Riverbed Cross section Observation During Flood.
Grant-in-Aid for Scientific Research (C).
|Research Institution||Tokyo Denki University|
YANAGUCHI Takayuki Tokyo Denki Univ, College of Science and Engineering, Professor., 理工学部, 教授 (90256628)
|Project Fiscal Year
1997 – 2000
Completed(Fiscal Year 2000)
|Budget Amount *help
¥2,600,000 (Direct Cost : ¥2,600,000)
Fiscal Year 2000 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1999 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1998 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1997 : ¥1,100,000 (Direct Cost : ¥1,100,000)
|Keywords||Riverbed Observation During Flood / Supersonic Depthmeten / Radio Currentmeter / 洪水時横断観測 / 曳航型測深機付ボート / 電波流速計 / 洪水時河床観測 / 洪水流量 / 曳航型蒸人ボート / 曳航型無人ボート / 洪水時表面流速 / 洪水時横断 / 曵航式無人ボート / 洪水時河床横断 / 河川横断観測 / 洪水時河床変化 / 洪水時流量観測|
The authors has been analysing radio current meter data during flood (non-contact with water surface) and found that bed level change resulted in velocity change (H〜V relation change). They started cross section observation during flood in the rapid rivers.
The feature of this study is that because cross section observation is undertaken at the cross section where velocity measurement is being done, and therefore the relation between velocity and bed level change can be investigated.
They chose 2points, one is curved point, and the other is the point with back up from confluence point and measured cross sections at low flow and during flood.
At the curved point, central sand bar was scoured much and scoured part at the bent was accumulated during a big flood in the river (1998). Velocity at the central part got to 8m/s.
After 2years, the scour at the bent was restored by small floods, but the scour at the central part has not been changed. A little bigger flood but smaller than 1998flood may be needed for restoration of the central part.
At the point backed up, they succeeded 11hours cross section measurements including flood peak. The results show, the river bed level degraded first stage, rose during peak, and degraded again during reccession. From the cross sectional viewpoint, the main flow part was scoured much, and the other part was accumulated, but total flow area has changed a little.
Cross section measurements were done with small boat (length 60cm) towed from bank or bridge with supersonic depth meter and is successful within V=3m/s, but with manpower.
In the future it must be done automatically without manpower.
Research Output (19results)