Runoff quality modelling for urban catchments

An investigation was carried out to model the flow and water quality for runoff from the KC01 catchment in Kranji. EPASWMM is a Lumped conceptual model and has several models available for storm routing, infiltration and water quality washoff function. Although it was originally intended to conduct the modelling studies for the Marina Catchment but due to the limited data available, only land use study was conducted. Instead calibration of stormwater runoff and quality was conducted for the Brickland subcatchment (KC01) in Kranji, which is aimed to test the applicability of EPASWMM for both stormwater runoff and quality. Brickland subcatchment was modeled as a single runoff block and adopted the Horton’s equation as the infiltration model, and Kinematic Wave Routing as the hydrograph routing method. For evaluation of the Stormwater runoff calibration Nash-Sutcliffe (NS) and mass difference was use. A sensitivity test on the calibration parameters was conducted and it was found that Width and Manning’s N for impervious area were the most sensitive parameters. The NS value for the calibration ranged from 0.64 to 0.97, with an absolute average of 8.31% for mass difference. For water quality simulation, modeling was conducted using event mean concentration (EMC) and rating curve (RC) methods, with both methods giving reasonably good results. The EMC method achieved an average of 8.05% for mass difference, while the RC method achieved an average of about 43.97%. A preliminary simulation of exponential buildup and washoff produced reasonably good results.Bachelor of Engineering (Environmental Engineering