From July 30th to mid-August in 2010, there happened red tide in the Shenzhen coastwise. Although the max area was
only 15 km2
, but it caused the close of the nearby seawater baths which had directly affected people's daily life and the local
tourisms. This paper takes HJ-CCD multi-spectral remote sensing image and MODIS remote sensing image as major data,
studies the method of extracting red tide information of Case 2 waters in coast zone, applies it to the Shenzhen near-shore
and the Pearl River Estuary, and finally compares the results.