Sand dunes help protect coastlines during storms, but wave overwash can erode them, increasing flood risk. This study looked at how plants affect dune erosion and overwash. Tests showed that wide vegetation covering both the front and back of dunes reduced erosion and prevented wave overtopping. Narrow vegetation only on the back didn't help as much. High dunes with wide vegetation had less erosion and overwash, while low dunes were significantly protected by the vegetation.