Syr Darya(redirected from Sir Derya)
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Syrdarya(both: sēr däryä`, –där`yə), ancient Jaxartes or Yaxartes, Pers. Sihun, river, c.1,380 mi (2,220 km) long, flowing through Uzbekistan, Tajikistan, and Kazakhstan. One of the principal rivers of central Asia, it is formed in the Fergana ValleyFergana Valley
or Ferghana Valley,
region, 8,494 sq mi (22,000 sq km), Central Asia, divided among Uzbekistan, Tajikistan, and Kyrgyzstan. The Fergana Range (part of the Tian Shan system) rises in the northeast and the Pamir in the south.
..... Click the link for more information. , E Uzbekistan, by the junction of the Naryn and Kara Darya rivers, which rise in the Tian Shan mts. It flows W through Tajikistan, then NW through Uzbekistan and Kazakhstan, past Kyzylorda, and into the northern basin of the Aral Sea. Its shallowness makes it unfit for navigation. Its waters are used for irrigating the important cotton-growing areas along its course and for hydroelectric power, but the river has become seriously polluted. The Syr Darya forms the northern and eastern limits of the Kyzyl Kum desert. It is paralleled in its lower course by the Trans-Caspian RR. Alexander the Great in his conquest of Persia reached the river c.329 B.C. and may have founded the chief city on its course—Khudjand—on the site of an older city.
a city (since 1971) under oblast jurisdiction and administrative center of Syr Darya Raion, Syr Darya Oblast, Uzbek SSR. Situated on the left bank of the Syr Darya River, 10 km from the river. Railroad station (Syrdar’inskaia) on the Tashkent-Khavast line; branch line to Dzhizak (123 km). Population, 23,000 (1975). Syr Darya has a milk plant and a combine for the manufacture of construction materials. The city has a pedagogical institute.
a river in the USSR; the longest river in Middle Asia and the second largest river by volume of water, after the Amu Darya. The Syr Darya is formed by the confluence of the Naryn and Karadar’ia rivers and empties into the Aral Sea. The Syr Darya proper is 2,212 km long; from the sources of the Naryn, it is 3,019 km long. The river basin extends from southeast to northwest. The southeastern part is mountainous, and the northwestern part is a plain with watershed boundaries that are not clearly defined. The area drained is conventionally given as 219,000 sq km. The basin is a complex interweaving of natural and artificial waterways—rivers, canals, and water collectors; the total length of the canals and collectors is much greater than that of the natural rivers.
In the Fergana Valley, the Naryn and Karadar’ia rivers and the Syr Darya itself have a broad floodplain 3–5 km wide. Most of the Syr Darya’s tributaries flow from the mountainous regions that ring the valley. The right tributaries in this region are the Kasansai, Gavasai, and Chadaksai, and the left tributaries are the Isfairamsai, the Shakhimardan, the Sokh, the Isfara, and the Khodzhabakirgan. Almost none of the tributaries actually contribute water to the Syr Darya, since they are used for irrigation or are lost in broad alluvial fans. Approximately 700 canals lead from the rivers flowing into the valley, and approximately 50 canals lead from the Syr Darya within the confines of the valley. The largest canals include the Great Fergana (supplemented from the Karadar’ia), Great Andizhan, and Northern Fergana canals, all leading from the Naryn; the Andizhansai, Shaarikhan-sai, and Savai canals, all leading from the Karadar’ia; and the Akhunbabaev Canal, which leads from the Syr Darya. The mountain rivers and the Syr Darya receive waters from more than 100 collectors and drains, including 43 that empty into the Karadar’ia and 45 that empty into the Syr Darya. The largest collectors are the Sarysu, Karagugon, and Severo-Bardad.
From the Fergana Valley, the Syr Darya cuts through the Farkhad Mountains, forming the Begovat Rapids. It then turns to the northwest and acquires a broad, sometimes swampy floodplain 10 to 15 km wide as it intersects the Tashkent-Golodnaia Steppe Depression.
In its middle course—from the point where it leaves the Fergana Valley to the point where it enters the Chardara Reservoir—the Syr Darya receives waters from the Akhangaran, Chirchik, and Keles rivers. The Iuzhnaia Golodnaia Steppe Canal begins at the Farkhad Hydroelectric Power Plant and flows northward.
The lower Syr Darya flows through the eastern outskirts of the Kyzylkum Desert. Here the riverbed is higher than the surrounding land, and it follows a meandering and shifting course. Floods are frequent. The last tributary is the Arys’, which enters from the right; the small rivers flowing from the Karatau Mountains do not reach the Syr Darya. At the mouth, the Syr Darya forms a delta with numerous branches, channels, lakes, and swamps.
Runoff forms in the mountain section of the Syr Darya’s basin. The river is fed chiefly by snow and to a lesser degree by glaciers and rain. High water is in spring and summer, from March or April through August or September. In the plain section of the river basin, high water occurs with less regularity, and the quantity of water diminishes, principally because the waters are used for irrigation. The perennial mean flow rate of the Naryn at the kishlak (hamlet) of Uch-Kurgan is 434 cu m per sec, and that of the Karadar’ia near the settlement of Kampyrravat is 122 cu m per sec. Below the confluence of the two rivers, the rate is 492 cu m per sec near the kishlak of Kal’, 566 cu m per sec at the exit from the Fergana Valley, 703 cu m per sec below the influx of the Chirik River, and 446 cu m per sec near the city of Kazalinsk. The total mean annual flow of the rivers is 37.8 cu km at the point where they leave the mountains and 14.1 cu km near Kazalinsk; that is, in the region where the water is led off and distributed, the flow is reduced by 23.7 cu km per year, which constitutes 63 percent of the water flowing from the mountains.
In 1970 more than 40 cu km of water was diverted into canals to irrigate 2.2 million hectares of land; 13 cu km of water was diverted into collectors. The flow is regulated by reservoirs, the largest of which are the Kaikarakkum and Chardara reservoirs on the Syr Darya, with a total usable capacity of more than 7 cu km. The Toktogul Reservoir (14 cu km) on the Naryn and the Andizhan Reservoir (1.6 cu km) on the Karadar’ia are under construction. Small reservoirs have been built on the Syr Darya’s tributaries; more are under construction. The Syr Darya basin has 61 hydroelectric power plants, with a total capacity of 1.6 gigawatts, including the Charvak Hydroelectric Power Plant on the Chirchik River, which has a capacity of 0.6 gigawatt. A number of other power plants are under construction, including the Toktogul Plant (1.2 gigawatts) on the Naryn.
The Syr Darya is navigable in sections from the mouth of the river to Bekabad. It supports commercial fishing for carp (Cyprinus carpió), sheatfish, the species Aspius aspius, shemaya (Chalcalburnus chalcoides), barbel (genus Barbus), European bream, Amur pike (Esox reicherti), domesticated carp, and Eurasian perch (Perca fluviatus). The cities of Leninabad, Bakabad, Chardara, Kzyl-Orda, and Kazalinsk are located on the river.
REFERENCEShul’ts, V. L. Reki Srednei Azii, parts 1–2. Leningrad, 1965.
T. N. ATKARSKAIA