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Volume 491: debated on Monday 20 April 2009

To ask the Secretary of State for Environment, Food and Rural Affairs if he will publish the electronic maps developed by the Environment Agency which identify those areas vulnerable to flash flooding from surface water. (268404)

[holding answer 2 April 2009]: The Environment Agency completed actions in response to the urgent recommendation from Sir Michael Pitt’s interim report in August 2008 which stated

‘The Review recommends that the Environment Agency, supported by local authorities and water companies, should urgently identify areas at highest risk from surface water flooding where known, inform Local Resilience Forums and take steps to identify remaining high risk areas over the coming months’.

The Environment Agency sent map data to Local Resilience Forums to help them plan their response to surface water flooding emergencies.

The information on the maps is still under development and is for emergency planning purposes. The maps give an indication of the broad areas likely to be susceptible to surface water flooding based upon an extreme summer rainfall event with no drainage systems working. The information is not sufficiently accurate to use for individual properties. For example, it excludes the impact of buildings and kerb heights on surface water flows which at the local level can be significant. There will be properties at risk from surface water flooding that will not be included in the outline areas on the maps. The Environment Agency has not published the maps because of these uncertainties.

The Environment Agency is committed to providing the public and businesses with accurate and meaningful information about surface water flood risk in conjunction with local authorities and water companies in the future. Work is ongoing to validate the model results against historic surface water flood events. The information will be published once there is confidence in the results.

I have balanced the need to share surface water flood risk data with the public against the risks of publishing nationally un-validated data based on extreme scenarios for some types of surface water flooding. The public interest is best served by the current situation where Local Resilience Forums have information that will help them plan for emergencies and it is better to wait until more reliable data are available before publishing the Environment Agency’s maps. In the meantime, members of the public can purchase maps on surface water flooding on the internet from at least one commercial company.