The Zayandehroud, which means ‘life-giving river’, is the largest river in central Iran and has traditionally been a major source of water for the country

The Zayandehroud Basin covers 41,500km2 in central Iran and includes three main rivers: Zayandehroud River, Pelasjan River and Samandegan River

The primary source of water in the marshlands is the Tigris and Euphrates rivers, with several major tributaries flowing from Iran towards Tigris and Hawizeh. From the head of the Upper Mesopotamian Plain to the Gulf, the rivers meander slowly.

For many years, negotiations between Turkey and Syria over the Orontes or Asi River were linked to issues concerning the Euphrates and Tigris rivers shared between Turkey, Syria and Iraq, and progress of the former was dependent on progress of the latter

The length of the river is open to discussion. Depending on the source consulted, this ranges from 248km to 556km. Rainfall in the basin is about 644mm annually. The average temperature is around 16°C. The climate is semi-arid to arid in Lebanon, with annual rainfall of about 400mm

The annual amount of water used in Syria is about 15BCM. This comes from the Euphrates (50 per cent) and the Asi River basins (20 per cent). Of the water usage from the Asi River, 2,230MCM are used for irrigation, 320MCM for domestic purposes and 270MCM for industrial purposes. The total amount of water withdrawn from the Asi River is 2,730MCM

The total long-term annual renewable water resources are estimated at 120BCM, of which about 78BCM go to surface run-off, and groundwater recharge is estimated at about 42BCM per annum, 11BCM by qanats (underground water supply systems) and springs, plus 31BCM by wells.

Dams have always played an important role in harnessing precious Iranian water reserves, and the long-term objective of Iran’s water resources development plan is based on the control and regulation of water through dams. In 2015, a total of 647 dams were in operation, of which 352 are considered significant reservoirs, with a total capacity of 48.39BCM.

According to Iran’s water legislation, three ministries are directly responsible for water resources assessment and development, and namely are : The Ministry of Energy (MoE) , The Ministry of Agriculture (MoA), and The Department of the Environment (DoE).

Internal renewable water resources are estimated at 92BCM, with another 13CM coming in from transboundary resources. Surface run-off represents a total of 97.3km3/year, of which 5.4 km3/year come from draining the aquifers.