Isfahan an Sirjan basin

This basin is composed of smaller basins such as Abarkoh desert, Gavkhoni swamp and Sirjan desert.  Its area is 90,700 km2 and Zaianderod is the largest river. Its water is supplied from snow melting in Western. It's supplied from melting snow in western mountains of Isfahan. Rivers have the most water- supply at spring. Construction of Kohrang tunnel and transferring Kohrang river water to Zaiandehrod river has regulated it.

Lack of water in stouten part of this basin has changed the rivers to arroyos.