Effect of Low-Impact Development Scenarios on Pluvial Flood Susceptibility in a Scantily Gauged Urban–Peri-Urban Catchment

AbstractDue to frequent pluvial flooding in different urban and peri-urban catchments worldwide, understanding the flooding situation is necessary for effective flood management. However, limited hydrological data availability, for example, lack of discharge information at required spatiotemporal scale or unavailability of local rating curve, can hinder modeling urban pluvial flooding and extracting useful information for flood mitigation. To deal with this situation, the physically-based Variable Parameter Muskingum Stage-routing (VPMS) module was coupled with the popular Storm Water Management Model (SWMM) using the GIS-derived morphological features of a typical urban and peri-urban catchment in eastern India. The study further explored the effect of urban channel representation in the SWMM-VPMS coupled model on the catchment response for the monsoon periods of the years 2009, 2011, and 2014 and confirmed the better performance of high-resolution channel representation with a Nash-Sutcliffe efficiency (NSE) of 0.86, mean absolute error (MAE) of 0.24 m, and percentage bias (PBias) of −2.33% compared to low-resolution channel representation with NSE, MAE, and PBias of 0.85, 0.23 m, and −2.95%, respectively. Further, this coupled model was applied to understand the flooding situation across various channels considering conditions without Low-impact Development (LID) for 2-h and 3-h design rainfalls under 1-year, 2-year, 5-year, and 10-year return periods. Subsequently, the effect of implementing green roof (GR) and bioretention cell (BRC) as LID techniques was evaluated in mitigating pluvial urban flooding. The results reveal that, although both the BRC and GR perform well in reducing flooding across various critical locations, the BRC is more effective in reducing flooding than the GR.