City of Johannesburg spokespeople have discussed the reasons for the flooding in Randburg on 17 February, and what is being done to reduce the risk of another flood. City spokesperson Nthatisi Modingoane and Johannesburg Roads Agency spokesperson Bertha Peters-Scheepers spoke on 24 February, one week after the Klein Jukskei River flooded.
“The houses which were most severely affected [in Fontainebleau, Randpark Ridge and Malanshof] were built many years ago on the basis of the flood lines applicable at the time,” Modingoane said. “Over time, the flood line has shifted, due to the extensive development which has taken place in the upstream catchment, which has changed the hydrological regime.”
Modingoane added that changes in rainfall patterns, due to climate change, have increased the risk of flash floods. Thus, extreme rainfall in a short space of time in the upper reaches of the sub-catchment, especially in Constantia Kloof, appears to have contributed to the flooding by the “collapse of embankments and retaining structures”, Modingoane said.
Furthermore, “unauthorised structures and walls within the floodplain” created a build-up of water that increased the force of flooding when they gave way. Peters-Scheepers said, “Any person living on a river bank is and will always be exposed to actions of this nature.” She added that the City is trying to ensure that no developments are allowed below the one-hundred-year flood line (have less than one per cent chance of flooding per year).
She said the City appointed a team in April last year to study the river between Constantia Kloof and Malanshof, with a view to alleviate the affects of flooding.
The study “is basically complete” with an application for environmental authorisation to take up to six months, and a water-use-licence to be received afterwards. Then a project will begin with remedial measures such as river bank protection, weirs, retention dams and general energy breaking structures.
Jukskei Park, Bromhof and Sharonlea also experienced flooding on the day.
Details: City of Johannesburg 011 375 5555; Johannesburg Roads Agency 011 298 5001.
