1995 Fiscal Year Final Research Report Summary
Field study on mechanism of topography variation of bottom surface of tidal flat in which benthos are living in lagoon
| Project/Area Number |
06650570
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
水工水理学
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| Research Institution | TOHOKU GAKUIN UNIVERSITY |
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Principal Investigator |
UEHARA Tadayasu TOHOKU GAKUIN UNIVERSITY,ENGINEERING,PROFESSOR, 工学部, 教授 (80048818)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Gamo Lagoon / Tidal flat / Change of bottom topography / Tidal velocity / Water level / Benthos / Bioturbation / 水位 |
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| Research Abstract |
1.Topographical factors having effects on bottom topography of main tidal flat in Gamo lagoon are closing lever which separate lagoon and river, opening in closing lever, concrete-made revetment, and part of contraction or enlargement of width in lagoon.
2.The appearance of bottom surface of main tidal flat are two cases : first is not uneven and smooth, second is uneven. Most days in a year, bottom height of a half in main tidal flat is high and a little uneven, and bottom height of the rest is lower and more uneven.
3.Maximum inflow velocity and Maximum outflow velocity in a day at a measuring point near main tidal flat is respectively 0.6m/s and 0.5m/s.
4.Variation of height of bottom surface in main tidal flat in a year is 5 to 10cm. Toward winter, height of bottom surface rises in one year, and drops in other year.
It rises from spring to July all of the three years. and it seems mostly to change at flood in spring tide.
5.Bottom sediments in main tidal flat is sandy. Medium diameter is 0.3mm. Following Hjulstrom's diagram erosion velocity is 0.12m/s.
6.There are many moments exceeding erosion velocity, but variation of height of bottom surface do not occur. It seems to occur at flood when low water is high.
7.Effect of benthos on variation of height of bottom surface is not evident.
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