A conceptual framework to disentangle land use and climate change impacts on water balance components and sediment yield

Individual and combined impacts of land use and climate change on water resources in a river basin cannot be easily categorized due to feedback effects. These impacts should be assessed separately to determine the dominant role of land use and/or climate change affecting planning and management of natural resources. In this study, a conceptual framework is proposed to disentangle individual as well as combined impacts of land use and climate changes on hydrology of the Betwa River basin in central India. Land use maps of the years 2013 (classified) and 2040 (simulated) were used as inputs in the Soil and Water Assessment Tool (SWAT) model for the land use change impact study. Downscaled and bias-corrected CMIP5 GCM data was firstly evaluated using observed station data, and then used in the SWAT model for simulation of basin hydrology over five periods of time, i.e., baseline (1986-2005), horizon 2039 (2020-2039), horizon 2059 (2040-2059), horizon 2079 (2060-2079), and horizon 2099 (2080-2099). The study reveals that the impact of climate change dominates effects on water resources in the future, especially due to increased precipitation. Changes in dense forest, agriculture and waterbody induce positive responses; nevertheless, changes in degraded forest and barren land induce negative responses to the changes in hydrology of the Betwa basin. The proposed conceptual framework can disentangle individual and combined impacts of land use change and climate change on basin hydrology. Thus, it can be utilized as an important tool for sustainable river basin management.