都市における洪水氾濫 ―大規模な洪水氾濫模型装置を用いた実験と解析―

Abstract

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.