学会誌「自然災害科学」

中小河川の洪水氾濫対策に関する研究 －1998年8月新潟下越地方における豪雨災害を例として－

Towards Effective Countermeasures against Flood Disaster in Small-scale Rivers - Flood Disaster in the Kaetsu area, Niigata Prefecture, in August 1998 -

武藤 裕則*・中川 一*・戸田 圭一*・市川 温**

Yasunori MUTO*, Hajime NAKAGAWA*, Keiichi TODA* and Yutaka ICHIKAWA**

Abstract

In August, 1998, local heavy rainfall caused severe flooding in the Kaetsu area, Niigata Prefecture, mainly within the Orii River basin. This study looks into damages caused by the flood and their reasons through field surveys and numerical simulations by mathematical tools. A model which comprises a runoff model and a 2-D inundation flow model is proposed. The surveys show that the flood was basically caused by the extraordinary heavy rainfall in a short period. However prior improvement works for several weak reaches in the river are expected to some extent to reduce the flooding damages. The mathematical model could express the inundation process due to effluence from the river qualitatively well. The model also gives some indication on studying evacuation problems and land-utilization planning. Flood alleviation schemes effective especially for small-scale rivers are mentioned on the basis of the analyses.

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