The Flood Estimation Handbook (FEH), developed by the Centre for Ecology and Hydrology, is a comprehensive set of five volumes providing guidance on rainfall and river flood frequency estimation in the UK. It was originally published in 1999 and reprinted in 2008. The methods largely supersede the Flood Studies Report of 1975 which was the previous national standard.

The Flood Estimation Handbook is issued in a set of five printed volumes. A supplementary report on the methods underpinning the ReFH software is also available for download. The methods presented within the Handbook may be implemented using the range of FEH software products.

Volume 1 – Overview

Volume 1 contains an overview of the procedures, a summary of how the methods differ from earlier guidance and an introduction to the data and software accompanying the Handbook. It includes important guidance on the choice of method to address a specific flood estimation problem.

Volume 2 – Rainfall frequency estimation

Volume 2 presents the methods for estimating the rainfall depth for a given duration and return period for a point or catchment anywhere in the UK, based upon the FORGEX model of rainfall depth-duration-frequency. The parameters of the depth-duration-frequency model and estimates of design rainfall are provided on the FEH CD-ROM.

Volume 3 – Statistical procedures for flood frequency estimation

Volume 3 presents statistical procedures for using observed flood data to address such questions as “How rare was that flood?”, or “How big is the expected 100-year flood?”. The methods develop a flood frequency curve which shows the relationship between flood size and flood rarity. Where long flow records are available, the flood frequency curve can be estimated using flood peak data from this site alone. More commonly, where the site is either ungauged or has insufficient flow records for design, the flood frequency curve is estimated using data pooled from a group of similar sites. Methods are presented for selecting appropriate gauged sites for pooling and for combining the data. Procedures for urbanised catchments are also described. Volume 3 statistical methods are implemented within the WINFAP-FEH software package together with improvements made to the original methods by the CEH research team since the original publication of the handbook.

Volume 4 – Rainfall-runoff method

Volume 4 has been largely superseded by the development of ReFH and its associated publication the FEH Supplementary Report No. 1. Volume 4 presents a comprehensive re-statement of the Flood Studies Report rainfall-runoff method including a set of updated equations to allow the method to be used with digital catchment descriptors.

Volume 5 – Catchment Descriptors

Volume 5 presents a detailed description of the development and derivation of the catchment descriptors included within the FEH CD-ROM and an introduction to the software. Also included is an appendix listing values for 20 descriptors at the 943 gauged catchments used in the development of the parameter estimation models.

FEH Supplementary Report No. 1 – The revitalised FSR/FEH rainfall-runoff method

This Supplementary Report is not included within the Flood Estimation Handbook, but is available for download.

The Revitalised Flood Hydrograph (ReFH) model replaces and offers significant improvements over the original FSR/FEH model. It enables a more direct and transparent description of flood-generating mechanisms and introduces the concept of seasonal variation in soil moisture content (critical in determining percentage runoff), design rainfall and baseflow. The system allows the user to model the flood attenuation by reservoirs. The ReFH model was developed by the Centre for Ecology and Hydrology.