The
Noyyal River rises from the Vellingiri hills in the
Western Ghats in
Tamil Nadu, southeastern
India and drains into the
Kaveri River.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.