Turkey is a country located between Europe and Asia and has a surface area of 779 452 km(2) with a total population of about 68 million according to 1998 census. Annual rainfall in Turkey varies between 220 mm to 2500 mm with an average of 642.5 mm and this corresponds to an average annual rainfall of 501 km(3). Approximately 186 km(3) of this water flows in rivers as surface water. Since the Euphrates and Tigris rivers form 28.5 % of all the water resources of the country, they are the most important water resources of the eastern and southeastern part of the Turkey. After they originate in Turkey, they cross the border to Syria and Iraq and there has been always a water issue to be discussed among the neighbors. It is necessary to find an equitable and satisfactory means for allocating water of Euphrates and Tigris river system to the riparian states. At present, among the riparian states Iraq has the highest, and the Syria has the lowest amount of water consumption per capita but compared to water rich countries all three states use rather little amount of water.