Multi-Objective Optimal Planning and Deciding of Low Impact Development for an Intending Urban Area

As a storm management philosophy, low impact development (LID) is used to control the surface flow and its pollution, especially in the intending urban area in China. Finding the proper LID plan to balance the cost and surface flow effect is very important for the administrators of the cities. Firstly, we combined the SWMM with NSGA II to find the Pareto set of these optimal LID plans. Then, a structural decision-making approach was used to select the proper scheme from the Pareto set. The numerical tests consisted of 40 combinations of different return periods and durations and were conducted. The result shows that the SWMM-NSGA II model is a distributed model which could be used to find the multi-objective optimization LID plans for an intending urban area. When the SDA is used to select the suitable scheme from the Pareto set composed by the optimal alternatives, the weights could reflect the management demand of people. The LIDs might be more effective for more frequent, lighter, and shorter duration storms. It could cost too much, but the control effective might not be obvious in a heavy storm.