A Study on the Retention Effectiveness Analysis of a Green Wall as a Low Impact Development (LID) Facility

Urbanization and climate change produce distortions in urban water circulation. This issue can be resolved using a stormwater management technique called Low Impact Development (LID), which mimics natural processes and restores the hydrological state as it was before development. This study aims to evaluate the performance of a LID facility and calculate the runoff reduction and delay effect. The test-bed is a green wall of the Korea GI & LID Center. Scenarios for 30 mm/hr, 50 mm/hr, and 70 mm/hr were set based on the percentile of rainfall events from 2012 to 2021 in Geumjeong-gu, Busan. By setting an impervious surface as the control group, runoff reduction was found to be 91%~94% of 30 mm/hr, 50 mm/hr, and 70 mm/hr. The total outflow time increased by 47, 88, and 58 minutes, respectively, demonstrating the effect of reduced runoff and delayed time. A storm water management model (SWMM) was constructed to evaluate this effect quantitatively. Verification and correction were done using the experiment results. R2 was 0.96~0.98 for the test and 0.93~0.94 for the correction. This paper thus verified the retention effectiveness performance of a green wall and analyzed its quantitative effect through a SWMM. The study findings can be used as a guideline to test parameter-wise hydrological performance of the model.