ABSTRACT
Rivers originating in the Tien Shan and Pamir mountains do not reach the ocean but belong to closed inland watersheds, common in arid climates where evapotranspiration exceeds precipitation. The largest of these catchments are the basins of the Aral Sea (1.2 million square kilometers; 463,000 square miles), Tarim River (530,000 square kilometers; 205,000 square miles), and Ili-Balkhash (413,000 square kilometers; 160,000 square miles). The Aral has two inflows that do not reach the lake every year due to intense water consumption. The Amu Darya River (465,000 square kilometers; 180,000 square miles) drains the largest part of the Pamirs and is the main tributary of the Aral; about 68 percent of total runoff in the Aral Sea Basin is formed in its catchment (United Nations Environment Programme, 2006). The remaining 32 percent is provided by the Syr Darya River (777,000 square kilometers; 300,000 square miles) that originates in the Central Tien Shan. The Tarim River is formed at the confluence of three rivers from Inner and Central Tien Shan, Eastern Pamir, and Kunlun Shan. The Ili River, which flows into Lake Balkhash, drains the northeastern part of the Tien Shan.
