침투 트렌치로 인한 유출 양상의 실험 연구

Abstract

Infiltration facilities are effective instruments to mitigate flood and can increase base runoff in urban watersheds. In order to analyze effects of infiltration trenches physical model experiments were conducted. A part of experimental results was used to verify a modified SWMM code from other research that can simulate infiltration trenches. The physical model facility consists of two soil tanks, artificial rainfall generators, tensiometers, and piezometers. The experiment was conducted by nine times and each case differed in rainfall intensity, rainfall duration and the type of ground surface. Measured quantities in the experiments are as follows: surface runoff, subsurface runoff, trench pipe runoff, groundwater level, water content, etc. The following resulted from the model experiment: The volume of subsurface runoff at trench watershed was maximum 78.3 % compared with rainfall. This value is bigger than that of ordinary rate of subsurface runoff, and shows a groundwater recharge effect of trench. The time of runoff passing through the trench became earlier and the volume of runoff became larger with the increase of inflow into the trench, while trench exfiltration into ground became relatively smaller. The modified SWMM simulation results were different from the experimental results in groundwater level and water content. Trench pipe runoff and subsurface runoff, however changed in similar patterns between the two. Particularly in comparison of subsurface runoff for 24 hours, peak runoff was somewhat different, but the total volume of subsurface runoff obtained from SWMM was up to 98.5 % of the experimental results, showing that the two values were similar. The results of this study presented above show that infiltration trenches are effective instruments to increase base runoff during dry periods. In addition, the simulated results were close to the experimental results on the change of subsurface runoff. This verifies the validity of the modified SWMM. The experimental results and the parameters used in SWMM simulations can be reference data for field application of infiltration trenches.