Analysis Of Spectral Characteristics And Spatiotemporal Distribution Of Black And Odorous Water Bodies In Langfang City

The safety of water environment is closely related to human survival,and its impact on environmental safety is huge.With the continuous development of our country's economy,in recent years,the water quality of some rivers and lakes in our country has been continuously deteriorating,and the water body has become black and smelly.The black and smelly water in the city is a serious damage to the environment and it is a huge threat to the quality of life of the people living in the city,seriously affecting the life safety and health of the residents.With the increasing quality of life of residents,people are paying more and more attention to the issue of black and smelly water.With the development of remote sensing technology,its convenience and efficiency have gradually made up for the shortcomings of traditional black and smelly water monitoring.Satellite remote sensing can achieve long-term and continuous monitoring of water bodies at long distances,and remote sensing images cover a wide area,and the monitoring range is larger than traditional methods.For some remote areas or dangerous areas,remote sensing images can also realize the monitoring of black and odorous water bodies.,Thereby reducing the consumption of a lot of human and material resources.Experts and scholars can use remote sensing images to identify black and smelly water bodies,and long-term supervision on the basis of identification,so that they can clearly know how the black and smelly water bodies are distributed in the study area and how the black and smelly water bodies are distributed in various time areas.Use these data to study the law of black and smelly water bodies in the study area.In this way,on the one hand,the effectiveness of the treatment of black and odorous water bodies can be effectively evaluated,and on the other hand,data can be analyzed in areas with high incidence of black and odorous water bodies and seasons,which is conducive to long-term supervision of black and odorous water bodies and is convenient.Follow-up governance work.For the black and smelly water bodies,most of them are small water bodies within the scope of the county,with the characteristics of relatively scattered distribution.In this study,the study area was set up in Langfang City and its surrounding areas in Hebei Province,and a number of comprehensive remote sensing experiments on water bodies in the field were designed and carried out.The data obtained in these experiments were used to study the black and smelly water bodies in Langfang City.Due to the many shortcomings of traditional methods,this study is based on the Sentinel-2A satellite image in May 2020,using the CART fuzzy decision tree algorithm to synthesize the typical black and smelly water identification index to summarize the typical characteristics,and realize the black Construction of odorous water body recognition model.The main research results and conclusions of this research are:(1)Identify black and odorous water bodies based on several typical black and odorous water body discriminant index models,analyze the results,and find that these methods based on single spectral reflectance characteristics have certain fuzzy intervals in actual identification.The recognition accuracy in the fuzzy interval is very poor,so the fuzzy decision tree model is used to solve this problem.Combined with the research,the fuzzy decision tree model is selected,and the black and odorous water spectral reflectance characteristics used to establish the fuzzy decision tree model are studied.(2)Based on the reflectance characteristics obtained in the above experiment as typical characteristics,construct the fuzzy decision tree model,and use the decision tree to select excellent features.Using the decision tree model to distinguish the test samples in the study area Langfang City,the recognition accuracy rate reached 85%.The migration verification of the decision tree classification model was carried out,and Tongzhou City was used as the experimental area for migration verification.The identification accuracy of black and odorous water bodies in Tongzhou City reached80%.Analyzing the recognition accuracy of the fuzzy area and the definite area in these two experiments,it is found that the fuzzy decision tree model has an excellent recognition accuracy rate in the definite area.(3)Use the fuzzy decision tree classification model to analyze the spatial and temporal distribution of black and odorous water bodies in Langfang City.The areas with more serious black and odorous water bodies in Langfang City are Anci District and Wen'an County,while Sanhe City and Gu'an County have relatively good water environments.The second quarter of each year is a period of high outbreaks of black and odorous water bodies.At this time,the monitoring of black and odorous water bodies should be strengthened.Research on the causes of the formation of typical black and odorous water bodies in various regions found that the black and odorous water bodies caused by industrial wastewater have better intervention,while the black and odorous water bodies caused by residents' domestic sewage require long-term treatment.