When rivers are straightened and deepened, or, road and area runoff piped into rivers in an attempt to manage excess water, the result is habitat loss and poor water quality.

In Hout Bay, some tributaries have been canalised and storm water runoff is directed into the rivers to the detriment of the rivers’ ecology.

Water canalized in the picture on the right does not enter the wetlands as it should.

In Hout Bay the repeated historical dredging of the river in the lower reaches has effectively canalised the lower river making it deeper and straight. The negative effect this has on the whole system is to disconnect the river from the wetland such that the river is now lower than the wetland and to cause upstream erosion as the river runs fast and straight during the rainy season. Also lowering the riverbed causes upstream erosion.