Concentration of atmospheric greenhouse gas (GHG) has been increasing since the middle of 19th century. The Intergovernmental Panel on Climate Change (IPCC) estimated an increase of global GHG emissions by 25 to 90 % between 2000 and 2030. The global average surface temperature is expected to increase between 1.8 and 4.0 °C and precipitation by 5 to 20 % from 1990 to 2100. Understanding potential hydrologic influences of projected climate change is important for management of water resources. The objective of this study was to assess the impact of climate change on hydrologic processes of Bagmati basin in Nepal using the Soil and Water Assessment Tool (SWAT). A SWAT model was calibrated and validated based on observed flow for 2000–2006. The temperature and precipitation outputs from a global climate model (GCM) were used to drive the calibrated SWAT model in order to study the impacts of climate change. The GCM used in this study is from IPCC Fifth Assessment report. This study demonstrates the temporal differences in hydrologic responses to future climate changes in Bagmati basin, Nepal. The climate projection indicates an increase in annual precipitation in the basin, even though most of the precipitation will be concentrated within the summer monsoon. No appreciable change in the seasonality of rainfall was observed. The increase in precipitation results in an increase in annual water yield in future. Evapotranspiration is modeled to increase during the pre-monsoon dry summer, possibly indicating longer dry periods.
Dahal, V., Shakya, N. M., & Bhattarai, R. (2016). Estimating the Impact of Climate Change on Water Availability in Bagmati Basin, Nepal. Environmental Processes, 3(1). https://doi.org/10.1007/s40710-016-0127-5
