Analysis Of Poyang Lake Water Reflection Spectrum And Research On The Quantitative Inversion Of Suspended Sediment

Poyang Lake is the largest freshwater lake in China, is also one of the most important waterresources in our country, which has great significance in both ecological environment andeconomic society aspects. As a result, construction of Poyang Lake Eco-economic Zone has risento national strategy, and it is important to monitor and protect Poyang Lake. As an important waterquality parameter, the suspended sediment is one of the quality indexes of water environment.Along with the economic and social development and the progress of remote sensing informationtechnology, remote sensing technology is becoming more and more widely used for waterenvironment monitoring and quantitative inversion of water quality parameters, the method ofwhich is also growing mature. Based on this, the paper has carried on the analysis of the regionalspectral reflectance characteristics, as well as the quantitative inversion of suspended sedimentconcentration, with data obtained through field investigation in research area of Poyang Lake andlaboratory processing.According to the measured data, law of suspended sediment concentration and particle sizedistribution in the research period, as well as relations between the two were analyzed. In themeantime the paper analyzed the spectral reflection characteristics of the study area, and theresponse relationship between reflection spectra and suspended sediment concentration, as well asparticle size change. The paper also has carried on the simple classification to spectral reflectancecurve, including broad peak type and narrow peak type, corresponding to different suspendedsediment concentration, particle size distribution and water features.The spectral characteristics of the study water conform to the reflection law of typical case Ⅱwater, the spectral reflection curve of which has two obvious peaks. Suspended sedimentconcentration and reflectance has good response. Along with the suspended sedimentconcentration increasing, the water reflectance gradually rise, and the first reflection peak movestowards the long wave direction, ranging from575nm-605nm, whose peak value draws nearer tothe growing value of the second reflection peak, located at about775nm. Suspended sedimentparticle size is negatively related to the spectral reflectance, and the greater the particle size is, thelower the reflectance is.Reference for the research achievements of former researchers, this article has probed into thesensitive wave bands of suspended sediment concentration and particle size, on the basis of whichthe sediment concentration, particle size, and particle size distribution quantitative inversion models in different forms are established, using different remote sensing factors, and the modelprecision is verified. The best Landsat8sensitive wave band of suspended sediment concentrationis the ratio of the near infrared band and the green band. With this band the binomial model of allthe sediment concentration inversion models and the power model of all the grain-size-consideredsediment concentration inversion models turn out to be best accurate, whose R2are respectively0.9848and0.9852, and RMSE are respectively0.0094and0.0187. Normalizing with grain sizecan effectively increase the precision of all grain-size-considered suspended sedimentconcentration models. The best Landsat8sensitive wave band of suspended sediment particle sizeis the ratio of the red and the green band. With this band the exponential model of all the suspendedsediment particle size inversion models turns out to be best accurate, whose R2is0.6434, RMSE is0.9575. The accuracy of particle size distribution inversion models is overall poor, of which theexponential model is relatively better.Selected models are applied on preprocessed remote sensing image shot two days later afterthe survey, gaining distribution images of suspended sediment concentration and particle size,which show same distribution law of measured date.