Abstract
In recent years, disasters caused by typhoons, local downpours and other phenomena have occurredfrequently, and concern over the risk of large-scale water damage caused by river flooding has risen.Although damage resulting from levee breakages is particularly serious, there is a lack of technical data on the mechanism behind the phenomenon. Accordingly, clarification of this mechanism is an important task in reducing the risk of water damage.We have examined the relationship between the quantification of the levee breakage volume and hydraulic quantity. In the widening stage of levee breakage, the breakage phenomenon can be described in terms of the traction of soil masses from the levee body as a result of flood flow. It was also found that the relationship between the extent of dimensionless levee collapse and dimensionless traction force around the mouth of the breakage can be expressed in a form similar to the bed load formula.
