CHANGES IN SEDIMENT GRAIN SIZE BEFORE AND AFTER BEACH NOURISHMENT IN MIDDLE BEIDAIHE BEACH

The data of this article are from the beach nourishment project in Beidaihe of Qinhuangdao. Surface samples were collected in different periods for dry sieving analysis. Changes in sediment grain size distribution pattern and their influence on a nourished beach were studied with grain size parameters as a main tool combining with Gao-Collins grain size trend analysis. Results showed that after sixth months of beach nourishment, the new beach sediments became finer and better sorted, due to the influence of nourishment and the southeast summer wave as well as the mixing of nourishing materials with the original beach sediments. In contrast, the trend of grain size variation was opposite beyond the nourished zone. As a result of the increase in winter storm wave, the nourished zone was eroded and beach sediments became coarser and worse sorted after ninth months of nourishment. After fifteen months of nourishment, however, beach sediments became finer again and the eroded beach was recovered to some extent. The net sediment transportation was then perpendicular to the coast instead of the alongshore transport. The beach reached a balanced status after one year of nourishment.