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MAP Rain – New FEH 2013 Rainfall Return Period calculator

FEH is the industry standard used to estimate local flood risk and develop resilient infrastructure.

New service calculates Rainfall Return Period for any location using the FEH 2013 methodology

MAP Rain now includes the updated FEH (Flood Estimation Handbook) 2013 methodology as well as the original FEH99 method. This lets users calculate Return Periods for any location and any date in the past 4 years using the MAP Rain dashboard. These Return Periods are available for both Points and Polygons.

You can use the dashboard to calculate:

  • The depth (mm) and duration (hours) of rainfall that generates the largest Return Period on a particular day
  • The depth (mm) of rain for the location that generates a specific Return period for a specific rainfall duration (hours)
  • Predicted Rainfall Alerts
    MAP Rain can also apply the FEH 2013 methodology to the forecast rainfall so that we can send you e-mail alerts for any significant rain events that may impact flooding hotspots.

    API calls
    We have built two API calls into MAP to let you integrate the FEH 2013 return period calculations directly into your own applications.

    Returns depth (mm), duration (hours) and Return Period for a particular day and location

    Inputs

    Date 17th Sept 2017 (rainy day)
    Location in Long Lat (WGS84) or OS Easting and Northing

    Returns

    Rain Event Start and End Time 14:30 to 16:00
    Duration 1.5 hours
    Max Depth 16.68 mm
    Return Period 1 in 2.45 years

    Returns depth of rain (mm) for a specific duration (hours), return period and location

    Inputs

    Location in Long Lat (WGS84) or OS Easting and Northing
    Duration 5 hours
    Return Period 1 in 20 years

    Returns
    Max Depth 47.72 mm

    Acknowledgement
    FEH Return Periods calculated by Meniscus through use of FEH1999 and FEH2013 DDF model © and Database right NERC (CEH).

    Stewart, E. J.; Jones, D. A.; Svensson, C.; Morris, D. G.; Dempsey, P.; Dent, J. E.; Collier, C. G.; Anderson, C. A.. 2013 Reservoir Safety – Long Return Period Rainfall. Project FD2613 WS 194/2/39 Technical Report (two volumes). Joint Defra/Environment Agency Flood and Coastal Erosion Risk Management R&D Programme.

    Areal FEH99 calculation – Return Period calculation for polygons

    As part of our aim of continuing to add complex rainfall analytics into MAP Rain you can now return a FEH99 Return Period for a polygon – this is the Areal FEH99 methodology as set out in the Flood Estimation Handbook.

    How to run

  • From the dashboard click on Rainfall Return Period
  • Set the date you are interested in using the top date selector
  • Select the polygon you are interested in
  • Select the “Get Return Period for Item” option under Rainfall Return Period
  • MAP Rain will then calculate the Return Period and display all the coefficients and results in the map results pane along with a graph of the rainfall intensity for 3 days – includes the previous and the next days.