Flood Estimation Handbook

The Flood Estimation Handbook (FEH) and its related software offer guidance on rainfall and river flood frequency estimation in the UK. Flood frequency estimates are required for the planning and assessment of flood defences, and the design of other structures such as bridges, culverts and reservoir spillways. There is an increasing demand for estimates that can form the base for flood risk maps, important in the planning of new developments.

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

Flood Estimation HandbookThe FEH also provides methods for assessing the rarity of notable rainfalls or floods, which are of interest to insurers and others. The procedures are explained clearly. Supporting theory and results are included. The five volumes are accompanied by software (WINFAP-FEH) and digital data (FEH CD-ROM): these are available at additional cost*. The FEH largely supersedes the Flood Studies Report (1975).

The Flood Estimation Handbook is a set of five printed volumes (Centre for Ecology & Hydrology, 1999, ISBN: 9781906698003), priced from £260. Individual volumes from the set are not available. Wallingford HydroSolutions sell and support the Flood Estimation Handbook and its related software. Links to buy these products will take you to an external website.

Inside the Flood Estimation Handbook

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. Later chapters are either topic-oriented or essentially informative. The last section presents a UK-oriented bibliography of technical guidance in the many environmental planning and engineering issues that impinge on flood defence.

Volume 2: Rainfall frequency estimation

Volume 2 presents the methods for estimating rainfall frequency in the UK. The user obtains results from a model of rainfall depth-duration-frequency. There is a description of the underlying research, illustrations of the results and information on rainfall data. The Volume 2 procedure is built on rainfall growth factors, which relate the rainfall depth of a given return period to an index variable. Growth factors derive from the Focused Rainfall Growth Extension (FORGEX) method, which gives precedence to rainfall extremes observed locally and takes account of inter-site dependence in rainfall extremes to get estimates for long return periods.

Volume 2 also gives guidance on applying an areal reduction factor and in choosing a design storm profile: these are required when deriving flood estimates by the rainfall-runoff method.

The parameters of the depth-duration-frequency model and estimates of design rainfall are provided on the FEH CD-ROM, available separately.

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. Volume 4 of FEH presented 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.

Related software: FEH CD-ROM and WINFAP-FEH

Our flooding software products give users the power to apply the industry standard Flood Estimation Handbook methods in a quick, effective and objective way.

FEH CD-ROM

The FEH CD-ROM, developed by CEH, is at the centre of the flood frequency estimation procedures provided by the Flood Estimation Handbook. It holds catchment information (descriptors) for more than 4 million sites across the UK, which can be accessed by users for their site of interest through a powerful interface. These catchment descriptors are used at ungauged sites to estimate key model parameters, such as the median annual flood (QMED) and the unit hydrograph time to peak (Tp), and in judging hydrological similarity between catchments (providing a basis by which to 'transfer' and 'pool' data).

It also provides a Depth-Duration-Frequency (DDF) model, which allows assessment of the rarity of an observed rainfall event and the estimate of design rainfall depth for a user-defined duration and return period.

Descriptor values for the selected catchment can be exported to the FEH software package WINFAP-FEH.

Version 3.0 of the FEH CD-ROM is available on a three-year renewable licence. It includes three new catchment descriptors and offers the user improved functionality and extended coverage.

WINFAP-FEH

WINFAP-FEH is the tool for applying the statistical flood frequency estimation methods presented in Volume 3 of the Flood Estimation Handbook. This flexible package provides a range of statistical analyses, based primarily on annual maximum (AM) data, but including two applications of peaks-over-threshold (POT) data. It is linked to the FEH flood peak dataset, which is automatically loaded with the software, and provides utilities for implementing the methods described in Volume 3 of the FEH. A particular feature is the ability to undertake pooled analyses of AM data from a group of sites. WINFAP-FEH can also be used in a more general context, for example to fit statistical frequency distributions, make adjustments for urbanised catchments and to display results in tabular and graphical formats.

WINFAP-FEH v3.0 was released in 2009 and offers significant advances in software functionality and ease of use over earlier versions. It also includes the most recent HiFlows-UK data.

ReFH software

The revitalisation of the FSR/FEH rainfall-runoff method project (2001-2005), funded through the Joint Defra/Environment Agency Flood and Coastal Erosion Risk Management R&D Programme, produced the ReFH software package and a supplementary report to the Flood Estimation Handbook.

The supplementary report which accompanied ReFH 1 can still be downloaded: FEH Supplementary Report hi-res.pdf

The Flood Estimation Handbook and related software are sold and supported by Wallingford HydroSolutions. Links to buy these products will take you to an external website.

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