Bhavani river originates from Nilgiri hills of the Western Ghats, enters the Silent Valley National Park in Kerala and flows back towards Tamil Nadu. The Bhavani is a long perennial river fed mostly by the southwest monsoon and supplemented by the northeast monsoon. Its watershed drains an area of spread over Tamil Nadu (87%), Kerala (9%) and Karnataka (4%). The main river courses majorly through Coimbatore district and Erode district in Tamil Nadu. About 90 per cent of the river's water is used for agriculture irrigation.