Record Details
Beach foreshore response to long-period waves in the swash-zone
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Beach foreshore response to long-period waves in the swash-zone |
| Names |
Howd, Peter A.
(creator) Holman, Robert A. (advisor) |
| Date Issued | 1984-02-10 (iso8601) |
| Note | Graduation date: 1984 |
| Abstract | A field experiment designed to test the hypothesis that infragravity and lower frequency waves influence the patterns of erosion and deposition on the beach foreshore has been carried out. The data show coherent fluctuations in the foreshore sediment level which can be related to low frequency wave motions. The fluctuations have heights of up to 6 cm with typical time scales of 8 to 10 minutes. They can be characterized in two ways: by the progression of the fluctuations up the foreshore slope (landward), and by the decrease in the RNS height of the fluctuations as they progress landward. The velocity of migration also changes as the fluctuations progress landward. Analysis of runup time series obtained by time-lapse photography concurrent with the sediment level measurements reveals long-period waves of undetermined origin at frequencies and phases which strongly suggest that the waves force the original perturbation in sediment level. In order to better understand the characteristics of these sediment level fluctuations, a numerical model of sediment transport on the foreshore has been developed. Gradients in sediment transport define erosional and depositional areas on the foreshore. Runup velocities were modeled and the results were used in the sediment transport model. The model predicts that any perturbation in foreshore elevation will progress landward while decreasing in amplitude and in velocity, thereby matching the field observations. Relationships between beach slope and the profile response clarified by this model are used to explain the initial formation of the perturbations of sediment level. |
| Genre | Thesis/Dissertation |
| Topic | Beach erosion |
| Identifier | http://hdl.handle.net/1957/27799 |
