ВЫДЕЛЕНИЕ ВОДНЫХ ОБЪЕКТОВ НА УХАНЬСКОМ УЧАСТКЕ РЕКИ ЯНЦЗЫ ПО ДАННЫМ ДИСТАНЦИОННОГО ЗОНДИРОВАНИЯ СО СПУТНИКА “GAOFEN-1”

In this study, the water body information on the Wuhan section of the Yangtze River was extracted by four different methods based on Gaofen-1 satellite images. The four methods are the shaded water body index (SWI) method, the normalized water body index (NDWI) method, the normalized vegetation index (NDVI) method, and the modified shaded water body index (MSWI) method. The numbers of pixels of the water body obtained by the four methods were compared with the data from the Hankou station of the Water Resources Bureau. The overall accuracy and κ coefficients of the four extraction methods were also calculated using the confusion matrix. The results show that the MSWI method has the best extraction effect. It was found through the comparison of the water area in 2021 and in 2022 that the drought conditions of the Wuhan section of the Yangtze River were quite severe in the second half of 2022.