river in Tamil Nadu (Tamil Nādu) state, southern India, flowing 150 miles (240 km) generally southeast. Rising in the Varushanad Hills of western Tamil Nadu, it initially flows northeast through the Kambam and Varushanad valleys. In its central reaches the Vaigai flows eastward into the Vaigai reservoir at Narasingapuram. Near Sholavandan it bends to the southeast, passing Madurai on its course to its mouth on Palk Strait, which separates the southeastern coast of India from Sri Lanka. The Vaigai River rarely floods; its chief tributaries are the Siruliar, Theniar, Varaha Nadi, and Mangalar.