Comparative Rainfall-Runoff analysis of the Upper Murat River Basin in Turkey in context of Hydro-Meteorological variables

Abstract

This study was carried out to examine rainfall-runoff relationship in the Upper Murat River Basin in Turkey. Murat River Basin, which forms the study area, includes Tunceli, Muş regions and Upper Murat within the Upper Euphrates in Eastern Anatolia, forms the southern branch of the upper basin of the Euphrates River and corresponds to the Middle Euphrates section. Previous studies were carried out for entire Murat River Basin. The novelty of this study is that it focuses on Upper Murat Basin, and gives a different perspective to rainfall-runoff relationship by considering precipitation elasticity in addition to the existing studies. To figure out the basin characteristics, geographic information system based on digital elevation model was used. Annual mean flow records of four flow observation stations (1969–2019), annual total precipitation records and mean temperature records of seventeen meteorological observation stations (1964–2019) were used in the analyses. Rainfall-runoff and temperature-runoff relationship are shown on the graph. Trend analyses were performed by linear regression and Mann-Kendall trend test. Flow parameters were determined for all sub-basins and entire Upper Murat River Basin. The rational method and Thiessen polygons were used to determine flow coefficients. Besides, precipitation elasticities were determined by using elasticity equation to determine the sensitivity of streamflow to climate changes. Determining trends in precipitation, streamflow and temperature values, determination of flow coefficients and precipitation elasticities enabled a comparative rainfall-runoff analysis of the basin. Although there is no exact correlation between the results compared, a new perspective on the basin is presented. Runoff coefficients of sub-basins change between 0.42 and 0.72. Runoff coefficient for entire upper basin is 0.49. In precipitation elasticities, the values calculated for relevant sub-basins for last forty years change between 0.24 and 0.56. Precipitation elasticity for entire upper basin is 0.66. According to the results of the trend analysis, an upward trend was detected in precipitation at 2 stations, a downward trend at 3 stations, an upward trend was detected at 9 stations in temperatures, and a downward trend at 1 station in flows.