The Revitalised FSR/FEH Rainfall-

Runoff Method

User guidance to Spreadsheet implementation of the Revitalised FEH

Rainfall-Runoff method

Version 1.3 Centre for Ecology & Hydrology, Wallingford December 2005

ii

Disclaimer CEH (a component body of the Natural Environment Research Council) is not able to warrant the accuracy of the data, software or handbook supplied to the user, and indeed has no responsibility for determining the fitness of the data, software or handbook for their intended use by the user. The provision of such data carries no liability for its accuracy or reliability or any omissions, and we cannot be held accountable for any loss, damage, injury (other than death or personal injury) or any other occurrence arising from the use of the data, software or handbook. Our entire liability in respect of any tort or breach of our duties, statutory or otherwise, whether or not attributable to our negligence, is limited to fee you have paid for the data, software & handbook. It must be recognised that raw data may be transcribed, or may be acquired and processed using automated techniques. Although such processing is made subject to quality-control procedures, so as to ensure reliability where possible, some data may be subject to processing without human intervention with the result that errors may be undetected.

iii

Acknowledgements The revitalised FSR/FEH rainfall-runoff method is the outcome of a joint

Defra/Environment Agency funded research project (FD1913) undertaken at the Centre

for Ecology & Hydrology. The research team would like to thank the following people

and organisations for giving their time to test and give valuable feedback on a beta

version of the present spreadsheet model.

Peter Spencer and Jean Frost Environment Agency Paul Webster Hydro-Logic Ltd David MacDonald Black & Veatch Rob Lamb and Kate Durr JBA Consulting Luke Lovell Halcrow Sonja Folwell Centre for Ecology & Hydrology

iv

Table of content 1. Introduction…………………………………………………………………….. 1

2. Installation…………………………………………………………………….... 2

3. Getting started………………………………………………………………….. 3

4. Project sheet…………………………………………………………………….. 5

5. Catchment sheet………………………………………………………………… 7

6. Rainfall sheet……………………………………………………………………. 9

7. Model sheet……………………………………………………………………… 11

8. Results sheet…………………………………………………………………….. 13

9. Audit sheet………………………………………………………………………. 15

10. Additional information………………………………………………………... 17

11. References 18

1

1. Introduction

The current spreadsheet has been created to disseminate the results from the joint

Defra/Environment Agency funded research project FD1913 Revitalisation of the

FSR/FEH rainfall-runoff method (Kjeldsen et al. 2005). This spreadsheet is a user-

friendly implementation of the method to be applied for design flood estimation in the

UK. The spreadsheet application is found in the EXCEL file ReFH Rainfall-Runoff

Method.xls.

The spreadsheet allows the input data and output results to be graphed easily and can be

used to produce and print reports simply and quickly.

2

2. Installation

To use the spreadsheet it is necessary to have Excel (version 97 or later) installed on any

PC on which the spreadsheet is to be used.

To install the spreadsheet, double-click the file ‘setup.exe’ and follow the instructions.

The two files (ReFH Rainfall-Runoff Method.xls and FEHRRModel.dll) will be installed

in the directory Program Files\FEH Software\ReFH Spreadsheet. A shortcut to the

spreadsheet will be placed on the desktop.

Following installation, multiple copies of the spreadsheet can be made and stored

anywhere on the PC or network. However, if the spreadsheet is to be applied on a PC

other than the one where it was originally installed, the installation program must be run

again in order to provide access to the library functions.

3

3. Getting started

To use the spreadsheet, open it in Excel. Excel may notify the user that the file contains

macros, as in the picture below.

In order for the model to run, it is necessary to enable these macros to be run. Some

instances of Excel may have macros completely turned off. In this case the settings in

EXCEL must be changed for the macros to be run (through the Tools | Options menu

item and the Macro Security button on the Security tab within Excel 2002).

The spreadsheet consists of 5 core-sheets (Catchment, Rainfall, Models, Results and

Audit) allowing the catchment and model parameters to be set up and the results viewed.

Within these sheets catchment descriptors can be imported and design rainfall and model

parameters can be set, altered and overwritten. Having calibrated the Revitalised flood

hydrograph (ReFH) rainfall-runoff model, the specified design flood hydrograph can be

generated and the results viewed on the Results sheet. Values for model parameters can

be adjusted and the effect on results viewed immediately.

Following successful setup and application of the design method, a report can be

generated and viewed on the Audit sheet. The audit report will provide an audit trail of

the particular application of the revitalised FSR/FEH rainfall-runoff method. The report

contains a summary of the settings used and the model results are presented in both

4

tabular and graphic form. In addition users can add their own comments to this audit trail

within each individual sheet.

Many of the cells where model input values are required have been equipped with a

comment box giving guidance on the appropriate value.

5

4. Project sheet

The first sheet is the Project sheet where general information can be entered which can

be used to identify specific model applications. This information will be used by the

spreadsheet model in the audit report-writing functionality. The sheet also contains some

instructions on the use of the software and necessary legal limitations. The spreadsheet

can only be used once the disclaimer has been read and understood, and the box at the

bottom of the sheet has been checked.

Fill in the optional user name, project and company boxes as required.

The Clear Results and Clear All buttons can be used to reset spreadsheets for reuse. A

further explanation of the functionality of these two buttons is given in Section 10.

6

5. Catchment sheet

The Catchment sheet allows the import, view and edit of catchment details and catchment

descriptors. The simplest way to populate the catchment descriptor fields is to import an

FEH CD-ROM catchment descriptor export file (.csv) or a WINFAP-FEH export file

(.cd) by clicking the Import Catchment Descriptors button. The catchment descriptor

information will then be written to the appropriate locations within the spreadsheet.

All catchment descriptors can be overwritten and any changes to imported values for

descriptors affecting the model output will be noted in the ‘audit trail’ and written to the

Audit sheet.

The name of the catchment can be added to the Catchment name box from where it will

be transferred automatically to the Audit sheet and printed reports.

7

Comments can be added to the ‘audit trail’ by entering some text in the Catchment

Comment box and clicking the Add Comment to List button.

Note – exit the Comment box before clicking the Add Comment to List button. The

comment should then appear in the User comments dropdown list. To clear the list, click

the Clear List button.

8

6. Rainfall sheet

The Rainfall sheet allows the definition of a design rainfall event according to the FEH

depth-duration-frequency (DDF) model (Faulkner, 1999) combined with the seasonal

correction factor introduced in the revitalised FSR/FEH rainfall-runoff method. To define

a design storm the following parameter values need to be specified

Parameter Description Data type

Time step (hours)* Step by which model is to be incremented Decimal

Duration (hours)* Total length of event Decimal

Return Period (years)** Return period of design rain/flood event Decimal

Season Summer or Winter events can be selected Selection

Seasonal Correction Factor Select ReFH Design Standard or enter value Decimal

Areal Reduction Factor Select ReFH Design Standard or enter value Decimal

*Note – the number of steps or intervals, which is the duration divided by the timestep,

must be an odd integer, and a warning message will advise you if this requirement has

not been met.

** Note – In the Revitalised rainfall-runoff method the T-year flood is generated from the

T-year rainfall, i.e. to produce a 100-year flood, specify a 100-year rainfall event.

In addition, the spreadsheet model uses the catchment average DDF model parameters

(C, D1, D2, D3, E and F) from the Catchment sheet cells B26-B31.

In order for the spreadsheet to produce a T-year event, as specified by the revitalised

FSR/FEH rainfall-runoff method, the default values of the areal reduction factor and the

seasonal correction factor obtained by choosing the ReFH Design Standard option in the

drop down menus should not be altered.

9

When correct values have been entered the rainfall event will be calculated and the

resulting design rainfall hyetograph displayed in the graph at the bottom of the sheet.

User comments can be added to the ‘audit trail’ as appropriate using the box and button at

the bottom of the sheet.

10

7. Model sheet

The Model sheet allows input of parameter values for the three constituent components of

the ReFH rainfall runoff method; the loss model, the routing model and the baseflow

model.

Options are available for each parameter to allow it to be automatically calculated from

catchment descriptors, set to the ReFH design standard or set by the user manually.

In order for the spreadsheet to produce a T-year event, as specified by the revitalised

FSR/FEH rainfall-runoff method, the default values of Cini, Up, Uk and BF0 obtained by

choosing the ReFH Design Standard option in the drop down menus should not be

altered.

The parameters that can be set by catchment descriptors can also be adjusted by a Donor

correction factor, which can be entered manually. This sets the parameter to the

calculated value multiplied by the correction factor.

Manually editing the Donor Correction Factor or the model parameter will automatically

update the dropdown list.

11

User comments can be added to the ‘audit trail’ as appropriate using the boxes and

buttons below each set of model parameters.

12

8. Results sheet

When the required parameters have been set, the resulting design flood hydrograph can

be generated from the Results sheet.

Click the Run Model button to fill in the results.

Summaries of the rainfall and model settings can be seen at the top of the sheet. Below

this are the model output data and a graph of key results.

The model settings can be overwritten and, if the changes are valid, the results will be

updated, thereby allowing inspection of the effects of changes to each parameter before

finalising the final model output. Note that when input values calculated from catchment

13

descriptors or ReFH design standards are edited in the Result sheet, the new values are

transferred and their status changed in the appropriate dropdown list to ‘User defined’ in

the preceding sheets..

To produce a report on the final settings selected, click the Generate Audit Report button.

This will re-run the model with the specified settings and write the results to the Audit

sheet.

14

9. Audit sheet

The Audit sheet provides a full summary of the model parameters selected and the results

within an easily printed black and white report. The summary information is presented at

the top of the report as in the Results sheet. All of the automatically generated and user

added audit information is added at the bottom of the sheet.

15

To print the report use Excel’s File | Print or Print Preview menu options.

16

10. Additional information

To clear the results and reports click the Clear results button on the Project sheet.

To clear all of the sheets, including the catchment descriptors, click the Clear all button

on the Project sheet.

When the model has been run successfully, it may be useful to save the sheet and all of

the settings. For this purpose it may be found to be useful to keep a blank copy handy for

new model runs.

The appearance of some sheets can be altered if required, though adding additional lines

and columns will invariably cause problems when the model values are read.

17

11. References

Faulkner, D. (1999) Rainfall frequency estimation. Flood Estimation Handbook Vol 2,

Institute of Hydrology, Wallingford, UK.

Kjeldsen, T. R., Stewart, E. J., Packman, J. C., Bayliss, A. C. and Folwell, S. (2005)

Revitalisation of the FSR/FEH Rainfall-Runoff method. Final research report to

Defra/EA, Centre for Ecology & Hydrology, Wallingford, UK.