Extending USV surveying from offshore to inland waters

Extending USV surveying from offshore to inland waters

Subsea Europe Services’ expertise, equipment and fleet of uncrewed platforms are typically used for detailed surveys of offshore wind farms, coastal sites and harbours. However, the company undertook an inland project in March that highlights the versatility of its team and equipment.

The Chair of Physical Geography at the University of Greifswald initiated an environmental history research project on Lake Schwerin (Schweriner See in German) in collaboration with the Ministry for Climate Protection, Agriculture, Rural Areas and Environment of the German state of Mecklenburg-Vorpommern. This project aims to conduct morphological studies of the lake basin and nearshore areas, providing a detailed characterization of the seabed’s composition. An innovative approach was employed using an uncrewed surface vessel (USV), specifically the Subsea Europe Services-owned, MARTAC Systems-developed Mantas T12 system.

In March 2024, work began to survey a section of the Schwerin Outer Lake, collecting data to enhance existing bathymetric information. The surveyed area, covering 2.6km², included varied features such as shallows around one metre deep, an island and the lake’s deepest parts, reaching depths of up to 52 metres. The survey area was situated on the western edge of the Schwerin Outer Lake near Lübstorf.

Two bathymetric sensors for optimal results

The late winter/early spring period was chosen to minimize interference from submerged vegetation and to take advantage of high water levels and a less pronounced thermocline, which could negatively impact data quality. This timing is critical for capturing the clearest possible data on sediment surfaces, which will be used to map subaquatic structures and underwater habitats.

The project tasks included not only the deployment and operation of the USV but also the processing and digital visualization of the collected data, undertaken by Subsea Europe Services’ surveyors and data experts following the acquisition phase.

The flexibility of the USV was crucial in delivering high-quality data across the water depth range, necessitating the deployment of two different bathymetric sensors for optimal results: the R2Sonic Sonic 2026-V multibeam echosounder for deeper areas and the GeoSwath 4 from GeoAcoustics for very shallow areas.

The objective was to achieve comprehensive lakebed mapping, ensuring that the data collected met specified standards, regardless of water depth or external conditions. In addition to precision bathymetric data, backscatter data was collected to identify sediment properties.

This project serves as an example of Subsea Europe Services’ commitment to innovation and is aimed to enhance the understanding of Lake Schwerin and to test and evaluate future methods of hydrographic surveying in inland waters. The use of the USV marks a significant advancement in traditional surveying methodologies used on the lake, providing insights into more streamlined and cost-effective surveying practices.

View on Lake Schwerin. (Image courtesy: Sina Ettmer Photography/Shutterstock)
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