The Analysis Between Shore Erosion-deposition Processes And Influence Factors Of The Danzi Island Past50Years

With the effects of natural causes, such as wind waves and storm tides, the DanziIsland beach erosion is serious, and its area gradually decreases. In addition to theoverflow of trawl fishery, the vegetation is also seriously damaged, which made theDanzi Island beach severely exposed. Besides, it increased the erosive degree ofDanzi Island.This paper presents a data-based study of historical charts, the results of waveand current field numerical simulation, sediments, and storm tides by applying spatialanalysis and mathematical statistics analysis, in order to explore the process andfactors of coastal erosion in the Danzi Island from erosion-deposition variationcharacteristics and hydrodynamic action. The results are shown as follows:(1) Based on the analysis of ArcGIS softwares spatial analysis module and3Danalysis module, it can easily make the conclusion that the sedimentation area is muchlarger than the erosion area, and the sedimentation intensity is less than the erosionintensity in the study area. Besides, the erosion area around the Danzi Island isdistributed mainly over the zonal distribution in the west side of the island within5mdepth and the east side of the island within10m depth. As a whole, the erosion ratehas decreased; the erosion-deposition variation has shown a periodic change. Andthere is a balance among the erosion area, the sedimentation area and the depositionarea.(2) Comparison of the typical profile of the data showed that the upper parts ofprofile eroded, the lower parts silted in the coast of the Danzi Island. Differenterosion-deposition profiles have different erosion-deposition of conversion depth. Theerosion-deposition conversion often occurred on1.2m of the profile within the2mdepth. The difference of erosive intensity and deposition intensity resulted in the variation of erosion-deposition conversion in the profile.(3)The Coast of Danzi Island suffered severe erosion by the effects of marinedynamics. Erosion was mainly caused by waves in the west side of the Danzi Islandand the profile of erosive intensity reduced with depth increased.The dominantwind-direction of Storm surge was ENE, which caused the water level increasing inthe sea area of the Danzi Island. The mountainous waves which were generated in thestrong wind roles can cause seawater to flow, and which impacted on the Danzi Islandcoast, and disturbed the transport of submarine sediments, and caused coastal erosionin the southeast and northeast side of the Danzi Island.The presence of the trend haslittle part in the erosion of the Danzi Island.