Rising in the Varushanad Hills of western Tamil
Nadu, Vaigai River initially flows northeast through the Kambam and
Varushanad valleys. In its central it flows eastward into the Vaigai
reservoir at Narasingapuram. Near Sholavandan it bends to the southeast,
passing Madurai town on its course to its mouth on Palk Strait, which
separates the southeast coast of India from Sri Lanka.
The Vaigai River rarely floods and its chief tributaries are the Siruliar, Theniar, Varaha Nadi, and Mangalar. It flows through a length of 150 miles (240-km), generally southeast.
The Vaigai River basin (indicating agricultural areas) in Tamil Nadu has an area of 7,000-sq-km where current (and projected) supplies of surface and groundwater are not deemed sufficient to meet current (and projected) needs. In 1985 a tunnel diverted waters from the Periyar River in Kerala under a contentious 999-year agreement between Kerala and Tamil Nadu.
The western and northwestern parts of the basin receive heavy rainfall during the monsoons, with an average rainfall of 850mm over the basin. The land use is predominantly agricultural (consuming about 3,800 MCM of water annually), with paddy as the primary crop. There are significant water-sharing conflicts within agriculture itself, with the various agricultural areas competing for scarce water supplies.