| Popis: |
Monthly elevation surveys of a 1.5 km stretch of coast at Noordwijk, the Netherlands, were made (1) to quantify seasonal variability in the cross-shore position of high-, mean- and low-tide contours, beach width and beach volume, and (2) to examine the dependence of the variability on the offshore wave characteristics. Additionally, daily cross-shore positions of contours obtained from video images were used to examine daily beach response to wave characteristics between successive surveys. The more intense and frequent storm events in winter than in summer resulted in a seasonal change from a wide beach with a small volume at the end of winter to a narrow, large-volume beach in summer. The seasonal pattern in beach width resulted from the cross-shore sediment exchange between the supratidal and lower-intertidal part of the beach. In contrast to the coupling between beach behaviour and wave characteristics on a seasonal scale, beach variability between successive surveys was unrelated to day- to week-averages of the preceding offshore wave conditions partly due to the precise timing of a storm relative to the two survey moments. Moreover, daily variability determined from the video images showed that differing antecedent morphology to storms and alongshore variations in beach morphology contributed to spatially and temporally variable beach response. |
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