ABSTRACT
Water limited environments covered about half of the global land area. The likelihood impacts of climate change on rainfall patterns, in time and space will influence water availability of already stressed resources in arid and semi-arid regions. The Shatt al-Arab River water system, in terms of both water quantity and quality, is under escalating pressure. The demands for freshwater have increased rapidly mainly due to growing population. The Karun River is among the most important watercourses of Iran, with the largest discharge and being the only navigable waterway. It has total length of about 867 km. Similar to the Karkheh River it originates in the Zagros Mountains of western Iran. Mesopotamian Marshlands is an extensive system of ecologically important wetlands formed at the confluence of the Tigris, Euphrates, and Karkheh Rivers. The Tigris is characterized by high seasonal flow variation, as well as spatially along the river.
