Putting our residents first
Top menu
Search our website: Search

Preliminary Flood Risk Assessment

The Preliminary Flood Risk Assessment is a stock take of risk from flooding for the Borough.

By looking back at past events simple models are created and used to identify sites that are at potential flood risk. It evaluates flood risk from surface water (local rain), rivers and ground water.

The Preliminary Flood Risk Assessment has been compiled using readily available information from a number of sources. These include the Environment Agency's national datasets and existing local products (eg Strategic Flood Risk Assessments).

The Preliminary Flood Risk Assessment is a coarse assessment for identifying  potential flood risk using a precautionary approach. It is not an exact representation  of what will happen in the types of storm events that have been modelled.  Instead, it provides an indicative understanding of the areas that might flood and to what  extent. It provides a tool for allowing resources to be focussed on higher risk areas  with the aim of reducing the impacts of flooding.

The Preliminary Flood Risk Assessment report forms the first stage of the requirements of the Flood Risk Regulations 2009 and the evidence base which includes:

  • collected information on past (historic) and future (potential) floods
  • assembled the information into a preliminary assessment report
  • identified Flood Risk Areas

The identification of Flood Risk Areas will establish where the final two stages of preparing hazard and risk maps and flood risk management plans are required.

The hazard and risk maps will show the likely extent, depth, direction, speed of flow and probability of possible floods and their consequences. The flood risk management plans will set out what the risk management objectives are, the measures proposed to achieve those objectives and how the measures are to be implemented.

London Borough of Hillingdon Preliminary Flood Risk [1Mb]

Appendix - A Past Floods

Appendix A1 Surface Water Flooding Incidents - North [4Mb]
Appendix A1 Surface Water Flooding Incidents - South [3Mb]
Appendix A2 River Tidal Coastal Flooding Incidents - North [4Mb]
Appendix A2 River Tidal Coastal Flooding Incidents - South [3Mb]
Appendix A3 Groundwater Flooding Incidents - North [4Mb]
Appendix A3 Groundwater Flooding Incidents - South [3Mb]
Appendix A4 Sewer Flooding Incidents - North [4Mb] 
Appendix A4 Sewer Flooding Incidents - South [4Mb]
Appendix A5 Increased Potential for Elevated Groundwater - North [4Mb]
Appendix A5 Increased Potential for Elevated Groundwater - South [3Mb]

Appendix - B Future Floods

Appendix B1 Maximum Flood Depth 1 in 200yr Rainfall Event - North [4Mb]
Appendix B1 Maximum Flood Depth 1 in 200yr Rainfall Event - South [4Mb]
Appendix B2 Flood Hazard and Flow Direction 1 in 200yr Rainfall Event - North [4Mb]
Appendix B2 Flood Hazard and Flow Direction 1 in 200yr Rainfall Event - South [4Mb]
Appendix B3 Maximum Flood Depth 1 in 100yr Rainfall Event plus Climate Change - North [5Mb]
Appendix B3 Maximum Flood Depth 1 in 100yr Rainfall Event plus Climate Change - South [4Mb]
Appendix B4 Flood Hazard and Flow Direction 1 in 100yr Rainfall Event plus Climate Change - North [4Mb]
Appendix B4 Flood Hazard and Flow Direction 1 in 100yr Rainfall Event plus Climate Change - South [4Mb]

Appendix C Flood Risk Areas

Appendix C1 Revised Indicative Flood Risk Areas - North [4Mb]
Appendix C1 Revised Indicative Flood Risk Areas -South [3Mb]

Is there anything wrong with this page?

* What would you like to report?
Broken link
Out of date information
Missing information
Report a problem with a service

* Please provide further details:


Please include your email in case we need further details (optional):

This feedback tool is for improving our pages. To report a problem with a service, please email: contact@hillingdon.gov.uk

Your feedback could not be sent - please ensure you have completed all fields.

Thank you for your feedback.

Related column
Article utilities:  Bookmark and Share Print Print this page Last updated: 12 Jun 2017 at 10:33