Study on the destruction of riparian trees in a gravel-bed river caused by flood disturbance

洪水扰动对砾石河道河岸树木破坏的研究

基本信息

批准号：
14550508
负责人：
SHIMIZU Yoshihiko
金额：
$ 2.37万
依托单位：
Gunma University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550508/
关键词：
Riparian trees expansion Robinia pseudo-acacia gravel-bed river flood disturbance degradation maximum size of movable gravels destruction of riparian trees 樹木の破壊・撹乱平面流解析

项目摘要

Recently, bed degradation has been generated in many gravel-bed rivers. As the result, flooding areas exist only around the low-water channel and on the other hand, non-submerged areas or the regions affected by the weak flood disturbance occur in the river channel. Furthermore, riparian trees in the course of gravel bed-river have extremely increased and enlarged their covered-area over bars and flood plain.Such a situation causes the degeneration of the dynamic river system and that of inherent habitat environment in gravel-bed rivers, which brings about problems of river management for the environmental aspects as well as the safety of rivers against flood. In this paper, the magnitude of recent flood disturbance, the fall down process and the destruction mechanism of the riparian trees caused under the degeneration of river channel characteristics were examined through the field investigation in the segment-I reach of Watarase River. Based on the field study and numerical calculation with 2D-flow model, the destruction of the plant was classified into next four types : a)Yield of the tree due to the hydrodynamic force by the increase in the project area of trees to the flow because of trapping of flowing things, b)the disturbance of physical ground in stands, c)the disappearance of trees due to the erosion of the river bed/bank. As an index as such situation occurs, the maximum size of movable gravels and the local bed-degradation to be a key index of the scale of flood disturbance and results showed that the destruction mechanism of the riparian trees is caused by the disturbance of movable bed.

最近，许多碎石河河流已经产生了床降解。结果，洪水区域仅存在于低水通道周围，另一方面仅存在于河道中的洪水干扰的地区或受弱洪水干扰影响的地区。此外，在砾石床上的过程中，河岸树已极大地增加并扩大了其在酒吧和洪水泛滥的地方。这种情况会导致动态河流系统的退化以及碎石层河流中固有的栖息地环境，这带来了环境方面的河流管理问题以及河流的安全。在本文中，通过现场调查，在Watarase河的I Smogement-I resh ress tosem the the ress-I reshere tosection检查了最近的洪水干扰，下落过程和破坏机制。基于现场研究和2D流模型的数值计算，将植物的破坏分为下一个类型：a）树木的产量，由于树木项目区域的流体动力而导致树木的流动性陷入流动，因为捕获流动的事物，b）在架子上的物理地面的干扰，c）由于河流的覆盖层而导致树木消失。作为一种情况，这种情况发生了，可移动砾石的最大大小和局部床位降低是洪水干扰规模的关键指数，结果表明，河岸树的破坏机制是由可移动床的干扰引起的。