Experimental Study on Relation between Breach Process and Velocity Distribution on Levee due to Overflow

Coastal levee is an defensive structures important in low-lying coastal areas prone to floods, but is vulnerable to overflows when water levels increase extremely. Due to storm surge and high waves, water overflow and wave overtopping occur over coastal levee. Likewise, river levee is to protect lowland areas from floods. However, levee breaches due to aging of levees have caused huge damages on properties and human casualties. To advance as a society, it is essential to pursue meaningful implementations of solutions that prevent the erosion of levees during floods. To find a resilient structure of levee against overflow, this study has tested an environmentally friendly substance for reinforcing levee. With intent to testify the new method, a series of hydraulic experiments were carried out for to verify a flow state and surface velocity distribution according to levee breach progress by building a semi-prototype levee with a bottom width of 5 m, a slope of 1:2, a crown width of 1 m, and a height of 1 m in a 3 m bottom-wide natural channel. By building a measuring system using a number of imaging devices on site, the surface velocity distributions on the earthen levee and the levee reinforced with the new environmentally friendly substance were measured using a LSPIV technique. It is expected to be able to examine the characteristics of flow velocity distribution following breach processes on levees to evaluate the initial points of failure and the weak points during overflow.