Development of multi-objective Harris hawks optimization (MOHHO) algorithm in low-impact development systems considering the effects of climate change

In this research, to control and manage basin runoff by using Low-Impact Development (LID) systems in climate change conditions, a simulator-optimizer model is developed using the SWMM model and the MOHHO algorithm. Four LIDs of vegetative swale, bio-retention cell, permeable pavement, and infiltration trench have been used. Therefore, the areas of LIDs are determined in the sub-basins of Zone 1 and 3 of Tehran Municipality for the periods of the baseline (1988–2005), the near future (2030–2047), and the far future (2048–2065), with the objectives of (1) minimizing the cost of implementing and maintaining LIDs, (2) minimizing the amount of outflow runoff of the basin. In this research, the future rainfall under three emission scenarios RCP2.6, RCP4.5, and RCP8.5 has been simulated. By comparing the convergence diagram of MOHHO with the NSGAII algorithm, it was observed that the MOHHO has more dispersion of solutions and less run-time. Finally, with the help of this model, optimal management solutions were obtained in the form of the Pareto front. The results show that the flood volume was reduced by 50% on average compared to not using the system, considering the objective function of minimizing the outflow flood volume of the basin. But this value is reduced by 30% by giving importance to the second objective function, which is to minimize costs. Finally, due to the reduction of cost and economic efficiency, the implementation and use of these systems can be justified and have a significant effect in reducing the problems of the region.