Impacts of climate change and past land use change on the water resources in Pune, India

Global change affects local and regional water resources and is therefore of major concern in current hydrologic research. Especially in regions with scarce water resources, high climate sensitivity, and/or dynamic socio-economic development, research on developing suitable adaptation and mitigation strategies is needed. In this study, we used the well-established and widely-used hydrologic model SWAT (Soil and Water Assessment Tool) to study the impact of climate change and past land use change on water resources. Our study aims at analyzing the impact of global change on the water balance components in the meso-scale Mula and Mutha Rivers catchment upstream of the city of Pune, India. To analyze climate change impacts regional climate model data based on IPCC emission scenario A1B was used by employing a downscaling method that rearranges historically measured data. The hydrologic model was run with the rearranged scenario weather data and model results were analyzed for the scenario period from 2020 to 2099. Past land use changes between 1989 and 2009 were identified with the help of three multi-temporal land use classifications, which were based on multi-spectral satellite data. Two model runs were performed and compared using the land use classifications of 1989 and 2009. Climate change leads to a slight increase of evapotranspiration. Particularly in the rainy season and in the first months of the dry season higher evapotranspiration can be observed. Towards the end of the scenario period low water storages in the major dams of the catchment at the beginning of the dry season indicate severe impacts on water availability. The impacts of land use changes balance out on the catchment scale and are hence more obvious at the sub-basin scale, where e.g., urbanization results in increased runoff and decreased evapotranspiration.