The Iskar Reservoir (язовир „Искър“) is the largest

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedo ...

. It is situated on the

Iskar River The Iskar ( bg, Искър, ; la, Oescus) is a right tributary of the Danube. With a length of 368 km it is the longest river that runs entirely within Bulgaria.Sofia Sofia ( ; bg, София, Sofiya, ) is the capital and largest city of Bulgaria. It is situated in the Sofia Valley at the foot of the Vitosha mountain in the western parts of the country. The city is built west of the Iskar river, and h ...

, also being used for producing

hydroelectricity Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined an ...

. The reservoir has a total volume of 673 million m³, of which 580 million are in use and the rest is reserve. The reservoir has a

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

of 1,046 km² and is 25 km long. It is situated at 820 m above sea level, its dam being 204 m long and 76 m high.

History

The initial plans for the construction of a dam on the Iskar date to as early as 1900-1901, immediately after the building of the Pancharevo Hydroelectric Power Plant. In 1921, the idea was once again brought up, but its accomplishment failed due to the municipality's inability to indemnify the residents of the neighbouring villages of Gorni Pasarel, Shishmanovo and Kalkovo.

Topographic Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scien ...

photographs and a

geological Geology () is a branch of natural science concerned with Earth and other astronomical objects, the features or rocks of which it is composed, and the processes by which they change over time. Modern geology significantly overlaps all other E ...

assessment regarding the dam were made and observations of the Iskar's water level at Pasarel were conducted in 1932-1941 in order to build what was initially called the ''St Peter's Reservoir'' (named after the monastery in Dolni Pasarel which was supposed to be near the reservoir). New geological research related to the reservoir's construction began in 1947 at four places between Gorni Pasarel and

Pancharevo Pancharevo ( bg, Панчарево, , also transcribed as Pančarevo) is a resort village and district located on the outskirts of Sofia close to Vitosha, Lozenska and Plana mountains and occupies the southeastern part of the Capital Municipa ...

. The place at the Iskar's 37th kilometre was chosen as the most suitable in terms of geology, topography and economics. The waters of the river were further studied between 1947 and 1948. Work on the projects for an Iskar water power system commenced in early 1948 in the newly established Energohidroproekt. The design and the first draft were created by a team under the engineer Moiseev with the assistance of

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nation ...

specialists. The project was approved by the expert council of the Ministry of Electrification and Melioration, and it was planned that the reservoir had a working volume of 520 million m³ and a reserve volume of 60 million m³. The preparative works began in 1949, the main construction was carried out in the end of 1950, the water power system being officially opened on 6 September 1954. When it was under construction, its name was changed to "Giant Stalin Dam" (Гиган язовир Сталин), but later its name was returned to "Iskar Reservoir". There is also the Beli Iskar Dam, which is another smaller dam and is located in the upper reaches of the Iskar River.For Iskar - the largest dam in Bulgaria
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References

* *{{cite web, url=https://www.moew.government.bg/static/media/ups/tiny/filebase/Water/Povarhnostnivodi/Mesechen_grafik/2020/graf_1_20.pdf , title=MOEW government: Ministry of Environment and Water, language=Bulgarian, date=January 2020 Reservoirs in Bulgaria Landforms of Sofia City Province Samokov Municipality