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3.Results
Application of the acquired imagery have been carried out
with the existing hardware and software to the following
problem areas:
1) Water Sedimentation
The tidal environment of Wilhelmshaven creates a number of
sedimentation problems for the Ship channel or the beaches
and coastal structures of the adjacent East Friesian Islands.
While sand transport occurs at depth,
particles can be made visible in remot
at or near the surface of the water.
only suspended clay
e sensing imagery
Particularly the red spectral band permits to discern water
bodies composed of different levels of clay concentration.
Such images permit to determine the direction of flow.
Visual observation of images of coastal Structures
has shown, for example, that such Structures have not been
build in an optimal position with respect to the direction
of flow; most likely this has occured due to mistakes in azimuthal
recording of in situ current meters or due to errors of navigation
and interpolation.
Lines of flow can be seen as boundaries of water bodies
with different sediment concentration, if the images are
digitally processed for derivation of level slices of
second order. Lines of flow will then appear as contour lines
in the processed image, Such information is particularly
useful for the comparison of image scenes taken at different
intervals of the tidal cycle.
It is finally also possible to measure sediment concentration
at the water surface by correlating it to reflectance.
To make this correlation possible extensive laboratory
and field tests have been carried out. For varying light
levels (determinable by measuring global radiation of the sky)
samples of known sediment concentration have been used
to establish conversion curves relating reflectance with
sediment concentration.
Tests of this kind have proved successful; harbour engineers
cannot, however utilize this information in their sedimentation
models, since their aralytical approach so far has been too
simple.