Research On The Remote Sensing Inversion Of Poyang Lake Surface Suspended Sediment Particle

Poyang Lake as China’s largest freshwater lake, plays a very important role in ecosystem regulating in Yangtze River Basin, and at the same time as the international important wetland, has the important practical significance of ecological protection and monitoring in Poyang Lake. Suspended sediment is one of the key water quality parameters, is one of the standards for water quality. Poyang Lake many waters near the people’s livelihood and by the effects of sand mining, cause the water turbid, also caused damage to Poyang Lake’s living environment of fish. Remote sensing technology as a macroscopical monitoring means, the large area and high aging monitoring possible. Based on this, in the waters of Poyang Lake as the study area, and the concentration of suspended sediment grain size data obtained by field survey in three periods of sampling and laboratory measurement, were investigated in Poyang Lake area and the establishment of spectral characteristics of suspended sediment particle inversion model.According to the size of the observed data of three kinds of distribution mode, the median diameter, average diameter and the modal particle size were analyzed, there was a good correlation between the median diameter and average size, particle size by concentration effect to a certain extent, in high concentrations of waters, particle size and concentration the negative correlation, but in the low concentration region correlation is complex. Poyang Lake measured spectral reflectance increases with the concentration of suspended sediment in the water and become larger; with the increase of suspended sediment concentration, the first reflection peak moves to longer wavelength, peak moving range of 575nm-605 nm, and the second reflection peaks near 775 nm increased gradually, close to the first reflection peak; Turbid zone reflectance increases with grain size increases, the clear water zone reflectance increases with grain size decreases, the particle size and the reflectivity of the relationship showed different trends in different sediment concentration of water.In this paper, the correlation between grain size parameters of different distribution mode and the remote sensing reflectance are analyzed, found in turbidity area, suspended sediment particle and reflectance were negatively correlated, limpid area was positively related; Correlation analysis with environmental satellite HJ-1A /1B satellite CCD image data band reflectance, turbid area the volume percentage of the grain size mode and the reflectivity better correlation based on correlation coefficient of about-0.6, the clear water zone based on median percentage of the grain size and the reflectivity is a strong positive correlation, the correlation coefficient was 0.8; analysis of the correlation of image single band, band average, band ratio and granularity, find the better inversion method, established the inversion model of suspended sediment; the turbidity area with power function and the clear water area of the polynomial function model to fit the highest degree, the coefficient of determination R2 were 0.4774 and 0.9102.Based on the research of regional research quasi synchronous remote sensing image preprocessing, the inversion model are applied, obtained the distribution map of suspended sediment particle size, and particle size distribution of the four season of change within the year were analyzed.