Noyyal River Traditional Irrigation and Ecology of Coimbatore

The Noyyal river, originating in the Velliangiri Hills south of Coimbatore, flows east through the district and feeds a chain of water tanks — the Krishnampathi, Selvampathi, and Orathupalayam reservoirs — that historically irrigated thousands of acres of paddy and dry crops. The Noyyal's traditional irrigation system, built around a cascade of tanks, represents centuries of community hydraulic engineering. However, from the 1980s, industrial effluent discharge from Coimbatore's textile dyeing and bleaching units severely polluted the Noyyal, turning the river black and destroying the tank irrigation ecology. Remediation efforts including zero liquid discharge mandates for textile units and TNPCB enforcement have partially restored water quality, enabling renewed cultivation in the tank command areas.