固定化砂州での掘削路開削による洪水攪乱の誘発と樹林化抑制対策に関する研究

抄録

Gravel-bed rivers in Japan are now facing a multitude of problems relating to fluvial environment and flood control. These problems include the growth of riparian trees on riverbeds and the high-speed water flow in a low-flow channel, which became pronounced due to increasing channel degradation and cross- sectional elevation change that are triggered by the change in external factors. This study aims to propose effective measures for reproducing gravel bars by leading flood flow over vegetated bars. The bed excavation over the vegetated gravel bar in the segment-1 zone of Watarase River was conducted for the management of riverine trees and the recovery of gravel bars with geomorphic changes caused by flood disturbance. As result of the field survey before and after 2009’s flood in Kiryu Ohashi Bridge area, an effective bed variation was caused in the channel excavation area around on a stable gravel bar and it was confirmed that channel excavation was effective forestation control measures on a stable gravel bars.