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The geological properties of bedrock and superficial deposits that make up riverbeds and banks are fundamental controls on the susceptibility of any given river reach to scouring. Geological data is therefore a key input into any predictive models attempting to understand and resolve this issue, as well as being an invaluable resource for infrastructure risk and catchment health assessments.

���ճԹ� GeoScour

In a previous blog post we discussed the economic and societal impacts of river erosion geohazards in the UK and identified significant gaps in available datasets for managing and modelling this hazard. In light of this, ���ճԹ� has developed the GeoScour data product. This is a national- to local-scale geological scour assessment based on the spatial variation in geological properties, allowing users to identify:

• river catchments with higher erosion activity due to landscape evolution and river sinuosity
• subcatchments that have a higher risk of scour due to river morphology, underlying geological factors and catchment size
• susceptibility to scour of specific sections of a given river’s current profile

GeoScour is based on the outputs of numerous research programmes, data analytics and stakeholder advice. It provides data sufficient for users to analyse and assess a range of riverine risks at various scales.

This suite of data is split into three tiers. These provide a consistent, nationwide scour assessment for Great Britain. Tier 1 and 2 datasets are freely accessible via the ���ճԹ� GeoIndex and are aligned to the Water Framework Directive management catchments. Tier 3 contains licenced datasets created at a riverine scale using the latest OS Open Rivers watercourse data, which also subsequently feeds into the Tier 2 catchment-scale data.

Tier 1

Data provides a summary overview of the catchment characteristics, typical response type and evolution. It can be used to provide a high-level overview (1:625 000 scale) for incorporation into catchment management plans, national reviews and catchment comparisons.

Tier 2

Data is available as smaller catchment areas (1:250 000 scale) and focuses on providing more detailed catchment management, natural flood management and other broad-scale assessments. It analyses geological properties such as flood accommodation space and geomorphology type, as well as additional summary statistics for worst-, average- and best-case scenarios for underlying surface-scour susceptibility.

Tier 3

Licenced data provides detailed riverine information (1:50 000 scale) that is designed to be incorporated into more complex river scour models. It provides the baseline geological context for river scour development and identifies important factors that should be considered in any scour model: characteristics such as material mineralogy, strength and density are key properties that can influence a river’s ability to scour. An assessment of river fall, sinuosity and flood accommodation space is also provided. This data is of use to those assessing the propensity for river scour for any given reach of a river across Great Britain and can be used as an input into hydraulic or hydrodynamic models.

Geological susceptibility to river scour

It is worth noting that the term ‘scour’ is commonly associated with bridge scour and has come to be an all-encompassing term covering various elements of scour action at hydraulic structures, as defined by the Construction Industry Research and Information Association (CIRIA) manual on scour at bridges (Kirkby et al., 2015).

���ճԹ� GeoScour is solely concerned with providing a susceptibility to natural scour assessment based on the geological properties of the riverbed and bank material. It does not consider hydraulic factors such as flow contraction or velocities, nor turbulence generated by structures or the engineering properties of said structures. By providing an assessment of the geological susceptibility to river scour, GeoScour is a valuable addition to any infrastructure scour risk assessment and, in combination with hydraulic and engineering properties, it can contribute to a complete understanding of scour conditions from catchment scale down to individual site assessments.

Who is GeoScour for?

GeoScour is targeted at stakeholders concerned with catchment management, such as local authorities, river trusts and national park authorities. It can be applied to erosion hazard models as a key input and used in assessments by asset owners and managers, such as transport authorities, insurers, lenders and other infrastructure owners, to highlight threats to their infrastructure networks or asset portfolios.

For more details on the potential applications of GeoScour data as well as an opportunity to interact with sample data for all three tiers, please read our ESRI StoryMap.

Join our live webinar – 8 Sept 2022

Join our data products team for a live webinar on September 8^th and discover more about our new data product to underpin river erosion hazard decision making.

Get in touch

To find out more about our GeoScour data product, including arranging sample datasets or learning more about licensing, please contact our digital data team (digitaldata@bgs.ac.uk)

Previous entries in this blog series

• River erosion: the forgotten hazard of flooding

About the author

Rob Shaw

Geospatial data analyst

���ճԹ� Keyworth

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