Calibrated Hydrodynamic Model for Sazlidere Watershed in Istanbul and Investigation of Urbanization Effects

Abstract

Protecting and improving water resources play an important role for meeting the future demand for drinking water and preventing flood events. Increasing population tends to cause a shift from rural to urban areas, which results in the alteration of concentration time, water quantity, and flow rate. Because of these changes, specific solutions need to be investigated to prevent flood and overflow. For this purpose, calibrated hydrodynamic models should be developed to understand the hydrodynamic behavior of the catchment. Sazlidere Watershed, which provides an average of 55 million m(3) of water per year, is one of the most important watersheds of Istanbul, Turkey. There is a tremendous population increase in the area, and moderate flood events are frequently observed. Therefore, in this study, a calibrated hydrodynamic model for Sazlidere Watershed was developed by using the Environmental Protection Agency Storm Water Management Model (EPA SWMM). The model is calibrated by using the rainfall and flow data obtained from the stations we set in the area. The most sensitive parameters of the hydrodynamic model are determined to be Manning's roughness coefficient for both channels and subcatchments followed by the infiltration parameters, i.e., hydraulic conductivity and the initial soil-moisture condition. The flow developed on the watershed was simulated both under typical rainfall events and under extreme cases, namely, high urbanization and storm events with a high return period. It is observed that even under typical storms, floods developed on the watershed; and finally, several flood control options are suggested. DOI: 10.1061/(ASCE)HE.1943-5584.0000600. (C) 2013 American Society of Civil Engineers.