Spatial Optimization of Low-Impact Development Facilities Based on a p-Median Model and an Ant Colony Optimization

Determining the scales, types, and locations of low-impact development (LID) facilities is the basis for LID practice. Spatially available rainwater on site is first calculated in this study to obtain the scales of LID facilities using the geographic information system technique. Spatially available harvested rainwater in different land-use types is then calculated to determine types of LID facilities according to potential facilities’ performance. Next, a p-median model and an ant colony optimization (ACO) algorithm are used to obtain spatially optimal locations for LID facilities. Main runoff pollutants [e.g., suspended solids (SS), total phosphorus (TP), dichromate oxidizability (CODcr), and ammonia nitrogen (NH3-N)] are sampled, interpolated, normalized, and spatially overlaid to identify heavily polluted areas and adjust LID facilities for decontamination. Finally, the performance of the ACO for the p-median model is compared with that from the genetic algorithm. Determining the scales, types, and locations of LID practices can effectively guide construction of LID for practitioners and stakeholders.