A Multi-Objective Optimal Design of Low-Impact Development Techniques for Parking Lots in Uljin City, South Korea

Purpose: This study proposes a sequential optimization approach utilizing a coupled simulation-optimization model to evaluate the performance of low-impact development designs at two parking lots in Uljin City, Korea. The objectives were to reduce runoff volume and remove total suspended solids. Two alternative low-impact development scenarios were designed: one with an individual infiltration trench and the other combining an infiltration trench with a rain garden. First, simulations of individual infiltration trenches were employed to identify the most sensitive parameters and their optimal values. The optimal parameters for the infiltration trench and a set of parameters for the rain garden were simulated to determine the optimal solutions. Moreover, global optimization with one-step simulation was performed to determine the optimal solution. Subsequently, the results of both optimizations were comparatively analyzed. Method: To achieve these purposes, a coupled set of tools, including SWMM, Pyswmm, and Modefrontier, is used for sequential optimization simulation. Result: The findings revealed that the most sensitive parameters were inconsistent across different scenarios. The combined scenarios highlight the effectiveness of surface runoff management compared with the individual scenarios. This approach demonstrates that the integrated model is valuable for producing different optimal low-impact development configurations within their parameter ranges. The results showed consistent performance between sequential and global optimization, indicating that sequential optimization is a promising tool for simulating complex combinations of low-impact development techniques. This study also identified four optimal low-impact development configurations for the two parking lots, supporting stakeholders in urban runoff management in similar areas.