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都市域における洪水氾濫の危険性を行政および住民が正しく認識し，災害時にあっては適切な避難等を行うには，高精度な洪水ハザードマップの作成と公表が重要である。従来，洪水ハザードマップ作成の基礎となる洪水氾濫解析モデルの妥当性については，小規模でかつ単純な模型実験装置を用いたデータで検証されてきたため，モデルの検証が十分なされてこなかった。本研究では，京都大学防災研究所宇治川オープンラボラトリーに設置された大規模な洪水氾濫模型実験装置を用いて市街地における洪水氾濫模型実験を行い，地上部における氾濫特性や地下空間への流入流量を把握するとともに，数値解析を実行して氾濫モデルの妥当性を検討した。, Hydraulic physical model experiments concerning the inundation by river water in Kyoto City are carried outin order to clarify the characteristics of the behavior of flooding water on a complicated city area. The physicalmodel scale is 1/100 and it is a non-distorted model. The model can make allowance for the intrusion of floodingwater into underground space. Flooding processes were simulated by using a numerical model that incorporatedthe finite volume method and unstructured meshes. The flooded area and depth of water in case of nointrusion of flooded water into underground space were reasonably well evaluated by this method, while incase of intrusion of water into underground space calculated results were not well evaluated. The reason isthat the drop flow equation was used to estimate the discharge into underground space and that theentrances into underground space were not taken into account reasonably. The suitable equation forevaluating the discharge into underground space must be developed and also the unstructured mesh ofentrances must be constituted reasonably.

本報は，京都市市街地を対象に，鴨川氾濫時の地上部における氾濫水の挙動を水理模型実験と数値計算手法を用いて調べ，考察したものである。実験は，実現象により近い縮尺1/100の市街地地上模型を用いて行い，数値計算は平面2 次元非圧縮流れの基礎式を差分化し，SIMPLE法による計算を行った。その結果，氾濫水の拡がり方を把握することができ，洪水弱地域が明らかとなった。, Using the experiment model and numerical model has been investigates and considersinnudation process in Kyoto. The experiment was conducted using the ground-surfacemodel of scales 1/100. 2-D averaged numerical model was used to calculate the velocitydistributions, and the solutions follow an iterative procedure based on the SIMPLEscheme. Consequently, we could express inundation flow behavior in underground spaceand flow hazard space from the hydraulic and disaster preventive aspects.

平成9年7月10日午前1時頃, 鹿児島県出水市針原地区で発生した土石流によって, 死者21名, 負傷者13名がでる災害となった。本研究では, 洪水流出解析を行って針原川の洪水流出特性を検討するとともに, 深層斜面崩壊を模擬して土石流を発生させた数値解析を行い, その氾濫・堆積過程の再現を試みる。さらに, この計算結果をもとに, 計画を上回るような土石流に対して今後どのように取り組めばよいかについて言及する。, A severe debris flow disaster occurred at the Harahara River, Izumu City, Kagoshima Prefecture, Japan at the midnight of June 10, 1997.Twenty‐one persons were killed and 18 houses were destroyed by the debris flow. The debris flow was caused by a big slope failure with sediment volume of 160, 000 cubic meters due to heavy rainfall.In this paper, a numerical simulation was performed to explain the behavior and the depositional processes of the debris flow.The actua phenomena such as a sediment depositional area. And a thickness of deposits are fairly well explained by the the calculation.