Assessing the Impacts of Land Use, Land Cover, and Climate Change on the Hydrological Regime of a Humid Tropical Basin

Climate change and land use land cover (LULC) change are two major factors influencing river basin hydrology. This study explored these drivers' isolated and combined impacts on the ecologically relevant flow in the Achencoil basin, Kerala, India. The LULC classification in the study is carried out with the Random Forest (RF) algorithm in the Google Earth Engine (GEE) platform, and Land Change Modeler (LCM) is incorporated for change detection and projection. The future climate data from the National Aeronautics and Space Administration Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) is used for climate change impact assessment. The Soil and Water Assessment Tool (SWAT) is employed to simulate streamflow under LULC and climate change scenarios. The historical and projected future LULC change in the basin revealed an increase in the built-up and barren land, with a significant decrease in agricultural and forest areas. The results show that the projected future precipitation will decrease under the RCP 4.5 and increase under the RCP 8.5 scenario. The projected average maximum and minimum temperature are expected to increase under both scenarios in the basin. The LULC 2050 scenario shows the most significant rise in average annual streamflow, at 7.5%. Whereas in the climate change scenarios, the average annual flow decreases under RCP 4.5 and increases under RCP 8.5. The combined impacts of climate change and LULC change are relatively higher than the isolated effects of these drivers in the basin. The study outcomes are expected to help policymakers consider the effect of climate change and LULC change on the river's hydrology so as to implement the management activities that account for the riverine ecosystem. Changes in land use land cover and meteorological parameters are important environmental issues that must be pointed out. These changes will affect the river flow and eventually affect the river ecosystem. The current research investigates the combined effects of land use land cover and climate change in the flow of the Achencoil basin in India. This study area is one of the most frequently flooded in the state. As a result, the projected climate and land use land cover provide an idea of future streamflow in the basin. This research enables a better understanding of the response of streamflow components to climate variability and land use land cover changes in the Achencoil basin, which might help policymakers develop strategies for regional water resource management. Implementing these policies and management strategies will necessitate collaboration and coordination across various levels of government, private sector, and local communities in order to mitigate the risk and support a sustainable riverine ecosystem.