Validation of satellite snow products, application in hydrolojical model and investigation of climate change impacts

The extent and variability of snow cover, which is one of the main components of the hydrological cycle, are important parameters for climate change and water resources management studies. Especially, in mountainous basins with high snow potential, temporal and spatial monitoring of snow cover is a significant input variable in terms of modeling of changes in annual flow due to snowmelt. In the first stage of the study, 292 ground stations are utilized to validate IMS daily snow cover products provided by NOAA/NESDIS with 1, 4 and 24 km resolutions in Turkey and its geographical regions taking 2019 water year as reference using categorical statistical methods (POD, FAR, HR). The POD and FAR results for 1, 4, 24 km resolutions are found to be 0.81, 0.80, 0.67 and 0.19, 0.23, 0.28 respectively. In the second stage, SCA curves are obtained for the mountainous headwater basins of Çoruh, Fırat and Aras (E21A054, E21A022, D24A096 and E23A004) having average elevations above 2000 m, using IMS images with 4 km resolution for the 2004–2020 period. SCA is used as one of the main variables of the SRM hydrological model. As a result of the calibration in SRM for these adjacent basins having similar altitudes and climate; model performance results for Karasu, Murat, Kayabaşı and Bayburt are calculated as 0.86, 0.86, 0.88, 0.89 using R2 while Dv is calculated as 1.11%, 0.99%, 0.92%, 2.91% respectively. The margin of error in the results are found low while the R2 value is above 0.86 and the Dv below 3% in the basins In the last stage, climate change studies are carried out in the basins by increasing the temperature between 1–5 ⁰C using SRM during the melting period of 2008-2011 water years. By 4 ⁰C temperature increase in the melting period, SCA decreased between 12–28 days and the center-time date for reaching 50% runoff volume is shifted forward between 9-21 days.