FLOOD AND CSO SUSPRESSION EFFECT BY GREEN INFRASTRUCTURE TARGETING UPSTREAM ZEMPUKUJI – RIVER BASIN

Abstract

 We investigated the flood and Combined Sewer Overflow(CSO) volume suppression effect in the case of intro-ducing green infrastructure (GI) in the catchment area of CSO at the rainy weather sewer system in the Zenfukuji Upstream Basin.

 We used three types of rainfall forms in flood case: two annual exceedance probability (1/100) and torrential rain with maximum possible rainfall in the Kanto region, in CSO case: annual rainfall. GI was introduced for each land use, such as private houses and roads, etc. By introducing all countermeasures, it became clear that the flood volume of more than 90% can be suppressed, the annual number of CSO occurrences and the amount generated per year can be drastically reduced.