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Impact of sea-breeze activity on nearshore and foreshore processes in southwestern Australia
- Source :
- Continental Shelf Research; November 1997, Vol. 17 Issue: 13 p1539-1560, 22p
- Publication Year :
- 1997
-
Abstract
- In coastal regions sheltered from the direct impact of swell- and storm-wave activity, locally generated wind waves, particularly those associated with strong sea-breeze activity, play a dominant role in controlling nearshore and foreshore processes. Field data collected from the Perth Metropolitan Coast (western Australia) during a typical summer sea-breeze cycle, are presented. It is demonstrated that the nearshore environment responds rapidly to an increase in wind speed (up to 12 m sā1) during the sea breeze, resulting in considerable changes to the nearshore hydrodynamics and morphology. Incident wave energy increased during the sea breeze and was associated with development of a wind-wave field with significant wave heights up to 0.9 m. Nearshore currents responded to this change in wave climate with the development of net offshore near-bed currents and a rapid increase in the mean longshore current from < 0.05 m sā1 to 1.0 m sā1 A 10-fold increase in suspended sediment concentration and a 100-fold increase in the longshore sand transport resulted from the effects of the sea-breeze system. Erosion of the beachface was coincident with the development of the wind-wave field. Sea breeze wave-driven water circulation also completely eroded beach cusps (wavelength 20ā30 m), overwhelmed the rip current system associated with the beach cusps and suppressed the infra-gravity wave frequencies in the incident wave and swash record. The beach cusps reformed after the cessation of the sea breeze. It is demonstrated that the beachface is in a constant stage of adjustment to the incident wave energy through the diurnal sea-breeze cycle alternating between dissipative and reflective morphodynamic regimes. The results may be used to determine the impact of a medium-sized storm on the beachface. It is clear that the sea-breeze system plays a major role in controlling the nearshore and foreshore processes not only in this region, but also on other geographic locations where strong sea breezes are present.
Details
- Language :
- English
- ISSN :
- 02784343
- Volume :
- 17
- Issue :
- 13
- Database :
- Supplemental Index
- Journal :
- Continental Shelf Research
- Publication Type :
- Periodical
- Accession number :
- ejs3064823
- Full Text :
- https://doi.org/10.1016/S0278-4343(97)00016-2