An Optimization-Simulation Method for Low-Impact-Development (LID) Facilities Based on CCMO Algorithm Combining an Integrated Finite Volume Coastal Ocean and Drainage Pipe Model

The employment of Low Impact Development (LID) facilities is an effective means to alleviate urban flood in the context of climate change and urbanization. Existing methods for evaluating the hydrological reduction and control effect of LID facilities are mostly based on hydrological models, which have inherent shortages in accurate flood process simulation. In this study, a fully-distributed bidirectional-coupled hydrodynamic model based on the Finite Volume Coastal Ocean Model (FVCOM) and a one-dimensional drainage pipe model is used to evaluate the effectiveness of LID facilities combining the Coevolutionary Constrained Multi-objective Optimization (CCMO) algorithm. The proposed method is applied to investigate the responses of LID facilities effectiveness in hydrological reduction and control to rainfall patterns in the Yuelai New City, Chongqing, China. Results show that the overflow volume and peak overflow under unimodal rainfall are larger than those under other rainfall patterns. The time lag between initial and peak overflow under unimodal rainfall is the shortest, and it is shorter under small rainfall return period. The flood reduction and delay effect of LID facilities under unimodal rainfall is lower than that under bimodal rainfall, and it is the best under uniform rainfall. At low costs, the peak flood reduction effect of combined LID facilities may be lower than that of a single LID facility with strong permeability, but as costs continue to increase, combined LID facilities show its superiority. The proposed optimization-simulation method is of great significance for environmental managers to seek best solutions in urban flood control.