On the Changing Snow Contribution to Runoff Across Turkiye

Contribution of snowfall to runoff is especially important in snow-dominated regions where hydrological processes are mostly influenced by snowmelt. In this study, the contribution of snowfall to runoff in Turkey for the last 21 years was examined in the light of the observed data and hydrological model results globally provided by NASA. The snow dominant regions of Turkey for the last twenty-one years were revealed, and the ratio of the spatially averaged maximum snow water equivalent to runoff (Rsr) values, an indicator showing snowmelt contribution to runoff, were calculated for two separate periods (2000-2010, 2012-2022). These Rsr values were compared across Turkey to see if they are decreasing in snow-dominated regions. According to the results of the analysis, it was concluded that Rsr values are decreasing in all snow-dominated regions except Aras and Çoruh basins. Rsr values decreased by up to 50 percent in the last 11-year period in regions with high snowfall, such as the upper Euphrates basin.