谷沢川・丸子川小流域におけるgi導入によるコストおよび雨水流出抑制効果

The purpose of this study is to verify the cost of GI implementation in urban areas based on land cover classification and a hypothetical model of GI implementation in the building envelope, and to clarify the effect of GI on stormwater runoff control in the current situation and after GI implementation. The rainfall-runoff volumes were calculated based on the current land cover classification for the catchment areas of the entire Yazawa River and Maruko River watersheds. In addition, in order to understand the cost of introducing GI and to verify the effect of GI on runoff control at the district scale, the catchment boundaries were subdivided into district scales, and three small watersheds in and around Tamagawa Nogemachi Park, Setagaya Tokyo, were selected. The modeling results showed that stormwater runoff was reduced in all three watersheds. The cost of installing rainwater infiltration pipes in the entire Yazawa River and Maruko River watersheds was calculated to be about twice that of installing GI, indicating that GI can be installed at low cost.