Hazard management of inundation and pollutants in urban floods using optimal conventional and novel strategies

Urbanisation by decrease in imperviousness areas would result in increase in the risk of flood inundation and cause more discharge of pollutants into receiving water bodies. This paper presents the management of urban flood hazard in terms of inundation and pollutants discharge into receiving water bodies using a combination of the conventional and novel techniques. Conventional techniques include increasing the dimension of conduits as well as decreasing their roughness. Novel techniques on the other hand include bio-retention systems, pervious pavements, infiltration trenches, and detention ponds in urban drainage networks. In this study the multi-objective optimization model is developed using multi-objective genetic algorithm coupled with a simulation model of urban drainage system using SWMM software. The objectives are to minimize the economic cost, the inundation flood hazard, and the expected pollution reaching the receiving waters. Pollution control is put on pollutants of TSS, TN, and TP. The suggested methodology was applied to a case study for the urban drainage system of Golestan city in Tehran Province. Results indicated that applying the optimal methods can considerably decrease the expected flood and pollutants. Results of Pareto front showed that indirect relation exists between the solutions of optimal control of expected inundation and the optimal control of expected pollutants in receiving water bodies