Integrating hydrological modelling and geospatial analysis for sustainable water conservation in the manali watershed, India

ABSTRACT Effective water resource management is critical in humid tropical regions like Kerala, India, where intense monsoonal rainfall often leads to high runoff and seasonal water scarcity. This study developed a decision-support framework integrating the Soil and Water Assessment Tool (SWAT) with GIS-based multi-criteria evaluation (MCE) for sustainable water conservation planning in the 140.94 km2 Manali watershed. The SWAT model, calibrated and validated with satisfactory performance (R2 = 0.785, NSE = 0.785), indicated that nearly 78% of annual rainfall contributes to streamflow, suggesting significant scope for water retention and groundwater recharge. Monthly water balance analysis revealed pronounced deficits during November–April, coinciding with peak agricultural demand. A weighted overlay analysis using six thematic layers, slope, land use/land cover, soil permeability, drainage density, stream order, and surface runoff, was conducted following IMSD guidelines. The results classified 15% of the watershed as highly suitable and 84.8% as moderately suitable for conservation interventions. Accordingly, 32 farm ponds, 7 percolation ponds, and 4 check dams were strategically proposed. The integrated approach offers a robust, replicable framework for optimising conservation measures, improving water availability, and enhancing climate resilience in monsoon-dominated and data-scarce watersheds.