Pipe laying operations
Combining the data provides detailed information too costly to obtain
from echosounding alone.
Radar images, such as those derived from the ERS-1 satellite, show the
bottom topography in swallow waters, when currents are present.
This figure shows the effect caused
by the underlying topography on the sea surface, and so on the intensity of
the returning radar signal.
Traditionally, pipeline laying operations follow these steps:
Today, tradition merges with modern techniques. One example is the Bathymetric Assessment System, developed in Holland, which combines echosounding and ESR-1 SAR observations.
Starting from radar imagery, a first-guess of depth is made using a relatively simple imaging model which describes how the radar can read the bathymetry. Based on this depth estimate, a detailed conventional survey is planned. The imaging model is used to reconstruct the final depths from radar imagery and using the conventional depth observations as standards.
The system has been used succesfully in surveying an area northwest of Zeebrugge,
off Hollands North Sea coast. This ERS-1 image
has been aquired over the area, on the 1st of September 1993. The yellow box
denotes the mapped area.
An absolute accuracy in the order of 30 cm has been achieved, which is
comparable to that obtained by most standars echosounders. Similar systems
can be used in other swallow water regions of the world.
Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry
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