Analyzing the Effects of Climate Change for the Water Tower of Mesopotamia, Turkey

Climate change drastically threatens water supply systems and ecosystems especially in water towers that maintain water demands downstream. Analyzing future implications in the timing and amount of snowmelt runoff is a crucial mission to develop required adaptation strategies against climate change effects. This study aims to estimate future snowmelt runoff and snow extent in terms of various metrics i.e. timing and the quantity for the Upper Euphrates Basin (41,109 km²). As the most upstream basin of the water tower Mesopotamia, the basin is located in the Eastern mountainous part of Turkey. The future characterization of snowmelt runoff and snow cover area is investigated taking the regional climate model projections into account through hydrological model applications. Furthermore, changes in snow line elevation and lag time in the snowmelt processes are examined. The basin is divided into two major sub-basins as Karasu Basin and Murat Basin. The conceptual hydrological models, HBV and HEC-HMS, have been utilized to establish a rainfall-runoff relationship. The models are calibrated and validated with observed daily total precipitation and average temperature data for the 1980-2010 period. Future projections are employed for 2025-2100 periods using EU-CORDEX data with various global circulation models.  CNRM-CM5 and HadGEM2-ES data sets and RCP 4.5 and RCP 8.5 emission scenarios are used for future projections. Climate data sets are subjected to local bias corrections. The preliminary results indicate decreases in snow cover extent, snow duration, and snowmelt runoff. The overall assessment will help us to understand how these changes will affect operations of water resources systems (downstream reservoirs) in terms of flood control, energy production, irrigation, and water supply, etc.