CHANGES IN BEACH PROFILE MORPHOLOGY AFTER NOURISHMENT——A CASE FROM WESTERN AND MIDDLE BEIDAIHE BEACHES

Beach nourishment is widely adopted as a main measure to combat coastal erosion in Europe,the USA,Japan and other developed countries.Usually,beach profiles changes are obvious after the nourishment.Studying the morphological change of beach profiles can help us understand the relationship between the beach morphology and the driving force and assess the consequences of beach nourishment.In this paper,we presented the profiles measured at the western and middle Beidaihe Beaches before,immediately(in a month),3 months,6 months,9 months and 1 year after the beach nourishment.Immediately after the nourishment,the shoreline of the beach moved seawards for about 30m on average,then after 3 months,it retreated back significantly in the nourished area for about 7~14m.The unit erosion rate in most of the profiles,however,decreased gradually after 6 months,the beach berm was eroded by 4m only comparing to that after 3 months.The beach erosion after 9 months and 1 year of the nourishment was much less than before.In some of the profiles there is even siltation around the beach boundary.1 year later,the beach berm was broadened by about 12~16m comparing to that before nourishment.The ratio of sand preservation in the western and middle beaches reached 88.7% and 75% respectively,showing a great success.