3.1 Extraction Method of Water Area
Using the multi-band pixel value comparison method to extract water
information and calculate water area. Using spectral characteristics of
water images to set thresholds, and extract lake water information,
calculate the mean area of the annual flood and dry season(Vahtmäe and
Kutser 2013). Landsat7 satellite broke down, repaired it, and the result
was consistent with the pixel values of adjacent pixels. After manual
visual verification, the extraction of water information is accurate.