Modelling flow of the major canals of Sylhet city using the EPA SWMM runoff model

Geographically, local canals in Sylhet city, Bangladesh, mostly transport the rainwater to the Surma River as the city lacks typical drainage infrastructure for runoff control. Hence, proper hydraulic and hydrologic models are required to assess the current potential of these canals to withstand significant runoff and enhance the protection of flood problems during a severe storm. In this study, the Malni Chara and Goali Chara drainage sub-systems of Sylhet city's major drainage sub-systems were calibrated and verified using the EPA SWMM, respectively, using the hydrological data from 2016 to 2019 and the meteorological data from 1975 to 2019. Overall, the models will be suitable for the runoff quantity measuring since the simulated results matched the observed data well. For the Malni Chara sub-system, R2 of 0.94, Nash–Sutcliffe efficiency (NSE) of 0.92, d of 0.97, percent bias (PBIAS) (%) of 2.96%, and RMSE standard deviation ratio (RSR) of 0.05 have been found and for the Goali Chara sub-system, R2 of 0.96, NSE of 0.90, d of 0.93, PBIAS (%) of 1.54%, and RSR of 0.08 have been found.