Zapadnaia Dvina

a city (since 1937), the administrative center of Zapadnaia Dvina Raion, Kalinin Oblast, RSFSR. Located on the right bank of the Zapadnaia Dvina River, the city has a railroad station (on the Moscow-Riga line) 321 km to the southwest of Kalinin. A wood-products combine, logging and timber distribution establishment, and flax-processing plant are located here.

(Western Dvina), a river in the RSFSR, Byelorussian SSR, and Latvian SSR (where it is called the Daugava). Length, 1,020 km; basin area, 87,900 sq km.

Originating on the Valdai Upland to the west of the sources of the Volga, the Zapadnaia Dvina flows into the Gulf of Riga in the Baltic Sea. Its basin is characterized by comparatively high bluffs (Vitebsk, Gorodok, Latgaliia, Vidzem’) and wide lowlands (Polotsk, the Eastern Latvian, Middle Latvian). The basin is situated in an area of high precipitation and humidity.

The Zapadnaia Dvina begins as a small brook; passing lakes Dvinets and Okhvat-Zhadan’e, the river widens to 15m and flows in a deep valley with steep shores. The steep banks of the valley continue the entire length of the river, with the exception of a small stretch 150 km from the source, where the valley is less sharply defined (the river at this point passes through lakes Luka and Kalakutskoe). There are low banks in the plains region by the sea. The river possesses many rapids as a result of accumulated boulders and occasional extrusions of dolomite.

The lower Zapadnaia Dvina breaks up into several arms; the mouth is an eroded delta 35 km in length. An underwater bar has been formed in the Gulf of Riga at the mouth of the river. The river’s left tributaries are the Mezha, Kasplia, Luchesa, Ulla, and Disna; the right tributaries are the Toropa, Drissa, Dubna, Aiviekste, and Ogre. Ground and snow waters feed the river for the most part. The spring high-water period is from the end of March to the beginning of June; the summer low-water level is interrupted by rain floods, which occur more and more frequently with autumn. The winter low-water level stretches from December until mid-March, but in some years floods occur because of warm spells. The average water discharge at the mouth is about 700 cu m per sec. The river is covered with ice from December until March.

The V. I. Lenin Pliavinias Hydroelectric Power Plant and the Kegum Hydroelectric Power Plant are situated on the Zapadnaia Dvina; the Riga Hydroelectric Power Plant is under construction (1972). Individual sections of the river are navigable, and the Berezina Canal links the Zapadnaia Dvina with the Dnieper. The cities of Vitebsk, Polotsk, Daugavpils, Ekabpils, and Riga lie along the river, with Riga serving as a seaport.