Optimization of low-impact development facilities in urban areas using slime mould algorithm

Qualitative and quantitative evaluation of urban runoff is a major concern for urban management, imposing significant costs on the urban management system every year. Numerous; factors affect the quality, and quantity of urban runoff, such as population growth, urbanization, land use change and climate change. This paper aims to optimally design low-impact development (LID) strategies for qualitative and quantitative management of urban areas. Three runoff management methods, including vegetated swale, bioretention system, and porous pavement, were considered along with an urban drainage network. The stormwater management model (SWMM) was adopted to simulate urban runoff, and the slime mould algorithm (SMA) was employed to optimize LIDs. An urban area in Tehran, Iran, was examined using the proposed SWMM-SMA model, and the result was an optimal combination of LIDs. Three LIDs were individually defined for each subcatchment, and the results were compared to the combination of all LIDs in the whole catchment. The results indicated that the bioretention system was the most effective LID in improving the water quality in the case of individual LIDs. The system could reduce total suspended solids (TSS), total nitrogen (TN); and zinc (Zn) concentrations by 91, 78, and 74%. The results also suggested that the optimal combination of LIDs was more efficient, and it was able to further reduce TSS concentration by 14-16% compared to individual bioretention systems. Furthermore; the optimal combi-nation of LIDs was successful in minimizing TSS concentration in the runoff by using the SWMM-SMA model. By using the simulation-optimization model (SWMM-SMA), optimal LIDs and runoff quality could be effectively designed and controlled.