Sediment and pollutant load modelling using an integrated urban drainage modelling toolbox: an application of City Drain

摘要

Numerical and computational modelling of flow and pollutant dynamics in urban drainagensystems is becoming more and more integral to planning and design. The main aimnof integrated flow and pollutant models is to quantify the efficiency of different measuresnat reducing the amount of pollutants discharged into receiving water bodies and minimisenthe consequent negative water quality impact. The open source toolbox CITY DRAIN developednin the Matlab/Simulinkq environment, which was designed for integrated modelling of urbanndrainage systems, is used in this work. The goal in this study was to implement and testncomputational routines for representing sediment and pollutant loads in order to evaluatencatchment surface pollution. Tested models estimate the accumulation, erosion and transportnof pollutants—aggregately—on urban surfaces and in sewers. The toolbox now includesnmathematical formulations for accumulation of pollutants during dry weather period and theirnwash-off during rainfall events. The experimental data acquired in a previous research projectncarried out by the Environmental Engineering Research Centre (CIIA) at the Universidad denlos Andes in Bogota´ (Colombia) was used for the calibration of the models. Different numericalnapproaches were tested for their ability to calibrate to the sediment transport conditions.nInitial results indicate, when there is more than one peak during the rainfall event duration,nwash-off processes probably can be better represented using a model based on the flowninstead of the rainfall intensity. Additionally, it was observed that using more detailednmodels (compared with an instantaneous approach) for representing pollutant accumulationndo not necessarily lead to better results.