A laboratory experiment consisting of 5 tests was conducted to examine the effects of woody plants on erosion and overwash of high and low dunes. Scarping occurred on the foreslope for three high dune tests and no scarping occurred for two low dune tests. A narrow vegetation zone on a steep backslope of a high dune did not reduce wave overtopping and overwash in comparison to the corresponding bare dune. A wide vegetation covering the high dune reduced foreslope scarping, prevented wave overtopping initially, and reduced sand overwash after the initiation of wave overtopping. A wide vegetation zone covering an entire low dune reduced dune erosion by retarding wave uprush and reducing wave overtopping and overwash.

No abstract

Sand dunes play a significant role during coastal storms by absorbing the impacts of storm surge and high waves. Therefore, rapid profile changes and destruction of sand dunes, which may be caused by wave-induced overwash, lead to an increased flood risk landward of dunes. The effects of vegetation on dune erosion and overwash during storm events, however, have never been studied. This study is based on a laboratory experiment investigating the effects of woody plants on dune erosion and overwash of high and low dunes. During the five tests conducted foredune scarping was observed for the three high dune tests but did not occur for the two low dune tests. A narrow vegetation placed on the steep backdune of the high dune did not reduce wave overtopping and sand overwash. However, the wide vegetation figuration, which covered the backdune and foredune, reduced foredune scarping, prevented wave overtopping initially and reduced sand overwash after the initiation of wave overtopping for the high dune. It also slowed down the erosion process of the low dune significantly by retarding wave uprush and reducing wave overtopping and overwash.

No abstract

No abstract