کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4532332 | 1626162 | 2012 | 14 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Observations of alongshore variability of swash motions on an intermediate beach Observations of alongshore variability of swash motions on an intermediate beach](/preview/png/4532332.png)
Alongshore variability in swash motions – shoreline oscillations about the mean water level on the beach face – were investigated using video images and a high-resolution morphology survey on an intermediate beach. Under mild, swell-dominated offshore wave conditions, alongshore variation of up to 78% in significant runup height Rs (defined as 4 times the standard deviation of the swash time series) was observed. This variation was predominantly driven by energy at the incident (>0.05 Hz) frequencies (where most of the swash energy was observed), and, consistent with previous observations, was mainly controlled by changes in the slope of the beach face (measured at the mean swash location). However, alongshore patterning in wave breaking over the sandbar caused variation in the degree of wave dissipation along the beach and also resulted in alongshore changes to swash motions. Although alongshore changes in beach slope and wave breaking patterning over the bar were observed to be typically correlated, both were needed in a regression model to provide the best explaination of alongshore changes in Rs. At infragravity frequencies (<0.05 Hz), alongshore variability was not well associated either with changes in beach slope or wave breaking patterning. Low-mode edge waves were observed in the swash measurements and their contribution to the total energy spectrum was greatest near the location where a shoal was observed, suggesting this shoal may play a role in forcing. The edge waves may have contributed to the swash variability observed at infragravity frequencies. However, in these reflective conditions, the infragravity band plays a secondary role in controlling alongshore variations to swash motions.
► Alongshore changes to swash were related to bed slope and bar-induced wave breaking.
► The incident band of the swash was dominant and modulated most of these changes.
► Low-mode edge waves caused alongshore changes to infragravity swash motions.
► Low-mode edge wave contributions were greatest near the location of a shoal.
Journal: Continental Shelf Research - Volume 48, 1 October 2012, Pages 61–74