Increasing infiltration as a measure to reduce flood risk in an urbanized area

Shaohua Marko Hsu, Pi-Fang Hung, Siao-Ting Syu

Monday 29 june 2015

18:00 - 18:03h at North America (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Adaptation measures, Poster pitches

Parallel session: Poster pitch: 2I: FloodRisk - Adaption

This study targeted on the geological condition in Taichung basin, and taking the current condition of a parking lot in Feng-Chia University, Taichung City as the study site. By adding vertical infiltration pipes beneath the permeable pavement of the parking lot, the saturated conductivity of double-ring test could be increased 18~35 times. The experimental results show that the vertical infiltration pipes is applicable to be one LID component for increasing permeability with regard to Taichung basin’s geological condition. The related parameters and field-test results collected from the study site (60m×15m) were utilized for simulation by Storm Water Management Model (SWMM). Firstly, all simulation situations were based on current conditions. For the conditions changed to the parking lot built with water impermeable pavement, the surface runoff volume would increase 15% and the peak discharge would increase 10%; If the pavement changed from the current interlock brick to grass brick the surface runoff volume and the peak discharge volume could be decreased by 12.5% and 5.4%, respectively. Next we simulated the study-site watershed and pavement rebuilt situation and added into LID module. With regard to installed area and runoff reduction percentage, the optimum reduction benefit occurred when the installed area is 10% of the total, which effectively reduced surface runoff volume and peak discharge; while the installed area of pavement rebuilding situation reached over 20%, the peak discharge occurring time could be delayed by 10 minutes. By rebuilding interlock brick with grass brick to install the LID module 10% and compared with the original condition, it showed that the rainfall pattern design for one, two, and five years’ recurrence interval could all reduce surface runoff volume over 15%. The LID module of one year recurrence interval of rain design could reduce more percentage of surface runoff volume and peak discharge volume than the five years recurrence interval, which explains that the LID setting has relatively larger benefit on small rain.