Evaluating climate change impacts using swat in a mountainous region of Turkey

Subjects like runoff prediction and climate change attracts attention at snow fed mountainous basins. This is also an important topic in Turkey which bares the headwaters of the Euphrates Basin having a large surface area of transboundary waters. In this study, hydrological modeling is conducted at the two mountainous headwater basins of Euphrates River exploiting ArcSWAT. During the modeling stage, hydro-meteorological data, snow observations and MODIS snow cover satellite products are utilized. Firstly, SWAT parameters are calibrated using satellite imagery and then validated by ground snow measurements. Then, the hydrological model is adjusted according to runoff values with the help of SWAT-CUP whereby over 0.7 daily and 0.8 monthly Nash-Sutcliffe Efficiency performance results are achieved, respectively. Once the model is made ready, it is run daily for two periods (2041-2070 ve 2071-2099) applying two different climate scenarios (RCP 4.5 ve RCP 8.5) in order to evaluate the impacts of climate change on snow and runoff. The results indicate that for both basins, snow water equivalent (SWE) decreases by 30-39% and the snow season narrows in the order of 37-43 days. In terms of runoff, streamflow is not as dramatically affected as snow which shows a reduction of 3-4%, but center time volume is push earlier by 9-11 days until the end of the century.