Experimental Study for Over Flow and Scouring Effects Around Tetra Block Embankment

In recent years, overflowing due to torrential rain caused by abnormal weather and floods.at Tohoku and around Tokyo area in September 2015. Due to the torrential rain, various river bank has breakdown.
Therefore,damage risk and damage mitigation due to flooding are inpotant issue and damage mitigation must be considered. In order to delay the erosion and collapse process and surface of river bank must be protected by covering by protective work for scour prevention., experiment for riverbed changes are con-ducted and discussed for several surface tipes of riverbank foreffect of reduction suppressing effect. As a result, scouring is smaller, and the scouring depth was reduced by the flat block with the protrusion. In addition, since the scouring depth decreases as the length of the flat block becomes longer, it is clear that Tetra block has higher effect that the flat block with protrusions is longer.