Visual Image Interpretation

Often the first step in a remote sensing change detection study investigating coastal dynamics is to delineate the actual coastline from theavailable images. This can often be a difficult task, partly because of the uncertainty over what is and is not the coastline. Whilst it may appear to be common sense to use the water line (where sea meets land) as the best indicator it may not be that easy in tidal environments. Many agencies employ the mean high tide (high water mark) position as the definitive coastline. Remote sensing instruments, however, make an instantaneous measurement at the time of overpass and satellite orbits are not designed to correspond to tidal cyles! Obviously, the timing of data acquisition is an important consideration in coastal environment remote sensing applications.