INTERNATIONAL SOIL AND WATER ASSESSMENT TOOL CONFERENCE - SWAT 2019, Viyana, Avusturya, 17 - 19 July 2019, ss.121
Subjects like increasing energy demand and climate change, attract the attention especially for mountainous catchments where snowmelt is dominant. In mountainous eastern part of Turkey, snowmelt runoff constitutes approximately 2/3 in volume of the total yearly runoff during spring and early summer months. Hence, monitoring the snow potential in the accumulation season and modeling during the depletion period is of great importance for optimum reservoir planning and management especially in the transboundary Euphrates Basin. In this study, two headwater basins of the Euphrates River, ranging in elevation between 1500-3500 m are selected as the application area. The necessary digital data are analyzed using ArcSWAT in order to formulate the HRUs. Besides streamflow, both in-situ snow measurements and remotely sensed data of snow covered area (SCA) using daily cloud-free MODIS images are utilized to incorporate in SWAT. Although point measurements show a varying correspondence to the model elevation bands, areal SCA have a noteworthy agreement with the SWAT output. Daily (model) SWE-SCA (satellite) relations are derived for each snow season with a high consistency. SWAT-CUP is employed for a more detailed hydrologic modeling application. 13 years of hydro-meteorological data is divided into 3 years of warm-up (1999-2001), 6 years of calibration (2002-2007) and 4 years of validation (2008-2011). According to the results, model discharge performance using Nash-Sutcliffe efficiencies for calibration are 0.66-0.76 daily and 0.75-0.87 monthly, and for validation 0.73-0.82 daily and 0.82-0.89 monthly values are achieved. A sensitivity and uncertainty study is also undertaken for model parameters. Future studies will concentrate on climate change scenarios and their effects on snow and runoff variations till the end of the century.