Noyyal
The Noyyal rises from the Vellingiri hills in the Western Ghats and covers a total area of 3,500 km² (1351 mi²), the basin is 180 km (112 mi) long and 25 km (16 mi) wide. Cultivated land in the basin amounts to 1,800 km² (695 mi²) and the population density of the basin is 120 people per km² (311/mi²) in the countryside, and 1000 people per km² (2590/mi²) in the cities. During Northeast monsoon this 173 km (107 mi) long tributary of the Cauvery, can fill up 32 eries (tanks).