Ivankovo ​​reservoir

It is the largest reservoir in the Moscow region , in the Tver region it occupies the third place after the Rybinsk and Uglich reservoirs in full and the second place after the Rybinsk reservoir in useful volume . Among the large Russian reservoirs, Ivankovskoye is the shallowest: water areas with depths of less than two meters at a normal retaining level comprise almost half the area of ​​the water mirror ^[5] .

It was formed in 1937 by the dam of the Ivankovo ​​hydroelectric power station near the former village of Ivankovo, where the Volga river bed was washed off with the use of medium-grained sands with an earthen dam of 22.5 m in height and 300 m in length, passing from the left bank to a concrete spillway dam with eight 20-meter spans for water discharge. On the right bank there is a gateway with an approach channel and an outport , adjacent to the entrance to the Moscow Canal ^{[5] [9] [10]} .

As a result, 32.7 thousand hectares of land were flooded, including 7.4 thousand ha of forests and shrubs, 14.8 thousand ha of agricultural land (7 thousand ha of arable land, 7.8 thousand ha of hayfields and pastures), 4, 8 thousand hectares of settlements, 3.5 thousand hectares of water bodies and 2.2 thousand hectares of inconvenient land. Territories of over a hundred villages, including the once-county town of Korchev ^{[# 1]} and part of the working village of Konakovo, were under water. The process was associated with the removal of a large number of buildings, structures and communications, deforestation , forestry, special events with cattle burial grounds and the relocation of about 50 thousand inhabitants from the flood zone ^{[5] [9] [10]} .

The normal retaining level (according to the Baltic elevation system) is 123.89 m, the dead volume level is 119.39 m, the forced retaining level is 124.09 m. The total reservoir volume atNPU is 1120 million m³ , usable volume is 887 million m³ , the area of ​​the reservoir’s mirror is 316 km², which is more than twice the area of ​​pre-revolutionary Moscow . Backwater extends to 113 km along the Volga channel, 80 km along the Shoshi channel and 15 km along the Sozi channel. Length - 120 km, average width - 4 km, maximum width - 12 km, coastline - 520 km. The average depth is 4 m, the maximum is 19 m. The catchment area, covering most of the Tver region, sections of the Smolensk , Moscow and Novgorod regions, is 41 thousand km² ^{[5] [7] [10] [12] [13] [14 ]} .

The relief of the reservoir basin is flat and hilly with a pronounced eastern and southeastern slope. In the northwestern part of the basin, in the Valdai Upland , there is a large-hilly relief with large massifs of hills and elevations of 200-300 m above sea level. In the east, an area of ​​hilly-plain relief adjoins it, gradually turning into moraine and sandra plains ^[15] . The climate is temperate continental with prevailing westerly winds and an average annual air temperature of 3.0-3.7 ° C ^[16] .

There are many lakes in the reservoir basin. Verkhnevolzhsky and Seligersky large lake regions are located in its northwestern part, Orshano-Petrovsky lake region - on the swampy watershed of the Volga and Medveditsa , flowing lakes of the Verkhnevolzhsky district - Sterzh , Vselug , Peno , Volgo - are combined by the Verkhnevolzhsky reservoir . The coefficient of lakeiness ^{[# 2] of the} basin is 2.2%, the largest lake is Seliger . The density of the well-developed river network of the basin varies from 0.30-0.35 km / km² in the Valdai Upland to 0.12-0.15 km / km² in the Upper Volga Lowland. The rivers feed mainly snow, the average annual runoff modulus is 6.5–9.0 l / (s × km²), about 40-60% of the annual runoff passes during the spring flood, from 10 to 20% in the summer ^[18] .

  And w
 Length, km 27 84 36
 Breadth Extreme, km 8.0 2.1 5.0
 Average width, km 5.9 0.9 4.0
 Insularity,% 10.8 6.3 21.6
 Area under the NPU, km² 141 74 112 
 Percentage of reservoir area 43 23 34
 Average depth at NPU, m 3.3 4.9 1.7
 Coefficient of development of the coastline 6.6 - 10.1
 Volume at NPU, km³ 0,46 0,47 0,17
 Percentage of reservoir volume 41 42 17

The Ivankovo ​​reservoir has a rather complicated configuration, and according to the shape of the basin, the shape and nature of the banks, it is divided into three reaches - Ivankovsky, Volzhsky, Shoshinsky. In some sources, the Ivankovsky reach is called Nizhnevolzhsky, part of the Volzhsky reach above the mouth of the Shosha - Verkhnevolzhsky, below the mouth of the Shosha - Srednevolzhsky ^[20] .

Ivankovsky reach is the deepest (up to 19 m) and widest (up to 8 km) section of the reservoir from the mouth of the Sozi to the dam, which is a lake-shaped extension, always located in the backwater zone. It is characterized by a very rugged coastline, many islands and overgrown bays. The average depth is 3.3 m ^[21] .

Volzhsky reach - section from the mouth of Sozi to the city of Tver . It is located in a variable backwater zone and looks like a river with a width of 900 to 1,500 m with hilly banks. Depth increases downstream ^[21] .

Shoshinsky reach - flooded Shoshi valley from its former mouth to the village of Turginovo . Here, open water spaces are combined with numerous islands, channels and overgrown shallow waters, often turning into coastal swamps ^[21] .

The main supply of the reservoir occurs due to surface runoff (97%). The basins of the three main rivers flowing into the reservoir - the Volga, Tvertsa and Shoshi - occupy 84% of its catchment area, while the Moscow Sea has 10 tributaries, the length of which exceeds 10 km. The Volga accounts for 59% of the total inflow, Tvertsa - 24%, Shoshi and tributaries of the Shoshinsky reach - 11%. Most of the annual runoff falls in the spring (51%), 17% each in the summer and autumn, another 15% of the water flows in the winter. About 2% of the total income comes from precipitation falling on the mirror of the reservoir, 80% of the total number falls from April to October. The first place in the discharge part of the water balance of the reservoir is occupied by the discharge of water through the Ivankovo ​​hydroelectric complex and amounts to 7.7 km³, or 83% of the total discharge, of which 47% in April - May. About 14% go to the Moscow Canal. The maximum water flow through hydraulic structures is 7350 m³ / s ^{[10] [22]} .

The ratio of the small volume of the reservoir to the volume of surface runoff determines the high water exchange, the average annual coefficient of which is 9.0–13.6, which allows updating the average annual volume of the reservoir for about a month. The most intense water exchange occurs in spring, when the volume of the average long-term inflow is 4 times the volume of the bowl of the reservoir at a normal retaining level. The annual change in water level includes three characteristic phases of seasonal flow regulation - spring filling, summer-autumn standing near NPU and winter runoff, starting from the moment of freezing up , which lasts 150 days on average, and the maximum ice thickness reaches 82 cm. Runoff of the water level is about 4 m ^{[5] [23]} .

In the navigation period, at a reservoir level close to NPU , the flow velocity in the Volzhsky reach varies from 0.1 to 0.4 m / s, in the Shoshinsky reach inferior in flow rate (its water exchange is almost three times lower) does not exceed 0.06 m / s even along the Shoshi channel. The nature of the flow in the Ivankovo ​​reach is influenced by the uneven operation of the hydroelectric power station, discharges of the Konakovskaya state district power station and the wind; the current velocity in the upper head of the hydroelectric station is 0.03-0.16 m / s, and at the upper boundary of the reach is 0.04-0.12 m / s. The highest flow rate of 0.5-1.0 m / s is observed when the flood passes. The height of the waves at a wind speed of 20 m / s can reach 1.4 m in the Ivankovo ​​reach, 1.8 m in the Volzhsky reach and 1 m in the Shoshinsky reach ^{[24] [25]} . The temperature regime of the Ivankovo ​​reservoir in winter and early spring is close to the river, in late spring, summer and autumn - to the lake ^[26] . In summer, the surface water temperature is 22.9 ° C, and the bottom water temperature is 16.7 ° C ^[27] . The release of heated water from the Konakovskaya TPP has a significant effect on the temperature regime only in a small area adjacent to the discharge site, however, on some parts of the ecosystem, the influence zone can be traced within a radius of 10-12 km ^{[28] [29]} .

  Spring Summer Autumn
 Volzhsky reach 0.97 0.92 1.20
 Ivankovsky reach 1.00 0.95 1.17
 Shoshinsky reach 0.75 0.47 0.77
 VDP average 0.95 0.88 1.12

The water of the Ivankovo ​​reservoir is low mineralized, calcium-bicarbonate type, with an average salt content of 248 mg / l. The quality corresponds to the class of polluted , and in areas of the water area in the region of Tver and Konakov, at the mouth of the Shoshinsky reach, in places of sewage discharge, the urban-type settlement Radchenko is very polluted . The indicators of biochemical and chemical oxygen consumption , maximum permissible concentrations of total iron, ammonium nitrogen, petroleum products, zinc, synthetic surfactants are exceeded by 1.5-3 times; the concentration of manganese is 20-50 MPC ^{[5] [28]} .

According to the set of indicator biochemical, hydrochemical and biotic indicators, the Ivankovo ​​reservoir is estimated as a eutrophic reservoir, in some areas - as a hypereutrophic reservoir, especially in places where sewage is discharged from enterprises and farms, as well as in the area where large volumes of heated water are discharged from Konakovskaya GRES (Moshkovsky Bay) ) ^[5] . Water transparency in summer is 0.5 m, in winter 3.0 m ^[27] .

In autumn and winter, the biochemical decomposition of aquatic vegetation has a negative effect on a number of indicators of water quality - the concentration of dissolved oxygen decreases, methane formation occurs, the concentrations of nitrogen, phosphorus and carbon compounds, and compounds of a number of heavy metals that were absorbed by the vegetation during the growing season increase ^[5] .

According to research data from 1967–1972, the taxonomic diversity of the phytoplankton of the reservoir included 611 species, varieties, and forms, most of which were green and diatoms ^[31] . In terms of weighted average biomass, diatoms are the absolute leaders; blue-green algae are almost three times behind them. The richest development of phytoplankton was recorded in the Shoshinsky reach, its biomass in the Ivankovo ​​reach is twice as high as in the Volzhsky reach ^[32] . An insignificant fluctuation in the values ​​of the average vegetation phytoplankton biomass characterizes the Ivankovo ​​reservoir as a stabilized ecosystem ^[33] . The main part of the benthos of the reservoir are oligochaetes , chironomids and mollusks ; zooplankton - mainly rotifers and crustaceans ^{[5] [34]} .

The ichthyofauna of the reservoir is represented by 38 fish species, 22 species belong to the cyprinid family, 4 species belong to the perch family , the remaining families have one representative. In different years, peled , carp , eel , smelt , grass carp and silver carp were inhabited in the reservoir. Of the native species, bream occupies the leading place in terms of number and economic importance, the second is roach , the third is perch , the fourth is pike , the most valuable is pike perch . The actual catch of fish is 63.1–857.6 tons; commercial fishing was discontinued in 2007 ^{[5] [35]} .

Ivankovo ​​reservoir serves as the main source of uninterrupted water supply in Moscow. Water is supplied through the 128 km long Moscow Canal, with an average annual volume of 1.7 km³. In the first twenty years, 900 million m³ of water were supplied to the canal. Part of the water goes to the sanitary-hygienic flooding of the Moscow River and its tributaries. Water supply to cities and towns located on the shore of the reservoir also occurs at its expense ^{[5] [19]} .

The hydropower value of the reservoir is not so great, the capacity of the Ivankovo ​​hydroelectric station is only 28.8 MW, the average annual output is 119 million kW⋅h. Since 1964, it has also been used as a reservoir-cooler for condensers of the powerful Konakovskaya GRES, through thermal units and installations of which 87% of the reservoir’s useful volume passes annually ^{[5] [19]} .

The Ivankovo ​​reservoir is a deep-water water transport artery from Dubna to Tver for vessels with a draft of up to 4 m. About 1 million m³ of sand-gravel mix is mined from its bottom every year ^[5] .

At least 2.5 million people visit the reservoir every year, recreational fishing, hiking and hunting are very popular. In different years, on the coast of the reservoir there were numerous houses and recreation facilities, tourist camps, sports and recreation camps, tent camps, hunting farms and fishing and sports centers ^{[5] [36]} . Most of the nearly 300 islands formed in the water area of ​​the reservoir are a resting place for residents of Konakovsky district, neighboring regions and regions ^{[27] [37]} . Part of the Shoshinsky reach is located within the boundaries of the Zavidovo National Park - a specially protected natural area ^[38] .

Such large settlements as the cities of Dubna (74,851 ^[39] people) and Konakovo (38,486 ^[40] ), urban-type settlements Novozavidovsky (6597 ^[40] ), Kozlovo (3696 ^[40] ) and Radchenko (1411 ^[40] ).

• Technical report on the construction of the Moscow-Volga Canal / Ed. A.R. Berezinsky. - M. , L .: State Publishing House of Building Literature, 1940. - 316 p.
• Ivankovo ​​reservoir and its life. Proceedings of the Institute of Biology of Inland Waters / Ed. N.V. Butorina. - Academy of Sciences of the USSR. - L .: Nauka, 1978.- T. 34 .-- 304 s. - 1000 copies
• Cities under water. Traveling along the flooded shores of the Upper Volga / Compiled by V. I. Erokhin. - Tver: Grand Holding, 2010. - 112 p. - ISBN 978-5-9971-9016-3 .
• Rules for the use of the Ivankovo ​​reservoir on the river. Volga (project) . - M .: Rosvodresursy, 2014 .-- 160 p.