2023 Volume 79 Issue 27 Article ID: 23-27034
In this study a quantitative evaluation of changes in peak flood discharge and erosion potential under a future climate and effects of various adaptation measures on water level reduction and erosion control was conducted for rivers in Toyama Prefecture, Japan. In particular, this study examines the differences in flood and erosion risks and the potential for adaptation when the impact of global warming is limited to a 1.5°C increase instead of a 2°C increase based on mitigation efforts. The results show that the peak flood discharge of five rivers is reduced by an average of 1.21 times with a 2°C increase, but by 1.13 times with a 1.5°C increase. In addition, the proportion of sites with high risk of erosion potential could be limited to a 2% increase. Furthermore, it was found that adaptation measures were highly effective in the Oyabe River, and that a 1.5°C increase in water level and erosion potential could be controlled by implementing rice paddy dams in 30% of the total paddy field in the basin under the combination with river vegetation management. It was found that the percentage of the paddy field area in the basin area at the middle and upper region is the key for the effects of the paddy field dam. Also, the existance volume of the vegetation in rivers and the flood flow time on the flood plain are the key for the effects of the vegetation cutting and management.
