Cross-shore (onshore-offshore) sediment transport has been studied to determine
the importance of sediment permeability on the equilibrium beach slope. Quick (1991)
has proposed that the permeability of the beach material effects the onshore-offshore
transport by changing the stresses on the beach through the infiltration and exfiltration
processes. Based on Hazen's (1911) idea that the sediment's D₁₀ value (that is, 10% of
the material is finer than this value) may be used to represent its permeability, Quick
developed a relationship between the wave height, the sediment D₆₀ value, the D₁₀ value
and the equilibrium beach slope. Three series of experiments which used sand (D₅₀=0.59
mm) and gravel (D₅₀=5.5 mm) in varying proportions to represent a range of
permeabilities. Gravel and sand beaches were exposed to wave action and the resulting
beach profiles noted. Mixtures of the two sediments were then put through the same tests
and their equilibrium beach profiles measured. From this data, it was found that as little
as 25% (by volume) sand could cause a gravel beach to behave much like a sand beach.
The beach permeability was an important factor in determining beach response to wave
conditions, along with the wave height. Further experimental work is necessary in order
to determine the minimal amount of sand required to shift a gravel beach's response to
wave attack. The fact that so little sand is require to make the shift, caution is necessary
when designing artificial beaches and in modifying existing beaches.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/7668 |
| Date | 05 1900 |
| Creators | Dyksterhuis, Patricia Lynne |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Relation | UBC Retrospective Theses Digitization Project [http://www.library.ubc.ca/archives/retro_theses/] |
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