ABSTRACT
ABSTRACT: River discharge is a critical component of the global water cycle and much concern has been raised regarding the changes it has experienced in recent years due to unprecedented changes in temperature and precipitation. The Soil and Water Assessment Tool (SWAT) was used for hydrologic modeling of the Thoothapuzha basin to compute the effect of climate change on stream flow by simulating the model using dynamically downscaled climate data. Future changes in climate were assessed using Global Climate Models (GCMs). A dynamic downscaling model was applied to reduce large-scale atmospheric variables in the GCMs into localized weather variables. Climate data were dynamically down scaled using a Regional Climate Model (RCM) REMO2009 under the driving GCM, The Max Planck Institute for meteorology Earth System Model-Low Resolution (MPTESMLR) for a future period of 2016-2030. An emission scenario of RCP 4.5 was considered. A delta change method of bias correction was applied to the downscaled data in order to get the corrected daily weather data. The model was calibrated and validated and the performances evaluated using historic weather data (1974-2012) in terms of R2, Percentage Bias (PBIAS), Nash-Sutcliffe Efficiency (NSE), and the values obtained were 0.79, 6.829 and 0.78, respectively, which shows that this basin could very well be modeled in SWAT. Stream flow forecasting was carried out with bias corrected RCM data in a calibrated SWAT model. The decreasing trend in the forecasted stream flow for the period of 2016-2030 under RCP 4.5 shows the impact of increased greenhouse gas emissions and the necessity of remedial measures to be taken in order to preserve our water resources for the coming generations.
