A GIS-based method of red tide hazard degree assessment

To calculate and analyses the spatial distribution of red tide hazard degree and the probability of red tide outbreak, a geographical information system (GIS)-based method was proposed based on the hazard degree assessment model and the in-situ conventional monitoring data in Bohai Bay conditions. The results indicate that the spatial distribution of red tide hazard degree in Bohai Bay presents an annular band around the shore, and that from near-shore waters to open waters, the red tide hazard degree first increases and then decreases with the increase of the distance from shore. The red tide hazard degree within the optimum distance accounts for the high-hazard degree areas (“red”, “yellow”, H=0.5-1), while the low-hazard degree areas (“blue”, “green”, H=0-0.5) are found in the near-shore waters and open waters.