Site selection of areas influencing to flood control programming with using of HEC-HMS Model Case study in talaqan basin

This recent study in Talequn catchment, placed in Alborz province, has been performed to prioritize affecting peak flow areas and generally areas that have a greater role in flood occurrence. To do this task, Arc Gis (Geographic information system) has been utilized to prepare maps of physical properties of Talequn basin catchment and also rain gauge date and equivalent run off statistics of Tehran regional water, for 20 years(1993-2013) has been received. As a result of existing data, four flood events were extracted and were calibrated under the (HEC-HMS) model. TO do calibration, SCS method was used to simulate flood hydrograph and lag-time method was utilized for channel routing. Also, Hydrologic Modeling System (HECHMS) was used to estimate the amount of contribution of sub-basin in output discharge of the total basin catchment on the basis of return periods of 2-510-25-50-100 years old and finally by the use of the 50-year return period and sub-basin individual remove method under the effect of HEC-HMS model, sub-basin were prioritized in terms of flooding potential. The research results show that sub-basin participation rate in output of basin catachment discharge is not only of affected area and sub-basin peak flow but also of factors such as curve number (CN) and soil hydrologic group which have significant role in flood occurrence. Another significant factor is sub-basin located in basin output, which has greater share in output discharge. In addition, short intervals in occurrence of peak flow of sub-basin water flow synchronization role, human changes such as construction activities like housing, have significant impact on the production of the whole basin flood areas.