Temporal Evaluation Of Snow Depletion Curves Derived By Optical Satellite Data For Simulating Snowmelt Runoff in Turkey

Water is becoming very important issue day by day with descending usable water resources and regarding hydro-electrical powerhouses as energy resources. Predicting runoff for large reservoirs by applying hydrologic model is becoming very important in the aspect of water resources management, especially dam management. The model predictor parameters to predict runoff may be area, perimeter, main channel length, basin relief, circulated ratio, drainage density, and variables are to be mean annual depth of rain, temperature, snow etc. It is seen that many predictor variables should be integrated with Geographic Information Systems (GIS) and Remote Sensing Techniques especially for hydrologic model variable preparation like spatial and temporal distribution of snow covered area (SCA), temperature and precipitation. Satellite products have the potential for obtaining those kinds of data in near real time. In this study, the changes of Snow Depletion Curves (SDC) are observed over the years and runoff is simulated for Upper Euphrates Basin (10195 km2) which is a sub basin of Euphrates Basin. Main objective of this study is deriving the spatially and temporally distributed SCA percentages from different optical satellites which are required as one of the main input variables of the hydrological model used in the application. SCA percentages and SDC are obtained for snowmelt years 2004-2007 by using high temporal resolution optical remote sensing data: Terra Moderate Resolution Imaging Spectroradiometer (MODIS). Terra MODIS snow cover map product (MOD10A1) is in gridded sinusoidal projection with coverage of approximately 1200 km by 1200 km containing scientific data set of snow cover. Daily MOD10A1 data are processed for the years between 2004 and 2007 and after processes they are used to create SDC of the area. In addition, MOD10A1 data are compared with SEVIRI images which are produced by Meteosat Second Generation (MSG) satellites (from Meteosat-8 onwards) for the year 2007. The results of previous studies show that SDC are highly effective on the accuracy of the hydrological model simulation as an important model input. Snowmelt Runoff Model (SRM) was applied to the basin for the snowmelt years 2004-2007. SRM was built up on the well known degree day approach. SRM became to use detecting SCA when the data derived from satellite products could be joined with degree-day method. By this study, simulation and forecasting of inflow can be produced well for Upper Euphrates Basin in Turkey to have optimal water resources management.