The Noyyal River is a small river in Western Tamil Nadu, and a tributary of Kaveri River. It rises from the Vellingiri hills in the Western Ghats in Tamil Nadu, very close to Kerala border, and flows through many villages and the cities of Coimbatore, and Tirupur finally draining into the Kaveri River at Noyyal, a village in Karur district named after the river itself. The river's basin is long and wide and covers a total area of . Cultivated land in the basin amounts to while the population density is 120 people per km² (311/mi²) in the countryside, and 1000 people per km² (2590/mi²) in the cities. The area is known for its scanty rainfall and the development of the Noyyal River Tanks System to hold any overflow from the rains plus the water of the Northeast and Southwest monsoon season was ecologically important. The long tributary of the Kaveri River filled 32 tanks. These interconnecting tanks held the water flowing from the Noyyal.