Donets


The Seversky Donets or Siverskyi Donets, usually simply called the Donets, is a river on the south of the East European Plain. It originates in the Central Russian Upland, north of Belgorod, flows south-east through Ukraine and then again through Russia to join the river Don, about from the Sea of Azov. The Donets is the fourth-longest river in Ukraine, and the largest in eastern Ukraine, where it is an important source of fresh water. It gives its name to the Donets Basin, known commonly as the Donbas, an important coal-mining and industrial region in Ukraine.

Etymology

The names Don and its diminutive Donets are derived from Iranic, Sarmatian Dānu "the river". Scytho-Sarmatians inhabited the areas to the north of the Black Sea from 1100 BC into the early medieval times.
In the 2nd century CE Ptolemy knew the river Don, into which the Donets flows, as Tanais, and Western Europeans recognized that the Don had a significant tributary which they called either the small Tanais or Donetz. The Slavic name of Seversky Donets derived from the fact that the river originates from the land of Severians. As the Italian-Polish chronicler Alexander Guagnini wrote: "There is also another, small Tanais, which originates in the Seversky Principality and flows into the large Tanais above Azov".

Geography and hydrology

The Donets is the largest river in eastern Ukraine and the largest tributary of the Don. Its total length is and the basin area is. Most of the river's length stretches across Ukraine. The average annual flow is near the source and at the confluence to the Don.
The Donets originates on the Central Russian Upland, near Podolkhi village, Prokhorovka area, north of Belgorod, at an elevation of above sea level. Its basin contains over 3000 rivers, of which 425 are longer than and 11 are longer than ; 1011 of those rivers directly flow into the Donets. These rivers are mostly fed by melting snow, and thus the water supply is uneven during the year. The spring flood lasts about two months, from February to April – during this period the water level rises by. Excessive flooding is rare due to numerous artificial water reservoirs constructed along the river.
The width of the river mostly ranges between, sometimes reaching and even in the reservoir area. The river bottom is sandy and uneven, with the depth varying between and the average value of. The river freezes from around mid-December until late March and is covered by thick ice. It flows into the Don from the latter's mouth, at an elevation of above sea level; thus the fall of the river is with the average gradient of 0.18 m/km.
;Tributaries and reservoirs
The flow is slow, between at Chuhuiv and near Lysychansk. The river valley is wide: from in the upper part and up to downstream, and is asymmetrical. The right bank is usually high, sometimes with chalk cliffs, and is dissected by gullies. The left bank is more flat, contains numerous swamps, lakes and oxbow lakes, the largest of which is lake Lyman. The river is meandering, especially above the Oskil tributary.
Upstream, above Belgorod, the river contains several dams and small reservoirs. Downstream, below the confluence with the Wolf River, there is the Pechenizke Reservoir, which supplies water to the city of Kharkiv. Below the Pechenizke Reservoir, the Donets is fed by the Udy and by its largest tributary, the Oskil. There the valley widens and its floodplain creates numerous oxbow lakes. Within Ukraine, the river flows between the Cisdesna plateau and the Donets lowland. In its middle, the river is partly fed by the Dnieper waters, which are brought though the Dnieper–Donbas–Seversky Donets channels which provide water to the coal industry of the Donets Basin. Near the Russian city of Donetsk, the river crosses the Donets Ridge and flows in a narrow valley with steep and rocky slopes. In the lower part of the Donets lowland, the flow is interrupted by sluices and is slow. At the delta, it splits into three distributaries.

Navigation

At present, the Donets is navigable up to the city of Donetsk, 222 km from the mouth. Navigation on the last section is supported by six dams, built from 1911 to 1914. Each consists of a long concrete dam and a single-chamber sluice, long, wide and deep. At the end of the 19th - beginning of the 20th centuries, a number of attempts were made to revive shipping, in particular, for the sake of the possibility of water transportation of minerals in the Donbass. One of the enthusiasts of the project was D. I. Mendeleev, who wrote about the need to “arrange the Donets for our Russian needs because the Donets, due to the importance of the interests involved in it, is most necessary”. The developer of the project was the Russian hydraulic engineer Nestor Platonovich Puzyrevsky, known for his contribution to the Volga-Don Canal project. In 1903-1904, he conducted a detailed study of the channel of the Seversky Donets and proposed a project to restore the navigation of the Seversky Donets to the city of Belgorod, which involves the construction of a large number of locks were interrupted by World War I, Russian Civil War and lack of funds. The design of the dams and their old age slowed the navigation of the river, which is currently rather limited.

History

Pre-industrial era

The river played a crucial role for its ancient settlers as a source of water and food, means of transportation and trade route. The first archaeological evidence of settlers relates to Cheulean and Acheulean periods of Lower Paleolithic through stone tools found on the river banks near Izium city of Kharkiv Oblast and in Luhansk Oblast. Over the ages, the river banks were populated by tribals of various cultures, including Mousterian, Yamna, Catacomb, Scythian, Alan, Khazar and later Slavic cultures. Many of the related tribals had nomadic lifestyle characteristic of Kipchak people, Golden Horde and later of Cossacks. The river flows through the historic lands of Sloboda Ukraine as well as the lands of Don River Host. The many Cossacks became later assimilated into the strengthening Russian Empire, which had rebuilt and reinforced the fortress of Belgorod and cities of Kyiv, Izium, Luhansk, Chuhuiv and others in order keep defensive lines against the raids of nomads from the south-east. Later, the protective role of the river basin gave way to economic needs. In the 18th–19th centuries, the river was extensively used for watermills, which numbered by hundreds by the end of the 18th century, and the mill dams interrupted navigation on the river.

Industrial era

in the 20th century shifted interests to mineral exploitation in Donbas, with water-hungry plants concentrated mostly in Kyiv, Luhansk and Donetsk. Already by the 1930s, Kharkiv, Donetsk and Luhansk were lacking water forcing the authorities to gradually create a network of canals and reservoirs. In 1936, the Kochetok Reservoir was created and coupled to the water system of Kharkiv. By the 1950s, this measure proved insufficient, and in the 1960s, Pechenizke Reservoir was constructed in place of the Kochetok Reservoir. It has with the capacity of 400 million m3 and provides about 75% of water consumed by Kharkiv. To supply water to southern Donbas and Donetsk, the 130-km long Donets-Donbas channel was built around 1958 starting near Raigorodok city, and in compensation, the Dnieper-Donbas channel was created to supply water from Dnieper River to the upstream of the Donets via the Bereka River. As a result of the industrial activity, the wild nature of Donets Basin transformed into an industrial settlement. After the breakup of the USSR, most of the basin territory became part of Ukraine.

Russo-Ukrainian War

During the War in Donbas, Luhansk Oblast was roughly split along the river between the Luhansk People's Republic, which controlled most of the portion of the oblast south of the Donets, and the Ukrainian government, which controlled most of the territory north of the Donets.
In May 2022, Russian attempts to cross the Donets above Lysychansk were stopped in the operationally decisive Battle of the Siverskyi Donets.
File:Donets near shipilivka2.JPG|thumb|Donets in Luhansk Oblast, near Shypylivka.

Environment

Being one of the largest rivers in Ukraine, the Donets is very intensively used in farming and industry. Ukraine alone uses more than of river waters per year, half of which is returned as polluted discharges; this consumption effectively reduces river runoff by.
Donets suffered greatly even back in the 18th century, when old oaks were cut down along its banks. The industrial development of the 19th century reduced the groundwater levels of the basin. This resulted in shallowing of the river and slowed navigation. Until the mid-19th century, the river was rich in fish which population rapidly declined since then. The water quality is graded as level IV to V. The main pollutants are fertilizers, petroleum, phenols, zinc, chromium and copper. In Kharkiv Oblast, water is contaminated by industrial and communal wastes of Belgorod, Izium and Shebekino cities, but the water is partially purified through the Pechenizke Reservoir. The density of plants and thus the contamination increase downstream in Donetsk and Luhansk areas, especially around Lysychansk and Sievierodonetsk, about 400 km from the mouth. Some tributaries of the Donets, such as Kozenyi Butt, Bakhmut and Lugan are so polluted that consuming fish caught there is dangerous.
The purest segment of Donets is between the source and Belgorod, and between the Pechenizke Reservoir and Chuhuiv. Average water salinity is 650–750 mg/L, and it increases in winter to 1000 mg/L mostly due to industrial wastewater.