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Subsidence and flooding data for the UK insurance industry

Natural Perils Directory

Output from one of Cranfield's NPD subsidence scenario models. Image Copyright CSAI, Cranfield University.

The Natural Peril Directory (NPD) datasets are used within the finance sector, by insurers and reinsurers to refine products and pricing. Success requires accurate information of sufficient detail. UK subsidence claims rise to exceed £500m per annum following dry years - a good reason to manage subsidence risk more effectively.

Cranfield University have designed an easy-to-use and unique dataset, the Natural Perils Directory, to assist the insurance market with risk-management decisions on subsidence, flood and wind, through using their wholly owned, Government-recognised National Soils Data.

Use of the Natural Perils Directory is allowing several of the leading British insurance companies to improve or protect their claims experience on existing buildings insurance portfolios and to target products at lower risk areas where the potential for profit growth is highest.

Why use the Natural Perils Directory

Cranfield's NPD Data in use. Image Copyright CSAI, Cranfield University.

NPD offers a number of attractive benefits and features, enabling:

  • The maximisation of financial opportunities by targeting products at lower risk areas where the potential for profit growth is highest;
  • An increase in the understanding of your exposure to risk through accurate and detailed environmental datasets;
  • The ability to make decisions based on interpretations of the soil layers that support most foundations directly, rather than upon underlying geology;
  • A unique solution that works to enhance your current subsidence, flood and wind exposure risk underwriting techniques- not necessarily to replace them;
  • Flexible output at Postcode Unit or Postcode Sector (sector or delivery point);
  • The use of clay-related subsidence climatic scenario outputs to introduce or to enhance in-house claims forecasting models;
  • Easy incorporation within in-house actuarial risk modelling.

Modelling Environmental Vulnerability

Greater risk requires greater knowledge

Soil property variability. Image Copyright CSAI, Cranfield University.

Changing climate and extreme events means damaging floods and subsidence are increasing in frequency and intensity. Insurers need to have accurate and appropriate information to assist in managing their insurance portfolios. This means using environmental datasets which can provide a greater understanding of the potential risks associated with these major challenges.


Ground Subsidence

House underpinning due to foundation subsidence. Picture Copyright S.Hallett, Cranfield University.

The soils of Britain vary extensively in their texture (the amounts of sand, silt and clay they contain), and their respective property insurance claims rate. Each soil type responds in a specific way to seasonal variations in climate, and it is this response that determines the impact on building foundations. Unlike other currently available models, which concentrate on the underlying geology, Cranfield's Natural Perils Directory incorporates information on the layer that most affects one and two storey building foundations and therefore the domestic building insurance market.

House underpinning due to foundation subsidence. Picture Copyright S.Hallett, CSAI, Cranfield University.

Cranfield's Ground Subsidence Model has evolved from the understanding and evaluation of a number of complex elements including clay-related shrinkage, the compression of unconsolidated, soft subsoils, frost-heave and underground sand abrasion and cavitation. For clay-related subsidence, the soils' potential shrinkage rating is combined with climatic information detailing the intensity of soil drying through the summer to provide the final ground subsidence rating. Almost 1,000 soil types have been individually assessed.


Clay Shrinkage Explained

Here is a short, explanatory video of Cranfield soil scientists explaining how clays shrinkage occur.


Flood Extent


Cranfield's Flood Extent dataset comprises three elements - the riverine, lacustrine and coastal/marine flood provinces. The riverine and lacustrine province is defined by the actual distribution on the ground of alluvial sediment - the tell-tale evidence left behind by past flood waters. The same principle applies at the coast where marine sediments blanketing low-lying areas around the coast that are vulnerable to flooding during storm and tidal surges.


Wind Exposure

Storm throw wind damage to tree. Picture Copyright S.Hallett, CSAI, Cranfield University.

Cranfield's Wind Exposure dataset provides a high-level empirical summary of areas subject to prolonged exposure to wind. Whilst not being a storm-track model, the wind exposure dataset has been used to determine areas more subject to wind damage, such as tile-blow.


The NPD Offering

What Cranfield and NPD offer

Cranfield's NPD CD-ROM. Image Copyright CSAI, Cranfield University.

The Natural Perils Directory provides:

  • Accurate assessment for subsidence, flood and windstorm exposure for Great Britain;
  • Unique data based on the National Soil Maps for England, Scotland and Wales;
  • Output on CD-ROM, in GIS and textfile format;
  • Postcode updates provided regularly via Geoplan Ltd.;
  • Six probability categories for clay subsidence;
  • Peat, Sand, Silt and soft soils subsidence ratings;
  • Flood area extent identification;
  • Wind exposure area identification;
  • Technical support visits from expert Cranfield scientific and technical staff;
  • Comprehensive User Manual;
  • Assistance in-house with system application and integration;
  • Four product options to suit your level of requirement.

Access to Cranfield's:

  • Scientific and Technical consultancy expertise;
  • Development and Research. For example the impacts of extreme weather on geohazards under future climates - for instance, see our Crew Project website, where our research considers the inclusion of the UKCP09 climate predictions as will affect South London in 2020 and 2050.

Obtaining the Natural Perils Directory

Contact details

The Natural Perils Directory is supplied to the full exit-level Postcode Unit (1.6 million items). Other spatial interpretations, for instance using the Ordnance Survey's Address Point product, may be undertaken by arrangement.

Natural Peril Directory (NPD) is developed by Cranfield University's National Soil Resources Institute and marketed via Cranfield's wholly owned company CIM Limited. For further details concerning the Natural Perils Database, please contact us:

Caroline Keay
Senior Research Fellow in Geospatial Informatics
Cranfield Centre for Environmental & Agricultural Informatics
Cranfield University
Building 53a
Cranfield campus
MK43 0AL
Tel: (01234) 752992
Fax: (01234) 752970
Personal web page
Institute home page