Retrieval And Application Of Remote Sensing Water Quality Of Complicated Water Body In Coastal Zone

The Hangzhou Bay area contains a variety of typical complex water bodies,and its water quality is not only affected by natural phenomena,industry,agriculture,tourism,urbanization activities and population growth.This study focuses on two important water quality parameters for studying water bodies in the region,TSM(total suspended matter)and CDOM(colored dissolved organic matter),which play a key role in the aquatic environment.In this paper,the TSM,CDOM absorption coefficient and water body remote sensing reflectance spectrum of the Hangzhou Bay area were measured on site,and the Landsat-8 image was synthesized.The relationship between the absorption coefficient of CDOM and TSM and the remote sensing reflectivity was studied.Furthermore,the spectral characteristics of water bodies in different regions and the TSM inversion are applied to the hyperspectral range,and the causes of CDOM inversion are analyzed.In the West Lake area of Hangzhou,the performance of different atmospheric correction models on the Landsat-8 satellite data was tested.It was found that the 6S atmospheric correction model had good correction results;and all possible band combinations of the TSM and CDOM absorption coefficients of the field sampling spectra were inverted.It was found that the model did not work well for CDOM.For TSM,the best function form is exponential form,the best model input is Band1/Band2,the best band range of Band1 is 600?720 nm band,and the best band range of Band2 is 500?535 nm band.By comparing the range of the Landsat-8 band with the optimal band combination,it is found that the best band combination of Landsat-8 is red band and green band,and the TSM remote sensing inversion model of Landsat-8 is ap(440)= 51.17·e-7.75x,x=(OLI3-OLI4)/(OLI3+OLI4).After constructing the Landsat-8 region inversion model,it is applied to remote sensing images to analyze the spatial distribution characteristics of TSM and CDOM obtained from remote sensing images.It is found that the TSM absorption coefficient in the main lake region is higher in each region,followed by Beili Lake.The Xili Lake is the smallest;while the spatial distribution,the TSM absorption coefficient decreases from north to south;in the time distribution,the monthly variation of TSM concentration is reduced from January to April,and increases from September to November.In the Xili Lake,the main lake and the Beili Lake area fluctuate from May to August.In the annual dimension,the average annual TSM of the West Lake is relatively stable.Based on the detailed analysis of the driving factors,it is found that there is a positive correlation between the tourism population and the TSM absorption coefficient in the study area,and the correlation between the rainfall data and the TSM absorption coefficient is not significant.In the Zhoushan waters,the field applicability of the TSM and CDOM optimal inversion algorithms is estimated.It is found that in the Zhoushan area,whether it is a reservoir or a sea area,the optimal empirical model for inversion of TSM is the exponential function model of band division.It is also recommended to use the green,red or near-infrared band for remote sensing inversion of TSM.However,for CDOM inversion,the applicability of the empirical model is not good.Through spectral comparison of the West Lake,Zhoushan Reservoir and Zhoushan Sea,it is found that there are different spectral characteristics at 570nm,670 nm,700 nm and 820nm,which are closely related to the internal matter of water.The TSM model has high applicability,but CDOM inversion is still difficult.The CDOM inversion is still a work that requires further research.