Woodhead Dam

Woodhead Dam is a dam on Table Mountain, Western Cape, South Africa. It was built in 1897 and supplies water to Cape Town. The dam, which was the first large masonry dam in South Africa, was designated as an International Historic Civil Engineering Landmark by the American Society of Civil Engineers in 2008.^[2]

Woodhead Dam
Woodhead Dam
Location of Woodhead Dam in Cape Town
Location	Table Mountain, Western Cape, South Africa
Coordinates	33°58′35″S 18°24′08″E
Construction began	1894
Opening date	1897
Owner(s)	Cape Town Municipality
Dam and spillways
Type of dam	Masonry gravity dam
Impounds	Disa Stream
Height	50 m (164 ft)
Length	277 m (909 ft)[1]
Spillway type	Free overspill
Spillway capacity	20 m3/s (706 ft3/s)
Reservoir
Creates	Woodhead Reservoir
Total capacity	927,000 m3 (32,737,000 cu ft)
Surface area	13 ha (32 acres)

History

View over Woodhead Dam in 1906, from Popular Science Monthly Volume 68

In 1870, the growth of Cape Town led to shortages of drinking water. It was decided to build a reservoir on Table Mountain to provide water to the city. Scottish hydraulic engineer Thomas Stewart was engaged to design and build the reservoir.^[2]

The Woodhead Tunnel was built between 1888 and 1891. It was used to divert the Disa Stream, a tributary of the Hout Bay River, westward to provide water for the reservoir.

An aerial cableway was constructed to transport men and materials to the construction site.^[2][3] The dam was constructed between 1894 and 1897. This dam was followed by four others in the area. The Hely-Hutchinson Dam and reservoir were built by 1904 just upstream of the Woodhead reservoir. The Alexandra Dam and Victoria Dam were built on the original Disa Stream by 1903. The last of the five dams was the De Villiers Dam in 1907. This was built downstream of the Alexandra and Victoria Dams. Today, these five dams supply around 0.4% of the water for Cape Town.^[4]

Design

The Woodhead Tunnel is 640 m (2,100 ft) long. The Woodhead Dam is a masonry gravity dam that is 277 m (909 ft) long and 50 m (164 ft) high. It has a free overspill spillway with a capacity of 20 m³/s (706 ft³/s). The reservoir has a capacity of 927,000 m³ (32,737,000 cu ft) and a surface area of 13 ha (32 acres).^[1]

See also

• List of reservoirs and dams in South Africa

References

1. "South African Large Dams". South African Large Dams-1-2009 v3.0.xls. SANCOLD. January 2009. Archived from the original (zip) on 5 July 2009. Retrieved 5 March 2010.
2. "Led by ASCE President, Delegation Visits S. Africa To Honor Dam as Civil Engineering Landmark". ASCE International Page. American Society of Civil Engineers. Archived from the original on 25 July 2011. Retrieved 6 March 2010.
3. Murray, Tony. "Thomas Steweart - First South African Consulting Engineer" (PDF). American Society of Civil Engineers. Archived from the original (PDF) on 25 July 2011. Retrieved 6 March 2010.
4. River Health Programme (2003). State-of-Rivers Report: Diep, Hout Bay, Lourens and Palmiet River Systems (PDF), Pretoria: Department of Water Affairs and Forestry, 2003, pp. 17–18, archived from the original (PDF) on 2010-02-14, retrieved 2010-03-28