Western Cape Water Supply System
Encyclopedia
The Western Cape Water Supply System (WCWSS) is a complex water supply system in the Western Cape
region of South Africa
comprising an inter-linked system of six dams, pipelines, tunnels and distribution networks. Some elements of the system are owned and operated by the Department (Ministry) of Water Affairs and Forestry and some by the City of Cape Town.
The principal dams are all located in the Cape Fold Mountains to the east of Cape Town. They are:
In 2009, 63% of the water in the system was being used for domestic and industrial purposes in the city of Cape Town
, 5% in smaller towns and 32% in agriculture.
flowing North towards the Atlantic Ocean and Eerste River
that flows into False Bay
.
Its centerpiece is the Theewaterskloof Dam on the Sonderend River, the largest dam in the system with a storage capacity of 480 million cubic meter. It is linked to the Berg River via a tunnel system through the Franschhoek Mountains. During winter, when water requirements are lower, this tunnel system conveys surplus flows from the Berg River Dam and the tributaries of the Berg River to the Theewaterskloof Dam, where the water is stored. In summer, when water requirements are high, water can be released back via the tunnel system into the catchments of the Berg and Eerste River.
Other storage dams of the WCWSS are the Voëlvlei Dam
(159 million cubic meters), the Wemmershoek Dam
(59 million cubic meter) in the Berg River basin, the Upper and Lower Steenbras Dam
s on the Steenbras River as well as the Palmiet Pumped Storage Scheme
dams on the Palmiet River
, from which water can be transferred to the Steenbras dams.
In 2009 storage capacity in the system was increased by 17% from 768 to 898 million cubic metres through the completion of the Berg River Dam
.
The system also generates hydropower using an installed capacity of 200 Megawatt (MW) on the Palmiet River and 160MW on the Steenbras River.
and if water conservation measures in Cape Town should not be as successful as envisaged. A number of additions to the system, such as the heightening of dams, are considered as well as seawater desalination
in order to cope with rising demand.
Western Cape
The Western Cape is a province in the south west of South Africa. The capital is Cape Town. Prior to 1994, the region that now forms the Western Cape was part of the much larger Cape Province...
region of South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
comprising an inter-linked system of six dams, pipelines, tunnels and distribution networks. Some elements of the system are owned and operated by the Department (Ministry) of Water Affairs and Forestry and some by the City of Cape Town.
The principal dams are all located in the Cape Fold Mountains to the east of Cape Town. They are:
- Theewaterskloof Dam
- Wemmershoek DamWemmershoek Dam- References :* from the Department of Water Affairs and Forestry...
- Steenbras DamSteenbras DamThe Steenbras Dam is a dam in the Hottentots-Holland mountains near Cape Town in South Africa. It is one of the city's water supplies. The Steenbras pumped-storage scheme was opened in 1979 to supplement the city's electricity supply during peak demand periods....
s (Upper and lower) - Voëlvlei DamVoëlvlei DamVoëlvlei Dam is dam in South Africa. It was established in 1971.The history of Voelvlei Dam located near Gouda in the Western Cape of South Africa date back for a thousand years or more...
- Berg River DamBerg River DamThe Berg River Dam is a 68 m high dam on the Berg river in South Africa. It is the centerpiece of the Berg Water Project which is designed to capture the winter rainfall and store it for supply to Cape Town during the dry summer months...
In 2009, 63% of the water in the system was being used for domestic and industrial purposes in the city of Cape Town
Cape Town
Cape Town is the second-most populous city in South Africa, and the provincial capital and primate city of the Western Cape. As the seat of the National Parliament, it is also the legislative capital of the country. It forms part of the City of Cape Town metropolitan municipality...
, 5% in smaller towns and 32% in agriculture.
Components
The largest component of the WCWSS is the Riviersonderend Government Water Scheme, which is a large inter-basin water transfer scheme that regulates the flow of the Sonderend River flowing South towards the Indian Ocean, the Berg RiverBerg River
The Berg River is a river located just north of Cape Town in the Western Cape Province of South Africa. It is approximately 294 km long with a catchment area of 7,715 km² and outlets into the Atlantic Ocean. About 65% of the Berg River area is under agriculture...
flowing North towards the Atlantic Ocean and Eerste River
Eerste River
Eerste River, located in the Western Cape, South Africa, rises on Dwarsberg 60 km east of Cape Town at the head of Jonkershoek. The Eerste River catchment covers the eastern part of the Cape Flats lying to the west of the Hottentots Holland Mountains and south of the Tygerberg where the Kuils River...
that flows into False Bay
False Bay
False Bay is a body of water defined by Cape Hangklip and the Cape Peninsula in the extreme South-West of South Africa.- Description and location :...
.
Its centerpiece is the Theewaterskloof Dam on the Sonderend River, the largest dam in the system with a storage capacity of 480 million cubic meter. It is linked to the Berg River via a tunnel system through the Franschhoek Mountains. During winter, when water requirements are lower, this tunnel system conveys surplus flows from the Berg River Dam and the tributaries of the Berg River to the Theewaterskloof Dam, where the water is stored. In summer, when water requirements are high, water can be released back via the tunnel system into the catchments of the Berg and Eerste River.
Other storage dams of the WCWSS are the Voëlvlei Dam
Voëlvlei Dam
Voëlvlei Dam is dam in South Africa. It was established in 1971.The history of Voelvlei Dam located near Gouda in the Western Cape of South Africa date back for a thousand years or more...
(159 million cubic meters), the Wemmershoek Dam
Wemmershoek Dam
- References :* from the Department of Water Affairs and Forestry...
(59 million cubic meter) in the Berg River basin, the Upper and Lower Steenbras Dam
Steenbras Dam
The Steenbras Dam is a dam in the Hottentots-Holland mountains near Cape Town in South Africa. It is one of the city's water supplies. The Steenbras pumped-storage scheme was opened in 1979 to supplement the city's electricity supply during peak demand periods....
s on the Steenbras River as well as the Palmiet Pumped Storage Scheme
Palmiet Pumped Storage Scheme
The Palmiet Pumped Storage Scheme consists of two 200MW turbine units located 2km upstream of the Kogelberg Dam wall on the Palmiet River near Cape Town, South Africa. The pumped-storage hydroelectricity plant is capable of responding to a surge in peak power demand in minutes...
dams on the Palmiet River
Palmiet River
Palmiet River,is located in the Western Cape province South Africa. The Palmiet River is a typical Western Cape river, experiencing winter rainfall. It has a small catchment area of 500 km2. It has five irrigation and hydro-power dams along its length, and provides water for agricultural and...
, from which water can be transferred to the Steenbras dams.
In 2009 storage capacity in the system was increased by 17% from 768 to 898 million cubic metres through the completion of the Berg River Dam
Berg River Dam
The Berg River Dam is a 68 m high dam on the Berg river in South Africa. It is the centerpiece of the Berg Water Project which is designed to capture the winter rainfall and store it for supply to Cape Town during the dry summer months...
.
Agricultural Use
The system also provides water to irrigate about 15,000ha of farmland, where high-value fruit and vegetables are grown. From the early 1970s until the mid-2000s water consumption in Cape Town increased by about 300%, increasing the competition for water with irrigated agriculture. This has been exacerbated by several unusually dry years, such as in 1994-1995 when storage in the system was only one third of average storage. Farmers have adapted by significantly improving irrigation efficiency and shifting even more land into the production of high-value crops.The system also generates hydropower using an installed capacity of 200 Megawatt (MW) on the Palmiet River and 160MW on the Steenbras River.
Future Developments
It is expected that demand in the area served by the system will exceed supply by 2019, and possibly even earlier if water availability diminishes because of climate changeClimate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
and if water conservation measures in Cape Town should not be as successful as envisaged. A number of additions to the system, such as the heightening of dams, are considered as well as seawater desalination
Desalination
Desalination, desalinization, or desalinisation refers to any of several processes that remove some amount of salt and other minerals from saline water...
in order to cope with rising demand.