The Dnieper reservoir cascade () is a series of dams, reservoirs and hydroelectric power stations (HPPs) on the Dnieper in Ukraine. The first HPP on the Dnieper was built at Zaporizhzhia in the 1920s. It was created to prevent uncontrolled flooding, and improve water transportation infrastructure. In 2018, the reservoirs stored approximately 70% of Ukraine's fresh water resources. Water is used to cool nuclear power stations, in transport, for fisheries, by industrial and urban centres for numerous purposes, and to irrigate farmland. The cascade’s shipping lane provides a navigation route from Kyiv to the Black Sea.
The first HPP provided energy for the armaments industries of southern Ukraine. In 1941, NKVD agents , supposedly in an attempt to hinder the German advance across Ukraine. The resulting explosion killed thousands of civilians and Red Army troops. It was rebuilt in 1947, and over the next two decades, three new HPPs were built. After Russian armed forces took control of the Kakhovka Dam at the start of the Russo-Ukrainian war, Ukrainian troops fortified the five other dams. On 6 June 2023, the Kakhovka Dam was breached; the reservoir has since drained away.
As a result of the construction of the reservoirs in the Dnieper cascade, many of the features of the river were permanently transformed, causing severe disruption to the hydrology of the Dnieper basin. Pollution levels worsened in the 1990s and there has been little improvement to the cascade since, in part as a result of mismanagement of the issue by the Ukrainian government, a situation that has attracted international criticism. The geoecological state of the cascade has been degraded by ecological and manmade causes (radioactive and chemical pollution, eutrophication, the increased risk of flooding, erosion, abrasion of the banks, silt accumulation, the increase of karst processes, Increased evaporation, and waste from farmland). Many fish species have been adversely affected, and measures to re-establish fish populations have not been successfully implemented.
Description and uses The Dnieper reservoir cascade in Ukraine is a series of six dams, reservoirs and hydroelectric power stations (HPPs) on the Dnieper. Together with the Kyiv Pumped Storage Power Plant and the , the Dnieper cascade was part of United Energy Systems of Ukraine until the company was closed down in 1997; the coordination and operation of all the dams on the Dnieper is now controlled by Ukrhydroenergo, a government-owned company. The cascade was created to prevent uncontrolled flooding, and to improve the region's water transportation infrastructure.
In 2018, the reservoirs together stored approximately 70% of all Ukraine's fresh water resources; the Dnieper supplies the fresh water needs of 30 million people. Water from the Dnieper is used in the to cool four nuclear power stations, in transport, and in fisheries. Its waters are used by 50 industrial and urban centres for numerous purposes, and 50 irrigation systems provide water for of farmland. The previously chronic water shortages incurred by industry in the Donets Basin and Kryvyy Rih were eradicated, and it became possible to irrigate farmland in southern Ukraine and Crimea.
Prior to 2023, the capacity of the cascade's HPPs (excluding the Kyiv pumped storage power plant) was , and the average annual electricity production was . The Kyiv Pumped Storage Power Plant began operation in 1970. It can produce 235 MW and has an average annual electricity production of 135 GWh.
Hydrology
Before the Dnieper's reservoirs were built, the river flowed more slowly during the summer and the winter than during other times of the year. The dams along the river's course now cause the highest flows in spring and the lowest flows from September to March. Snowmelt from the river’s upper basin during the spring provides the greatest part of the annual discharge of water into the cascade. Ice that starts to form at the end of December begins to thaw in early March.The average annual flow of the river at its mouth is per second.
As a result of the construction of the reservoirs in the Dnieper cascade, many of the features of the river were transformed beyond recognition. The disruption of the hydrology of the Dnieper basin due to the construction of the cascade was severe, and the natural development of the Dnieper floodplain was permanently changed.
Infrastructure The Dnieper reservoir cascade consists of six HPPs and one pumped storage power plant:
+ Power plant Reservoir location of dam Built map Power / MW Production / GW/h Reservoir volume / Gm3 Notes Kyiv Hydroelectric Power Plant Kyiv Reservoir Vyshhorod 19601964 408.5 750 1.17 - Kaniv Hydroelectric Power Plant Kaniv Reservoir Kaniv 19631975 444 930 0.28 - Kremenchuk Hydroelectric Power Plant Kremenchuk Reservoir 625 1500 8.97 Due to its volume it can be used to increase electricity production at all downstream HPPs. Middle Dnieper Hydroelectric Station Kamianske Reservoir 19541960 352 1290 0.53 - Dnieper Hydroelectric Station Dnieper Reservoir 19271932 1538.2 3920 - One of the largest HPPs in Eastern Europe. Rebuilt following its destruction during the Second World War; reconstructed in 1980 Kakhovka Hydroelectric Station - Nova Kakhovka 19501956 - - - Destroyed in June 2023; previous capacity 351MW.
Use as a transport route
Locks were constructed at each of the cascade's HPPs to allow ships to navigate from the mouth of the River Pripyat to the Black Sea. The completion of the cascade thus created a shipping lane. The channels and locks on the cascade have a width of , and a depth of . The shipping lane provided nine inland ports that can access the Black Sea: Kyiv River Port, Cherkasy River Port Kremenchuk River Port Kamianske River Port Dnipropetrovsk River Port Zaporizhzhia River Port Nikopol River Port Nova Kakhovka River Port Kherson River Port
Prior to the dissolution of the USSR, 50-60 million tons of goods were transported through the Dnieper locks water per year. A record number of ships passing through the cascade’s locks during the 1970s; almost 22,000 vessels passed through the Kaniv lock in 1974. The number of ships moving through the cascade significantly decreased during the 1990s.
History Obstacles to navigation along the Dnieper
Ever since the Dnieper first became used to connect the Kievan Rus’ lands with Scandinavia and the Byzantine Empire, it has been an important trade route. The main obstacles to navigation were the Dnieper rapids, first described during the 10th century. At the rapids (between modern-day Dnipro and Zaporizhzhia), the Dnieper was strewn with cliffs, rocks, and boulders that blocked off part of the river (), or that cut right across it (). The rapids made continuous navigation almost impossible; Kyivan Rus’ merchants, forced to circumvent them by land, were often ambushed by bandits at the rapids.
The government attempted to overcome how the rapids effectively divided the navigable river into two separated parts. During the 1840s, canals were constructed, but these were inadequate for ships, and even smaller craft continued to take the original ‘Cossack’ route through gaps in the rapids and barriers—and then only when the water level was high. After the Russian railway system was extended to the Crimean peninsula, the Dnieper trade route near the rapids now became safe from attack, and was able to play a greater role in reviving the region's economy.
The rapids ceased to exist when the Dnieper Reservoir was built in 1932, and the river's water level was raised by .
Flooding prior to the regulation of the flow of the Dnieper The worst flood during the 19th century in that affected the local population was in 1845; flood levels in Kremenchuk reached . The 1931 flood caused catastrophic damage, when all the population centres on the eastern, more gentle-sloping, shore of the river from Kyiv to Zaporizhzhia were flooded. Such an event is thought to occur once every 300 years. That winter's snowfall melted quickly in the spring, so that the snowmelt happened quickly, and the water level in the Dnieper rose rapidly as a result.
In 1970, the Kyiv Dam partially prevented a repetition of the flooding that devastated Kyiv in 1931.
Construction of the Dnieper dams and power station
Plans for a HPP on the Dnieper were first made in 1905, but were not realized due to World War I. Following the plan of the State Commission for the Electrification of Russia (GOELRO), the first HPP on the Dnieper was built at Zaporizhzhia.
The problem of navigating through the Dnieper rapids remained unsolved until the Russian engineer Ivan Alexandrov supervised the construction of the HPP. The dam was made in the shape of a horseshoe, with a base made of concrete rather than rubble. A lack of heavy equipment meant that the construction of the dam was mostly done manually. Prior to completion, the number of on-site workers exceeded 60,000, most of whom were villagers from southern Ukraine. When it commenced operations, HPP provided energy for all of southern Ukraine, and proved to be vital for the manufacturing of heavy weapons and the production of aluminium and steel for aircraft and tanks.
Second World War
In August 1941, NKVD agents acting under orders from the Soviet leadership , supposedly in an attempt to hinder the German advance that was believed at the time to be approaching Zaporizhzhia. The resulting explosion created a tidal surge that reached a height of , destroying everything in its path, killing thousands of civilians in settlements along the Dnieper, and devastating homes, villages, and towns. Hundreds of retreating Red Army troops drowned, as no warning had been given to them of the plan to sabotage the dam. Following the attack, the Soviets falsely blamed the destruction on the advancing Germans. No records of the death toll were ever made, so that the total number of people killed by the disaster remains unknown.
The Germans repaired the dam after they captured it later that year. In March 1943, it was blown up again using more than 200 tons of explosives and aerial bombs, this time by German troops as they retreated from the Red Army. The Soviets prevented the retreating Germans from completely destroying the dam, by cutting some of the wires to the explosives.
Among the reconstruction projects undertaken in Ukraine in the decade following the end of the war, the one given high priority by the newly-appointed party boss of the Zaporizhzhia Oblast, Leonid Brezhnev, was the rebuilding of both the HPP and the destroyed Zaporizhzhia steelworks. They became operational again by September 1947, but the ruined city of Zaporizhzhia and its surrounding villages were left devastated long afterwards, a crime which led to famine and thousands of deaths.
Completion of the reservoir cascade It was discovered soon after the Dnieper HPP that when the reservoir levels were low in the autumn and the winter (due to the irregular flow of the river), the power output noticeably decreased, and ships were unable to pass through the locks. In 1936, Gosplan concluded in a report that considered solutions to these problems that:
During 1938–1941, the scheme for the building of the new Kremenchuk and Dniprodzerzhyn Reservoirs on the Lower Dnieper was developed, with the aim of regulating the flow of the river at the Dnieper HPP.
in the 1950s and 1960s three new HPPs were built. Their construction caused the flow of the Dnieper to be diverted, huge areas of farmland to be destroyed, and mines to be flooded. The decision to build the Kakhovka HPP was made in September 1950. The project, seen as part of Stalin’s “Great Plan for the Transformation of Nature”, was estimated to be 2.5 billion rubles and was planned to be finished in 6 years. Its construction required new towns, railways, roads highways, power lines, locks, and a port. It was emphasized by the authorities that: