Seabed Classification Reports
Acoustic seabed classification reports provide information on the characteristics of the sediment or surficial geological formation of the seabed & shallow sub-strata.
Accurate seabed mapping information is important on a number of levels, not least with increased activity in the offshore renewables industry and a need for information on shallow geology for appropriate site selection and foundation design.
The need for information within the first few metres of the seabed is also useful in the context of cable and pipeline burial projects and associated engineering techniques.
In addition, the demarcation of marine protected areas (MPAs) requires the identification and mapping of benthic habitats and both marine and environmental legislation, e.g. Marine Strategy Framework Directive, can only be enforced where the most accurate information is available.
Information is often collected using remote sensing techniques including singlebeam echosounders, multibeam echosounders and side-scan sonar which, in turn, is analysed by industry specific software which aims to classify the acoustic classes of information.
Side-scan sonar provides extensive spatial coverage and in some cases immediately useful information on bottom type. Multibeam systems offer high-resolution seabed topography information and also yield linked backscatter data.
Classification maps are subject to ground-verification in order to identify the compositions and bottom type that characterize each class. These classes could be, for example, fine to medium sand, shingle or gravel, coarse sand and mud.
When comparing these acoustic classifications further with side-scan sonar imagery it is possible to identify the extents of each cluster and any relating seabed feature or features.
The clusters can be quantified by means of surface grab samples or visual imagery, often useful when assessing potential dredge sites and quantifying the composition of material to be disposed of.
