2013 Fiscal Year Final Research Report
Mechanisms of maintaining cobble-bar vegetation - focused on the intensity of disturbances and the refugia of the vegetation during large floods -
| Project/Area Number |
23510298
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Multi-year Fund |
|---|
| Section | 一般 |
|---|
| Research Field |
Resource conservation science
|
|---|
| Research Institution | University of Hyogo |
|---|
Principal Investigator |
ASAMI Kayo 兵庫県立大学, 自然・環境科学研究所, 准教授 (40464656)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NAKAYAMA Akihiko 一般財団法人建設工学研究所, その他部局等, その他 (30237458)
FUJITA Ichiro 神戸大学, 工学(系)研究科(研究院), 教授 (10127392)
|
|---|
| Project Period (FY) |
2011 – 2013
|
| Keywords | 礫原植生 / カワラハハコ / 乱流シミュレーション法 / 画像解析 / 撹乱 / 洪水 / レフュージア / 掃流力 |
|---|
| Research Abstract |
A vegetation monitoring study and a field survey using an image velocimetry of river flows as well as a fluid-dynamic numerical simulation have been conducted to find the effects of disturbances caused by floods of different intensities and return periods on a cobble-bar vegetation that is sustained by these disturbances. It has been found that there is an area near the downstream edge of a cobble bar where the bed shear force stays below the critical level required to move bed material and vegetation during very large flood events. This area coincided with the location where some vegetation actually survived large floods and served as a 'refugia'. Furthermore, it has been suggested that this special condition needed to maintain the cobble-bar vegetation is created by the morphologic characteristics of a sharp bend, a shortcut secondary channel and a bar with a steep-sloped downstream edge.
|
