Calitzdorp Dam – Celebrating South Africa's oldest working concrete gravity dam wall

Abstract

Tucked behind Besemkop in the Nel’s River valley, about 5 km north of Calitzdorp in the Little Karoo lies the Calitzdorp Dam or, more correctly, Nel’s River Dam. Completed in 1918 it is South Africa’s first and oldest concrete gravity dam that was built for irrigation purposes and that is still in working condition – a living pioneering engineering achievement. Nel’s River Dam, which took about five years to build, comprises approximately 110 000 cubic tons of concrete. The dam wall has a height of 18 mand length of 213 m. The spillway consists of a low concrete overflow with a drainage canal that was blasted into the side rock and left unlined. The permissible height of the overflow is 1.8 m. The dam provides water to 70 irrigation users of the Calitzdorp Irrigation Board with their 520 ha of scheduled irrigation lands, as well as the approximately 4 700 residents of the town. Associate Professor of History at the University of Stellenbosch, Wessel Visser, has captured the fascinating history of the dam and the irrigation scheme it serves.

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