Modeling future hydrology in the Tungabhadra Basin: interactions between land use dynamics and climate change
摘要
Changes in climate and Land Use Land Cover (LULC) would have a major effect on the hydrological process, which in succession would affect the water availability and flow patterns of the catchment. This study explores potential future changes in LULC and the coupled impact of climate and LULC change on the hydrology of a Tungabhadra River Basin (TRB). The concept of Symmetric Uncertainty (SU) is used to select the most suitable Global Climate Models (GCMs) in TRB for future climate change analysis. The coupled impact of climate and LULC change assessment on Water Balance Components (WBC) is carried out using the Soil and Water Assessment Tool (SWAT). As per the coefficient of determination (R2 = 0.75) and Nash Sutcliffe efficiency (NSE = 0.75), the model showed good performance during the calibration and validation period (R2 = 0.70, NSE = 0.72). Two “Shared Socio-economic pathways (SSPs)” scenarios, SSP1-2.6 and SSP5-8.5, are used to model potential future climate change, in addition to the proposed future LULC based on SSP-RCP scenarios for the periods (Near Future: 2026–2040, Mid Future: 2041–2075, and Far Future: 2076–2100). The results entail that under the SSP5-8.5scenario, grassland and barren land will be completely transformed into cropland by 2100. Urbanization and cropland are projected to increase by 0.36% and 10.87% respectively, under the SSP5-8.5 scenario. The ensemble mean temperature is projected to rise by 1.56 °C and 4.65 °C under SSP1-2.6 and SSP5-8.5 scenarios, respectively. The maximum Multi Model Ensemble (MME) mean of annual precipitation is projected to increase by 21% and 54.25% under SSP1-2.6 and SSP5-8.5 scenarios, respectively. The annual surface runoff of the ensemble mean is projected to increase by 72.7% to 178.8%. The annual ensemble mean of future soil moisture is projected to increase by 7% in the far future under the SSP5-8.5 scenario. The water balance of the study suggests a significant increase in precipitation, surface runoff, water yield, and soil moisture, accompanied by a decrease in evapotranspiration across the basin.
Research highlightsThe coupled influence of climate and land use land cover changes on water balance components are evaluated in the Tungabhadra River Basin. The symmetric uncertainty technique was used to screen top 50% best performing CMIP6 GCMs. High values of R2 and NSE at Mantralayam guage location suggested that the SWAT model is performing well. The uncertainty bounds of simulated water balance components were calculated to understand the behaviour of selected GCMs along the future LULC.