User guide : BGS Debris Flow Susceptibility Model for Great Britain (version 6.1)

A debris flow is when there is a “rapid downslope flow of poorly-sorted debris mixed with water” (Ballantyne, 2004). The BGS Debris Flow Susceptibility Model for Great Britain (v6.1) is a 1:50 000 scale raster dataset of Great Britain providing 50 m ground resolution information on the susceptibility/ spatial likelihood, at a given location, to initiate a debris flow. It is based on a combination of geological, hydrogeological and geomorphological data inputs and is primarily concerned with potential ground stability related to natural (rather than anthropogenic) geological and geomorphological conditions. The dataset is designed for those interested specifically in debris flow susceptibility at a regional or national planning scale such as those involved in construction or maintenance of infrastructure networks (road or rail or utilities), or other asset managers such as for property (including developers and home owners), loss adjusters, surveyors or local government. The dataset builds on research BGS has conducted over the past 15 years investigating debris flows. The model underpinning the dataset was designed to identify potential source areas for debris flows rather than identify the locations where material may be deposited (i.e. the track and debris deposit). It focuses on the natural geology and geomorphological controls that are likely to influence the formation of debris flows. It therefore, does not consider the influence of anthropogenic slopes (such as embankments, cuttings, quarry slopes) beyond their identification in the underpinning slope model input, nor does it consider land use or land cover factors. This user guide provides the information required to enable the reader to understand and use this BGS data product.