巨椋低平流域の都市化と内水 (2) -現状と将来-

Abstract

This paper discusses the effects of urbanization on flood in the Ogura basin situated in southof Kyoto City. The Ogura basin, the catchment area of which is 52 km2, is rapidly being urban-ized mainly in hill and high ground zone. The urban area of the basin was under 8% in 1965.But the urban area has been extended to 35% in these ten years and anticipated to exceed 50% inthe near future.First, the flood runoff characteristics in the present have been examined by applying thekinematic surface runoff model for a non-inundation sub-basin and the dynamic tank model pro-posed by the authors for a back water reach of channel flow and an inundation zone, and decidedthe principle of the watershed modeling and the parameters of the mathematical models.After then, the flood runoff analyses have been performed to find the effects of the futureurbanization on flood assuming the past heavy rainfall conditions in August, 1959, and July, 1972, whose return periods are regarded as 30 years in maximum one-day depth and 10 years in three-day depth and as 10 years in maximum one-day depth and 30 years in three-day depth, respectively.The urbanization effects have been evaluated by the form of changes in the runoff volume, thepeak discharge or water level at a point and the operation time of drainage pumps. As the results, the necessity of the precautionary measure for flood disaster has been pointed out.