The Challenge
More often than not people settle in areas where there is not a good source of water nearby. This is the case with the Witwatersrand area. At the end of the 19th century, many people came to the Witwatersrand in search of gold. As the mining town of Johannesburg grew, there wasn’t enough water in the area to meet everyone’s needs. Attempts by the Johannesburg Water Works Company to meet the demand were hampered by the
Great Drought of 1895. Frequent complaints concerning water led to the appointment of the Water Works Commission in 1895 to examine ways in which Johannesburg could be provided with good quality drinking water.
A geologist by the name of Dr Draper, was commissioned by the commission to assist. After some search on the farm Zuurbekom, Dr Draper found what everybody was looking for. He tied his handkerchief to the branch of a thorn bush and arriving back in Johannesburg, told the Water Works Commission “go to Zuurbekom, you will find my handkerchief tied to a tree, sink a borehole there and you will find water, plenty of it.” In 1896 and 1897 the Water Works Commission secured a stable supply of water from the Zuurbekom Water Supply Companies wells. In 1903 the Water Works Commission established Rand Water in order to ensure that the Witwatersrand received enough clean, safe drinking water.
Groundwater
Initially Rand Water used groundwater from the Zuurbekom Wells on the West Rand. This water was of such good quality that it didn’t require any cleaning (purification).
Natural Drainage
When the water from the Zuurbekom Wells could no longer supply enough water for the growing population of the Witwatersrand, the Vaal River to the south of Johannesburg was chosen as a new water source. In 1923 Rand Water dammed the Vaal River to form the Vaal River Barrage Reservoir. In 1938 the Vaal Dam was built upstream of the Vaal River Barrage Reservoir, which is now the main source of water for Rand Water. Rivers such as the Vaal, Klip and Wilge Rivers naturally flow into the Vaal Dam. These rivers flow through agricultural land and rural settlements with very little industry. This means that the water in the Vaal Dam is of a good quality by international standards.
The Vaal River System
The Vaal River system has its beginnings in the eastern highveld plains, in the vicinity of Ermelo. Shallow hollows and low hillocks form a natural sponge where water collects in pans, vleis and streams. These streams link up and the Vaal River is born, flowing westward on a long course, without rapids or waterfalls, broadening into a large river. To the Bushmen, the river was known as Gij’Gariep (“tawny”) from its muddy colour. The European name, Vaal, also means tawny. The Sotho called it iliGwa (“erratic”) because of the unpredictable variations in its flow.
As the Vaal River flows westward it flows into the Grootdraai Dam. This dam has a total storage capacity of 350 million cubic meters, a surface area of 39 square kilometers and an average depth of 27 meters. On its course to the Vaal Dam a number of rivers join the Vaal River:
- the Little Vaal that begins in the escarpment near Ermelo;
- the Klip River that begins near Memel in the Free State;
- the Watervals River that begins in Secunda;
- the Wilge River, that used to meet the Vaal River before the Vaal Dam was built but now flows straight into the Vaal Dam.
This river begins in the escarpment near Harrismith. On its course to the Vaal Dam a number of other rivers flow into it, i.e. Nuwejaarspruit, Elands, and the Liebenbergsvlei rivers.
The Vaal River is one of the major rivers in South Africa but the runoff is not constant (erratic). This means that large dams have to be built in order to store water. In earlier times, many little dams were built to irrigate farms. These dams were the forerunners of the great barrages and dams which today control the river on which the gold fields of the Witwatersrand and the surrounding industrial complex depend so heavily.
The
Vaal Dam was built in the early thirties and was completed in 1938. The dam was built as a joint project between Rand Water and the then Department of Irrigation. At present Gauteng gets its water from the Vaal Dam. The
Vaal Dam has a catchment area covering 38 505 square kilometers and a capacity to hold 2575 million cubic meters of water which, under normal circumstances and without a substantial inflow, will last for 2 years.
This dam has a surface area of 321 square kilometers and an average depth of 22,5m. Even though the Vaal Dam is only the fourth largest dam in South Africa in terms of storage capacity, it is without a doubt the most important dam in view of its role as the primary supplier of water to the economic heartland of South Africa.
The present Vaal Dam wall has been raised twice. In the early fifties the wall was raised by 6.1 meters enabling it to store 2 188 million cubic meters. The ever increasing demand for water made it necessary for a further raising in 1985. The wall was raised by another 3,5 metres which increased the volume of the dam to 2 536 million cubic meters. The remaining 1.95 meters is used for temporary flood storage, which amounts to 662 million cubic meters.
The Vaal River Barrage Reservoir, created by a set of gates across the Vaal River, was built by Rand Water downstream of the Vaal Dam, in 1923. The reservoir is 64 kilometers long and has a total storage capacity of 63 million liters, a surface area of 168,35 square kilometers and has an average depth of 4,5 meters. The rivers, i.e. Suikerbosrant, Klip, & Rietspruit, that feed into the Vaal River Barrage Reservoir flow from industrial and heavily populated areas such as Johannesburg, Vereeniging and Sasolburg. This reservoir was used to supply water to the Witwatersrand but no longer does so because the quality of its water is deteriorating due to pollution. This reservoir, which is managed by Rand Water, is used for many recreational activities, such as boating, skiing, fishing, swimming and many holiday resorts have grown up on its banks.
The key to maintaining our water resources in a good state is effective management. This involves the monitoring of all our major rivers and dams, a task which involves regular sampling and analyses from over 140 points in Rand Water’s catchment area, undertaken by Rand Water’s Catchment Management Department. Incorporated in the management of our water resources is the monitoring of wastewater from industries and municipalities.
When the water leaves the Vaal River Barrage Reservoir it meanders its way passed Parys, in the Free State, and then into the Bloemhof Dam. This dam has a surface area of 233 square kilometers, an average depth of 18 meters and a total storage capacity of 1,26 billion cubic metres. At Christiana there is a complex series of canals which takes water to 1200 farms in one of the largest irrigation’s schemes in the southern hemisphere. At Douglas the Vaal River meets the Orange River, 1200 kilometers from its source. The Orange River, which has as its origin in Lesotho, then continues westward and eventually flows into the Atlantic Ocean at Alexander Bay.
