Evaluation of capacity adequacy in lid according to lid structure

The interest in low impact development (LID) facilities for recovering natural water cycle systems degraded by urbanization is increasing worldwide. However, problems occur when installing LID facilities due to the incomplete and incomprehensive analysis of their design capacity adequacy. In this study, the removal efficiency and design volume adequacy of LID facilities were analyzed based on rainfall monitoring data in four LID facilities (grassed swale, vegetative filter strip, bio-retention, and permeable pavement). The group of LID facilities designed on WQV showed a higher flow (37%) and pollutant (total suspended solids, biochemical oxygen demand, total nitrogen, and total phosphorus) removal efficiencies (20%~37%) than the group of LID facilities designed on WQF. A surface area/catchment area (SA/CA) graph was developed for the evaluation of design volume adequacy based on rainfall monitoring data. The graph’s coefficient of determination showed over 0.5 in all parameters. In particular, flow and TP were more than 0.95. The SA/CA and L/CA graph considered the difference of structure mechanisms in LID facilities and confirmed an improved coefficient of determination in flow, TSS, and TP compared to the SA/CA graph. These results confirm the feasibility of applying a SA/CA and L/CA graph for the evaluation of design volume adequacy in LID facilities. Further research for generalization and normalization is necessary.