Hrazdan

The Hrazdan (Հրազդան գետ, Hrazdan get) is a major river and the second largest in Armenia. It originates at the northwest extremity of Lake Sevan and flows south through the Kotayk Province and Armenia's capital, Yerevan; the lake in turn is fed by several streams. In the Ararat plain it joins the Aras river along the border with Turkey. Its waters join the Kura river, before flowing into the Caspian Sea. A series of hydro-electric plants have been constructed on the river. Its waters are in demand to irrigate crops. The river was called Ildaruni in Urartian. Its name in Turkic languages is Zangu, Zanga, Zangi, or Zengy. The Sevan Lakes (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.