Estimation of Shallow Water Bathymetry from Remote Sensing Data in Consideration of Variation of Water

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It is important to accurately estimate a water depth in shallow water from remote sensing data, since data on water depth in a wide region can be obtained with a cheaper cost. In existing researches on estimation of shallow water bathymetry, bottom reflectance and water attenuation coefficients are assumed to be uniform in shallow water, nevertheless they are varied by bottom materials and suspended particulates. In this investigation, a new method of estimating water depth have been developed in consideration of variation of water attenuation coefficients and bottom reflectance. In order to retrieve an effective information on shallow water bathymetry, a new noise reduction algorithm which includes an 4th-order partial differential equation for an absolute radiance logarithmic value has been developed. Spectral reflectances of sand bottom in shallow water is measured to evaluate water attenuation coefficients with the data of water depth along a reference line. Both the spectral reflectance of the bottom and water attenuation coefficients estimated are not uniform but slightely vary in a trough region. The water depthes shallower than 4m have been evaluated with SPOT/XS image data and these parameters. The estimated water depthes in the range of 600m distant bothside from a reference line have an error with the standard deviation of less than 0.4m.