Applicability of SWMM for semi Urban Catchment Flood modeling using extreme Rainfall Events

Abstract

Urban floods are different type of flooding event as compared to normally occurring riverine floods which is very often seen along the river banks during heavy rainfall in monsoons. Continuous human interventions in natural vegetative land for rapid Urbanization activities has given rise to Urban Flooding. So, there is a need for capacity analysis of existing storm networks and identification of overflow locations is the need of the study. Hence, in the present study an attempt has been made to simulate Urban Flood scenario for a semi Urban catchment using Storm Water Management Model (SWMM). The whole area is divided into 20 sub catchments and the data acquired from 2017 rainfall events is used for modelling. The study area is represented in SWMM by the help of Master Plan AutoCAD maps having drain lines and Reduced Levels (R.L.s) information. From this detailed elevation information of various nodes and length of pipe lines has been estimated to make the schematic view of the study area in SWMM. The focus of the present study is to model runoff conditions using Dynamic wave method of flood routing and Green-Ampt Infiltration model in SWMM. The results showed that SWMM has capability to model and interpret flows at various channel sections and nodes for mitigating floods. Due to unavailability of gauged flow data the model Parameters needs calibration for more reliable results. Model has effectively given catchment responses for peak flow and volume of runoff which is considered as one of the essential components of Urban drainage planning to mitigate the risk of flood.