Study On Models For The Estimation Of Suspended Sediment Concentrations In Taihu Lake Based On Experiment And Field Spectral Data

For the purpose of finding sensiteve band and building models for estimation of suspended sediments concentration(SS)under controlled experimental conditions,the sediments,which were collected at the bottom of Tai Lake,were used to mix with water to simulate water samples of different concentrations of suspended sediments.The spectrum reflectance was measured and water samples were collected simultaneously for water quality analysis in laboratory.This study adopts the measurement standard of surface water spectrum put forward by NASA,the radiance of water,sky scattered light and standard reflecting board was measured and transformed into remote sensing reflectance.An comparison between the models built by field data and experimental data was made so as to provide certain reference and theory to the inversion model for the concentration of suspended sediment.The results indicated that:(1)Under controlled experimental conditions,780-820 nm,740-775nm and 860-890nm,all of them have high correlation ralationship with SS;The best regression analysis is the linear model SS=11129*R1+1.59,R²=0.9939,p＜0.0001,where R1 is the average value of the reflectance spectrum of 780-820 nm.The remote sensing reflectance was processed by spectrum derivation with order 1,it is found that spectrum derivation at 522nm has the best correlation and the optimal model is linear model,and model is SS=1042135*de_R522+16.23,R²=0.9993,p＜0.0001,where de_R522 is the spectrum derivation at wavelength 522nm.The model based on ratio of the first and second spectral peaks also has high correlation with SS,and the model is SS= 198.25*(R580/R810)²-1067.6*R580/R810+1446.2,R²=0.83,p=0.0019.(2)For models based on the filed data in Taihu Lake,the analysis indicated that the best band ratio is R570/R811,and the model is SS=84.12*(R570/R811)^-0.95,which is different form the model under controlled experimental conditions,R²=0.7,p＜0.0001.The models based on reflectance spectrum and spectrum derivation with order 1 showed lower correlation with SS.(3)The analysis showed the two conditions have the similar sensitive band which is near 570nm and 810nm.However,the models of the two conditions are different with each other because of the difference in water component and hydrodymic conditions.