Calculation points WINFAP

WINFAP enables estimation of peak river flood flows for catchments across the UK using WINFAP software from Wallingford HydroSolutions.

WINFAP enables you to estimate peak flows and flood frequency curves for both gauged and ungauged catchments across the UK. The WINFAP tab in a calculation point allows you to perform these analyses to calculate the peak flows, and save the results to the calculation point ready for further review.

The WINFAP tab in a Calculation point allows you to perform analyses to calculate estimate peak flows and flood frequency curves and save the results to the Calculation Point ready for further review. Multiple WINFAP analyses can be undertaken and saved in a calculation point (for example, if multiple pooling group compositions are tested). Once analysis is complete, results can be viewed within Flood Modeller without an WINFAP licence.

User Caution

While WINFAP provides a framework for flood estimation, it is important that you have the appropriate technical and regulatory knowledge required to use the software effectively. Further guidance is referenced here.

Info

Flood Modeller v7.4.0 is compatible with WINFAP v5.3 and supports the FEH 2025 methodology where a v5.1.0 catchment descriptor dataset is supplied to WINFAP. In particular:

• Flood Modeller can import and display results produced using the “GL non-flood years” distribution option for pooling group analyses.

• Enhanced single-site analyses are supported for compatible NRFA sites when annual maxima (.am) and peaks-over-threshold (.pt) data are present in the connected Peak Flow Dataset.

Creating a new analysis

To start a new WINFAP analysis, click the Initiate new analysis button. You must have a WINFAP licence (and must have WINFAP installed on your machine). The software will open ready for you to start your analysis. To find out more about using WINFAP, online technical guidance and supporting science reports are available here: Introduction - WINFAP Technical Guide (hydrosolutions.co.uk).

Enhanced Single-Site (ESS) WINFAP Analyses

From Flood Modeller v7.4.0, Hydrology+ supports enhanced single-site WINFAP analyses in addition to pooled analyses. When a calculation point initiates a WINFAP analysis from a Peak Flow gauge location, Flood Modeller now automatically supplies WINFAP the associated annual maxima (.am) and peaks-over-threshold (.pt) files where available. This functionality is available for calculation points located at NRFA gauge sites with compatible data contained in the connected Peak Flow Dataset (v14 or later). Single-site analyses are stored within the Hydrology+ database and can be used directly to derive boundary hydrographs for 1D and 2D models.

Once you've completed the WINFAP analysis, in the File menu, select Save to Flood Modeller, then select Exit. This will close WINFAP and allow you to save the analysis within your calculation point.

Once WINFAP exits, Flood Modeller will ask for details of the analysis to import. The time and data of analysis alongside the user who undertook the work will automatically be populated with optional fields for analysis name and user comments.

Flood Modeller can display either WINFAP derived growth curves or flood frequency curves (FFCs) for each analysis, with a separate curve for each statistical distribution selected. Users can also choose between rural and urban results and choose to overlay WINFAP flood frequency curves with a FFC from the preferred ReFH analysis from the previous tab. Results are also tabulated below the chart.

Selecting an analysis

To select a WINFAP analysis to use in your session, use the Set As Preferred toggle. This version then becomes the default WINFAP analysis the software will use, for example when reconciling the hydrographs.

For each analysis, the data is plotted on the right-hand-side of the tab. A toolbar provides options to select which data to view, and to customise the appearance of the plot. Full details of all options provided within WINFAP tab are provided in the Calculation Points technical reference.