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

In all three riparian countries, the river is used mainly for irrigation, domestic water supply and hydropower. The Asi River is diverted to the Homs-Hama water channels and Ghab-Roudji irrigation systems to meet the needs of Lebanon and Syria. The water is also stored in the Zeita Dam for domestic and irrigation purposes and energy production.

The Islamic Republic of Iran covers a total area of 1.75 million km2 and is bordered by Armenia, Azerbaijan, the Caspian Sea and Turkmenistan to the north, Afghanistan and Pakistan to the east, the Gulf of Oman, the Strait of Hormuz and the Persian Gulf to the south, and Iraq and Turkey to the west.

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.

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.

Sustainable water resource management in Iraq has no shortage of challenges. Some of Iraq’s water hardships, like seasonal floods and droughts, occur naturally. Many of the most disruptive and destructive problems are, however, man-made: water infrastructure debilitated from decades of war and neglect; inefficient and outdated agricultural practices; rapid population growth and urbanization; competing water management approaches within transboundary river systems; and the looming crisis of climate change. The government of Iraq has plans to address the situation but it remains to be seen whether major reform will transpire.

Presently, Iraq is contending with two types of water quality issues. One is salinity, the other is the concentration of pollutants in the water related to municipal, industrial and agricultural activities that introduce return flows into freshwater sources.

The two dominant rivers in Iraq are the Tigris and Euphrates. The watersheds, including their tributaries, account for 100% of the country’s surface water.

Agricultural water uses in Iraq are the the vast majority among the other sectors. Municipal and industrial needs are tied for second place