Foster-Smith, B.

Van Lancker, V.R.M.

Verfaillie, E.

Verfaillie, Els

Foster-Smith, B

Van Lancker, Vera

Ghent University Academic Bibliography

Analysis of bathymetrical derived features on the Belgian Continental Shelf as a support for marine habitat mapping

Open Marine Archive

  - 63 - 
ANALYSIS OF BATHYMETRICAL DERIVED FEATURES ON THE BELGIAN 
CONTINENTAL SHELF AS A SUPPORT FOR MARINE HABITAT MAPPING 
Verfaillie Els, Bob Foster-Smith, Vera Van Lancker 
1  Renard Centre of Marine Geology, Vakgroep Geologie en Bodemkunde, Universiteit Gent, 
Krijgslaan 281, S8, B-9000 Gent, Belgium 
E-mail: Els.Verfaillie@ugent.be 
2  Envision, University of Newcastle 
Newcastle upon Tyne, United Kingdom 
 
Applications of terrain analysis are mostly found in a land-related geomorphological 
and ecological context (e.g. fire risk analysis, land management, habitat mapping of 
species in mountainous areas). In the context of marine habitat mapping, it becomes 
more and more important as topographic features are assumed to be important 
possible habitats for marine organisms.  
 
A 2 meter resolution multibeam dataset with both bathymetry and backscatter data of 
the Westhinder sandbank on the Belgian continental shelf was analyzed, together with 
sedimentological grab samples. The bathymetry was available as a digital terrain 
model, allowing to calculate topographic derivatives in GIS. For this study, the following 
derivatives were calculated: slope, aspect (direction of slope), bathymetric position index 
or BPI (measure of where a location with a defined elevation is relative to the overall 
landscape) and rugosity (topographic roughness with a surface area to planar area 
ratio). The combination and 3D visualization of all of these layers already contributes a 
lot to the physical understanding of the area. Submarine bedforms (with a spacing 
between 10-100m and a height between 0.4-3m) with their crests, depressions, slopes 
and flats can easily be recognized and automatically demarcated using a combination 
of the BPI and slope indices. This is very useful for an automated detection of sediment 
transport pathways. Moreover, very-high resolution observations have shown that some 
habitats are closely related to well defined zonations of the terrain. Since those habitats 
represent the most rich and diverse macrobenthic communities, an automated detection 
of such zones is extremely interesting from a planning/conservation perspective. 
Furthermore, the indices will be tested towards their ability to serve as input parameter 
for physical and biological models (e.g. rugosity as an input parameter for sand 
transport or biological models). 
 
The calculation of the terrain analysis depends a lot on scale, since different images are 
obtained using different search radii. Small scale structures such as ripples will require 
other search radii than large scale structures such as large dunes. A series of residuals 
of filters with varying window sizes revealing different scale features has been tested and 
compiled to an isocluster unsupervised classification map resulting in a combined map 
of different scale features. 
 


Analysis of bathymetrical derived features on the Belgian Continental Shelf as a support for marine habitat mapping

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