Iran, with more than 65 million people, is one of the driest countries in the world. Urbanization, industrialization, and agriculture have increased demand for water while sapping the county’s scant supplies. Only 10 percent of the country receives adequate rainfall for agriculture. Water scarcity is a national concern and creates pressure to construct large infrastructural projects to transport water to drier parts of the country. A water tunnel has recently finished construction linking the Dez River and the central desert province Qom. Called the largest water tunnel in the Middle East, the project took five years to complete. At 27.3 miles long, the tunnel will move 120 million cubic meters of water each year.
Much of Iran's water is stored underground. Iranians centuries ago developed man-made underground water channels called qanats which are used more than wells to access those supplies. A qanat taps water that has seeped into the ground and channels it via straight tunnels to the land surface. Flood control and management of water resources have made dams popular projects in Iran since the Islamic Revolution in 1979. The 42 dams are used for irrigation, flood management, hydropower, and in some cases drinking water. In numerous localities, there may be no precipitation until sudden storms, accompanied by heavy rains, dump almost the entire year's rainfall in a few days. Often causing floods and local damage, the runoffs are so rapid that they cannot be used for agricultural purposes. The dangerous relationship with water supplies in Iran poses many challenges for the future. Sudden innundation following drought make agriculture and safe water more unreliable and difficult.