Geoenvironmental Assessment of Kechery–Puzhakkal, a Tropical Small Catchment River Basin, India, Using a Multi‐Indexing Approach With Special Reference to Pollution and Sustainability

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Freshwater resources in the world are on the verge of severe deterioration and crisis. In developing countries like India, water‐quality studies of rivers linked to wetland systems are crucial for improving public health, economic growth, and environmental sustainability. This study evaluates the surface water quality of the Kechery–Puzhakkal river basin, a tropical riverine system in the Southern Western Ghats, India, that drains the international Ramsar Kole Land and is a major source of drinking and irrigation water for the people. Except for turbidity and bacteriological contamination (Coliforms and E. coli), all other physicochemical parameters such as pH, EC, TDS, Salinity, SiO 2 , NO 3 − , PO 4 2− , Cl − , SO 4 2− , HCO 3 2− , TF, TH, Na + , Mg 2+ ,K + , Ca 2 meet WHO and BIS standards. Based on the WQI (Water Quality Index), 70% of the water falls under the poor category due to exceeded turbidity. Irrigation suitability indices, mainly MH (magnesium Hazard, which ranges from 72.89 to 86.96), reveal cationic imbalances that suggest potential risks to long‐term crop productivity. The higher CO 2 partial pressure values indicate CO 2 outgassing from the Kole Wetlands. Although the calculated Hazard Index (HI) and Carcinogenic Risk (CR) are within acceptable thresholds, the Heavy Metal Pollution Index (HPI, ranging from 3.93 (S 13) to 259.66 (S 14) indicates critical anthropogenic trace element enrichment, with several sites exceeding safety guidelines for Hg, Al, Mn, Ni, and Fe, driven by both anthropogenic and geogenic factors. By integrating WQI, HPI, Health risk, and Carbon dynamics, this study provides the precise baseline empirical framework required to establish the models for River Health Assessment (RHA) that safeguard socio‐environmental resilience and are thereby linked to United Nations Sustainable Development Goals (SDGs 2, 3, 6, 13, and 15). The findings necessitate urgent, integrated management strategies to mitigate microbial contamination, reduce carbon outgassing and metal enrichment, and ensure the long‐term socio‐environmental resilience of a tropical, sensitive riverine‐wetland system to achieve environmental sustainability.