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Theewaterskloof Dam is an earth-fill type dam located on the Sonderend River near Villiersdorp, Western Cape, South Africa. Administratively it is located within Theewaterskloof Local Municipality. It was established in 1978 and forms a major component of the Western Cape Water Supply System.[1] The dam mainly serves for municipal and industrial use as well as for irrigation purposes. The hazard potential of the dam has been ranked high (3).

Theewaterskloof Dam
Theewaterskloof between Grabouw and Villiersdorp, South Africa.jpg
View of Theewaterskloof reservoir between Grabouw and Villiersdorp
Location Western Cape, South Africa
Coordinates 34°4′41″S 19°17′21″E / 34.07806°S 19.28917°E / -34.07806; 19.28917Coordinates: 34°4′41″S 19°17′21″E / 34.07806°S 19.28917°E / -34.07806; 19.28917
Purpose Irrigation and domestic
Opening date 1980
Owner(s) Department of Water Affairs
Dam and spillways
Type of dam Earth fill dam
Impounds Sonderend River
Height 25 m
Length 646 m
Reservoir
Creates Theewaterskloof Dam Reservoir
Total capacity 480 406 000 m3
Catchment area 500 km2
Surface area 5 059 ha

It is the largest of the 6 major dams in the Western Cape with a capacity of 480 188 million litres. 8 minor dams also contribute to dam levels supplying water to the province. The dam stores about 41% of the water stored for cape town city council.

A dry period of rain in 2017 saw the levels drop to 12.9%.

3 water extraction towers are in operation, one for drinking water and the other two for municipal and irrigation uses.

Theewaterskloof Dam water extraction point.jpg

Contents

Water restrictionsEdit

A heavy rain event in June 2017 saw an increase in the catchment areas[dubious ] and the level increased to over 15%. The last 10% is mostly unusable. Water restrictions by provincial government to meet a target of 600 million litres of water per day were introduced in 2016.[2] Currently, residents are restricted to 100 litres of water per day with car washing, pool level filling and lawn watering not allowed.

The City of Cape Town Council increased the water restriction level from 4 to 4b, on 1 July 2017, encouraging water users to utilise no more than 87 litres of water per person per day.

Media footage of the declining dam level sparked the importance of conserving water. Provincial government is considering tapping into a sensitive aquifer and investing in a desalination plant to augment the water supply.[3] It is expected that at least 3 years (past 2020) of winters are necessary for this dam to return to previous healthy levels.

Rainfall and capacityEdit

Theewaterskloof dam has a capacity of 480 406 000 cubic metres of water. The catchment area of 500 square kilometers is served by streams emanating in the Hottentots Holland mountain range. This area has a long-term average of 69 days with precipitation per year[4]. Historically[5] records show we are in a dry period [6] 1mm of rain per square meter equates to 500 000 000 litres falling on this area. Hence it requires a full metre of rainfall with 100% runoff to fill the dam from totally empty, which is unlikely to happen in any single year. It takes a few days for all the runoff to reach the dam. Evaporation and how saturated the ground is affects the amount of water reaching the dam. An average amount of between 9% and 15% is used to offset the values against evaporation and soil absorption. A deeper dam has less evaporation due to less surface area.

 

Social eventsEdit

The Theewaterskloof Dam is also the home of the annual Synergy Live music festival, one of the biggest outdoor music festivals in South Africa, which typically takes place on the last weekend of November or the first weekend of December.[7]

See alsoEdit

ReferencesEdit

  1. ^ List of South African Dams from the Department of Water Affairs
  2. ^ "Residential water restrictions explained". www.capetown.gov.za. Retrieved 2017-06-13. 
  3. ^ "Western Cape dam levels up only 1.5% after storms". www.enca.com. Retrieved 2017-06-13. 
  4. ^ institutt, NRK og Meteorologisk. "Weather statistics for Theewaterskloofdam". yr.no. Retrieved 2017-07-10. 
  5. ^ "Rainfall History". 
  6. ^ "Western Cape rainfall". 
  7. ^ "Synergy". Synergy. 2015. Retrieved 30 May 2017. 

External linksEdit