Modeling of rainflow-runoff relationship with HEC-HMS in Berta river basin

In this study; The rainfall-runoff relationship of the basin was modeled by using the data of the Bağlık, Köprükaya and Dutlu Stream Observation Stations, where flow measurements were taken in the Berta Stream Basin located in the Eastern Black Sea Basin, and the precipitation data of the Hydrometeorology and Remote Sensing Center (CHRS Data Portal) of the University of California. For this, a digital elevation model with a resolution of 12.5x12.5 m was created with the Alaska Satellite Facility (ASF)-ALOS PALSAR using 1/25000 scale topographic maps of the Berta Stream Basin and the basin was modeled by taking the Bağlık exit point. The drainage network of the basin was created by using the digital elevation model and flow directions of the basin. The rainfall-runoff relationship of the Berta Basin was investigated using the HEC-HMS hydrological model. The effective precipitation in the basin was calculated by the SCS curve number method, which takes into account the soil type and land use of the basin. The SCS unit hydrograph method was chosen for effective precipitation-to-flow conversion. In the cluster analysis, the number of curves, lag time and precipitation data for each sub-basin are used as variables. Conversion method parameters such as time of concentration and time of lag were calculated by considering some approaches used in the literature. Statistical measures of Nash Sutcliffe Efficiency (NSE) and Coefficient of Determination (R2) were used to determine model performance. In this study, NSE was calculated as 0.81, R2 as 0.88 at the basin outlet point. As a result, when the statistical criteria NSE and R2 values were examined, successful results were obtained and it was concluded that the SCS Curve Number and SCS Unit hydrograph methods represented the basin well. A good agreement was obtained between the observation and HEC-HMS hydrological model values. The study performed and the results achieved serve as examples in applied hydrology and have a prediction value for Berta Basin.