The Inversion Algorithm Research Of Water Constituents In Three Gorges Dam Water

Three Gorges Dam water was chosen as the study subject in this paper,based on the water spectrum reflectance in situ and the absorption characteristics of the water constituents (chlorophyll,suspended substance,and Colored dissolved organic matter) we analyzed,we established the relationships between water spectrum reflectance and water constituents' concentrations.With the experiential method and semi-analysis method respectively,the water constituents' concentration inversion models were established and applied in the hyperspectral/multiangular remote sensing data-CHRIS.The research offered certain foundations for water quality remote sensing monitoring real-timely,promptly,efficiently, accurately in the future,consequently to protect and improve the environment of the Three Gorges Area.The study has led to the following findings and conclusions:1.The absorption spectra of total particulate matter in the Three Gorges Dam water is similar with that of the non-algal particulate matter,and the absorption coefficient decrease power exponentially from short to long wavelength;the contributions of phytoplankton and non-algal particulates in different wavelengths are different and the proportion of they contributes is not invariable,which is a variable related with wavelength.2.The absorption spectra of non-algal particulate and Colored dissolved organic matter (CDOM) decrease exponentially from short to long wavelength.We used 440nm and established the non-algal particulate absorption model and CDOM absorption model between the wavelength and the natural logarithm of a(λ)by non-linear regression with the measured absorption spectrum.3.The absorption coefficient of phytoplankton has a better polynomial relationship with chlorophyll a concentration in Three Gorges Dam water,which is different from Taihu and otherⅡclass &Ⅰclass water.While in other water,the absorption coefficient of phytoplankton has power,exponential relationship with chlorophyll a concentration.4.Based on the correlation analysis between the water constituents' concentrations and water spectrum reflectance,we chose the beat sensitive band and established the water constituents' concentrations inversion models.With the hyperspectral/multiangular remote sensing data-CHRIS in different times to analyze the precision of those models,the results show the precision and the time expansibility of the chlorophyll concentration,dissolved organic carbon (DOC) concentration inversion models are better.5.Based on the contrition analysis of the water constituents to water absorption and back-scattering coefficient,with the Gordon model,we established the semi-analysis water constituents' concentration inversion model of the Three Gorges Dam water.We obtained the concentration of the chlorophyll and suspended substance by the algebra method.The results show that the inversion precision of the suspended substance concentration was better than that of the chlorophyll concentration.