Based Geomorphology And Dedimntary Characterisitcs Aftr Nourishment

Beach nourishment has been regarded as the main measures to combat coastal erosion. It has been widely developed in many Foreign countries.In recent years, Our country has begun to attach importance to the beach nourishment, but the relative lack of experience and theoretical guidance. And most of them focused on the design and simulation for the nourishment lacking of the study on the evolution of the nourished beach which need to analyses the beach sediment, geomorphology, hydrodynamics, and ecology etc. after the project. In this paper, sediment and geomorphology of the west was studied in order to analysis the effectiveness of beach nourishment and provide the reference to the follow beach nourishment project.The article relies on the beach nourishment projects in Beidaihe of Qinhuangdao. Surface samples collected in different period were analyzed by dry sieving experiment and obtained the grain size parameters. The changes in sediment characteristics and its influence on a nourished beach were studied with grain size parameters as a tool combining with Gao-Collins grain size trend analysis. Data of beach profile in different period monitored by Electronic Total Station and bathometer were analyzed and mapped by RMAP associated with the long shore transport rate to analysis the variation between before and after the nourishment.The results showed that after the beach nourishment the new beach sediments tends to thinner and better sorted, Beach nourishment with good results. The net sediment transportation changed from along shore transport to vertical toward the shore transport; artificial headland has a positive effect in the stability of the beach nourishment. Nourishing materials gradually mixed with the original beach sediments, and influence on the grain size composition of the sediment s in the beach nourished and its nearby streams. But, the influence will fade out with time. After the nourishment, the shoreline immediately went seaward significantly as well as the widened berm, and retreated back in the filling area later especially during the earlier period. Eighteen month later, the filling with sand saves about 43%, nourishment area on the average boarding 15m, nourishment area outside t boarding llm. Erosion rate has slowed down significantly, showing a stable trend in the evolution of the beach; The impact of the long-shore transport (total annual net long-shore transport rate is about 4.18×104m3) on the beach geomorphology is greater than the cross-shore transport. Dominated orientation of the long-shore transport was from NE to WS resulting in various erosion in the filling area and deposition in the down-stream.