New Build Property sales and Flood Risk/Warning areas

Two interesting developments in the open and LinkedData worlds have grabbed my attention in past couple of months.

In February, the Floodhack event generated lots of great ideas for new apps to help flood relief, and some data from Environment Agency.  In March, I attended the superb Linking Geospatial Data workshop, which produced much food for thought on blending the Geospatial and LinkedData worlds.

This got me thinking: what if I could combine the two and develop an app focussed on flooding, and which also employed LinkedData and geospatial technologies? I’ve come up with this – an app to explore sales of new build properties by postcode sectors, in and around flood alert and flood warning areas.


I’ll blog separately about how it works under the bonnet, but in summary:

  • I’ve used the following public sources:
    • Environment Agency’s Flood Alert and Flood Warning boundary files, available on
    • Postcode Sector boundaries, produced by GeoLytix
    • Land Registry’s Price Paid Transactions data
    • For the backdrop map, Microsoft’s Bing Aerial Imagery and (via a layer switching button) a nice blue version of OpenStreetMap that I’ve developed and published at
  • I’ve published the Environment Agency flood boundaries, Postcode Sectors, and total numbers of transactions by postcode to a Geoserver that I set up for DCLG.  This makes the data available in various Open Geospatial Standard formats, some of which I’m using in the app.
  • I’m also using LinkedData from DCLG’s OpenDataCommunities (to find postcodes within postcode sectors), and Land Registry (to get lists of transactions since 2009, within individual postcodes).

Using the app: an introduction

The app opens with a map (shown above) of flood alert and warning areas in purple, overlaid with postcode sectors in which there have been 100 or more new build property sales since 2009.  The top 50 postcode sectors – i.e. those with the greatest number of sales – are outlined in light blue.

From here, you can locate and explore transactions within  postcode sectors by:

  • Choosing a postcode sector, from the “top 50” list in the top right hand corner
  • Clicking anywhere on the map  (within England and Wales).

This will display a screen like the one below – in this case the “GL2 2 – Gloucester” postcode sector.


As noted above, you can use the layer select button (top right corner of the map) to switch between aerial imagery from Bing, and the blue OpenStreetMap, like so:












From here, you can click the “Show Transactions” button (beneath the chart) to get and view data from Land Registry on individual property sales. This can take a a minute or two, so please be patient.

Once complete, the map should update to show clusters of property sales within the postcode sector.


Zooming in (using the controls at the top left of the map) will get you to details on individual properties:


To select a different postcode sector, click the “Hide Transactions” button then zoom out and click on the map as desired.

I hope this gives you enough to get started and enjoy the app.   Please do get in touch if you run into problems, or have ideas on improving it.

Separate post to follow on how it works under the bonnet.

Thanks for stopping by and reading.




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