Keskin, F: Hydrological Modeling in Yuvacik Dam Basin with G

Hydrological modeling is an important issue for determining the hydrological responses of a basin under several weather conditions. In order to model the Yuvacik dam basin, semi-distributed hydrological model studies were carried out with the Mike11 model. The basin with a drainage area of 257.8 km2 is located in 12 km South East of Izmit city in Turkey. The largest peaks of inflow were observed when the storm events occur due to both snowmelt and rain. Therefore, observed flows for the period of 2001-2006 were grouped as daily and hourly storm events according to the event types such as rainfall, snowmelt or mixed events. Rainfall-Runoff Model (NAM) module of the model was used for the simulation of daily snowmelt and rain on snow events and Unit Hydrograph Method (UHM) module was used for the simulation of hourly rainfall events. A new methodology is suggested for the determination of Curve Number (CN) of the sub-basins by using the fractional area and topographic index values combined with hourly model simulations. The resulting CN values were used in the UHM module and the suggested CN approach has been validated with the classical SCS-CN approach with GIS analysis.