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Study on effects of storm-water detention facilities in an urbanized watershed using a distributed model
storm-water detention pond
Construction. Civil engineering
A distributed hydrological model - WEP (Water and Energy transfer Process) model is improved at first by adding overland flow and storm-water detention pond's components, as well as changing the kinematic wave method into the dynamic wave method for the flow routing of main rivers to consider tidal effects. The modified model is then utilized to evaluate the effects of storm-water detention ponds and infiltration trenches in the Ebi river watershed with a grid size of 50m and a time step of 10 minutes. The simulation of the Shibayama-Danchi No.1 storm-water detention pond at the upstream of Miyamae tributary is performed by adopting a design rainfall of one day duration and 50mm/hour peak. Four cases, namely, with pond, with trench, with pond and trench and without pond and trench are studied at 4 sites, namely, pond outlet, Miyamae river downstream, Ebi river middle-stream and Ebi river mouth. Through comparing the hydrographs at the 4 sites in the 4 cases, it is found that the storm-water detention pond plays a much bigger role than infiltration trenches in flood peak reduction in the upstream reach, whereas infiltration trenches distributed over the watershed play a dominant role in the downstream reach. Therefore, the joint implementation of storm-water detention ponds and infiltration trenches may be necessary for effective flood damage mitigation in a whole watershed.
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Graduate School of Engineering