Evaluating Various Low-Impact Development Scenarios for Optimal Design Criteria Development

Low-impact development (LID) practices as a new approach to urban stormwater management have demonstrated their positive effects through the reduction of surface runoff volumes and pollutant loadings in a substantial amount of research. The effectiveness of LID practices can be affected by various LID conditions such as type, location, and area. Cost is also an important factor to be considered in the evaluation of LID effects. This study presented the optimal LID conditions that can achieve targeted reduction goals with minimal cost, and analyzed the effectiveness of LID practices under optimal LID conditions and the consequential cost on a watershed scale. To determine cost-effective LID conditions, three types of LID practices (rain gardens, rainwater harvesting tanks, and permeable pavements), two locations (residential and commercial areas), and percent allocation of LID practices were considered. Manual optimization was conducted under those LID conditions for five targeted reduction goals which were set for surface runoff and nutrient loadings. The results provided various configurations of cost-effective conditions in treating the targeted goals, and represented the impacts of the optimized LID conditions on the effectiveness of LID practices and the consequential cost. The present study could ultimately assist regulators in establishing proper watershed-scale strategies of LID conditions for effectively managing watersheds.