HYDRO 2016 Paper 7A3

Use of laser bathymetry at the German Baltic Sea coast

Wilfried Ellmer


In order to study the recent technological development in laser bathymetry, and to investigate its usability for hydrographic surveying in the Baltic Sea, the BSH (Bundesamt für Seeschifffahrt und Hydrographie) executed a three-year scientific project.

The German Coastal Waters are quite shallow. The idea arose to use airborne laser bathymetry (ALB) for hydrographic surveying of near-shore areas of the German Baltic Sea. Since these waters are relatively turbid, it became necessary to investigate to what extent modern ALB systems can be of practical use in an area large enough for hydrographic purposes especially in the Baltic Sea. The basic question to be answered by the project was: Which areas can be measured by this method, and how expensive will this be in relation to traditional methods?

From 2012 to 2014, four test surveys have been accomplished in an area north of Wismar. During these surveys, many relevant questions have been solved. In the accompanying scientific studies, turbidity measurements were evaluated in order to expand the findings from the test area to the whole German Baltic Sea coast. Thus, it could be estimated which areas were candidates for future bathymetric airborne laser scanning projects.

The main conclusion is that bathymetric airborne laser scanning will not replace traditional hydrographic surveys as such, but will be an important supplement in shallow areas with minor importance for mariners. ALB has its advantages in these areas to derive a full coverage survey with fewer costs compared to hydroacoustic methods in shallow near shore waters. Disadvantages like poor object detection and seasonal dependencies have to be taken into account. Special attention has been paid to a sophisticated data processing. For a cost-effective use of ALB in the areas in question, a collaboration of different agencies and users is essential.

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