Remote Sensing Classification And Recognition Of Urban Black And Odorous Water Based On Multi-source High-resolution Images

In recent years,with the rapid development of urbanization and industrialization in China,black and odorous water has become a serious urban disease,seriously affecting the healthy life of urban residents.It is urgent to monitor and improve urban black and odorous water.Traditional methods of monitoring black and odorous water are time-consuming and laborious,and can not meet the urgent requirements of water quality monitoring in a wide range in China.Remote sensing monitoring technology,with its advantages of large scale,long time series,low cost and high efficiency,provides a new technical means for the monitoring of urban black and odorous water.However,there are few studies on monitoring urban black and odorous water by remote sensing.The existing remote sensing recognition algorithms can only recognize black and odorous water,but can not classify the pollution degree of black and odorous water,and can not provide detailed water pollution status.In addition,in the research of using high-resolution images to recognize urban black and odorous water,there are some problems,such as low efficiency of fine extraction of urban small water,low temporal resolution of single high-resolution image,and so on.Therefore,a series of field water comprehensive experiments were carried out in Shenyang and Beijing built-up areas.Comparing and analyzing the water quality parameters and spectral characteristics differences of heavy black and odorous water,light black and odorous water and general water,a model of Black and Odorous water Classification Index(BOCI)was proposed.Then the BOCI model is compared with the existing recognition model of black and odorous water.Aiming at the low efficiency of fine extraction of urban small water,a method of extracting black and odorous water based on the river center line is proposed and its feasibility is analyzed.Then,the applicability and classification precision of BOCI model are analyzed by using measured spectral data and multi-source high-resolution images.Finally,the BOCI model was used to monitor the black and odorous water in Shenyang in a multi-temporal dynamic manner,analyzing the distribution characteristics of the black and odorous water,and evaluating its control effect.The main achievements and conclusions of this paper are as follows:(1)According to the difference of reflectance spectral characteristics between heavy black and odorous water,light black and odorous water and general water,a urban Black and Odorous water Classification Index(BOCI)is proposed based on GF-2 image.The model is validated by ground measured spectral data.The results show that the BOCI model can distinguish the heavy black and odorous water from the light black and odorous water,solve the problem that the existing remote sensing recognition model of the black and odorous water can not classify the pollution degree of black and odorous water.(2)The applicability and classification precision of BOCI model is evaluated by using measured spectral data and multi-source high-resolution images.The results show that the BOCI model based on GF-2 image is also applicable to GF-1,ZY-3,BJ-2 and Gaojing-1 images.Meanwhile,the BOCI model can be applied to other satellite images that has similar visible band settings with GF-2 sensor.(3)In this paper,the water quality of the river center line is chosen to replace the water quality of the river surface.A method of extracting black and odorous water based on the river center line is proposed.Experiments show that compared with the traditional method of extracting black and odorous water based on fine water extraction,the accuracy of the method of extracting black and odorous water based on the river center line can be guaranteed,and the extraction efficiency has been significantly improved.This study solved the problem of low efficiency of fine extraction of urban small water,and was beneficial to the operational application of remote sensing monitoring of urban black and odorous water.(4)Using the BOCI model proposed in this paper,the dynamic monitoring of black and odorous water in Shenyang was carried out.The results show that the black and odorous water in Shenyang is mainly distributed in Yuhong district,Heping district,Tiexi district and Huanggu district,among which the black and odorous phenomena in Heping and Yuhong districts are the most serious.The total length and total area of black and odorous water in Shenyang show a decreasing trend year by year,which shows that the black and odorous water treatment measures in Shenyang are effective.