Appraising spate risks in urban drainage systems using stormwater management model (EPA-SWMM); Case Study: District 4 of Tehran

Urban runoff and flood damage is one of the most important and fundamental issues in the field of urban management, which in recent decades has been strongly affected by the rapid growth of cities and increasing urbanization. Today, to show these processes, in the design and evaluation of urban drainage network system, the use of existing computer models has a special place to simulate the flow. The purpose of this study is to use the SWMM model to quantitatively simulate rainfall floods for District 4 of Tehran.

In this research, using the capabilities of the SWMM model for region 4 of Tehran, according to environmental factors, two plans of the best management strategies (BMP) under the garden and green roof climate scenario and a combination of both scenarios, for Maximum runoff control has been done quantitatively and finally their efficiency in reducing the total volume of runoff out of the basin has been investigated.

The results of sensitivity analysis of the model showed that among the seven parameters studied in this study, the amount of CN, the percentage of impermeable areas, the coefficient of roughness in impermeable areas and the equivalent width had the greatest effect on peak flow change, respectively. According to the obtained results, the third scenario (simultaneous combination of the first and second scenarios) will have the greatest impact on reducing the flow depth and flow rate in the entire surface water collection network.

In general, if we consider the flow depth factor for evaluation, in total four modes of model implementation, the third scenario has the most impact on the Tehranpars channel (output 7) and the least impact on the ice channel (output 3) and if Consider the peak discharge factor for evaluation. In general, the third scenario has