EFFECT OF LANDSIDE POOLED WATER DEPTH ON EROSION PROCESS OF EMBANKMENT BY OVERFLOWING WATER

Abstract

 The pooled water depth on the landside of a river embankment can affect the embankment’s erosion and breaching process. This phenomenon is understood as ‘water cushion effect’ that decreases the energy of overflowing water and therefore suppresses erosion. The 2019 Typhoon Hagibis, Japan, such landside inundation conditions may have influenced the behavior of levee failure. This study aimed to clarify the effects of this inundation on the erosion by overflowing water on an embankment. A laboratory experiment using a sand embankment model and simulated result showed that the higher pooled water depth, the lower the erosion due to overflow was observed. Reproduction calculation under the conditions at the embankment of the Tokigawa River where the levee failure occurred in the Typhoon Hagibis also showed a similar tendency.