Background to the Flood Studies Update (FSU) Programme
In 2005, the Office of Public Works (OPW) began the Flood Studies Update (FSU) Programme, in line with the recommendation of the 2004 Report of the Flood Policy Review Group which stated that the development of new or recalibrated flood estimation methods in Ireland could significantly improve the quality and facility of flood estimation for the purposes of flood risk management.
The OPW is responsible for the specification, procurement and direct management of the FSU Programme with technical direction provided by a Technical Steering Group, comprising representatives of the primary state / semi-state organisations involved with hydrology, hydrometric monitoring and associated research in Ireland.
The original FSU development comprised of six work groups, details of which can be found here.
FSU Web Portal
In 2014 The OPW launched the Flood Studies Update (FSU) Web Portal that was a key output of the FSU Research Programme that was initiated, managed and funded by the Office of Public Works. The Web Portal has been in use for the last 10 years by practitioners from several backgrounds. However, there are about 20 years of new data generated since the programme was initiated. New mapping data such as land use, land cover, digital terrain models and river networks have been made available. There was technological advancement in computing capacity and geo-spatial analysis. More importantly, the hosting environment upon which the FSU Web Portal architecture was built was getting old and outdated. In this context, it is now necessary to replace the FSU Web Portal.
Since the launch of the FSU web portal, the OPW have been continually looking at ways to improve the FSU methodologies. The OPW are currently developing a website to replace the old Flood Studies Update Web Portal. In the meantime, a Flood Estimation Package (comprising spreadsheet and GIS layers) has been developed to help FSU users to carry out flood frequency analysis for their selected site. The GIS files assist practitioners in locating the site of interest and the spreadsheet enables users to carry out flood frequency analysis and hydrograph shape development.
In 2022 OPW completed a new review of hydrometric gauges across Ireland for FSU purposes and updated the approach for estimating QMED at ungauged locations. While the pooling group approach is still used for the estimation of growth factors for ungauged locations, the network of gauges deemed suitable for pooling purposes have also been revised. This updated methodology has been tested and is deemed by OPW as suitable for flood estimation in ungauged locations. At present, this methodology is available in spreadsheet form and is known as the FSU spreadsheet.
The spreadsheet utilises a revised set of gauges and takes into account flow data up to the hydrometric year 2022. As a result, the FSU equation has been revised to reflect the improved information. Estimating design growth curves has therefore also been updated to reflect the changes in the data.
Features of the Flood Estimation Package
The Flood Estimation Package, which includes the FSU spreadsheet based tool and GIS layers, is developed for use by competent hydrologists who are familiar with hydrological techniques. The package facilitates the estimation of extreme flows, extreme rainfall depths, and generation of hydrograph shapes at nodes along river networks. It also provides physical catchment descriptors (PCDs) and other hydrological variables, for the nodes located at 500m spacing along river networks in the Republic of Ireland. The main features of the Flood Estimation Package are as follows:
1. FSU Spreadsheet Disclaimer
This contains the OPW disclaimer regarding use of the Flood Estimation Package. The package is complete on its own with
minimum need of additional data. The flood estimation package is evolving and live with opportunities to improve. Therefore,
users are strongly advised to adhere to the disclaimers in the package. Users are also welcome to provide feedback and
comments, which contributes to enhance the functionalities of the tool.
2. Readme File
The "Readme" file, accompanying the Flood Estimation Package, gives a step-by-step guide on how to use the Flood and Depth
Duration Frequency Analysis and Hydrograph generation spreadsheet. All the steps are explained in the text to which the
user is referred to for more help.
3. Flood Estimation GIS Layers
The Flood Estimation GIS layers comprises a number of spatial data layers that assist the user in finding their location of
interest (The Subject Site) and the associated data for that location. The most important layers being the rivers and FSU
node point layers amongst others. Within the Flood Estimation Package, there is a project file named ‘240924 – Flood
Estimation GIS Layers.qgz’. By double clicking on this file, all of the layers will automatically open in QGIS.
The layers include river network, lakes, FSU gauged stations, FSU ungauged node points, hydrometric areas, and grid format of the rainfall depth duration frequency. Clicking at a node point provides Node ID, Easting and Northing and other physical catchment descriptors.
4. Flood Frequency and Hydrograph – Rev 4
The first tab of spreadsheet tool is the "Cover", where most of the analysis is executed. Entering a Node ID of the
subject site at the cell indicated will populate the table provided with the site’s coordinates and necessary PCDs
to commence the analysis. For more details, on how to use the spreadsheet, please refer to the text of the ‘Readme’ file.
The tool also includes an additional tab, namely, the Report tab. The "Report" tab records the final outputs of the analysis. This is intended to be the output from the spreadsheet that users can incorporate into their own flood estimation reports.
The GIS layers help the user to navigate and locate the site of interest. The layers include river network, lakes, FSU gauged stations, FSU ungauged node points, hydrometric areas, and grid format of the rainfall depth duration frequency.
250401 - FLOOD ESTIMATION PACKAGE – Rev5
ZIP, 162 MB