1996 Fiscal Year Final Research Report Summary
Re-examination of the Equilibrium Beach Profile Model to Estimate Long-Term Erosion
| Project/Area Number |
07650587
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
水工水理学
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| Research Institution | Ibaraki University |
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Principal Investigator |
MIMURA Nobuo Ibaraki Univ., Urban and Civil Eng., Professor, 工学部, 教授 (60133089)
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| Co-Investigator(Kenkyū-buntansha) |
NOBUOKA Hisamichi Ibaraki Univ., Urban and Civil Eng., Res.Associcate, 工学部, 助手 (00250986)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Beadh erosion / Equilibrium profile / Beach profile / Sea-level rise / Bruum Rule |
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| Research Abstract |
The purpose of this study ia to reexamine the concept of "equilibrium beach profile" to develop a firm basis for the estimation of beach erosion due to long-term environmental changes, such as sea-level rise. First, it was obtained that sea-level rise induced by global warming could accelerate beach erosion significantly. The Bruun Rule used in such estimation, however, is based on only geometric consiederation, so it is needed to take into account a dynamic relationship into the equilibrium beach profile model.
The present study was performed as follows ;
(1) Data on the beach profile change in prototype wave flumes were gathered.
(2) Positions of shoreline and contours were correlated with the conditions of incident waves.
(3) The beach profiles were categorized into seven patterms, which were then normalized.
(4) The wave conditions which corresponded to the categorized profiles was identified.
(5) It was tried to reproduce an observed equilibrium profile by superposing the categorized profiles.
It found to be difficult to reproduce the equilibrium profile by this method. This is because the cumulative effect of the precedent waves are apparent. The same result was also concluded from the analysis of the correlation of the time histories between incident wave conditions and shoreline position. Therefore, inclusion of such hysteresis effects of the wave actions to develop to an realistic equilibrium beach profile model.
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