Assessment of Land Use and Land Cover (LULC) Changes in the Hydrological Parameters in Teesta Catchment, Bangladesh

Abstract

The Soil and Water Assessment Tool (SWAT) is a comprehensive, publicly available simulation model, which is used to assess the effect of land use and land cover changes on water, soil erosion and chemical yields of agriculture in catchments which is developed by the USDA Agricultural Research Service. SWAT models soil erosion and sediment transport, providing insights into how land management practices influence soil loss and sedimentation in water bodies. The Teesta basin has a significant soil erosion issue due to deforestation, excessive grazing and agricultural expansion; specifically, the cultivation of unproductive peripheral areas and steep slope terrains. The SWAT model is used in this study to quantify streamflow and evaluate the resulting sediment yields. In this context, SWAT is employed to simulate runoff and estimate sedimentation originating from the Teesta watershed due to changes in land use. The SWAT model is calibrated and approved for river flow for extended validation periods. The Consecutive Vulnerability Fitting (SUFI2) worldwide affectability strategy inside SWAT Calibration and Vulnerability Procedures (SWAT-CUP) was utilized to distinguish the foremost touchy streamflow parameters. The model satisfactorily simulated stream release from the watershed. The model execution was decided with distinctive measurable strategies. The study revealed that both streamflow and average overland sediment yield in the watershed have risen over the observation period. Higher runoff rates may lead to more frequent and intense flooding, reduced water quality, and lower crop yields. Consequently, it is essential to implement thorough water management strategies to mitigate surface runoff in the catchment area. This marks the first application of the SWAT model to the Teesta catchment to measure the sediment yield. Land use and land cover changes affect sediment yield; around 18 % increase in residential land leads to increase around 1% sediment yield, when Agricultural Land increased around 30% and Evergreen Forest decreased around 25% the sediment yield is decreased 1.73% and increase Deciduous Forest decreased the sediment yield. These findings suggest that, with minimized uncertainties, a properly calibrated SWAT model can produce reliable hydrologic simulations concerning land use, which is beneficial for water and environmental resource managers, as well as policy makers and decision makers.