Author(s): Daisuke Naito, Kenichi Kanenawa, Kazuhisa Fukunaga, Fumiko Imamura, Yuichi Kayaba
Linked Author(s): Daisuke Naito
Keywords: Vegetation in the channel, tree growth, channel excavation, height difference from the regular water level, distance from the water's edge
Abstract: Climate change is expected to not only increase the risk of flooding but also affect vegetation in river channels because of changes in river flooding pattern and flow regime. Channel excavation, which has been widely adopted for many rivers in the country as a development method for flood control, is also used as an approach to nature restoration that aims to restore natural bare land and swamp environments by excavating land area created by sandbars and is, therefore, considered an effective approach to both flood control and environmental preservation even under climate change. At present, however, there is an issue that sandbar excavation has failed to maintain vegetation as expected and resulted in the need of reforestation in some cases. Therefore, techniques are sought for forecasting vegetation after channel excavation. In this study, we have focused on two formation factors, i. e. , the height difference from the regular water level and the distance from the water's edge, as forecast indicators, and organized their relationships with the distribution of vegetation in river channels across the country. As a result, it is found that the distribution characteristics of plant communities by height difference and distance from the water's edge vary according to segment and that vegetative distribution in low height difference zones where the height difference is not more than 1 m is different according to region. As a result of analysis focused on dominating plant communities after excavation, a closer relationship is found in segment 2-2 between the dominating plant communities in the low height difference zone where the height difference is not more than 1 m and the dominating plant communities after excavation. All of these results show that the height difference can serve as an indicator for forecasting vegetation after channel excavation
Year: 2017