The Hrazdan (, ) is a major river and the second largest in

Armenia Armenia, officially the Republic of Armenia, is a landlocked country in the Armenian Highlands of West Asia. It is a part of the Caucasus region and is bordered by Turkey to the west, Georgia (country), Georgia to the north and Azerbaijan to ...

. It originates at the northwest extremity of

Lake Sevan Lake Sevan () is the largest body of water in both Armenia and the Caucasus region. It is one of the largest freshwater Alpine lake, high-altitude (alpine) lakes in Eurasia. The lake is situated in Gegharkunik Province, at an altitude of abov ...

and flows south through the

Kotayk Province Kotayk (, ), is a provinces of Armenia, province (''Administrative divisions of Armenia, marz'') of Armenia. It is located at the central part of the country. Its capital is Hrazdan and the largest city is Abovyan. It is named after the Kotayk c ...

and Armenia's capital,

Yerevan Yerevan ( , , ; ; sometimes spelled Erevan) is the capital and largest city of Armenia, as well as one of the world's List of oldest continuously inhabited cities, oldest continuously inhabited cities. Situated along the Hrazdan River, Yerev ...

; the lake in turn is fed by several streams. In the Ararat plain it joins the

Aras river The Aras is a transboundary river in the Caucasus. It rises in eastern Turkey and flows along the borders between Turkey and Armenia, between Turkey and the Nakhchivan exclave of Azerbaijan, between Iran and both Azerbaijan and Armenia, and, fin ...

along the border with

Turkey Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a relatively small part called East Thrace in Southeast Europe. It borders the Black Sea to the north; Georgia (country), Georgia, Armen ...

. It joins as a left tributary the Kura river, which then flows into the Caspian Sea. A series of hydro-electric projects have been constructed on the Hrazdan. Its waters are in demand to irrigate crops.

Names

The river is called Ildaruni in Urartian inscriptions. The name ''Hrazdan'' derives from a

Middle Iranian The Iranian languages, also called the Iranic languages, are a branch of the Indo-Iranian languages in the Indo-European language family that are spoken natively by the Iranian peoples, predominantly in the Iranian Plateau. The Iranian language ...

form of

Avestan Avestan ( ) is the liturgical language of Zoroastrianism. It belongs to the Iranian languages, Iranian branch of the Indo-European languages, Indo-European language family and was First language, originally spoken during the Avestan period, Old ...

, which in

Zoroastrian Zoroastrianism ( ), also called Mazdayasnā () or Beh-dīn (), is an Iranian religion centred on the Avesta and the teachings of Zarathushtra Spitama, who is more commonly referred to by the Greek translation, Zoroaster ( ). Among the wo ...

mythology is the body of water by which Vishtaspa converted to Zoroastrianism. is composed of the elements 'elevated, high' and 'river'. derives from the same

Iranian Iranian () may refer to: * Something of, from, or related to Iran ** Iranian diaspora, Iranians living outside Iran ** Iranian architecture, architecture of Iran and parts of the rest of West Asia ** Iranian cuisine, cooking traditions and practic ...

root as a number of

hydronyms A hydronym (from , , "water" and , , "name") is a type of toponym that designates a proper name of a body of water. Hydronyms include the proper names of rivers and streams, lakes and ponds, swamps and marshes, seas and oceans. As a subset of top ...

in Europe, such as Don,

Dnieper The Dnieper or Dnepr ( ), also called Dnipro ( ), is one of the major transboundary rivers of Europe, rising in the Valdai Hills near Smolensk, Russia, before flowing through Belarus and Ukraine to the Black Sea. Approximately long, with ...

Danube The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...

and

Dniester The Dniester ( ) is a transboundary river in Eastern Europe. It runs first through Ukraine and then through Moldova (from which it more or less separates the breakaway territory of Transnistria), finally discharging into the Black Sea on Uk ...

. The change of word-initial to can be seen in a number of Iranian borrowings into Armenian. The Hrazdan is mentioned in Movses Khorenatsi's history. In the history attributed to Sebeos, the form is used, while some later Armenian historians use the form . Its name in

Turkic languages The Turkic languages are a language family of more than 35 documented languages, spoken by the Turkic peoples of Eurasia from Eastern Europe and Southern Europe to Central Asia, East Asia, North Asia (Siberia), and West Asia. The Turkic langua ...

is Zangu, Zanga, Zangi, or Zengy. It was called Zanga in Tsarist Russian nomenclature.

Geography

Lake Sevan (with 30 rivers contributing to its storage), the largest located in the central part of the country and the Hrazdan River which originates from it, together form the "Sevan-Hrazdan Management Area", which is one of the five sub-basins of the 14 sub-basins of Kura and Araks basins of Armenia. The river originates from the lake at an elevation of . The river which flows from the lake in a southern direction passes through a deep gorge as it enters on the western side of the Yerevan city, and then debauchees into the Aras River on the southern side of the city. The geological formations along the river course are made up of lava flows (existing as basalts) generated from three volcanoes in the Gegham range. The lava surfaces represent environments that existed in the form of "lakes, river channels and floodplains". The chronology of landscape of the upper most layer of basalts indicates an age of 200,000 years. The river drains a total catchment area of . Precipitation volume is 1572 million cubic metre from an annual rainfall of with a maximum of in May and a minimum of during August. The average temperature recorded in the basin varies from in January to in July with diurnal variation with the lowest night temperature of in January and highest day temperature of in July. The total flow in the river is 733 million cubic meter. The regulated outflow into the river, which forms the Ararat Valley, is utilized for irrigation and hydro-power benefits. File:Davtashen panorama.jpg, A panorama of the Hrazdan River gorge and Davtashen from Arabkir, Yerevan

Fauna

The fauna reported from the river includes 33 species of chironomids and 23 species of blackflies. The chironomids belong to five subfamilies of Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae, and

Chironominae Chironominae is a subfamily of midges in the non-biting midge family (biology), family (Chironomidae). Genera *Tribe Chironomini **''Axarus'' Roback 1980 **''Baeotendipes'' Jean-Jacques Kieffer, Kieffer, 1913 **''Beckidia'' Ole A. Sæther, Sæth ...

. 25 species of invertebrates comprising two species of

rotifers The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris ...

, 13 species of

cladocerans The Diplostraca or Cladocera, commonly known as water fleas, is a superorder (biology), superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory. Over 1000 sp ...

and 10 species of

copepods Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (living in the water column), some are benthic (living on the sediments), several species have ...

have been recorded in the river. While the fish species contained in the lake consist of the Sevan trout (''Salmo ischchan'') or “Prince Fish,” siga, crucian, carp, crayfish, bojak (''Salmo ischchan danilewskii'') and winter bakhtak (''Salmo ischchan ischchan'') and summer bakhtak (''Salmo ischchan aestivalis''), the river is reported to have species of crayfish as well as karas and

crayfish Crayfish are freshwater crustaceans belonging to the infraorder Astacidea, which also contains lobsters. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some spe ...

in abundance.

Development

The lake waters have been used for irrigation since the 19th century, and from early 20th century hydro-power development has also been implemented. The lake waters were planned to be used through the river for irrigating in the Ararat Valley out of which an irrigation of was created. The hydro-power development was planned on the river as the Sevan–Hrazdan Cascade involving seven schemes in a stretch of the river with a total installed capacity of 560 MW with mean annual energy generation of around 500 million kilowatt hours; it is the largest hydro-power generating scheme in Armenia. This scheme was implemented between 1930 and 1962. These are small- and medium-size projects built as run-of-the river power plants. The seven power stations are: Sevan HEP with installed capacity of 34.2 MW with two units completed in 1949; the Hrazdan HEP of 81.6 MW with two units commissioned in 1959; the Argel HEP with installed capacity of 224 MW completed in 1953; the Arzni HEP with capacity of 70.6 MW with installation of 3 units commissioned in 1956; the Kanaker HEP with installed capacity of 100 MW with 6 units completed in 1936; the Yerevan-1 HEP commissioned in 1962 with installation of 44 MW with 2 units; and the Yerevan-3 with capacity of 5 MW with one unit commissioned in 1960. However, priority of release of water from the lake is for irrigation and accordingly the power stations are operated. The civil works involved construction of diversion works, open canals or tunnels and power house which over the years were in need of substantial rehabilitation as they were all built around the middle of the twentieth century. In 2003, the International Energy Corporation", a Closed Joint Stock Company, acquired the projects from the Public Services Regulatory Commission of the country under a license No. 0108 for generation of electrical energy. Right from the time of acquisition they started rehabilitating the projects to maximize power generation. The works were completed during 2004. The works were carried out under a US$25 million loan from the

Asian Development Bank The Asian Development Bank (ADB) is a regional development bank to promote social and economic development in Asia. The bank is headquartered in Metro Manila, Philippines and maintains 31 field offices around the world. The bank was establishe ...

River pollution

The river water is polluted by effluent flows from agricultural, commercial, industrial, and residential development, but particularly by the untreated wastewater from Yerevan. This affects the water quality in the river with dissolved oxygen (DO) levels (less than 5% of the saturated dissolved oxygen level) remaining much lower than the permissible limits. A study carried out in 2008 indicates that a 16 km stretch of the river, from 2 km upstream of the Yerevan wastewater outfalls to 14 km below, is insufficiently aerated to provide a healthy environment for aquatic life.

References

Bibliography

* Rivers of Armenia Geography of Yerevan Geography of Kotayk Province {{Category Commons, Hrazdan River