How has irrigation changed the drainage network of the Tien Shan?

Human intervention, particularly through extensive irrigation schemes, has severely modified the drainage network of the Tien Shan at lower elevations.1

These irrigation projects in the foothill valleys have significantly curtailed the flow of water that historically reached the Aral Sea and the Tarim Basin. Consequently, the flow into many traditional watercourses has become negligible. This diversion of water for agricultural and urban use is especially prominent regarding the Ili River and the Kaidu River in the eastern Tien Shan. Furthermore, peripheral water diversion has contributed to the lowering of Lake Ysyk.1

Beyond irrigation, the drainage network has been further altered by the construction of hydroelectric plants, such as the Toktogul Dam on the Naryn River, and smaller facilities designed to harness energy from western rivers like the Aksu River.1