Optimal spatial priority scheme of urban LID-BMPs under different investment periods

The optimal spatial layout of low impact development best management practices (LID-BMPs) can be used to inform LID-BMP construction to prioritize resources to achieve the highest comprehensive benefits. An objective decomposition algorithm is designed to decompose the control objectives of total rainwater runoff, peak discharge, pollution reduction and rainwater utilization for each pixel of a raster image. A type selection algorithm is then designed to optimize the types of LID-BMPs deployed in each pixel. The most suitable positions for the construction of LID-BMPs are identified using a topographic index model to determine spatial priority level of LID-BMP construction sequence. A multi-objective model, including the maximum average reduction ratios of runoff and pollution and minimum total cost, is constructed. An adaptive differential evolution algorithm (ADEA) is designed to solve the multi-objective optimization problem. The optimal grid-based priority scheme is obtained for high-resolution spatial planning. It is shown that the most suitable positions for implementing LID-BMPs are located in regions with negative soil moisture deficits. Optimal total cost and reduction ratios of runoff and pollution to construct LID-BMPs in Yinchuan, China are $49,463,516, and 0.46 and 0.38 in the first priority scheme; $50,920,496, and 0.74 and 0.62 in the second priority scheme; and $99,207,806, and 0.92 and 0.86 in the third priority scheme. The optimal spatial priority schemes of LID-BMPs obtained from the ADEA can maintain the maximum runoff and pollution controls under different investment periods.