Prediction of the presence of rock at outcrop or subcrop at the seabed across the UK shelf area. This shapefile was produced through a semi-automated approach, using a Random Forest model combined with an expert interpretation phase.
Use the field "ROCK_TYPE" to distinguish between rock at the surface and rock covered by sediment when using the data for habitat analysis.
The "CONF_TOTAL" field provides the final value of the confidence analysis for the feature.
The audit dataset documents the changes applied to a modelled output detailing the presence of rock at outcrop, or subcrop, in the shapefile. These changes were made on the basis of expert judgement and this shapefile provides a record of additions, deletions and modifications.
This dataset is the result of 3 individual BGS/Cefas semi automated rock mapping predictions (found within the Raw folder of the BGS data). It maps rock at surface, or rock and thin sediment as predicted across the United Kingdom shelf. Confidence scores also provided for predictions of seabed character. Manual amendments to the rock in Welsh waters were made by BGS in February 2018 following a consultation with Natural Resources Wales.
The method consists of two elements, namely 1) the automated spatial prediction of the presence and absence of rock at the seabed using a random forest ensemble model, and 2) manual editing of the model outputs based on ancillary geological data and expert knowledge.
A Random Forest model using bathymetric, derived bathymetric, geological and modelled hydrodynamic inputs was combined with an expert interpretation phase. The changes made by BGS during the interpretation phase are logged in a supplementary dataset.
The Defra Astrium bathymetry dataset was used both as a predictor variable and to provide derived predictor variables (roughness, slope, aspect, curvature, BPI) along with (Telmac & POLCOM) modelled hydrodynamic data and BGS geological inputs.
Final confidence scores are based on three-steep confidence assessment developed by JNCC (Lillis H., 2016, JNCC Report 591).
The individual reports are:
Diesing, M. Green, S.L., Stephens, D., Cooper, R. & Mellett, C.L., 2015, Semi-automated mapping of rock in the English Channel and Celtic Sea, JNCC Report 569, A4, 19pp, ISSN 0963 8901;
Downie, A.L., Dove, D., Westhead, R.K., Diesing, M., Green, S., Cooper, R., 2016. Semi-automated mapping of rock in the North Sea. JNCC Report 592;
Brown, L.S., Green, S.L., Stewart, H.A., Diesing, M., Downie, A.-L., Cooper, R., Lillis, H. 2018. Semi-automated mapping of rock in the Irish Sea, Minches, western Scotland and Scottish continental shelf. JNCC Report 609
This version include updates requested by NRW in Welsh waters (manually edits by BGS in February 2018, refer to audit shapefile for details).
Available at:
http://jncc.defra.gov.uk/page-2132
This dataset has a DOI: https://doi.org/10.25603/840424.1.0.0