| In the past three decades,there have been three major bleaching events around the world.Coral reefs are under unprecedented pressure to survive.There is still a lack of an effective method to extract the spatial distribution of coral reef in the complex near-shore water environment.The research area is sanya coral reef national nature reserve.On the spectral reflection characteristics of benthic material such as coral and carries on the summary analysis,spectrum index found near 700 nm wavelength red edge band reflection characteristics of chlorophyll in water can be used as the key to build reefs information extraction threshold segmentation,in order to build to adapt to the complex coral reefs in the aquatic environment of information extraction threshold segmentation.Based on the sentinel-2 image,the spatial distribution of coral reefs in sanya was extracted by the fixed threshold segmentation method.Confounding matrix and Kappa coefficient were used to verify the accuracy of the extraction results.The extraction accuracy based on threshold segmentation method was 87.8%.The spatial distribution of coral reefs in sanya was analyzed by landscape shape index and standard deviation ellipse.The influence index of natural factors on the spatial distribution of coral reefs was established by the comprehensive index method,and the influence relationship and degree of natural factors on the spatial distribution of coral reefs were analyzed.The spatial distribution of coral reefs in sanya is caused by the combined action of wind direction and slope direction.The results show that the fixed threshold segmentation method can effectively extract the coral reef information.The accuracy of the extraction in dongximao island area and yalong bay area is high,while the accuracy of yulin bay remains to be improved.The main factors affecting the spatial distribution of coral reefs in sanya are slope and slope direction.Figure 34;Table 13;Reference 64. |
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