PAMUKKALE UNIVERSITY JOURNAL OF ENGINEERING SCIENCES-PAMUKKALE UNIVERSITESI MUHENDISLIK BILIMLERI DERGISI, cilt.31, sa.1, ss.141-146, 2025 (ESCI, TRDizin)
The development of predictive tools that enable synchronization of rain and snowmelt times is desired for efficient water supply management in the snowmelt-dominant basins. This study aims to separate the streamflow hydrograph into its components, such as base flow, rainwater, and snowmelt, to be used for the snowmelt simulation studies of the Upper Karasu Basin, Erzurum, Turkey. The region covers an area of 242 km2, where snow cover prevails for about 150 days in a year. The surface water flow component of the total runoff has been determined by using the chloride contents of surface water and groundwater end-members. The volumes of the rain and snowmelt water components in the surface water have been identified from the oxygen-18 contents of the rain, accumulated snow, and surface water. The hydrograph separation calculations have been performed daily by using the end-member contents of the total runoff during the snowmelt period between March 6, 2008, and June 15, 2008. The results show that the total runoff in the river during this period was composed of 9% groundwater, 73% snowmelt water, and 18% rain. The stream water's oxygen-18 isotope content indicates an effective mixing of snowmelt water and rainwater components during the surface flow process. This study also suggests that isotopic exchange is an important process that determines the snowmelt water's isotope content.