Impacts of climatechange on streamflows:case study of İkizcetepeler dam basin

Climate change occurs for various reasons and affects our planet in many ways. In the AR5, significant changes in meteorological parameters, especially temperature, are forecasted in many regions of the world in the future due to climate change. The forecasted changes may significantly affect river flows, one of the components of hydrological cycle. The aim of the study was to determine to what extent the river flows may be affected by the changes in temperature and precipitation at the İkizcetepeler Dam Basin scale in the future due to climate change. 12 GCM were run under the selected RCP4.5 and RCP8.5 scenarios. Changes in temperature and precipitation were forecasted with each of the GCMs. The changes were reduced to the station scale with the statistical downscaling method to reach the local climate change. GR2M and dynamic water budget parametric rainfall-runoff models were used for the rainfall-runoff relationship. Flow values were derived by using the forecasted temperature and precipitation values under the RCP4.5 and RCP8.5 scenarios of each climate model used in the rainfall-runoff models. In this way, forecasted flows were obtained under two scenarios for the 12 GCMs. Accordingly, temperatures may increase by 0.6 ºC optimistically and 3.3 ºC pessimistically, and precipitation may increase by 23% optimistically, decrease by 41% pessimistically. Flows can decrease 29% optimistically and 52% pessimistically. As a result, serious problems in water supply from dams may be experienced. It is thought that relevant institutions must carry out comprehensive studies to prevent water supply problems in the future.