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Predict, plan and prepare for effective flood management with OS MasterMap Networks – Water Layer

Ordnance Survey is pleased to announce the beta release of OS MasterMap Networks – Water Layer, which offers early users a chance to preview the product before it is released in April 2014. The product has been created in conjunction with the Environment Agency® and the Scottish Environment and Protection Agency (SEPA).

View OS MasterMap - Water Layer desk image.

Year-on-year, businesses and homeowners large and small throughout Great Britain continue to face the devastating impacts of ever-increasing climate changes that bring extreme flooding.

Across the United Kingdom, 2.2 million homes and 185,000 businesses are situated in flood-risk areas. Without adequate investment in flood defences, it has been estimated that this figure could rise to 840,000 by 2035. Department for Environment, Food and Rural Affairs (Defra) valuation of assets at risk of flooding stands at £221 billion.

Since 2000, insurers have paid £4.5 billion to customers whose homes or businesses have been hit by flooding. This has increased by 200% on £1.5 billion paid in the previous decade. In 2012, insurers paid £1.19 billion for flood and storm damage across the United Kingdom. Some 47,000 business properties made claims following flood and storm damages and insurance companies paid £373 million for damages. In addition, firms received £40 million to help them continue trading whilst their premises were being repaired.

In order to understand the risks and impacts of flooding, environmental consultants must have the most accurate and current data to carry out strategic flood-risk assessments. The ability to assess the impact of surface water, river flooding, groundwater flooding, sewer and canal flooding, interaction with main rivers and the consequential impacts of these occurrences is critical.

OS MasterMap Networks – Water Layer provides information such as geometry, topography, flow focus, height information, drainage and sewerage outlet sites, culvert data and the location of watercourses that may retain water – this information is particularly crucial in populated areas and locations in which businesses are concentrated.

The overall findings can help to build flood-risk indicators, which can be used to determine the impacts of flooding on human health, economic activity, cultural heritage and the environment – saving both lives and money.

When flood-risk management data is used in conjunction with other Ordnance Survey datasets, such as OS MasterMap, OS Terrain® 5, and AddressBase®, the value added and customer benefits are increased significantly.

Members of our early user group ‘OS Insight’ will have received the beta data and we are keen to receive their feedback to help us improve the product which is due for release later this year.

Get involved, find out more and sign up for the OS Insight programme.

What is the Water Layer product?

OS MasterMap Networks – Water Layer data is a three-dimensional link node network for water features across Great Britain. It includes rivers, streams, lakes, lochs, canals and drains.


  • 3D geometry
  • Inferred features to indicate connectivity under roads and railways
  • Heighted on the vertices (ability to indicate gradient within the link),so the fall of water is visible from any point

Attributed with:

  • Catchment data
  • Names of primary watercourses in native languages
  • Flow and connectivity focus
  • Gradient
  • Relative position of water courses over or under each other
  • Average widths
  • Geometry
  • Additional information provided by national and local authorities, for example – culverts

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