August 2011 Issue

DAMS - Why do we need these huge expensive items ? We need them to store water; The eternal bond between us and life.

Our country is actually rated one of the 30 driest in the world. We depend mostly on our rivers, dams and underground water for our water supply. South Africa has more than 500 government dams spread around strategic areas for, irrigation schemes, human use in cities and towns and hydro power for electricity. Our rivers provide us with the capacity to construct massive dams for storage of our water needs.

The majority of our dams were planned and constructed between 1900's and 1950's some dam walls were raised at various times during the 1970”s. During those years the advent of the 2 World War caused delays in the completion of some dams.

South Africa has four internationally recognized river basins : The Orange, Limpopo, Incomati and Maputo. These international basins transcends neighboring countries' borders promoting co-operation between our adjoining countries for water use. We share our river basins with six of our neighbors: Lesotho, Swaziland, Mozambique, Zimbabwe, Botswana and Namibia.

Our largest dam is The Gariep Dam ( previously the Hendrik Verwoerd Dam ) A newer dam, built in 1966 on the Orange river. At the time it was the biggest project of its kind in Africa and one of the largest in the world. The Gariep stores 5.5 billion m3 water and has a Concrete Gravity and Double Curvature Arch Wall. Apart from providing water for irrigation and to various towns it also provides vital hydro power to Escom for electricity.

The Vaal Dam was constructed during the 1930's and provided much needed employment during the devastating Wold Depression years. Workers were paid 2 shillings per day plus a bonus for each day worked of 6 pennies. The dam has a storage capacity of 2.57 billion m3 water and a shoreline of 880 km. It provides water to Gauteng and surrounds.

Loskop Dam is situated in a gorge on the Olifants River 32 km from Groblersdal, Mpumalanga. Built in 1934, as a Mass Concrete Dam, the wall was raised in 1979 and it can now store 348 million m3 of water. The poverty as a result of the Great Depression of the time created the work force which was paid 5 shillings per day including free accommodation and food.

Cape Town and surrounding towns is supplied by the Wemmershoek Dam. Built in 1953 and completed in 1957, as a Earthfill Dam, it stores 2,9 million m3 water. It took 75 years from the first thought of constructing a dam in the Wemmers River Valley to its final construction date!

WHO KNEW ? Some 4,500 years ago there was a water-war between two Sumerian cities – since then the world has signed 3,600 water treaties to keep the peace!

NEXT MONTH – Dams continued.