Detection of Oyster and Groundwater Discharge in Tidal Flats Using Synthetic Aperture Radar

Tidal flat, a transition zone between the ocean and land, forms a unique ecosystem, providing the habitat for various specious of fauna and flora, which is very important in purifying pollutants discharged from land and in providing marine products such as oysters and many kinds of shellfishes [1]. Thus, monitoring and mapping of tidal flat is urgently needed for sustainable managements and the conservation of tidal flats. However, tidal flat is very tough place to access and investigate. Microwave remote sensing technique can provide broad spatial coverage and temporally regular observations. Most studies using synthetic aperture radar (SAR) – one of the microwave remote sensing – have been conducted to extract surface geophysical parameters on bare soils or on vegetation areas. Very few studies have been carried out for monitoring and mapping of tidal flats [2-4]. Tidal flats can also be considered as bare soil, but they are different from typical bare soil from an electromagnetic scattering point of view. Furthermore, benthic fauna habitats in tidal flats can form a relatively rough surface by their unique structure or their survival activities. So they can make distinguished scattering signatures which are different from the background mud or sand flats. In this study, we tried to extract the distribution of oyster reefs by analyzing their unique scattering characteristics from polarimetric SAR data. We also investigated why the oyster reefs can be generated naturally in these tidal flats.