Dahla Dam

Dahla Dam
Aeria view of Dahla Dam in June 2012
Location	Kandahar Province, Afghanistan
Coordinates	31°51′20″N 65°53′33″E / 31.855544°N 65.892413°E / 31.855544; 65.892413Coordinates: 31°51′20″N 65°53′33″E / 31.855544°N 65.892413°E / 31.855544; 65.892413
Opening date	1952
Dam and spillways
Impounds	Arghandab River
Height	55 metres
Length	535 metres

The Dahla Dam is the largest dam in Kandahar Province, and the second largest in Afghanistan. It was built in 1952. Over the years during the wars due to neglect the project was subject to siltation of the reservoir, the canal system and other appurtenant works which reduced its irrigation benefits. This necessitated undertaking rehabilitation of the project which was envisaged in two phases with the first phase involving desiltation works and pertinent components of the project to improve the water delivery system; this component was completed during March 2012 with full assistance provided by the Government of Canada. The second phase involves raising the height of the dam and the relevant dykes to compensate for the loss of storage in the dam due to siltation, and to achieve the full benefits of irrigation for which the dam was originally built. This component is now under implementation with financial and technical support from the US government

The dam is 34 kilometres (21 mi) north of the Kandahar City in the Kandhar Province. It is built on the Arghandab River which flows over a length of 250 miles (400 km).

The Dahla Dam was first built with full funding and technical support provided by the US government, between 1950 and 1952 during the reign of Zahir Shah, the last King of Afghanistan. The dam is an embankment structure made of earth and rock fill. It is 55 metres (180 ft) in height. The length of the dam at the crest is about 535 metres (1,755 ft). In the periphery of the dam six saddle dams have been built which together measure 2,040 metres (6,690 ft) and with varying heights of 15–25 metres (49–82 ft). To pass the design flood discharge two spillway structures have been built. To release water for irrigation to the canal system low level sluices have been built at the downstream toe of the dam with two control valves of the Howell-Bunger type which function as energy dissipation bypass valves. The reservoir created by the dam has a storage capacity of 314 MCM. The irrigation system designed to provide irrigation to 30,000 hectares (74,000 acres) of land in the Kandahar province consisted of 77.6 kilometres (48.2 mi) of the main canal and 415 kilometres (258 mi) of branch canals; with the main canal designed to carry a discharge of 42.5 cubic metres (1,500 cu ft) per second. The contractor for the project was Morrison-Knudsen Afghanistan Incorporated. The dam and the irrigation system are under the control of the Helmand and Arghandab Valley Authority.