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Section 1: Coastal and fluvial geohazards |
Department of Geology and Applied Geology, University of Natal, Durban 4041, South Africa
Ladysmith was founded in the mid-19th century alongside one of the meanders of the Klip River. The location was chosen for protection against native tribesmen, but in the last 110 years, Ladysmith has experienced 29 notable floods. The most recent floods occurred in February 1994, when the highest water levels in the last 71 years were recorded. An attempt to control flooding was made with the construction of the Windsor Dam in 1949. Unfortunately, the reservoir has been largely silted up so that its live storage capacity has been reduced to around 5%. The present flood walls in Ladysmith can be overtopped by a flood with a recurrence period of once every five years. This happens when channel flow exceeds 700 m3 s-1.
A number of flood alleviation schemes have been discussed over the years including the construction of artificial levees and river canalization. The scheme in vogue at present would involve the construction of another dam and reservoir. Although the reservoir would offer protection to the town, to do so it would have to remain at 10% of its storage capacity in order to retain a 100 year flood. An alternative solution, which would be less expensive, would be to relocate those properties affected most by the recent floods.
