Multi-criteria decision analysis-based irrigation water quality index for the Noyyal river basin, Tamil Nadu

Abstract

The study aims to develop an irrigation water quality index (IWQI) for the semi-arid region of the Noyyal river basin. The groundwater samples were collected from the basin, and its physico-chemical and trace element characteristics were analysed in the laboratory. The samples were classified depending on their hazardous nature to crops through a Multi-Criteria Decision Analysis (MCDA) with the aid of the Geographic Information System (GIS). The result indicates that the lower basin is affected by excessive electrical conductivity, total dissolved salts, hardness, cadmium, chromium, nickel, and manganese concentrations. The result indicates that textile industries are vital in polluting the basin’s groundwater resources. The chloride and nitrate ions are present above the crop tolerable limits in most samples. The spatial distribution of IWQI unveils that the groundwater is highly polluted in the floodplains of the basin and not suitable for irrigation purposes. The basin needs immediate water quality management actions to restore the aquifers and reclaim the productivity of agricultural lands. The index developed based on the MCDA approach would help planners to prioritise location-specific actions to implement mitigation measures.