Remote multispectral imaging for nearshore bathymetry

Simultaneous signatures of nearshore bottoms have been obtained using multispectral scanning sensors in a low altitude aircraft and in the LANDSAT 2 Satellite, The signatures were taken in nearshore environments ranging from an ocean front to the shallow waters of an enclosed bay. The water turbidity had absorption coefficients ranging from 0.15 to 1.60 and scattering coefficients ranging from 0.07 to 0.87. Using points of known depth the signatures have been analyzed by means of a simple algorithm to establish depth at a large number of other points in the scene. Lines of these points have been compared to transects obtained by a precision acoustic fathometer. The low altitude aircraft results demonstrate potential capability for accurate mapping of nearshore bottoms where the bottom reflectances are reasonably consistent. The technique is also useful on multispectral signatures obtained from LANDSAT satellites although the areal resolution is less by a factor of approximately 700 and the mapping results are more subject to degradation by cloud cover.