This study investigates the impacts of climate change on water resources through precipitation and discharge analyses in Omerli catchment Istanbul, Turkey. Precipitation and temperature data are obtained from GCM /RCM combinations based on A1B carbon scenario via Europen Union (EU)-ENSEMBLES project. The data is obtained at 25 km resolution on daily time scale for reference period between 1960 and 1990 and future period between 2071 and 2100. The HBV model is used to investigate discharge properties of study area. Because RCM scale is comparatively coarse (25 km) for catchment scale its...