Remote Sensing Study On Surface Sedimentation Characteristics Of Muddy Coastal Tidal Flat

The study of sediment types and grain size parameters of tidal flat are significant for indicating the change of sedimentary environment and hydrodynamic condition and it is also can be used to validate the scour-silt variation law of the beach. Restricted by natural conditions, traditional research method of tidal flat is not only time-consuming errort but also difficult to obtion widespread sediment information. Remote sensing technology has many advantages like informative, large-scale, multidate and not restricted by the terrain and compares with the traditional method, it has a huge advantage.Taking the tidal flat between Yunliang estuary and Chuandong port in the middle of Jiangsu province as study area, using the HJ-1A multispectral remote sensing image and field sampling data as data source to research the remote sensing inversion of sediment types and grain size movement tendency. The main content of this research and related conclusion are as follows:Firstly, by analysizing the correlativity of spectral reflectance and sediment composition contents as well as grain size parameters, choosing near-infrared band (0.76-0.90um) as the base band, establish the quantitative remote sensing inversion model of sand, silt, clay and mean diameter, sorting coefficient and skewness. The average relative error of sediment composition contents and grain size parameters inversion model are 19.85% and 11.00% respectively.Secondly, the sediment types distribution of study area presents obviously spatial differentiation characteristics, from land to sea, totally presenting as sand content increasing, silt and clay content reducing, sediment types transferring from sandy-silt to silty-sand. The main sediment types of the study area are silty-sand and sandy-silt fron north to south. Sand mainly distributes between Dafeng port and Chuandong port at south end of the study area and this is anastomotic with the hydrodynamic condition and sediment provenance.Thirdly, from land to sea, sediment grain size parameters totally present a spatial distribution tendency of mean diameter and sorting coefficient reducing, skewness increasing. That is to say, the sediment is getting coarser, sorting better and moving more positive.Fourthly, use the sediment grain size parameters spatial distribution of the layer obtained by remote sensing inversion to actuate the GSTA (Grain Size Trend Analysis) model and we get the tidal flat surface sediment space migration trend of the study area. Sediments of study area overall present a tendency of transporting to south and southeast along the shore. At middle upper of the tidal flat, Sediments mainly transporting to south and southeast along the shore and the transportation trend is a bit chaotic meanwhile appearing a transportation trend towarding the shore vertically in most area at bottom of the tidal flat. The result of the migration makes the flat silting and wilder.Fifthly, in order to reveal the local characteristics of sediment inversion more detail, paper chooses Sheyang estuary and Dafeng flat as representative regions to analysis the deposition characteristics. It is found that sediment types distribution and grain size transportation trend are more complicated. Small particles accumulate under the seawalls making the flat expands to the sea ahd it is consistent with the overall situation of the study area when far from seawalls.