while the development had become a “bone of contention” in the wake of Friday’s flooding, the City was not at fault for giving the go-ahead for the construction of houses in the immediate vicinity of the Arrebbusch River. “It is a private construction scheme. The City has very little role to play there. If we revert back to how the plans were approved, I can assure you the City Council will come out clean,” charged Shikongo. Both the City and Dannic Construction attributed the “unforeseen” flooding to the heavy rains which fell in the mountains south of the City. With more than 100 mm of rain falling in each of the two catchment areas feeding the Arrebbusch River, officials say the water level rose way above the flood level of Windhoek’s worst known floods in 1934. According to local authority legislation, development may only proceed taking into consideration the one to 50 year floodline [the magnitude of a flood expected to occur once in 50 years]. City officials say the water level rose over the one-to-100 year floodline, and said it had no legal grounding to enforce constructors to adhere to this estimation. “Unfortunately it was a disaster. The provision of one to 50 wasn’t enough to safeguard life and safeguard property,” said Harold Kisting, an official from the City’s Town Planning Division. Piet du Pisani, the City’s Strategic Executive for Infrastructure, Water and Technical Services, said even if the guideline had been strictly enforced, there was no indication that the situation wouldn’t repeat itself the very next day. “There is very little that can be done [to prevent such a situation]. We can just improve the conditions of our river beds and remove obstructions,” said Du Pisani. Dumping in the Arrebbusch riverbed has been singled out as the greatest controllable culprit of the Acacia area flooding. Building rubble just 500 metres upstream from the development is said to have prohibited the large volumes of water travelling down the river from flowing the entire width of its course. According to Pienaar, because of the restriction to its natural flow, the water was forced backwards against the current, causing the level to swell so much that it seeped along the sides of the river into the residential area. The bridge at the entrance of Acacia is about 3,5 metres in height. By the time the water reached this point it had swelled to about five metres and was forcing its way through the middle section of the bridge only. Large mounds of sand and other waste building material dumped in the river prevented the water from passing through the two end points of the bridge, officials said. “This bridge can hold a volume double that it took. The flood damage was not at the height of the river, but the level to which the water was pushed back. The river should be allowed to flow naturally,” said Pienaar, whose company built the bridge. The company says it will now spend between N$800 000 and N$1 million on taking the necessary precautions to prevent a repeat scenario and to repair the damage. An electric security fence which encircles the development, as well as sewerage lines which run along the river, hav
e been totally destroyed.