Cross-shore sediment transport under breaking solitary waves

Abstract

Laboratory experiments were performed to examine the cross-shore sediment transport processes under breaking solitary waves on a fine sand beach. The initial beach slope of 1/12 was exposed to a positive solitary wave eight times. The beach was rebuilt and exposed to a negative solitary wave eight times. The wave motion and sediment transport were not affected much by the beach profile change from the initial profile. The positive solitary wave plunged violently near the shoreline and suspended a considerable volume of sand. The plunging wave with no seaward flow impeding its run-up caused large run-up on the foreshore. The strong downrush following the large run-up resulted in erosion on the foreshore and deposition seaward of wave run-down. On the other hand, the negative solitary wave collapsed against the seaward flow induced by the free surface slope of the negative wave and caused less sediment suspension. The wave run-up against the seaward flow was much smaller. The weak downrush following the small run-up resulted in deposition on the foreshore and erosion near the wave collapsing point. These limited laboratory experiments indicate the importance of the initial wave profile for swash sediment dynamics and the capacity of a single wave in causing noticeable beach profile changes. Copyright 2004 by the American Geophysical Union.