river rising in the eastern Turkistan Range and flowing 545 miles (877 km) west through Tajikistan and southeastern Uzbekistan to disappear in the desert north of Chärjew near the Amu Darya, of which it was at one time a tributary. The river supplies water to a vast irrigation district, including the Qarshi Steppe to the south (which receives water from the Zeravshan by a canal). The Zeravshan Valley is densely populated, particularly within Uzbekistan.