FLOW ANALYSIS AT THE PORSUK WATERSHED STREAMS WITH USING

Determining low-flows and their periodicities is very important for sustainably using and managing streams which are one of the most important water resources. In this study, EPA’s DFLOW software has been used for the analysis of the main stream and tributaries of the Porsuk watershed. Flow data sets from selected stream flow gauge stations located in the Porsuk Watershed have been provided by the General Directorate of State Hydraulic Works. Hydrologically and biologically based low-flow criteria like 7Q10, 4B3 have been calculated by using the DFLOW software and how these stream tributaries have been affected over the last 45 years has been determined. Also temporal trends of low-flow periods and 7-day average low flows whose return period is a year (7Q1) have been examined. As a result of this study, increasing trends have been determined on some tributaries used for irrigation purposes and after reservoir construction. Undisturbed tributaries have decreasing low-flow patterns. Increases in temperature and precipitation changes due to climate change should be consideredwith more care. In addition, in the planning and use of water control structures, such as hydroelectrical power plant dams, such studies are important for the more efficient use and sustainabilityof the limited surface water resources in our country.