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2008年7月28日，神戸市灘区を流れる都賀川において，極めて短時間に集中した大雨によって水位が急上昇し，5名の人命が失われた。都賀川は，行政と住民が一体となって市街地の中に潤いのある親水空間を構築することに成功したモデル的な河川であるが，その親水空間において増水事故が発生した。本論では今回の大雨の頻度解析および流出解析を実施し，大雨の頻度とそれが河道に流出する経路を明らかにする。次に，流出解析の結果をもとに水難事故を防止するための技術的課題と対策を考察する。, The sudden water level rising caused by the severe rainstorm at the Toga River in July 2008 claimed five people. To prevent the water accident, a distributed rainfall-runoff analysis is conducted to understand the sudden runoff phenomena. The rainfall-runoff analysis and observed camera images revealed that discharge which caused the sudden water level rising came from the residential area and contribution from the mountainous area was quite small. It is proposed that only to monitor the discharge at the upper reaches is insufficient to prevent the accident; detailed distributed rainfall-runoff analysis with radar rainfall is essential to predict the runoff phenomena at the urbanized small catchment; and to foster the common view to keep off from the river at the alert of heavy rainfall warning is indispensable to avoid the accident.