The Study Of Sedimentary Characteristics And The Erosion And Deposition Environment Evolution In Dengzhou Shoal

Based on the grain size and detrital minerals data of the surface sedimentsamples in the Dengzhou Shoal, we investigated the surface sediment characteristicsand the sediments’ transport trends. By use of the topography data and the numericalsimulation results, we analyzed and forecasted the erosion-deposition environmentevolution in the Dengzhou Shoal.The grain size data shows that there are15sediment types in the study area andalmost all the surface sediments show a trend of migrating to the Shoal. So theDengzhou Shoal became the sink of the sediments in the study area. The detritalminerals results show that the heavy mineral assemblage in the study area ishornblende-epidote-schistose minerals-metal minerals-garnet-staurolite, and the lightmineral assemblage is quartz-feldspar-carbonate minerals-glauconite.Besides, we analyzed the scouring and silting changes in the study area with thetopography data collected in1974,1990,2004and2010. We found that from1990to2004, the scale of the Shoal began to restore, for the halt of the dredging. However,during2004to2010, the Shoal started to retreat, and we deduced the retrogradationmight be related to the dredging behavior in personally. In addition, based on thenumerical simulation method, we analyzed and predicted the influences of theartificial island project in the Penglai west coast on the hydrodynamic environmentand erosion-deposition environment in Dengzhou Shoal. The results indicate theconstruction of the artificial island will strengthen the velocity of the tidal current andenlarge the erosion area in the Erri Island of Dengzhou Shoal. While in contrast, itwill decrease the tidal current velocity and the erosion area in the Siren Island ofDengzhou Shoal.Combining the evolution of the erosion and deposition trend in the DengzhouShoal with the surface sediments migrating features, we concluded that the artificialisland construction will block sediments supply for the Dengzhou Shoal, and will increase the degree of erosion in the Erri Island in Dengzhou Shoal. So the artificialisland construction will influence the stability and restore of the Dengzhou Shoal.