A hydrological model for Ayamama watershed in Istanbul, Turkey, using HEC-HMS

摘要

In order to overcome the flood risk in urbanized regions with high population density, generation of hydrologicalmodels is essential. The aim of this study is to generate a hydrological model for the Ayamama watershed byusing HEC-HMS, simulate the flood event that occurred in Ayamama River in Istanbul, Turkey, on September9, 2009 and evaluate the modeling performance of the HEC-HMS. For this purpose, the basin area is dividedinto the subbasins; the sections and parameters of the natural water channel are defined; infiltration is takeninto account with the Green-Ampt method and the Clark Unit-Hydrograph method is used for calculation ofthe hydrograph over the watershed. The rainfall data measured during the aforementioned flood event is usedin simulation. Peak flow of the hydrographs for the subbasins, which were heavily affected by the flood, areobtained and compared with the results of the calibrated hydrological model generated by Rational Method inWMS in a former study. The results obtained by HEC-HMS model are in good agreement with the results obtainedby Rational Method in WMS. The strength of the HEC-HMS model over Rational Method is emphasized. Moreover,the subbasins located downstream of the Ayamama River are determined as the most critical region.