HYDRO 2016 Paper 3A4

Multibeam water column imaging for charting least depth value

Marco Filippone


Commercial maritime world expectation, mainly focus in trading between continents, is largely increasing during the past few years. This important developments could significantly alter the pattern of shipping in the near future in term of vessel building, logistic infrastructure and new seaways. The vessel size is increasing in order to maintain the market share, channel and straits are dynamically changing with the higher demand of passage. In this new scenario, the bathymetric data is inadequate or non-existent, with large areas either un-surveyed or surveyed with obsolete methods of measurement, were taken nearly a century ago.

It is therefore imperative that those governments and ports that are keen to herald the arrival of newer, larger vessels provide accurate bathymetric data to modern standards, where necessary, to ensure safe and navigable waterways.

The water column imaging is only part of large bathymetric data set can be collected with modern equipment and for different use (seeps detection, archeological feature analysis, wreak least depth definition).

WCD collected with high-resolution multibeam echo sounder and processed with the new state-of-the-art software, now available on the market (no more external tool for WCD identification) using internal algorithm, can significantly enrich the data set knowledge and assist during the quality control check. Wreck position and depth value (Z) listed on electronic/paper nautical charts must be provided within the best possible accuracy. Several number of methods can be used for identify the wreck least depth (side-scan sonar systems with backscatter interpretation, diving (not always possible) rudimentary methods (with higher risk of fail and bigger uncertainty) and of course WCD analysis). A combination of above methods is the suggested way to follow but the new software's available with WCD analysis tools are now supporting the cartographer for quality check better than other technique. Older data set, where WCD was recorded together with SSS or diving control/validation, can be reprocessed in order to increase the least depth accuracy. In this exercise, an older data set of several wreck, will be reprocessed and analysed in order to confirm that WCD method is the most accurate, safe and time-consuming method.

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