Application of Hy-1c Satellite Coastal Zone Imager in Island Reef Monitoring

Taking Yongle Atoll of Xisha Islands as the research area, the information extraction of reef landforms is studied by using the characteristics of HY-1C satellite wide-band, wide-spectrum and short revisit period. The calculation of CZI band histogram and signal-to-noise ratio shows that the images signal to noise ratio in the four bands of CZI of HY-1C satellite is 0.84 and the coverage value of the blue band is 28.53, which is the most obvious in the island landform, while the information of red band is not so obvious about the island reef. The payload CZI can express the information of coral reefs, and unsupervised classification method can be used to obtain the information of reefs, but the information of underwater reef flats is easy to be misjudged. In order to make full use of the band information of the HY-1C satellite, the weights of each band to the reef information expression are established by using the analytic hierarchy process (AHP). Based on the weight composite image, the information of reefs is extracted by supervised classification method, which will lead to effective extraction of information of natural islands, sandy beaches, underwater reef flats, hidden sand, gullies and so on. By consistency test, the Kappa coefficient can reach 89.97%, which can meet the requirements of large-scale and high-frequency island reef survey on the basis of medium-resolution remote sensing images.