Durban's Newest Water Resource ‐ The Inanda Dam

Abstract

AbstractThe Inanda Dam is one of a series of reservoirs constructed to utilize the water resources of the Umgeni River, which rises in the Natal midlands and reaches the Indian Ocean at Durban, South Africa. The structure exploits the local topography and geology, with mass concrete founded on the granite forming the right bank and river bed, and a clay core earth embankment on the weaker left bank. Due to high ambient temperatures, the placing temperature of the concrete had to be controlled to avoid crack formation. Mix designs were modified by the addition of blast‐furnace slag, and the mix water was cooled using liquid nitrogen to reduce the placing temperature of the concrete. Major floods also occurred, and although they caused little damage to the structure itself serious damage was sustained by the existing water‐supply infrastructure, resulting in a review of the operational strategy of the system. The reservoir is to be operated initially as a river regulator with downstream abstraction. However, in order to provide additional security, a tunnel aqueduct linking the reservoir directly to the water‐treatment works is under construction.