Research On The Optical Characteristics And Remote Sensing Recognition Of Black And Odorous Water Bodies In Changchun City

In recent years,with the acceleration of China’s urbanization process and the rapid development of industry,black and odorous water bodies have become a common environmental problem in urban and rural areas.At present,the remote sensing recognition of black and odorous water bodies is mainly concentrated in southern regions such as Beijing-Tianjin-Hebei and the middle and lower reaches of the Yangtze River.The construction of remote sensing recognition algorithms for water bodies is relatively small.Therefore,this paper takes the black and odorous water bodies in urban and rural areas of Changchun City as the research object,firstly analyzes the water quality parameters,absorption coefficient and fluorescence characteristics of the black and odorous water bodies in Changchun City,then establishes the remote sensing identification model of the black and odorous water bodies,obtains the spatial distribution characteristics of the black and odorous water bodies in Changchun City,and preliminarily discusses the formation reasons.The research results and conclusions of this paper are as follows:(1)Analysis of water quality parameters and optical characteristics of black and odorous waterBy analyzing the remote sensing reflectance spectra of normal water body and water body with different degrees of black odor,it is found that the reflectance values of visible light band of most black odor water body are greater than those of non-black odor water body,and the reflectance values of severely black odor water body are generally higher than those of mildly black odor water body.In this study,black and odorous water bodies were divided into two types(black and odorous water bodiesⅠand black and odorous water bodies II)according to their spectral shape differences.The remote sensing reflectance curve of black and odorous waterⅠfluctuates gently in the range of 550～700nm,showing the scattering characteristics of inorganic suspended matter,and the reflectance peak is wide.The content of chlorophyll a in the black and odorous waterⅡis higher,and the fluorescence peak and absorption valley are displayed at 550 nm and 675nm,respectively.By comparing and analyzing the inherent optical characteristics of different black and odorous water bodies,it was found that the mean absorption coefficient of total suspended particulate matter,absorption coefficient of non-pigment particulate matter,absorption coefficient of pigment particulate matter and absorption coefficient of CDOM in black and odorous water bodies were higher than that in non-black and odorous water bodies to different degrees.Three-dimensional fluorescence spectra of black and non-black water showed that the black water had higher molecular weight,more humic acid and less fulvic acid in the water.(2)Construction of remote sensing algorithms for black and odorous water bodiesBased on the Jilin-1 satellite image and measured remote sensing reflectance,a method combining the color purity and transparency of water body based on remote sensing reflectance estimation was constructed.When the purity of water body is less than0.24 or the transparency is less than 25 cm,it can be judged as black and odorous water body.Based on the measured verification data and the satellite-ground matching data,the results show that the black and odorous water body can be identified stably and reliably in both urban and rural areas.The identification accuracy of black and odorous water body in urban areas is 71.43%,and the average identification accuracy of rural areas is 54.7%.The identification accuracy of black and odorous water body in urban areas is higher than that in rural areas.(3)Spatial distribution characteristics and influencing factors of black and odorous water bodies in Changchun cityThe spatial distribution of black and odorous water bodies in urban and rural areas showed that the main distribution of black and odorous water bodies in urban areas was rivers,followed by small bubbles located in suburban and rural areas.The distribution of black and odorous water bodies in rural areas is mainly bubble type.The distribution points and areas of black and odorous water bodies in urban and rural areas were compared and analyzed.Ten black and odorous water bodies in urban areas were identified,with a total area of 0.1957 km~2.The black odor in rural black water bodies is relatively large and dispersed.The black odor phenomenon occurs most in Yushu City,with a total area of0.5032 km~2,and the least in Jiutai District,with an area of 0.0857 km~2.Through field research,urban black smelly occurs mainly divided into beheaded river,sediment resuspension of oxygen,water,algae and aquatic plants rot caused by water in black smelly,rural black smelly phenomenon and poor water,life and industrial waste water discharge,garbage heap of the place,untreated waste and aquaculture water and planting industry pollution(such as fertilizers,agricultural residues,agricultural waste).