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.

51ÁÔÆæ 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, BGS 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 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 BGS 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 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).

51ÁÔÆæ 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

51ÁÔÆæ Keyworth

Find out more

When considering natural hazards in a riverine or catchment setting, it is often high-magnitude flood events that grab the headlines.ÌýIn comparison, associated catchment hazards such as river scour are often overlooked, but these events can be no less costly in their societal and economic impacts.ÌýRecent studies have shown that, in the UK, river erosion and associated impacts exacerbate flood damage by £336million a year and are a considerable source of water pollutants, costing £238million a year to remediate.River erosion further increases the costs of water treatment and maintenance of drainage networks by £132million a year and accounts for 25percent of validsubsidence insurance claims (Li et al., 2021; Pritchard et al., 2013).

Infrastructure damage

Scour causes physical modification to riverbeds and banks via the removal of sediment or engineered materials. It occurs when the forces imposed by the flow of water on a sediment particle exceed the stabilising forces (Kirby et al., 2015).  This is an environmental process occurring in response to the natural variability of river stream flows and sediment regimes but, unlike hazards associated with flood waters that will eventually recede, the changes that result from river erosion can be permanent.This makes river scour extremely damaging when it intersects assets such as farmland, infrastructure, residences, historic sites, etc.

Of particular concern is the significant damage river scour can cause to infrastructure adjacent to rivers, such as bridges, flood defences and electricity pylons. The Climate Change Committee recent, independent assessment of UK climate risk has highlighted that the risk to bridges and pipelines from future erosion requires further investigation.

Currently, river scour risk to UK railway bridges is estimated to cause the loss of 8.2 million passenger journeys each year, with an accompanying economic cost of up to £60 million (Lamb et al., 2019). In 2009, flood events in Cumbria caused a tragic fatality and the partial or total destruction of 20 road bridges, costing the local economy an estimated £2 million per week during the recovery period (Pizarro et al., 2020).

Events such as these serve as a stark and increasingly frequent reminder of the destructive effects of river scour. As a result, the ability to predict where river scour is likely to occur across the UK river network is being recognised as increasingly important, both under current conditions and future climate change scenarios. The UK Government Environment Act (2021) has a target to reduce the impact of physical modification on the water environment and, between 2009 and 2015, £68 million was spent towards reaching this goal (UK Government, 2021).

Maintaining catchment health

Management and mitigation against river erosion is required at multiple scales and concerns a variety of stakeholders. Organisations involved in the maintenance of catchment health include:

• river basin and catchment management authorities
• charities such as the National Trust and various river trusts
• environmental protection agencies
• national park authorities

At a more granular level, the occurrence of river erosion is of interest to asset owners responsible for infrastructure, such as rail or road networks, local planning authorities and insurers, and lenders and property search companies when considering risks to assets, future developments and portfolios.

Efforts to model this costly geohazard have highlighted an important gap in available datasets. The joint efforts of the Environment Agency (EA), the Department for Environment, Food and Rural Affairs (Defra) and Natural Resource Wales (NRW) on the ‘’ flagged: ‘There is currently no nationwide information showing where erosion or deposition is likely to occur’, whilst a UK Climate Resilience Programme (UKCRP)-funded project, ‘’, found: ‘Creating resilient, sustainable infrastructure depends on understanding the potential future risks of changing erosion hazards and their impact. Yet at present, no predictive modelling framework exists for erosion hazard.’

The role of geological data

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. As such, geological data is a key input into any predictive models attempting to resolve this issue and is an invaluable resource for infrastructure risk and catchment health assessments at both catchment and reach scales.

Existing modelling efforts by the UK environmental protection agencies and the wider scientific community utilise various BGS data holdings. For example, the UKCRP project derives sediment compositions from the BGS soils texture maps, whilst Defra, EA and NRW are considering the use of BGS superficial deposits data as indication of the location of erodible deposits. Both have limitations: the latter project fails to consider erodible or soluble bedrock deposits and the former acknowledges that it lacks ‘sufficient information on the spatial variation in these [sediment] compositions’. This emphasises the need for consistent information on the erodibility of riverbed and bank material at national and granular levels.

Stay tuned for our upcoming blog to find out how 51ÁÔÆæ updated GeoScour data product can provide geological river scour assessments from catchment down to individual reach scale with national coverage.

Join the BGS GeoScour dataset webinar: 8 September 2022

51ÁÔÆæ Product Development invites you to the launch of our newly updated dataset, GeoScour. Our 30-minute webinar will give an overview of river scour and its associated river erosion hazards, including surface geology susceptibility and bedrock geology susceptibility, and will be followed by an introduction to the Open and Premium GeoScour data packages.

About the author

Rob Shaw

Geospatial data analyst

51ÁÔÆæ Keyworth

Find out more

51ÁÔÆæ GeoScour Open datasets provide a generalised overview of the natural characteristics and properties of catchment and riverine environments for the assessment of river scour in Great Britain.

We’ve brought together research experts and product development experts to provide an introductory overview of our two new datasets, which comprise of two different tiers of geographical information system (GIS) data containing seven different data layers. Each tier represents a different scale of assessment, from high-level catchment to subcatchment data.

Our 30-minute webinar provides an overview of river scour and its associated river erosion hazards, including surface geology susceptibility and bedrock geology susceptibility, and will be followed by an introduction to the Open and Premium GeoScour data packages.

Watch a recording of our BGS GeoScour launch webinar.