INTEGRATED MODELLING OF CLIMATE AND LAND USE CHANGE IMPACTS ON STREAMFLOW IN THE PENNAIYAR RIVER BASIN, TAMIL NADU, INDIA

This study provided a comprehensive modelling assessment of future streamflow responses in the Pennaiyar river basin under a changing climate and evolving land use. CMIP6 Global Climate Models (GCMs) were used to project mid-century and late-century climate scenarios (SSP245/SSP585), revealing substantial increases in rainfall (up to 88% by the 2080s under SSP585). High-resolution SRTM DEM, NRSC LULC, and TNAU soil maps formed the spatial foundation, while IMD gridded weather data (1980-2021) supported robust SWAT+ model setup. Model calibration and validation were done using observed discharge data from Gummanur and Vazhavachanur. Future land use for 2030 and 2050 was projected with the MOLUSE plugin (QGIS), trained using LULC maps from 2017, 2021, and validated with 2024 data. Future projections indicate that built-up areas will subsequently increase by 2100, while Drylands, Forest and waterbodies are expected to show a reduction, highlighting growing ecological vulnerability. Future simulations indicate that future land use intensification, such as urbanisation and agricultural expansion, will act synergistically with projected increases in precipitation to amplify streamflow peaks and overall hydrological variability, especially in rapidly changing sub-basins. Selected GCMs (EC-Earth3, MPI-ESM1-2-LR, MPI-ESM1-2-HR) provided reliable benchmarks for climate-driven analyses and simulated annual streamflow changes at Gummanur, ranging from −3.60% to 136.52%. The findings underscore the necessity for integrative land and water management strategies as higher flows and sedimentation risks are projected, challenging traditional flood and water security paradigms. This research exemplifies the value of integrated QGIS-SWAT-CMIP6 frameworks for generating actionable, scenario-based insights for river basin management in a changing environment. Keywords Climate change; Land use change; Streamflow; SWAT+; Pennaiyar River Basin 30/12/2025, 11:57 AGU 2025-iPosterSessions-an aMuze! Interactive system https://agu25.ipostersessions.com/Default.aspx?s=46-CD