Sistan Lake(sēstän`), marshy lake in the Sistan, c.5,000 sq mi (12,950 sq km), on the Iran-Afghanistan border. The lake, fed by the Helmand, Farah, and other rivers, varies in size during the year, achieving its maximum extent in the late spring, when it overflows via the Shelagh River (in Iran) into the Gaud-i-Zirreh, an area of salt flats and swamps in SW Afghanistan. The Hamun-i-Helmand has the potential to support irrigated agriculture in the area. The Helmand irrigation project in SW Iran has been undertaken to support irrigated agriculture.
(also Hamun), a group of freshwater lakes situated on both sides of the border between Iran and Afghanistan. The lakes are a result of estuary floods at the mouths of the Helmand, Farah, and Khash rivers, in Sistan. They lie approximately 480 m above sea level. The entire system of lakes is approximately 150 km long and 50–70 km wide. The lakes are 1–1.5 m deep and vary in size over time. Spring high water causes the lakes to form a single body of water that is reduced to separate lakes, such as the Hamun-i-Helmand and the Hamun-i-Sabari, in the other seasons. During major freshets, part of the overflow is discharged into the Gaud-i-Zirreh, which is south of Hamun-i-Helmand. Hamun-i-Helmand reached its greatest recorded dimension of approximately 50,000 sq km in 1903. Thickets of Scirpus (bulrush) and Phragmites grow along the lakes, which are used for commercial fishing and serve as wintering places for waterfowl.