How Ordnance Survey plays its part in a flooding emergency

Flooding has featured in the news regularly over the last few years, Boscastle, Cockermouth and Bournemouth to name a few examples. I wanted to share with you how Ordnance Survey can help with flood relief operations and working with The Environment Agency, to provide a flood risk application.

In August 2004, Boscastle in Cornwall was badly effected by a flood that cause major damage through the town. 75mm fell in the space of two hours, the average rainfall for the whole of August alone. The sudden deluge caused two nearby rivers to burst their banks and a torrent of water to sweep through the village’s main street

Bournemouth flood

Bournemouth flood

Cockermouth in Cumbria saw water levels rise to about 2.5 metres in November of 2009. The heavy rainfall caused the rivers Derwent and Cocker to burst their banks; both the rivers meet in the town of Cockermouth where torrents of water carried cars and debris away

More recently, in August this year, Bournemouth suffered torrential rain that left the gardens underwater and flash flooding to the level of car bonnets. Roads where split and manhole covers lifted under the pressure of water. The emergency services were called to stranded vehicles and roads that had turned into rivers.

Cockermouth flood

Cockermouth flood


Flood data
The Environment Agency team up with Ordnance Survey, to provide valuable information for flood risk and prediction. Using Ordnance Survey mapping and the Environment Agency research, predictions can be made as to the location and reach of a potential flood. This can be especially useful for home buyers and builders, council planning departments and emergency services when the time comes to deal with a flood. You can use the flood risk map, to find out about your local rivers.

Post flood, the Environment Agency fly their planes over the effected area using LiDAR, an airborne laser mapping technique, to produce precise elevation data. This helps with future emergency and construction planning.


Flood risk assesment
Insurance companies also use the data and research collected by both Ordnance Survey and The Environment Agency to map flood risk. This can be enhanced with their own flood model data or flood model data produced by third party company like JBA, to measure flood risk and give a policy rating for their commercial or home insurance customers.

Boscastle clean up

Boscastle clean up

Updates to mapping

Ordnance Survey also plays other roles in times of flooding. In an article written for our blog, entitled ‘After the floods – putting Cumbria back together’, Holly talks about the surveyors who visited Workington to survey a temporary bridge built over the River Derwent. This was to ensure our OS Mastermap database was up-to-date with the latest information. Ordnance Survey also supplied a set of OS Explorer maps to the rescue teams, to help them with the relief effort.

Were you near or effected by flooding near you? Where you part of a team that helped rescue people and restore your town? Let us know and share your experiences.

Images via Flickr from:
Boscastle: nigelrenny
Cockermouth: Brick_Man_Photos
Bournemouth: BHBeat.com

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2 Responses

  1. Topographical mapping and flood modelling are great starting points for understanding flood risk.

    However, there are many forms of flooding, local surface water, drainage and groundwater which are not covered by the Environment Agency maps.

    Hydrology is often complex requiring years of experience and not something that the public should be expected to understand. Critical therefore is that people obtain independent Flood Risk Assessments.

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