VERIFICATION OF SEDIMENT CAPTURING EFFECT BY PEKEREBETSU RIVER No. 2 SABO DAM

Abstract

 It is important to take effective and efficient measures to prevent and mitigate damage caused by sediment and flood damages. In recent years, there have been many cases of fine-grained sediments with a grain size of 2 mm or less flowing down and depositing in areas to be protected, such as the Oya-okawa River in the heavy rains in July 2018. While it is required to examine how much such fine-grained sediment contributes to the damage caused by sediment and flood damages, the effect of damage prevention and mitigation by Sabo facilities is not quantitatively clear. It is also important from the viewpoint of comprehensive sediment management in watersheds to quantitatively organize the capturing effect of fine-grained sediment by Sabo dam. In this study, a one-dimensional riverbed variation calculation was performed on the downstream side of the Pekerebetsu River No. 2 Sabo dam, which captured a large amount of fine-grained sediment in the August 2016 flood, and the capturing effect of the Sabo dam was verified. As a result, it was clarified that the Sabo dam has a certain degree of damage reduction effect.