狭窄部と盆地部が連続する千曲川における大規模洪水流下時の河道貯留・堤防浸透破壊危険性の評価と今後の治水整備のあり方

抄録

The Chikuma River characterized by the sequence of valleys and basins has a large river storage volume. However, the high water level continues for a long time in the basin areas and the risk of levee damage due to seepage flow will increase during a large flood event. In this paper, we developed the flood flow model which can grasp the hydraulic phenomena in the whole section of the Chikuma River based on the temporary changes of the observed water surface profiles during 2006 large flood. Then, the relationship between the river characteristics and river storage volume by the developed model was investigated. Also, the levee failure risk due to seepage flow was longitudinally evaluated based on the levee vulnerability index t^*. It was concluded that the most important future river improvement works in the Chikuma River were to strengthen the levee and utilize the river storage volume ability.