Also found in: Dictionary, Thesaurus, Legal.
a group of primarily hydroengineering measures carried out to supply arid and semiarid regions with water. Impounding is the first stage in the construction of water-supply and irrigation systems in areas with insufficient or no sources of water or with unsuitable water. The first to be impounded are local water resources, such as groundwater, rivers, lakes, and atmospheric precipitation. Water intake works (wells, cappings, underground irrigation canals, river water intakes), reservoirs for accumulating local runoff, and control reservoirs on rivers are constructed. If such sources are insufficient—if they are absent or unevenly distributed—distant water sources are located, and their waters are distributed by canal and pipeline to the region that needs water.
The type of impounding measures employed depends on the economic use of the land. To supply water to pastures, dug and Abyssinian wells are used, and water distribution points are established. In regions where dry farming predominates, water is supplied to the farms by a network of water conduits that combine the functions of impounding and supply. In regions where it is possible to develop selective irrigation, mainly in areas where vegetable and feed crops are raised, water-supply and irrigation systems are built. The water is delivered by canal.
In the USSR, extensive work in impounding is being carried out. More than 220 million hectares (ha) of pasture land was supplied with impounded water in 1974, including more than 110 million ha in the Kazakh SSR and more than 60 million ha in Middle Asia. The total area of pastures requiring water supply is about 300 million ha. Of this amount, 58 million ha were first supplied with water between 1956 and 1960, 44 million ha between 1961 and 1965, and 33 million ha between 1966 and 1970.
Conduits bring water to many valuable pastures, including mountain pastures. In 1972 the conduits extended for more than 4,300 km, with the major ones in the Caucasus and Middle Asia. The water conduits on the pastures of Dzheiranchel’ (Azerbaijan SSR) supply water to about 200,000 ha, providing water for 400,000 sheep and 20,000 head of cattle. Networks of water conduits are used in the Kazakh SSR, Siberia, the Caucasus, and the Crimea. For example, the Ishim network in the Kazakh SSR traverses 2.2 million ha of arid lands and provides water to 195 settlements. The length of its conduits is 1,750 km. Water-supply and irrigation systems have been built in the Northern Caucasus, the southern Ukrainian SSR, and the Caspian lowland. The most important systems are the Tersko-Kum (area supplied by impounding, 1.3 million ha; irrigated area, 53,000 ha), the Pravo-egorlyk (area supplied by impounding, 1.5 million ha; irrigated area, 32,000 ha), and the Kuban’-Kalaus (area supplied by impounding, 300,000 ha; irrigated area, 198,000 ha). The ninth five-year plan (1971–75) provided for the construction of water-supply and irrigation systems near the Tersko-Kum, North Crimean, and Karakum canals. According to the plan, a total of 41 million ha of pasture land were to be supplied with water.
Impounding projects are being carried out in the United States, Australia, and other countries.
REFERENCESSokolov, B. I. Obvodnenie pastbishch pustyn’. Tashkent, 1958.
Ovodov, V. S. Sel’skokhoziaistvennoe vodosnabzhenie i obvodnenie, 2nd ed. Moscow, 1960.
Askochenskii, A. N. Oroshenie i obvodnenie ν SSSR. Moscow, 1967.
Ratsional’noe ispol’zovanie obvodnitel’no-orositel’nykh sistem. Moscow, 1970.
N. A. KARAMBIROV