Eastern CFRAM Study Liffey Flood Controls & Flood Forecasting System Option
IBE0600Rp0010_Liffey Flood Controls & FFS Option_F01
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Eastern CFRAM Study
Liffey Flood Controls and Flood Forecasting System Option
DOCUMENT CONTROL SHEET
Client OPW
Project Title Eastern CFRAM Study
Document Title Liffey Flood Controls and Flood Forecasting System Option
Document No. IBE0600Rp0010
DCS TOC Text List of Tables List of Figures No. of This Document Appendices Comprises 1 1 70 1 1 4
Rev. Status Author(s) Reviewed By Approved By Office of Origin Issue Date
D01 Draft SV, SL GG GG Amersfoort, Belfast 03.04.2012
D02 Final draft SV, MS, BQ GG GG Amersfoort, Belfast 07.11.2012
D03 Final draft SV, MS, BQ GG GG Amersfoort, Belfast 21.11.2012
F01 Final SV, MS, BQ GG GG Amersfoort, Belfast 08.02.2012
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TABLE OF CONTENTS
0 EXECUTIVE SUMMARY ...... VI 0.1 SCOPE OF THE STUDY...... VI 0.2 FINDINGS WITH REGARD TO DEVELOPMENT OF FFS OPTION ...... VI 0.3 INDICATIVE COSTS OF FFS OPTION ...... VII 1 INTRODUCTION ...... 1 1.1 CONTEXT ...... 1 1.2 STUDY OBJECTIVES ...... 2 1.3 METHODOLOGY ...... 2 2 FLOOD FORECASTING AND RISK MANAGEMENT INITIATIVES ...... 3 2.1 BACKGROUND ...... 3 2.2 SOURCES OF DATA AND INFORMATION ...... 3 2.3 CFRAM STUDIES AND FLOOD FORECASTING ...... 4 3 AVAILABLE RELEVANT DATA ...... 6 3.1 HYDROMETRIC DATA ...... 6 3.1.1 Hydrometric Stations along modelled watercourses ...... 7 3.2 METEOROLOGICAL DATA ...... 10 3.2.1 Daily Rainfall Data ...... 10 3.2.2 Hourly Rainfall Data ...... 12 3.2.3 Rainfall Radar Data ...... 12 3.2.4 Rainfall Data Input Example ...... 14 4 FRAMEWORK TO ASSESS FEASIBILITY OF FFS ...... 16 4.1 MAIN COMPONENTS OF FFS ...... 16 4.2 FEASIBILITY CRITERIA ...... 17 5 PRELIMINARY ASSESSMENT OF DUBLIN RIVERS ...... 18 5.1 RIVER LIFFEY ...... 18 5.2 RIVER TOLKA ...... 20 5.3 RIVER DODDER ...... 21 5.4 CAMAC RIVER ...... 23 5.5 PODDLE RIVER ...... 24 5.6 RYE WATER RIVER ...... 25 5.7 HOW MANY RIVER AND RAINFALL GAUGES? ...... 26 6 REVIEW OF THE LIFFEY FLOOD CONTROL RULES...... 30 6.1 INTRODUCTION ...... 30 6.2 LIFFEY FLOW REGULATION INFRASTRUCTURE CHARACTERISTICS ...... 30 6.3 FLOOD OPERATIONS DURING FLOOD PERIOD ...... 33 6.4 LIFFEY FLOOD CONTROLS AND POTENTIAL BENEFITS FROM FLOOD FORECASTING SYSTEM .. 36 7 FFS BLUE PRINT ...... 39 7.1 ARCHITECTURE OF THE FFS ...... 39
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7.1.1 Data and modelling layer ...... 40 7.1.2 The business logic layer ...... 43 7.1.3 User interface layer ...... 43 7.2 END USERS INVOLVEMENT ...... 44 7.3 CONFIGURATION OF THE FFS TO THE TELEMETRY PROCESS ...... 45 7.4 REQUIRED HARDWARE AND SOFTWARE INFRASTRUCTURE ...... 48 7.5 CHARACTERISTICS OF THE PROPOSED FFS ...... 50 7.5.1 Number of FFS clients ...... 53 7.5.2 Presentation of the FFS results ...... 53 7.5.3 Third Party hydrologic and hydrodynamic models implemented in FFS ...... 55 7.5.4 Data management in FFS ...... 56 7.5.5 ‘Trigger Value’ Settings and Communication ...... 58 7.5.6 Quality Assurance and Testing of FFS ...... 59 7.5.7 Requirements for Effective Flood Warning ...... 59 7.5.8 Training Programme ...... 60 7.5.9 Basic Maintenance, Hosting and Support for the FFS ...... 60 7.6 ECONOMIC ANALYSIS ...... 60 7.6.1 Cost Assessment of the proposed FFS ...... 60 7.6.2 Assessing the Benefits from the FFS...... 61 7.6.3 Preliminary Net Present Value Analysis ...... 64 7.6.4 Other Considerations ...... 64 8 SUMMARY AND CONCLUSIONS ...... 66 8.1 CONCLUSIONS...... 66 8.2 TOWARDS INTEGRATED FLOOD FORECASTING AND WARNINGS SYSTEM FOR DUBLIN CITY ... 68
APPENDICES
APPENDIX A HYDROMETRIC GAUGING STATIONS AND THE OPERATING AUTHORITIES
APPENDIX B ANALYSIS OF THE RIVER LIFFEY RECENT FLOODING
APPENDIX C DISCUSSION TOPICS RELATED TO THE FFS WITH KEY STAKEHOLDERS
APPENDIX D NPV ANALYSIS SPREADSHEETS
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LIST OF FIGURES
Figure 1.1 Map of the Area HA09 and the identified AFAs...... 1 Figure 3.1 Map of the studied areas and the identified Hydrometric Areas ...... 6 Figure 3.2 Available Hydrometric Stations in HA09, River Liffey Catchment...... 7 Figure 3.3 Hydrometric Stations along the modelled watercourses in the Liffey Catchment...... 8 Figure 3.4 Hydrometric Stations for CFRAMS rating review ...... 9 Figure 3.5 Conceptualised models of the main streams in the Liffey Catchment...... 10 Figure 3.6 Location of Daily Rainfall Gauges of Eastern CFRAM study area...... 11 Figure 3.7 Hourly Rainfall Gauges in Eastern CFRAM Study area...... 12 Figure 3.8 Results of preliminary radar calibration on a monthly basis. Total rainfall volumes: uncalibrated radar 28 mm, calibrated radar 84 mm, station ‘9623’ (Kncklyon, St. Columcille’s) 90 mm...... 13 Figure 3.9 Calibrated radar data on an hourly basis compared with daily rain gauge data, station ’5623’ (Glenasmole, Supt’s Lodge)...... 13 Figure 3.10 Monthly precipitation sums based on the calibrated radar data for October 2005 for the Owendoher Catchment (part of Dodder Catchment) ...... 15 Figure 3.11 Measured v.s. simulated runoffs (NAM model) for October event at the Willbrook Road Gauge Catchment ...... 15 Figure 4.1 Schematic presentation of the flood forecasting and warning process...... 16 Figure 5.1 Schematic presentation of the Liffey reservoirs...... 18 Figure 5.2 Liffey Catchment and the travel times (source: DCC, GoC) ...... 19 Figure 5.3 Tolka river catchment area...... 21 Figure 5.4 Dodder river catchment area...... 23 Figure 5.5 Camac river catchment area...... 24 Figure 5.6 Poddle river catchment area...... 25 Figure 5.7 Ryewater river catchment area...... 26 Figure 6.1 Storage-elevation curve of Pollaphuca reservoir...... 31 Figure 6.2 Schematic presentation of the Liffey Controls (situation as is)...... 35 Figure 6.3 Schematic presentation of the Liffey Controls with an integrated FFS (possible future situation)...... 37 Figure 7.1 Proposed architecture of the FFS for Liffey...... 39 Figure 7.2. Example of a FFS desktop application which is used by water managers in the Netherlands on a daily basis. It provides user-friendly access to advanced meteorological information (precipitation radar, weather forecasting models, meteo- and telemetry stations) using webservices...... 40 Figure 7.3 Top: ArcGIS based user interface of a DSS with customisable pop-up graphs of forecasted discharges and water levels (Waterboard Fryslân). Bottom: web based user interface of a DSS with pop-up graphs (Water board Hunze en Aa’s, Water board Noorderzijlvest). A white background indicates measured (telemetry) water levels; a grey background indicates forecasted water levels in a maximum (red), average (blue) and minimum (green) precipitation scenario. The precipitation scenarios are derived from both the HiRLAM and the ECMWF-EPS meteorological model...... 41
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Figure 7.4 Example of FFS Explorer interface...... 44 Figure 7.5 Example of Internet browser showing HTML ‘clickable’ map reports generated by FFS web services...... 44 Figure 7.6 Configuration of the FFS for data streaming for existing data sources and telemetry process...... 46 Figure 7.7 Example of data import task configuration file of the FFS...... 47 Figure 7.8 Configuration of the FFS for data streaming for more efficient telemetry process...... 48 Figure 7.9 Proposed hardware client - server architecture of the FFS...... 49 Figure 7.10 Client-server setup of the FFS...... 49 Figure 7.11 FFS based on a Service Oriented Architecture using WCF (Windows Communication Foundation). FFS services are registered in the Windows services registry...... 51 Figure 7.12 Example of possible graphical and tabular presentation for selected station...... 53 Figure 7.13 Example of interactive location map and hydrograph presentation of the water levels (measured and forecasted) graphical presentation for a selected station: left thin client, right web- based interface...... 54 Figure 7.14 Example of thematic mapping of attribute information (data and forecasts) for a particular station...... 54 Figure 7.15 Example of hydrographs showing the different threshold values for water levels and discharges at a particular station (left) and threshold setting interface (right)...... 55 Figure 7.16 Log file management, with easy-to-use user interface for filtering logs on application type, user, urgency etc...... 55 Figure 7.17 Schematic interaction between FFS and the external forecasting models...... 56 Figure 7.18 Example of an ensemble forecast produced by the FFS...... 58 Figure 7.19 Source-Pathway-Receptor-Consequence model...... 61
LIST OF TABLES
Table 6.1 Effect of the operation of the Liffey dams on the flooding from November 2000...... 34 Table 6.2 Effect of the operation of the Liffey dams on the flooding from November 2009...... 34 Table 7.1 Example of initial configuration of the key FFS workflows...... 52 Table 7.2 Budget breakdown for implementing a FFS for Liffey River...... 60 Table 7.3 Overview of the software licenses costs...... 61 Table 7.4 Example of cost-benefit analysis...... 63
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LIST OF ABBREVIATIONS
AAD Annual Average Damages AEP Annual Exceedance Probability AFA Area for Further Assessment AFR Area of Flood Risk CFRAMS Catchment Flood Risk Assessment and Management Study DCC Dublin City Council DEM Digital Elevation Model DSS Decision Support System in relation to flood forecasting and warning DTM Digital Terrain Model GPRS General Packet Radio Service is a very widely-deployed wireless data service GUI Graphical User Interface of the FFS HIRLAM High Resolution Limited Area Model, is a numerical weather prediction system HTML HyperText Markup Language ECMWF European Centre for Medium Range Weather Forecasts EPA Environmental Protection Agency EPS Ensemble Prediction System ESB Electricity Supply Board FFS Flood Forecasting System FRC Flood Resilient City FSU Flood Study Update FTE Full Time Employee, related to staff necessary to operate FFS FTP File Transfer Protocol is a standard network protocol used to transfer files from one host or to another host over a TCP-based network, such as the Internet. HA Hydrology Area HEP Hydrological Estimation Point HRU Hydrological Response Unit LA Local Authorities (stakeholders) NAM Hydrological modelling system (DHI) OPW Office of the Public Works SAFER Strategies and Actions for Flood Emergency Risk Management, EU project SSA Spatial Scale of Assessment SMS Short Message Service is a text messaging service component of FFS in this context UFV Data format: one time series format consisting of a header and data pairs "date/time value". XML Extensible Markup Language.
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0 EXECUTIVE SUMMARY
0.1 SCOPE OF THE STUDY
This report analyses the potential to develop and implement an effective Flood Forecasting System (FFS) option (approach) for the identified Areas for Further Assessment (AFAs) within the Eastern Catchment Flood Risk Assessment and Management (CFRAM) study area; in particular HA09, the Liffey Catchment and the wider Dublin City area.
This analysis serves as one of the inputs to the potential flood risk management options in the Preliminary Options Report and covers the potentially available advance forecast period, the potential accuracy and reliability of the forecasts, the potential required hydrometric infrastructure and an assessment of the costs for the development and implementation of FFS for the Liffey Catchment.
0.2 FINDINGS WITH REGARD TO DEVELOPMENT OF FFS OPTION
The analysis work undertaken within this part of the Eastern CFRAM Study has clearly indicated that the development and implementation of a FFS for the Liffey Catchment (part of HA09) is a viable and cost-beneficial option. Integrating this system in a nation-wide FFS (service) will further strengthen the business case for such a flood risk management option. The main potential benefits of FFS are summarised as: • Reduction in risk to life or injury • Reduction in business impact & losses • Reduction in residential impact & losses • Reduction in social and environmental impacts (e.g. social and environmental stress, concerns, insurance premiums) • Improved hydrometric gauge network • Improved use of (calibrated) radar data at the Dublin Airport • Potential optimisation of flood management measures such as operation of dams and sluices • Improved emergency response
A preliminary economic analysis (source OPW and previous reports) indicates that the average damages from fluvial flooding in the River Liffey and the wider Dublin area is approximately €15-20 million for the Annual Exceedance Probability (AEP) of 0.01 (1 in 100 years event). Pluvial, groundwater and urban water and drainage asset failure flooding damages will add to this total. Due to the scarcity of this data and also the uncertainty of the effectiveness and response made to flood warnings, it is difficult to quantify how much the provision of an effective FFS would reduce these damages. Our estimate using data from The Netherlands, UK, Germany, France and FFS from other countries, where effectiveness of the FFS is between 10-30%, is that this could be at least €2-4 million of savings in terms of average damages. The key success factors for implementing FFS are summarised as:
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- Operational use of the Doppler radar system at Dublin airport operated by Met Éireann will increase the lead-time of forecasts and the quality of the precipitation data (spatio-temporal variability). In particular this link to real-time rainfall measurements can significantly improve insight to the expected runoffs and improve model forecasts through the provision of real time high quality (spatial and temporal) input data to drive the hydrological and hydrodynamic models. - Availability of an optimised telemetry network of rain gauges and hydrometric flow / water level recorders is essential for accurate and reliable forecasts and for producing longer lead-times. The minimum data required for calibration and real time model updating of the FFS used to warn the general public should be: o Rain Gauges – At least one telemetered hourly rain gauge (but preferably up to four) to calibrate in real time the radar data to drive local rainfall runoff models. The number of gauges required depends on several factors, with accuracy generally increasing with coverage. o Hydrometric Gauges – A minimum of one river level gauge at, or near to, the identified risk areas. This is required to calibrate forecasting models and correct their predictions in real time. In large river systems such as the Liffey Catchment, it is recommended to have several river gauges upstream of the risk area to allow calibration of network sub-components and real time updating of predictions (data assimilation techniques). - Hydrological and hydrodynamic models running frequently (on a daily or sub-daily basis), with the frequency increased (to hourly forecasts) pending a flood event. - A vital component of a successful FFS is the existence of a central body (agency) to make decisions and issue clear warnings in flood emergency situations. Due to the complexity of such situations, additional tools need to be implemented to aid authorities during emergency events. - FFS must also be comprehensible and accessible to all stakeholders to gain credibility. - The need for common assessment to review the performance of the FFS which can identify any operational problems with the system in order to improve the reliability of the forecasts. o Review and simulate historical flooding events (FFS hindcasting model); o Testing the FFS for a range of design flood events; o Using statistically significant calibration data to improve the reliability of the FFS; o Incorporating feedback and learning loops into the FFS.
0.3 INDICATIVE COSTS OF FFS OPTION
The set-up cost of developing and implementing the FFS and warning service for fluvial and coastal flooding in the Liffey Catchment, by integrating existing river (Eastern CFRAM Study: NAM and Mike 11 hydrologic and hydrodynamic models) and coastal models (Triton coastal FFS) and available data streams, has been estimated to €225,000 with annual operating costs of €27,000 excluding a core
IBE0600Rp0010 vii RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL team of 2 FTEs. This FFS can be easily integrated in a national flood forecasting and warning service1 that would be cost-beneficial.
1 Strategic Review of Options for Flood Forecasting and Flood Warning in Ireland, Stage I and Stage II Report. JBA Consultants (2011).
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1 INTRODUCTION
1.1 CONTEXT
This report analyses the potential to develop and implement an effective Flood Forecasting System (FFS) option (approach) focussing on the identified Areas for Further Assessment (AFAs) within HA09 of the Eastern CFRAM study area (the Liffey Catchment and the wider Dublin City area). A map of the 17 discreet AFAs within HA09 and the four High Priority Watercourses which make up the Dublin City and Santry AFAs for HA09 is depicted in Figure 1.1.
Figure 1.1 Map of the Area HA09 and the identified AFAs.
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1.2 STUDY OBJECTIVES
The main objectives of the study are: • Create an FFS analysis that serves as one of the inputs to the potential flood risk management options for the Liffey catchment as part of the Preliminary Options Report; • Review of the Liffey flood management operational rules and controls and its relation to the development of a potential FFS; • Look at the available hydrometric and meteorological data required for a FFS and propose any additional required hydrometric infrastructure; • Outline a blueprint of a FFS for the River Liffey; • Assess the potential accuracy and reliability of the forecasts including lead times and advise how those can be improved; • Assess the potential for operational use of Dublin radar data to increase the lead-time of forecasts and the quality of the precipitation data (spatio-temporal variability); • Assessment of the costs for the development and implementation of FFS for the Liffey Catchment including simple cost-benefit analysis • Report and present the findings.
1.3 METHODOLOGY
The main methodology applied in this work included the following: • Analysis of the existing documents, reports and data availability related to the FFS in Liffey Catchment area; • Conduct meetings and discussions with the key stakeholders: ESB, Met Éireann, Local Authorities and OPW staff; • Review the current ESB Regulations and water management guidelines related to flood operation and control of Liffey reservoirs with relation to a potential FFS; • Incorporate preliminary radar-data analysis into the FFS; • Application of experience gained in other countries; • Provision of blue print of FFS; • FFS preliminary cost benefit analysis
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2 FLOOD FORECASTING AND RISK MANAGEMENT INITIATIVES
This section briefly summarises a review of the past, current and proposed flood forecasting and flood risk management initiatives in Ireland to assess how any proposed FFS could be integrated with them.
2.1 BACKGROUND
Dublin City has experienced major flooding in the past – Hurricane Charlie in August 1986, extreme tidal flooding occurred in February 2002, fluvial flooding of the Tolka occurred in 2000/02 and most recently pluvial and fluvial flooding affected large parts of Wicklow and Dublin on the 24th October 2011. Such events are rare but can have very significant impacts. Following the 2002 flood event, Dublin City Council (DCC) participated in the SAFER flood project with 5 European partners. The SAFER project was initiated in 2002 and ran until 2008. The project has seen the implementation of an early tidal flood warning system and new coastal protection schemes along the Dublin coast. In more recent times Dublin has witnessed fluvial and pluvial (or extreme rain) flooding. Flood risk in Ireland has historically been addressed through the use of structural or engineered solutions (arterial drainage schemes and/or flood relief schemes). In line with internationally changing perspectives, the Government has adopted a new strategy in 2004 that is shifting the emphasis in addressing flood risk towards: • A catchment-based context for managing risk; • More pro-active flood hazard and risk assessment and management, with a view to avoiding or minimising future increases in risk, such as that which might arise from development in floodplains; • Increased use of non-structural and flood impact mitigation measures (“living with flood” approach).
2.2 SOURCES OF DATA AND INFORMATION
The following documents/websites have been reviewed for relevance to flood forecasting and warning:
• Report of the Flood Policy Review Group (OPW) • Flood Emergency Response Planning –'A Guide to Flood Emergencies' and 'Draft Protocol for Multi-Agency Response to Flood Emergencies' (Major Emergency Management Project Team – Department of Environment, Heritage and Local Government) • Lee CFRAM Study – Draft Catchment Flood Risk Management Plan (Halcrow) • River Dodder Catchment Flood Risk Management Plan (RPS) • FEM-FRAMS Draft Flood Risk Management Plan (HalcrowBarry) • The Planning System and Flood Risk Management (OPW) • The Flood Studies Update Programme (OPW), Work Packages 2.1, 2.2, 2.3 and 3.2. • Operational Programmes: Flood Relief Schemes (OPW website)
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• Strategic Review of the Hydro-Meteorological Monitoring Programme for Ireland (JBA Consulting, 2008) • The Irish Coastal Protection Strategy Study (RPS) • Irish Flood Warning Service website (University College Cork) • Reviews (by others) of the November 2009 flooding in Ireland (in particular Eastern CFRAM Study HA09 Inception Report, RPS) • Strategic Review of Options for Flood Forecasting and Flood Warning in Ireland (JBA Consulting, 2011) • Meetings and discussions with OPW, ESB, Met Éireann and DCC conducted in June 2011.
2.3 CFRAM STUDIES AND FLOOD FORECASTING
In 2004 the Government adopted a new policy that shifted the emphasis in addressing flood risk towards a catchment based approach for managing risk, with more pro-active flood hazard and risk assessment and management, and increased use of non-structural and flood impact mitigation measures (OPW, 2004). CFRAM Study and their product Catchment Flood Risk Management Plans are at the core of this national policy for flood risk management. The aims are to assess and develop a Flood Risk Management Plan (FRMP) to manage existing flood risk, and also the potential for significant increases in this risk due to climate change, ongoing development, and other pressures that may arise in the future.
The objectives of the Studies as outlined by OPW (2010a) are to: • Assess flood risk, through the identification of flood hazard areas and the impacts of flooding; • Identify viable structural and non-structural options and measures for managing the flood risks for Areas for Further Assessment (AFAs) and within the catchment as a whole; • Prepare a Catchment Flood Risk Management Plan and associated Strategic Environmental Assessment (SEA) and, as necessary, a Habitats Directive (Appropriate) Assessment, that sets out the policies, measures and actions that should be pursued by the relevant bodies (local authorities, OPW, and other stakeholders), to achieve the most cost-effective and sustainable management of flood risk within the catchment.
The CFRAM Study should deliver upon many of the principal requirements of the EU Floods Directive and deliver upon all of the requirements set out in Articles 6, 7, and 8 of the Directive related to flood mapping and flood risk management plans (European Commission, 2007). The CFRAM Studies will identify the flood risk in each catchment in the country and draw up a prioritised plan of measures to address the risk in areas where it is significant. The OPW are leading the coordination of these studies. Whilst the CFRAM Study considers flood risk on a catchment wide basis, they will focus on areas where the flood risk was understood to be, or in the future could be significant (Areas for Further Assessment - AFAs.) The CFRAM Study are intended to develop a strategic flood risk management plan with a set of prioritised measures, actions and works (both structural and non-structural) to manage the flood risk in the catchment in the long-term, and make appropriate recommendations.
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Non-structural measures, such as flood forecasting and warning, are seen as an important part of the CFRAM Study, which can usually be implemented in the short-medium term and at a relatively low cost independent of prioritisation at a national level (OPW, 2010b). These non-structural measures can have benefits that span the short, medium and long term and provide opportunities to increase the public awareness of flood risk and encourage action to reduce damage during a flood event.
As part of the analysis of potential flood risk management options, the Catchment Flood Risk Management Plans will examine the development of an effective flood forecasting system focusing on each AFA (or on wider Spatial Scales of Assessment), and shall report on such analysis under the potential flood risk management options in the Preliminary Options Report.
The main findings from this preliminary study of options for development and implementation of a potential FFS on an AFA / SSA basis may provide an important input to the Eastern CFRAM Study that can potentially be developed further during the appraisal and evaluation of the different flood risk management options.
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3 AVAILABLE RELEVANT DATA
3.1 HYDROMETRIC DATA
The availability of hydrometric data is a fundamental requirement of any flood forecasting system. The map of the studied area for the FFS option with the focus on HA09 is presented in Figure 3.1.
Figure 3.1 Map of the studied areas and the identified Hydrometric Areas
The establishment and maintenance of hydrometric gauges and the processing of data is a specialist and time consuming task, with the responsibility currently lying with the OPW, EPA and Local Authorities. The OPW network is operated and maintained by the OPW Hydrometric Section based in Headford, County Galway (Appendix A). Since 2000, hydrometric data has been processed directly to a specialised database suite - TimeStudio, and the Hydrometric Section is currently completing migration of data to the WISKI information repository system from Kisters - Germany. There are plans to further develop the OPW hydrometric website to enable the provision of real-time data (primarily for flood warning purposes). The majority of OPW gauging stations use OTT Duosens / Logosens loggers
IBE0600Rp0010 6 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL in the field and utilise Hydras 3 software for data transfer and storage management. The telemetry systems in place use variations of techniques for data transfer from the hydrometric stations such as: SMS messages daily transfer, ‘dial-up’ connections on demand or daily scheduled and GPRS data transfer system (on a small number of stations). EPA gauging stations use a range of loggers (Duosens, OTT Orpheus Mini with ITC - Intelligent Top Cap, OTT Thalimedes with ITC) with eight on telemetry within the Liffey catchment. Data is collected for all stations through the Hydras 3 software.
Figure 3.2 Available Hydrometric Stations in HA09, River Liffey Catchment.
3.1.1 Hydrometric Stations along modelled watercourses
There are 32 hydrometric stations with data available within HA09. Water level and flow are recorded at 27 stations; water level only at 4 stations and flow measurements only at 1 station, with locations shown in Figure 3.2. There are 19 stations with available data on watercourses to be modelled as shown in Figure 3.3. The Liffey Catchment as it nears Dublin City is relatively ungauged with the
IBE0600Rp0010 7 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL nearest flow measurements available on the main channel located at the Leixlip hydro power station. The Leixlip dam / hydro power station is located over 8km upstream of Palmerstown and continuous flow information can be derived from actual flow and water level data taken at the dam outlet structures by ESB . Reservoir level recordings, inflows and discharges at the reservoirs at Pollaphuca and Golden Falls are also available from ESB.
Figure 3.3 Hydrometric Stations along the modelled watercourses in the Liffey Catchment.
However, Dublin City Council, Fingal County Council and South Dublin County Council have ongoing initiatives and projects to solve this deficiency in hydrometric stations. Most of the existing gauges only issue results on a daily basis or on a phone call from the owner and are of limited use in a flood emergency situation. One new river and rainguage is proposed to be built in 2012 on the Liffey close to the Spa Hotel, Lucan. Also a number of hydrometric stations in the Liffey Catchment are currently subject to a review of the rating relationship as part of the Eastern CFRAM Study. These are presented in Figure 3.4.
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Figure 3.4 Hydrometric Stations for CFRAMS rating review
The schematisation of the main river streams within the Liffey Catchment for which hydrological and hydrodynamic models are being developed as part of the project work of the CFRAM Study and be potentially included in a FFS of the River Liffey are presented in Figure 3.5.
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Figure 3.5 Conceptualised models of the main streams in the Liffey Catchment.
3.2 METEOROLOGICAL DATA
Meteorological data was provided by Met Éireann through OPW at the project outset. A preliminary analysis was undertaken and additional data acquired directly by RPS. Additional rainfall data was also requested from Local Authorities if available. Further assessment of the radar data potential usage for a FFS required rainfall radar data at Dublin Airport. The screening analysis of the meteorological data was carried out in order to identify which daily and sub-daily stations are of interest for developing and implementing FFS.
3.2.1 Daily Rainfall Data
Within a wider area surrounding the Eastern River Basin District (ERBD) daily rainfall data was received from Met Éireann for 565 rainfall gauges with additional information provided from Local Authorities for a further 2 stations giving a total of 567 daily rainfall gauges. There are 260 stations within the Eastern CFRAM Study area. An additional 307 are located within a 100 [km] buffer zone
IBE0600Rp0010 10 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL around the Easter UoM boundary as shown in Figure 3.6. These additional stations can be potentially included, especially providing rainfall sums for the Dublin radar data calibration.
Figure 3.6 Location of Daily Rainfall Gauges of Eastern CFRAM study area.
Within HA09 there are 62 rainfall gauges with additional rainfall gauges from the local authorities (Dublin City Council, Fingal County Council and South Dublin County Council), giving a total of 75 rainfall gauges. A detailed status table for all daily rainfall stations has been compiled by RPS and is presented in Appendix B of the HA09 Inception Report (August 2012).
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3.2.2 Hourly Rainfall Data
Data for hourly rainfall stations was also provided by Met Éireann. Data for a total of 15 hourly rainfall gauges was provided for the Eastern RBD and surrounding area, with their locations shown in Figure 3.7. There are 5 stations within the Liffey river catchment area (HA09) for which hourly data is available. Information on the length of the records for each of the Met Éireann hourly rainfall gauges is compiled by RPS and presented in Appendix B of the HA09 Inception Report (August 2012).
Figure 3.7 Hourly Rainfall Gauges in Eastern CFRAM Study area.
3.2.3 Rainfall Radar Data
Based on the meeting at Met Éireann, the Dublin radar data (15 min resolution) is available for the period between 1997 – 2011 in both polar format and corrected grid format. Initially, the rainfall radar data was provided by Met Éireann for the period 2002-2006 and consisted of hourly PAC (precipitation
IBE0600Rp0010 12 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL accumulations) data on a 1 x 1 kilometre grid. This data was processed using HydroNET software, for preliminarily calibration of radar data on a daily and monthly basis using Met Éireann ground observation data from the rain gauges. The combination of spatially distributed rainfall intensities from radar and accurate rainfall amounts from rain gauges results in an improved dataset for use in hydrological modelling, both in terms of spatial resolution (1 x 1 kilometre grid) and temporal resolution (hourly data). The result of the preliminary radar calibration (Figure 3.8) was verified using independent stations (not used for calibration of radar). Figure 3.9 demonstrates the higher resolution in the temporal trend using the rainfall radar over a daily gauge.
Figure 3.8 Results of preliminary radar calibration on a monthly basis. Total rainfall volumes: uncalibrated radar 28 mm, calibrated radar 84 mm, station ‘9623’ (Kncklyon, St. Columcille’s) 90 mm.
(Calibrated)
Figure 3.9 Calibrated radar data on an hourly basis compared with daily rain gauge data, station ’5623’ (Glenasmole, Supt’s Lodge).
The applied radar calibration in this phase was only preliminary, using monthly correction factors and basic calibration techniques. Improved calibration of radar data could consist of several consecutive calibration steps on an hourly or 15 minute basis, similar to the steps described by Holleman (2007): Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL
1. Calculate the parameter (RG) describing the relationship between the amount of precipitation from rain gauges (G) and the corresponding radar pixels (R) for each pair of G and R:
⎛ R ⎞ RG = 1010 log⎜ ⎟ ⎝ G ⎠
2. Bias correction: the average of all available RG values is used to bias, for example, calibration errors. Moreover, the calculated standard deviation is used to perform a quality control on the RG values, and thus the radar and rain gauge observations.
3. Distance correction: correct for the height of the radar beam above the earth surface and related underestimation of the precipitation intensity at that location. This correction is described as a function of the distance to the radar r and the course of RG and r are fitted to a parabola.
4. Spatial correction: an inverse-distance method of the RG values is used to correct for local effects in the radar composite. This analysis yields a smooth field that does not necessarily fit the data points.
To apply the described correction methodology, the existing HydroNET tools together with the SCOUT software by Hydro&Meteo (www.hydrometeo.de) will be utilised. These tools are already widely used in the Netherlands and internationally. The result is a self describing dataset in the NetCDF format; a format which is well-known and widely used in meteorology.
3.2.4 Rainfall Data Input Example The spatially distributed rainfall per hydrological response unit can significantly improve calibration of hydrological models and increase the lead time. This was tested for the Owendoher catchment in South Dublin, a sub catchment of the Dodder River, using the preliminary calibrated radar rainfall data as described above (shown in Figure 3.10). Model results for October 2005 based on radar rainfall data were compared against model results based on daily rain gauge data (Figure 3.11). For this, rainfall input for the NAM model was generated using HydroNET software, for weighted averaging of the radar pixels above the Willbrook catchment area. In addition, HydroLogic and RPS carried out an extensive trial with radar-generated time series for the Dodder and Owendoher catchments to present the value of using hourly radar-derived rainfall data for hydrological modelling (see separate RPS report no. IBE0600Rp0007 Dublin Radar Data Analysis for the Dodder Catchment, Stage 1, issued to OPW).
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Figure 3.10 Monthly precipitation sums based on the calibrated radar data for October 2005 for the Owendoher Catchment (part of Dodder Catchment)
4.500
Qm (m3/sec) Qs_new(m3/sec) 4.000
3.500
3.000
2.500 (m3/s)
2.000 Discharge
1.500
1.000
0.500
0.000 9/25/2005 0:00 9/30/2005 0:00 10/5/2005 0:00 10/10/2005 0:00 10/15/2005 0:00 10/20/2005 0:00 10/25/2005 0:00 10/30/2005 0:00 11/4/2005 0:00
Figure 3.11 Measured v.s. simulated runoffs (NAM model) for October event at the Willbrook Road Gauge Catchment
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4 FRAMEWORK TO ASSESS FEASIBILITY OF FFS
4.1 MAIN COMPONENTS OF FFS
The HydroLogic and RPS knowledge and experience in implementing an operational decision support system for flood forecasting was used to develop the framework for this study. The methodology that encapsulates the flood forecasting and warning process is schematically depicted in Figure 4.1
feedback and fine tuning
Monitoring & Detection Warning Response
Forecasting Æ lead time
Simulation
Figure 4.1 Schematic presentation of the flood forecasting and warning process.
The main components of the FFS are:
Monitoring involves the collection of meteorological data and hydrological data, e.g. real-time and historic water level measurements. Forecasting entails utilising monitored data to model future situations and thus give a forecast, e.g. where and when will certain water levels occur. Warning incorporates receiving flood forecasts, interpretation of the data and subsequent issuing of warnings based on preset trigger criteria. Response involves informing the public, coordination of emergency response activities e.g. Major Emergency Plan (MEP) for Dublin and response measures such as placing of demountable flood defences. Evaluation assesses the overall performance of the aforementioned components individually as well as combined (e.g. carry out hindcasts, carry out flood emergency exercises) and results in feedback regarding the improvement of the FFS. As such evaluation and improvement are often considered separately.
The approach for flood forecasting, early warning and communication of the water levels (and flows) for the River Liffey in Dublin is based on implementation of a FFS that encapsulates the process summarised below:
Goal: To accurately forecast the water level and discharges at the defined hydrometric stations in a manual and automated model and provide accurate lead time of more than 12-15 hours, using existing (or new) forecasting models;
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Data: Frequently (automatically and on-demand) retrieve the monitoring data with the interval of 15 minutes (rainfall data and water levels from the available hydrometric stations). Alternative data planned to be implemented as data feeds in the FFS are the radar data provided by Met Éireann (currently under analysis) and ensemble meteorological predictions (on the basis of the Hirlam model, or ECMWF) provided by Met Éireann. These alternative data feeds can be used if requested and if the local accuracy of this data allows to extract and calibrate time series of forecasted precipitation on the different catchment locations necessary for the hydrological and hydrodynamic models.
Process:
• Data acquisition via telemetry process and alternative data feeds. • Data validation, inspection and labelling (error cleaning and gaps interpolation). • Preparing data and model parameters for the third-party forecasting models: e.g. NAM, Mike 11 models. • Running the models and post-processing modelling results. • Showing outputs (via interactive maps, graph, tables and profiles). • Running different scenarios by preparing alternatives (manipulating inputs). • Comparing output runs (via interactive graphs, tables and profiles). • On the basis of thresholds, approving ‘a’ forecast with a quality stamp and make it public. • Warning and dissemination. • Preparing emergency response.
4.2 FEASIBILITY CRITERIA
The main driver to assess the feasibility of implementing a FFS for the Liffey Catchment and the wider Dublin area is to establish the potential at an early stage for one of the inputs to the flood risk management options for the River Liffey which can then be further developed as part of the Preliminary Options Report. A more detailed assessment of the feasibility will be provided in future phases of the Eastern CFRAM Study, once more insight is obtained into the costs and benefits and other flood risk management options. However it is likely that social considerations as well as economic considerations will be prominent in deciding whether or not to develop and implement a FFS; considerations such as the despair caused by flooding and the public demand within flood prone areas to be informed of any potential flood event beforehand. In general terms physical, technical, social and economic factors will determine the boundary conditions as well as the need for the FFS. The performance of the FFS can be assessed via performance parameters such as timeliness, accuracy, reliability, user friendliness, flexibility and costs & benefits. Within the scope of this study, the focus has been on the first three parameters and result in an analysis of the following: - lead-time, i.e. time to response; - adequacy of the hydrometric and meteorological data; - assessment of the initial development and implementation costs. In later phases of the development, the focus will shift to user friendliness, flexibility and detailed costs – benefit analysis.
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5 PRELIMINARY ASSESSMENT OF DUBLIN RIVERS
5.1 RIVER LIFFEY
The River Liffey is the largest of the Dublin rivers with a length of 138 km and a total catchment area of 1300 [km2]. The upper stretches are heavily dominated by the Pollaphuca and Golden Falls reservoirs which provide substantial opportunity to contain floods (Figure 5.1). The lower stretches are far less controlled. The total lead-time is in the order of 12-15 hours. Herewith the lead-time is defined as the flood forecasting time horizon for which flood warning can be issued based on the hydrometeorological conditions and the flood travel times. At present, limited infrastructure is in place regarding monitoring (rainfall, water levels) and no models are currently available to carry out hydrological forecasts. There are however weirs and reservoirs that could aid in improving lead-times. The size of the catchment may also provide opportunities for new measures to be implemented to increase lead-times. The Electricity Supply Board (ESB) do however have considerable operational infrastructure in place in order to operate the Pollaphuca, Golden Falls and Leixlip reservoirs. Their control centre at Turlough Hill was established in 2003 (although since 1972 the Liffey power generation systems have been run from Turlough Hill) and makes use of meteorological information from Met Éireann, rain gauge measurements at the reservoirs in the Liffey Catchment and hourly rain gauge measurements at Tulough Hill to predict conditions at the dams and reservoirs. Operational decisions are taken based on expert judgement and experience.
Upper catchment
289 km² Pollaphouca reservoir 20 km² Golden Falls reservoir 2 km² Middle catchment
534 km² Leixlip reservoir 0.3 km² Lower catchment
422 km² Tidal effect
Figure 5.1 Schematic presentation of the Liffey reservoirs.
The most recent flood events in the Liffey Catchment were October 2011, November 2009, November 2000 and June 1993 (see Appendix B). The 2000 and 1993 events were analysed in order to develop a better understanding of how the flood was managed within the catchment. The return period of the selected events was 60 years for Pollaphuca for November 2000 event and 3 years for the June 1993 event. For Leixlip Reservoir the return periods were 22 and 45 years, respectively. Based on the analysis, it was more than evident that Pollaphuca acts as a flood relief reservoir for the middle and lower catchments. In the absence of the dam at Pollaphuca extensive flooding would have occurred in
IBE0600Rp0010 18 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL the Middle and Lower catchments. The typical travel times from Liffey upstream catchment boundary to various locations are presented in Figure 5.2.
Figure 5.2 Liffey Catchment and the travel times (source: DCC, GoC)
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With the Pollaphuca reservoir, downstream reaches are generally insensitive to any major events in the area upstream of Pollaphuca (although an event in November 2009 necessitated controlled releases at Pollaphuca). Golden Falls reservoir further reduces flood risk (by effectively regulating the discharges from Pollaphuca) but to a much lesser degree. The main consideration for the operation of Pollaphuca and Golden Falls reservoirs is to time release to minimise flood risk based on events that do directly impact on the middle and lower stretches of the Liffey. This is also one of the main operational objectives for the ESB control centre at Turlough Hill. The focus on flood risk and of the flood forecasting system should therefore be on the middle and lower Liffey stretches. This obviously would need to accommodate available operational infrastructure in place at Turlough Hill. Several flood risk management options can also be considered. It is obvious that there will be some degree of negativity with each option proposed to alleviate flooding. Following the above discussions the construction of new defences may be needed in the Middle and Lower Liffey catchments. This can be flood containment options (walls, embankments etc.), demountable rigid or floating defences etc. Those options together with the proposed FFS will be evaluated within the scope of the Eastern CFRAM Study.
In relation to the lead times of the River Liffey, one of the most important factors is an availability of accurate and reliable weather forecasts. Weather is the main source for fluvial, tidal and pluvial water flooding in the Liffey Catchment and its urbanised areas. For fluvial floods, the predictability depends on the scale of the river basin and hence its concentration and response times. The River Liffey with concentration times in excess of 12 hours is also likely to obtain most of its flood precipitation from the moist airstreams associated with major frontal systems and depressions which are reliably predictable for up to about 2-3 days ahead using 'state of the art' regional weather models, particularly if supplemented by regional ensemble forecasts. Hence using EPS weather forecasts (based on Hirlam or ECMWF models) in a FFS for the River Liffey is highly advisable. The smaller catchments and streams of the River Liffey in the Middle and Lower parts, especially those prone to flash floods may respond in less than 3-6 hours. For these, and for pluvial floods in the urbanized areas, the prediction horizon of weather forecasts becomes much more crucial, but the predictability may often be less because of the small scale of the weather processes involved. In such cases the use of the Dublin calibrated radar data to generate accurate spatio-temporal precipitation patterns and time series (with 15 min or hourly resolutions) is crucial. The radar-generated rainfall information can potentially extend the lead times for such smaller and flashy catchments up to 3 hours.
5.2 RIVER TOLKA
The Tolka is the second largest river in HA09, however substantially smaller than the Liffey with a total length of 33 [km] and catchment area of 152 [km2]. The lead-time is in the order of 5 to 6 hours. Also for the Tolka, at present limited infrastructure is in place regarding monitoring (rainfall, water levels). Hydrological and hydrodynamic models to carry out hydrological forecasts are partially available (GDSDS, 2005). There are limited measures currently in place that could aid in improving lead-times. At present, it is anticipated that meteorological information (use of radar data) and additional river gauges could improve lead-times.
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Figure 5.3 Tolka river catchment area.
The Tolka too flows through a substantial area of Dublin (see figure 5.3). Flooding can affect large areas and a substantial part of the Dublin population. As such the need for a FFS from a social perspective is substantial.
5.3 RIVER DODDER
The Dodder River has a total length of 27 [km] and catchment area of 113 [km2]. It rises on the slopes of Kippure mountain and discharges into the River Liffey near Ringsend. The swift transfer of rainfall into the river channel combined with the high degree of urbanisation within the catchment downstream of Bohernabreena makes the river system highly susceptible to flooding during periods of extreme rainfall events. Current estimates indicate that the peak volume of water which flowed through the River Dodder during the most recent flooding event from October 2011 was approximately 250 [m3/s] downstream of Ballsbridge.
The lead-time is in the order of 2 to 3 hours only. Also for the Dodder, at present limited infrastructure is in place regarding monitoring (rainfall, water levels) and hydrologic and hydrodynamic models. It had been uncertain whether meteorological forecast (use of radar) can help improve lead times, due to the relatively small catchment area that lies in the “shadow” of the Wicklow Mountains. The radar data analysis of the Dublin radar for the Owendoher catchment, conducted by HydroLogic and RPS, demonstrated a clear improvement of radar-generated rainfall data in comparison with the area- weighted derived rainfall data through hydrological modelling and ability to better estimate peak flows,
IBE0600Rp0010 21 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL their timing and overall water balance (expected runoff) from the catchment. There are also a number of flood mitigation measures in place (e.g. Triton coastal FFS, tidal flood gates and demountable walls) that could help in improving lead times and reducing flood risk and damages. Furthermore, it is expected that other measures could be put into place to reduce flood risk along the Dodder river: the proposed flood protection works include raising and replacing existing flood walls and embankments in certain locations on the west and north banks of the river to cater for the one in one hundred year river event or the worst 200 year combined tidal and river event in the tidal region. All of these flood protection works are currently being studied as part of the Eastern CFRAM Study. Certain flood alleviation measures may be classified as emergency works in the near future with a view to their quick implementation.
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Figure 5.4 Dodder river catchment area.
5.4 CAMAC RIVER
The Camac River originates at Brittas, south of Saggart in the Wicklow Mountains. The Camac is also fed by many tributaries running off the Wicklow Mountains south of Saggart and Jobstown and is particularly flashy. The total catchment area is approximately 60 [km²] and the main channel is at least
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22 [km] long. The Camac and its tributaries pass through much of the south west of Dublin before entering the River Liffey at Kilmainham.
Figure 5.5 Camac river catchment area.
During the flood event of October 2011 the Camac burst its banks and caused severe flash flooding to many parts of south west Dublin including Saggart, Jobstown, along the N7, Clondalkin, Walkinstown and Kilmainham. During this event the catchment responded within a few hours to heavy rainfall in South Dublin and the Wicklow Mountains.
5.5 PODDLE RIVER
The Poddle River is the smallest of all the main Liffey tributaries with a catchment area of approximately 12 [km²]. The Poddle is heavily urbanised and much of it has either been culverted or
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Figure 5.6 Poddle river catchment area.
During the flood event of October 2011 the Poddle burst its banks and caused severe flash flooding of parts of South Dublin including at Kimmage and Harolds Cross. During this event the catchment responded within a few hours to heavy rainfall in the South Dublin area.
5.6 RYE WATER RIVER
The Rye Water and its major tributary the Lyreen are tributaries which feed the middle to lower catchment of the Liffey at Leixlip. Both rivers originate from the north and south of the town of Kilcock. It is a mainly rural catchment and flows through Kilcock, Maynooth and Leixlip before joining the River Liffey just below the Leixlip reservoir. The total catchment area is over 200 [km²] and the Rye and Lyreen are approximately 25 [km] and 14 [km] in length respectively. The lead-time is in the order of 3 to 9 hours depending on location within the catchment.
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Figure 5.7 Ryewater river catchment area.
Flooding of the Rye Water and the Lyreen has affected Maynooth, Kilcock and Leixlip on a number of occasions, most notably December 1954, November 2000, November 2002 and August 2008.
5.7 HOW MANY RIVER AND RAINFALL GAUGES?
One of the main questions in relation to the development and implementation of an operational FFS for the Dublin rivers is the availability of real-time precipitation data (hourly, or 15 min) that feed hydrological and hydrodynamic models. At present there are only 3 such recorders within the Liffey catchment. Hence, use of real-time radar data is critical for providing spatio-temporal rainfall patterns over the catchment areas and its corresponding hourly (or 15 min) rainfall time series data.
In the literature, several theories have been developed to determine the minimum number of rain gauges necessary to provide sufficient real-time rainfall information. For example, using the US National Weather Guideline would suggest the following minimum number of real-time rainfall gauges in the three catchments: - Liffey river catchment (1300 km2) would require approximately 10 real-time rainfall gauges; - Tolka river catchment (152 km2) would require approximately 5 real-time rainfall gauges; - Dodder river catchment (113 km2) would require approximately 4 real-time rainfall gauges;
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According to the World Meteorological Organization (WMO) guidelines, the minimum density (gauge / km2) of the rain gauges based on the type of the topography (mixture of mountainous areas and flat catchment areas) would suggest a real-time rain gauge for every 100-150 [km2]. This results in a similar required number for the Liffey catchment of approximately 10 real-time rain gauges. However, for the Tolka river catchment area this will mean 2 real-time rain gauges and for the Dodder river catchment area 1 real-time rain gauge which is lower. In relation to the Liffey catchment and as described previously and based on historical flooding evidence, within the upper Liffey catchment the reservoir at Pollaphuca is well managed and most of the flooding problems are likely to occur in the middle and lower catchment. In such cases the soil needs to be saturated from previous events to give the biggest problems. Therefore installing rain gauges at the upstream / middle Liffey catchment will give the best lead-times, hence earliest warnings. In general, the minimum number of sub-daily rain gauges required to achieve a desired level of accuracy for the estimation of area-averaged rainfall can be determined statistically by the coefficient of variation approach and statistical sampling (optimization) approach using information theory.
Alternatively, the use of the Dublin calibrated radar data for deriving real-time rainfall information could significantly reduce the number of the required real-time rainfall gauges. In this case, the radar images can be calibrated using the daily and monthly sums from the available (and new) rain gauges and scaled down and verified using the subdaily rainfall information available at Casement and Dublin airport. For the Ryewater, Camac / Poddle, Dodder, and Tolka catchments, it would be advisable to have at least one real-time rain gauge per each catchment area for further sub-daily radar data calibration and validation.
However, for implementing an effective FFS, availability of telemetered hydrometric river level gauges is of critical importance. At least one river level gauge near to the risk area is required in order to calibrate forecasting hydrologic and hydrodynamic models and correct their predictions (by data assimilation) in real time. In larger rivers such as the Liffey, it is also advantageous to have several river gauges upstream of the risk areas to allow calibration of river network sub-components and enable real time data assimilation (updating) of predictions that can extend lead times. The costs for additional hydrometric gauges (telemetric), based on the site conditions and available infrastructure will typically add a €10,000-15,000 cost per river gauge for installation and €4,000-€5,000 per river gauge per year for operation and maintenance.
In terms of priority for a development and implementation of FFS for the River Liffey, the following phased approach is suggested: Phase 1: Installation of telemetered river gauges at key locations: • Installation of telemetered river gauge at Newbridge on River Liffey with a potential of improving lead times up to 12 hours (relative to Islandbridge location in Dublin city); • Installation of telemetered river gauge at Celbridge on River LIffey with a potential of improving lead times up to 5 hours (relative to Islandbridge location in Dublin city); • Installation of telemetered river gauge at Kilcock on River Rye Water with a potential of improving lead times up to 8 hours (relative to Islandbridge location in Dublin city);
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• Installation of telemetered river gauge at Maynooth on River Baltracey (confluent to river Ryewater) with a potential of improving lead times up to 5 hours (relative to Islandbridge location in Dublin city); • Installation of telemetered river gauge at Lucan on River Liffey (after the confluence of Ryewater and Liffey) with a potential of improving lead times up to 3 hours (relative to Islandbridge location in Dublin city);
Note that the ESB currently gauge water levels on the Liffey main channel through the dam outfall structures at Pollaphuca, Golden Falls and Leixlip and if continuous flow information were to be made available in real time such that it could be processed into flow data, it could potentially reduce the requirement for the installation of telemetered river gauges at Cellbridge and Lucan.
Phase 2: Making available operational Dublin radar rainfall data: • Analysis and adjustment of the Dublin rainfall radar data (PCA, CAPII) using all available daily and sub-daily stations in the Liffey Catchment area. This work is already commissioned by OPW as a Stage 2 Dublin Radar data analysis and is ongoing. The main deliverable is generation of gauge-adjusted radar rainfall time series (1-hour resolution) on a grid of 1x1 [km] for the available period of radar data (1997-2010), covering the complete Liffey catchment and the other catchments in the Eastern CFRAM study area; • Making online operational gauge-adjusted radar rainfall time series available through an interactive portal / suitable FFS platform. This work is already proposed to OPW and is pending approval subject to results from the Stage 2 and Stage 3 (Shannon) outputs. The main deliverable in relation to HA09 would be the provision of gauge-adjusted radar rainfall time series for any place and hydrological response unit in the Liffey Catchment, including statistical rainfall analysis and comparison with design rainfall events and historical events.
Phase 3: Implementation and roll-out of FFS for the River Liffey: • Installation, customisation and roll-out of a FFS for the River Liffey. The blue-print of the system is outlined in Section 7; • FFS fine tuning period (one year minimum) involving the key stakeholders, before the systems generate alarms and warnings to the public. • Development of a robust regression model (e.g. artificial neural network, genetic programming or similar) for flood forecasting at the AFAs using the previously installed river gauges and operational gauge-adjusted radar rainfall time series data. This model will act as a secondary model and complement the hydrological / hydrodynamic forecasting model as part of the FFS.
Phase 4: Installation of additional real-time telemetered rain gauges: • Upgrade and installation of additional telemetered rainfall gauges in the wider Liffey Catchment area as depicted in Figure 5.1; • These additional rainfall gauges are not necessary for the implementation of the aforementioned FFS if operational radar data is made available in real time. However the data
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streams of these additional rain gauges could be used for provision of real-time rainfall information through an interactive portal / suitable FFS platform and as ground information for further improvement and adjustment of the real-time Dublin radar information.
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6 REVIEW OF THE LIFFEY FLOOD CONTROL RULES
6.1 INTRODUCTION
The ESB operates the three reservoirs and hydro-electric plants on the Liffey River based on: ‘Regulations and Guidelines for the control of the River Liffey, Water Management Document, February 2006, ESBI’.
The distinct types of operations are summarised as: 1. Routine Operations 2. Flood Period Operation 3. Other Variations in Operational Modes.
The routine operation is the normal scenario where no threat of flooding exists and where oxygen levels in the river downstream of the reservoirs are satisfactory for the aquatic ecosystem.
The flood period operation begins when the conditions are such that require spilling of excessive flood waters until normal operating conditions are established. This flood period operation occurs when the Pollaphuca Reservoir level is greater than 186.30 [mOD] and/or the inflow to the Leixlip reservoir is greater than 50 [m3/s] or beforehand if a large inflow is expected into Pollaphuca or Leixlip reservoirs. During this period, the top priority is flood management to avoid any risk to dam safety. All other reservoir operation objectives, such as efficiency of electric power generation, system requirements, environmental, social, legal and economic considerations are secondary.
The other variations in operational modes occur when oxygen level deficiency in the water is significant and due to water abstractions by others.
The ESB in 1995 revised the Liffey Control Regulations based on the five years operational experience of the previous Regulations issued in July 1990 and took into account the experience gained during a major flood that occurred in the Liffey catchment in June 1993. As a result, the Maximum Normal Operating Level at Pollaphuca was reduced by 0.3 [m] and the spilling instructions at Pollaphuca were modified. The final revision of the Regulations is issued in February 2006 (Report no. PA449-R005-014) that improved the clarity by separating Regulations for Flood Management from the Water Management Guidelines and describing organisation and specific staff responsibilities in detail. These updated Regulations, in conjunction with the dam improvement works and the establishment of the ESBI’s Hydro Control Centre (HCC) in 2003, ensure that the dams at Pollaphuca, Golden Falls and Leixlip should be capable of dealing safely with floods having an expected annual probability of occurrence of 1:10,000.
6.2 LIFFEY FLOW REGULATION INFRASTRUCTURE CHARACTERISTICS
The River Liffey on its way to the City of Dublin, apart from passive weirs, is regulated at three main locations: Pollaphuca, Golden Falls, and at the Leixlip impoundments.
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Pollaphuca: Pollaphuca Reservoir is generally operated to guideline target levels, which are in place to provide for adequate storage for water supply for Dublin City Council. The impoundment at Pollaphuca has storage-elevation hydrological characteristics presented in Figure 6.1. Dublin City is abstracting water for the Ballymore Eustace Water Treatment Plant such that gravitational water intake is possible down to a TWL of 179.9 [mOD], for an abstraction of 318 [MLD]. Flows that are released to the Liffey from Pollaphuca are almost exclusively via the turbines to the Golden Falls impoundment. The main control levels (reference to Ordinance Datum Poolbeg) on Pollaphuca are: - Maximum Crest Level: 189.59 [mOD]; This level is also referred as exceptional reservoir level; - Maximum Normal Operating Level: 186.30 [mOD]; - Minimum Normal Operating Level: 179.90 [mOD]; - Zero Storage Level: 174.00 [mOD]. - Normal Operating Range: 186.30-179.90 = 6.40 [m]
Maximum Normal Operating Level
100 days storage @ 318 MLD for water supply
Minimum Normal Operating Level
Figure 6.1 Storage-elevation curve of Pollaphuca reservoir.
The catchment hydrology of the Liffey at the Pollaphuca reservoir has the following characteristics: - Catchment area above the dam: 309 [km2]; - Reservoir area of 20 [km2] at 186.60 [mOD]; - Normal operating capacity of 99.80 x 106 [m3] above 179.90 [mOD]; - Average annual long-term rainfall: 1390 [mm]; - Average annual inflow to Pollaphuca ranges: min 5.74 [m3/s] to max 12.58 [m3/s]; - Average long-term annual flows (1950-2004): 8.82 [m3/s]
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The control structures (3 x spillway gates) regulating the flows can be manipulated by electromotor and manually. Remote indication of gates movement can be received in the Turlough Hill Control Room. The discharges through the Kaplan turbines can be fully controlled from the Turlough Hill Control Room. The water level gauges located at the dam (fixed gauge, 3x SGS pressure level transducers and backup ultrasonic device) and at the tailrace (fixed gauge and 3x SGS pressure level transducers) send signals to the Turlough Hill Control Room via SCADA and are indicated locally (with digital display) at the Pollaphuca Control Room.
Golden Falls: The Golden Falls dam is situated about 2 [km] downstream of Pollaphuca and acts as a regulating reservoir for discharges from Pollaphuca, impounding approximately 800,000 [m3] of water. The flow to the Liffey river from Golden Falls is again predominantly through the turbines. Because of the characteristics of the turbines (Francis and Propeller), which do not work well on partial load, and which have a discharge of 30 m3/s on full load, releases from Golden Falls tend to be intermittent. The turbines are operated is such a manner so that the channel capacity of the Liffey river is not exceeded. The control levels of the Golden Falls reservoir are: - Maximum Crest Level: 140.55 [mOD]; - Maximum Normal Operating Level: 139.00 [mOD]; - Minimum Normal Operating Level: 136.00 [mOD];
The catchment hydrology of the Liffey at the Golden Falls reservoir has the following characteristics: - Catchment area above the dam: 5 [km2]; - Reservoir area of 2 [km2] at 139.00 [mOD]; - Normal operating capacity of 0.79 x 106 [m3] (136.00 – 139.00 [mOD]);
The control structures (3 x spillway gates) regulating the flows can be manipulated by electromotor and manually. Remote indication of gates movement and position can be received in the Turlough Hill Control Room. The discharges through the turbines can be fully controlled from the Turlough Hill Control Room. The water level gauges located at the dam (fixed gauge and 3x SGS pressure level transducers) and at the tailrace (fixed gauge and 3x SGS pressure level transducers) send signals to the Turlough Hill Control Room via SCADA and are indicated locally (with digital display) at the Golden Falls Control Room and can be displayed also in the Pollaphuca Control Room.
Leixlip: After passing through Golden Falls, the Liffey flows approximately 56 [km] through Co. Kildare to a relatively small reservoir at Leixlip, which is 20 [km] upstream from Dublin City. There are a number of small towns and villages located on its course, including Ballymore Eustace, Kilcullen, Newbridge, Straffan and Celbridge, all of which have the potential to be affected by extreme floods on the Liffey. Leixlip Dam contains two spillways and water releases are predominantly through the turbines with excess water spilled through the spillways. The catchment between the Golden Falls dam and the Leixlip dam is 529 [km2]. The control levels of the Leixlip reservoir are: - Maximum Crest Level: 46.74 [mOD]; - Maximum Normal Operating Level: 45.60 [mOD]; - Minimum Normal Operating Level: 43.00 [mOD];
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The catchment hydrology of the Liffey at the Leixlip reservoir has the following characteristics: - Catchment area above the dam: 843 [km2]; - Reservoir area of 0.3 [km2] at 45.60 [mOD]; - Normal operating capacity of 0.77 x 106 [m3] (43.00 – 45.60 [mOD]); - Average annual long-term rainfall: 1032 [mm]; - Average annual inflow to Leixlip ranges: min 7.88 [m3/s] to max 20.56 [m3/s]; - Average long-term annual flows (1950-2004): 13.17 [m3/s]
Hydrometric data at the Liffey reservoirs is available through automated water level recorders: - 9032 Pollaphuca Hydro Station (since 1944); - 9007 Golden Falls Hydro Station (since 1994); - 9022 Leixlip Hydro Station (since 1949); - 9006 Celbridge (since 1933); Historic data is also available through the automated water level recorder at the following locations: - Golden Falls Tailrace (1943-2000); - Straffan (1982-2000); - Ballyward (1983-1995).
The controlled stations discharges are computed as a sum of the turbine discharges + discharges through the fish paths + spillway discharges.
6.3 FLOOD OPERATIONS DURING FLOOD PERIOD
Water resources and capacities in the three reservoirs are managed by remote operation of the generating stations and dam spillway gates. However, personnel are in attendance at the dams during floods. In the Liffey catchment, Pollaphuca reservoir is the principal means of flood control through the storage and controlled discharge of upper catchment inflow. The operating regulations stipulate that the water level in Pollaphuca reservoir is maintained between a maximum normal operating level and minimum levels, which are in place to provide for adequate storage for water supply for Dublin City Council. Should a storm occur in the catchment and increase the inflow to the reservoir and thereby cause levels to rise, the regulations provide a clear flood operating regime to store this inflow. Pollaphuca reservoir has a substantial flood storage capacity which approximates to 50% of the average annual inflow and it is designed to safely discharge floods having an expected annual probability of occurrence of 1:10,000.
According to the Regulations, the “flood period” operation begins when the conditions are such that spilling of the excessive flood waters is required until normal operating conditions are established. During the flood period, personnel are in attendance at the dams and can take over if necessary from the HCC in Turlough Hill. This flood period operation occurs when Pollaphuca Reservoir level is greater than 186.30 [mOD] and/or the inflow to the Leixlip Reservoir is greater than 50 [m3/s] or beforehand if a large inflow is expected into Pollaphuca or Leixlip reservoirs. During this period, the
IBE0600Rp0010 33 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL top priority is flood management to avoid any risk to dam safety. All other reservoir operation objectives, such as efficiency of electric power generation, system requirements, environmental, social, legal and economic considerations are secondary. In general, discharges from the reservoir during a rising flood should be less than or equal to the inflow to the reservoir. The discharge during the falling flood should be less than or equal to the peak inflow rate for that period. The Regulations further clearly specifies the roles and responsibilities of each of the organisational staff during the flood period. Furthermore, the Regulations clearly provide tabular view of critical levels and corresponding storage volumes for the three Liffey reservoirs including operating discharge instructions during the flooding period.
The Liffey reservoirs have a major role in the control and attenuation of floods in the Liffey catchment. In the text below, the effect of the operating rules during the flood periods for 3 historical floods (June 1993, November 2000 and November 2009) are summarised based on a literature review and previous studies. Copies of the reports on these floods are available on www.floodmaps.ie. Of particular interest in this regard is a comparison between the estimated discharges that occurred during recent floods and the estimated discharges that would have occurred if the dams and reservoirs had not been constructed. These figures are presented for the 2000 and 2009 floods in Table 6.1 and Table 6.2 below.
Table 6.1 Effect of the operation of the Liffey dams on the flooding from November 2000.
Estimated peak discharge (m3/s) Location With dams Without dams Ballymore Eustace 55 425 Upstream of Leixlip 100 350 Downstream of Leixlip (inc. 170 400 Ryewater)
Table 6.2 Effect of the operation of the Liffey dams on the flooding from November 2009.
Estimated peak discharge (m3/s) Location With dams Without dams Ballymore Eustace 52 250 Upstream of Leixlip 112 300 Downstream of Leixlip (inc. 150 340 Ryewater)
In general, the upper Liffey catchment, upstream of Pollaphuca and Golden Falls Dams, is significantly controlled by the Pollaphuca Reservoir, which is substantial in relation to its inflows. During significant floods, the flood storage capacity of the reservoir is used to control and attenuate discharges to the catchment downstream of Golden Falls dam. The use of this storage capacity during floods provides
IBE0600Rp0010 34 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL major benefits to the areas downstream by significantly reducing flows in the River Liffey between Golden Falls and Leixlip dams, and also downstream of Leixlip Dam towards the Dublin City. The middle Liffey catchment, between Golden Falls and Leixlip reservoirs, is relatively flat. In contrast to the upper Catchment it displays a slow response to rain storms due to its geological formation. The flood storage capacity of Leixlip reservoir is very small and provides only marginal benefits during significant floods. Flows in the River Liffey are augmented by the River Ryewater, which joins the main channel just downstream of Leixlip dam and can contribute towards fluvial flooding in the lower Liffey catchment to the Dublin City area. The current Liffey control regulations and the flow of information during the three regimes of operation of the Liffey reservoirs are schematically depicted in Figure 6.2.
Remote control from the Hydro Control Centre (HCC) at Turlough Hill and Pollaphuca Control Room
data Liffey Control Control of discharges streams Regulations thru the reservoirs
Inflow and Water Flow control ththru:rough: Level Pollaphuca Routine - Gates; & Golden Falls Operations - Turbines; - Water supply; Inflow and water Actual situation at level Lexlip the reservoirs and Flow control rules: downstream at Flood Period -Dam safety; River Liffey, and Turbine and gates Operations -Gates status / position at the Islandridge - Turbines; gauge at Dublin Meteo forecast City. Other Flow control rules: from Met Eireann Operational - Ecological flows; Mode (low - Water supply; Info from Triton Data analysis (reservoirs conditions) flows period) - Turbines; coastal FFS
Monitoring & analysis Control of discharges Feedback
Figure 6.2 Schematic presentation of the Liffey Controls (situation as is).
The main data streams on which the conditions are analysed and decisions are made to shift to the “flood period” operation is predominantly based on the inflow in the Pollaphuca and Leixlip reservoirs, taking into account the current meteorological conditions and the coastal situation at the Dublin City. The current mechanism for weather warnings are provided from Met Éireann (twice daily for a number of locations within the Liffey catchment) and classified into 3 warnings criteria using information from numerical weather forecasting (ECMWF), current satellite images and current data from the weather stations:
(i) Weather alert (code yellow): Mean wind speeds in excess of 25 kts (45 km/h); Expected rainfall 30 mm /24 hours; 25 mm/12 hours or 20 mm/6 hours; Coastal gale force 8 or 9;
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(ii) Weather warning (code orange): Mean wind speeds in excess of 35 kts (65 km/h); Expected rainfall 50 mm /24 hours; 40 mm/12 hours or 30 mm/6 hours; Coastal storm force 10; (iii) Weather warning (code red): Mean wind speeds in excess of 45 kts (80 km/h); Expected rainfall 70 mm /24 hours; 50 mm/12 hours or 40 mm/6 hours; Violent coastal storm force 11 or greater.
The inflow to the Liffey reservoirs (in order to assess the rising parts of the hydrographs) is based on water balance computations taking into account the current water levels and discharges through the reservoirs. Although this is the best information that is available to the HCC control room, it does not take any forecasts (rainfall and hydrologic / hydrodynamic models) into account, especially in the middle and lower parts of the Liffey catchment areas.
6.4 LIFFEY FLOOD CONTROLS AND POTENTIAL BENEFITS FROM FLOOD FORECASTING SYSTEM
Whilst the above previous comparisons show the beneficial effects of the Liffey control operation of the dams and reservoirs, there is still the potential for significant fluvial flooding occurring downstream in the middle and lower Liffey catchments as a result of significant rainfall events even with the operation of the dams (such as the flooding recorded at Celbridge, Newbridge and Leixlip in November 2009). We must also consider the additional flood risk posed by storm surges and tidal effects on the River Liffey and pluvial flooding in the urbanised areas. It is important to mention that the public perception often appears to be that the Liffey reservoirs have practically eliminated the danger of natural flooding on the greater parts of the flood plains. Whilst this is true for the floods with short return periods, the flood control benefits of a relatively small reservoir, such as Leixlip, can become reduced when one considers larger and less frequent flood events. Possible adjustments of the Liffey control regulations and the flow of information during the three regimes of operation of the Liffey reservoirs, taking into account the implementation of a FFS, are schematically depicted in Figure 6.3.
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Remote control from the Hydro Control Centre (HCC) at Turlough Hill and Pollaphuca Control Room
Integral Flood Forecasting and Warning System for the River Liffey
data Liffey Control Control of discharges Integrating real-time Current and frcst streams Regulations thru the reservoirs information of River Liffey Inflow Pollaphuca and APSRs Flow control through: & Golden Falls Flow control thru: Routine - Gates; Current and frcst Operations - Turbines; - Water supply; Inflow at Lexlip Actual situation at the reservoirs and Turbine and gates Flow control rules: downstream status / position Flood Period -Dam safety; ASPRs at River - Gates Operations Liffey, and at the Radar and EPS - Turbines; Islandridge gauge meteo forecasts at Dublin City.
reservoirs conditions) Other Flow control rules: Triton coastal Operational - Ecological flows; flood forecasting Mode (low - Water supply; flows period) - Turbines; Current and frcst Data and scenario analysis (River Liffey and flows/levels at Liffey gauges
Monitoring, forecast & analysis Control of discharges
Feedback Figure 6.3 Schematic presentation of the Liffey Controls with an integrated FFS (possible future situation).
Provision of real-time information on flooding using a flood forecasting system especially focused on the middle and lower Liffey inundation areas, coupled with the existing flood operation and control rules of the Liffey reservoirs, can bring significant improvements in flood risk management and mitigation for the River Liffey and Dublin City in particular. The FFS can also serve as a decision support tool to run and compare different scenarios (joint probability events) that can potentially occur in the Liffey catchment and adjust the Liffey reservoirs control rules to avoid superposition of hydrographs in the middle and lower part of the Liffey catchment areas. In order to study these scenarios and potentially further optimise the Liffey reservoirs control rules, the availability of a calibrated hydrodynamic model of the River Liffey is essential. At this stage, without availability of additional real-time information (additional telemetered rain and river gauges), we cannot provide any recommendation for improvement of the existing Liffey control rules.
An important step towards an Integrated Flood Forecasting System for the River LIffey was made with one of the major outputs of the SAFER project that delivered the Triton flood forecasting and warning system for coastal flooding for Dublin City, which is operated & monitored 24/7 by Dublin City Council Engineering staff and supported by Met Éireann. ESB staff are informed of the Triton forecasts and when coastal flooding is expected, ESB staff are closely engaged in the operation of the Liffey reservoirs in order to control the downstream discharges in the River Liffey.
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An umbrella project, the Dublin Flood Initiative, was also rolled out with the aim of creating an integrated flood protection strategy for the city, which includes an integrated flood forecasting and warning system that includes risk from coastal flooding, fluvial (river) flooding and pluvial (monster rain) flooding. The missing blocks at the moment are FFS for the Liffey, Tolka and Dodder rivers that could be potentially implemented based on the results from the CFRAM Study projects. Currently within the framework of the Eastern CFRAM Study NAM hydrological models are being setup for the Liffey river and its tributaries that will be followed up with Mike 11 hydrodynamic routing model. Those models once calibrated and validated on historic flood events can be readily used as operational models for the FFS of the River Liffey. A blueprint of a possible FFS for the River Liffey is presented in the next section.
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7 FFS BLUE PRINT
7.1 ARCHITECTURE OF THE FFS
Flood forecasting systems require efficient and seamless interfaces to other data acquisition systems (e.g. radar data, telemetry, meteorological ensemble prediction system – EPS, remote sensing), integration with forecasting hydrological and/or hydrodynamic models (physically-based and data- driven), together with access to databases of historical data and real-time data. They also need to store, analyse and visualise forecasts and to publish warnings. As such, FFSs are demanding hydro- informatics systems that use state-of-art ICT technology. In different countries, various systems have been developed to provide a common platform or 'shell' from which different models can be run and the outputs analysed and disseminated. Some of the most commonly used systems are: HydroNET, DelftFEWS, FloodWorks, Mike Flood, FLIWAS (partially), Telemac and others. HydroLogic has developed and implemented various operational FFSs in The Netherlands and Germany using their own HydroNet proprietary technology platform and FEWS. Hence, the architecture of a possible FFS for the Liffey presented in this report is based on similar FFS software platforms. The blueprint of the FFS basically does not change much regardless of the employed FFS shell or platform.
The architecture of the proposed solution for the FFS is schematically presented in Fig. 7.1 with the HydroNET platform used as an example of an FFS platform.
Light client (browser) Standalone thin client
User interface Clickable maps, profiles User login layer tables and graphs
HydroNET DSS interactive web components Data and (GIS, Time Series, 2D Profiles etc.) User interactions Business logic layer HydroNET DSS web services with publisher
Monitoring data field measurements HydroNET calculation meteorological data UI management (radar & EPS data) geo- Telemetry and databases Data and meteorological with modelling modelling data layer Ftp server NAM model results Mike11 model … DBMS
InputsModels Outputs HydroNet FFS platform
Existing components of client Existing components HydroNET; to be configured) Customized development Configuration Input / output files (xml, csv, ascii, hdf5, grib, dat, etc.)
Figure 7.1 Proposed architecture of the FFS for Liffey.
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The key layers of the proposed FFS system architecture are: 1) Data and modelling layer 2) Business logic layer 3) User interface layer
7.1.1 Data and modelling layer
This layer provides the management of the monitoring telemetry and meteorological data, the main user interface, forecasting shells and results aggregation in a geospatial database. A brief description of this data and modelling layer that can be used to implement the FFS is given below.
The FFS is essentially a decision support system with (web) services and components that provide water managers with meteorological and hydrological information. The main goal of such FFS is to support water managers in taking operational and strategic decisions especially focused on flood forecasting, warning and management. The information is presented in a customised way that matches the daily routine of water managers and LAs. (Fig. 7.2).
Figure 7.2. Example of a FFS desktop application which is used by water managers in the Netherlands on a daily basis. It provides user-friendly access to advanced meteorological information (precipitation radar, weather forecasting models, meteo- and telemetry stations) using webservices.
FFS - based Decision Support Systems are used by several Dutch water boards running 24/7, for both day-to-day operational water management and for flood forecasting and management during crisis situations. The FFS DSSs use the meteorological and hydrological information provided by various web services. Using highly detailed hydrological and hydrodynamic models such as Mike 11, Sobek,
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Isis or similar, they automatically calculate water levels and discharges for the water systems, and present the results in a customised user interface (stand-alone application), ArcGIS user interfaces, web based (GIS) interfaces or in automatically sent e-mails or SMS text messages. In addition, the FFS offers a calculations management shell (implemented as windows and web services) for flood forecasting systems development using external hydrological and hydrodynamic models such as NAM, URBS, Sobek, Simgro, AQUARIUS and HEC-RAS. This module is a collection of customisable Web and Windows services designed for building a flood forecasting system customised to the specific requirements of an individual flood forecasting agency.
The philosophy of the FFS system is to provide a collection of modules and services for managing the forecasting process. It incorporates a wide range of general data-handling utilities, presentation and visualisation of modelling results, while providing an interface to a wide range of forecasting models.
Figure 7.3 Top: ArcGIS based user interface of a DSS with customisable pop-up graphs of forecasted discharges and water levels (Waterboard Fryslân). Bottom: web based user interface of a DSS with pop-up graphs (Water board Hunze en Aa’s, Water board Noorderzijlvest). A white background indicates measured (telemetry) water levels; a grey background indicates forecasted water levels in a maximum (red), average (blue) and minimum (green) precipitation scenario. The precipitation scenarios are derived from both the HiRLAM and the ECMWF-EPS meteorological model.
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The following data streams relevant to the Liffey Catchment can be provided by the FFS components and web-services: • Online connectors for telemetry networks; used for in-situ monitoring input of precipitation and water levels in the Liffey Catchment. • Online connectors for meteorological data feeds supplied by Met Éireann and/or other European weather bureaus (if requested by the client such as radar data), ready for analysis, calibration and graphical presentation. • Online connectors for forecasts of precipitation, wind and temperature (EPS of ECMWF, or HiRLAM from KNMI and other national weather bureaus), used for real-time extraction of time series of different variables. • Historical time series for hydrological and hydrodynamic model input and model calibration. These sets are also made available through web services. There are several possibilities to collect and store the real-time data within the FFS. For example, the data feeds can be prepared as inputs in XML format to the FFS data validation component for further validation and quality labelling. In addition, for back-up and redundancy purposes, the real-time data can be collected and stored in a cyclic xml-base, Oracle or MySQL databases. The stored data can be made available in various ways to fit the water managers’ needs. The data are presented in (web- based) GIS maps and graphs that are easy to configure. FFS can also provide data for analysis using statistical software, for example radar-derived rainfall data can be presented in grids of 1.0 x 1.0 kilometres. This data is also provided per hydrological response units (catchment and sub-catchment areas of the Liffey), ready for third-party distributed hydrological and hydrodynamic models (such as NAM, Mike 11, Isis, etc).
The FFS framework can be configured and customised based on the specific requirements for the flood forecasting and warning services. This configuration means: The system will be coupled to the input data streams provided by FFS data streaming modules in any data formats. The user interface of the FFS system (interactive thematic maps, configuration of the windows, presentation layout and symbology, etc.) can be configured based on the requirements of the client and different user’s roles. The FFS can be fed with data and model parameters through the model connectors and be able to run the NAM and Mike 11 models (for which a connector is made available). In addition other connectors can be made available for any other additional forecasting models (including data-driven models, such as neural networks and regression models). Web publisher based on FFS web services and reporting workflow can be configured to generate forecasting reports in HTML format accessible with an Internet browser.
The implementation of the FFS is not simply a technical matter of proper hardware and software configuration. It is important that the implemented FFS will be owned, trusted and adopt a user friendly interface that meets the needs of the operator. This means that one should put special attention on the user requirements and collaborative interaction during the configuration process (end-user workshop).
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7.1.2 The business logic layer
This layer provides the main logic for the different components and services implemented in the FFS system for web-based interaction with the input data streams, interacting with the web-based publishing and presentation of the modelling results from the geospatial database. During an implementation of the FFS, configuration of the existing available components can be carried out. In particular any existing FFS web-based services and components can be made available for forecasting results via interactive clickable maps over intranet / internet in a secure manner (using SSL layer and authentication mechanisms).
Additionally, several web components can be configured, such as: • Web components for presenting animated and interactive clickable thematic maps, 2D profiles: cross sectional and longitudinal for telemetered and forecasted data. • Sophisticated and customisable web components for publishing telemetry data, calibrated radar information (if the client requests so), location-based extracted time-series from meteorological EPS data and dynamic presentation for different forecasted scenarios.
7.1.3 User interface layer
This layer provides the interfaces for the management of the (web-based) FFS. The following interfaces are operational:
1. FFS Client (stand-alone Windows application) (Fig. 7.3) on networked computers as required by the owners / stakeholders of the system. 2. Web-based graphical user interface (light client) for displaying published reports from the FFS (Fig. 7.4).
In addition, the following web-based interfaces are available and can be configured: 1. Web-based Administration Manager (secure admin access) in order to fully configure the FFS: monitoring the system, scheduling tasks, management for forecasting models and status and enhanced forecast parameters setting. This admin user interface will run in an Internet browser and will not require any client installation and maintenance. 2. Full browser-based graphical user interface for display of telemetry data and forecasting results, based on the web components, for secure access to dynamic clickable catchment- wide thematic maps, real-time dynamic time-series graphs of measured water levels and computed water levels, real-time available telemetered data (water levels and rainfall time series), animated profiles and other presentations (partially depicted in Fig. 7.4, bottom part).
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Figure 7.4 Example of FFS Explorer interface.
Figure 7.5 Example of Internet browser showing HTML ‘clickable’ map reports generated by FFS web services.
7.2 END USERS INVOLVEMENT
The involvement of Office of Public Works, ESB and Dublin City Council staff and other stakeholders in the development and the implementation of the FFS is essential for successful anchoring of the new product in the respective organisations and to ensure that the benefit of local knowledge is maximised during development of the FFS. According to our experience, active collaborative participation of the relevant people during the project is appreciated very much by (potential) end-users.
Typically in the development and implementation path for the FFS, one will begin with a user workshop for gathering and analysis of the user requirements. Based on these requirements a concrete mock-up of the FFS will be presented and discussed with the end-users. This will form the basis for development of the test and the final versions of the FFS. By using such an approach, the
IBE0600Rp0010 44 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL end-users will have a clear picture of how the final product will look and which functionalities will be available.
The concrete involvement for the end-users is done through: • Frequent meetings of the user group. • Daily communication and contacts with the client on technical implementation issues. • Frequent teleconference and face-to-face briefings with the project leader of the operator and through him/her the involved end-users, regarding the project progress. • In discussion with the operator determine the level of third-party involvement (e.g. local municipal authorities, fire department, police department, crisis management body, etc.). • Organisation of a workshop and possible involvement of third parties in order to communicate the FFS.
7.3 CONFIGURATION OF THE FFS TO THE TELEMETRY PROCESS
Currently, there are 3 subdaily rain gauges within the Liffey Catchment, which will have the capability to be telemetered and 7 hydrometric stations (currently with telemetry capability) upstream of the Dublin central area. Additional 3 telemetry hydrometric stations are envisaged to be installed (see proposal of DCC – Mr. Gerard O’Connell) upstream of the Dublin central area in order to gather information for the water levels. The existing telemetric process for OPW managed stations involves the following: • There are separate locations (PCs) equipped with Hydra 3 software that currently telemeter the river stations, namely the OPW offices in Dublin and the Dublin Council office. • The river stations data used for the Liffey Catchment text their river level data every hour, with data stored in text format in suitable folders. Currently, the Dublin configuration pools all river stations data automatically once a day (at 07:00 am GMT), and then during a significant event, this data can be manually telemetered upon demand. • The existing telemetric process uses Hydra 3 software to contact the hydrometric river stations equipped with modems and connected to the GSM network. The water level data is 15-minute interval in ASCII format and it is stored on the dedicated PCs on selected - named folders. • The existing data transfer communication process for the telemetered rain gauges is in the same format as for the above river gauge stations.
Data is currently collected by EPA for Local Authority owned / operated hydrometric stations through a number of different systems. 8 stations are telemetered and the process for collecting the data involves the following: • The 8 telemetered stations in the Liffey catchment transmit data to Hydras 3 equipped computers at EPA Dublin office at Richview either every 8 hours or once a day at 7.15am depending on the equipment fitted at each station. • Data is uploaded to a WISKI database every 24 or 48 hours again depending on the type of station.
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• Only the two stations using Logosens dataloggers (Waldron’s Bridge and Glenasmole) can be manually telemetered on demand. • Dublin City Council have a separate system to collect data remotely from these stations.
Finally ESB collect continuous level data at various outlet structure and reservoirs points (and subsequently produce continuous flow data) at their facilities at Pollaphuca, Golden Falls and Leixlip. This information is sent from the power station’s control unit (Honeywell Plantscape System) to the Data Historian (PI) when the data changes. PI is a real-time data historian application with a highly efficient time-series database structure developed by OSIsoft. Data is stored in tags. A tag consists of time series set of data. Each data point consists of a timestamp and the data value. There is one tag per measurement or calculations and each tag is independent of each other.
The proposed FFS can be configured in order to be able to use the existing telemetry process in the following way (Fig.7.5): • File Collect service will be configured to monitor the dedicated PCs on different locations (intranet accessible via FTP or shared folders) for any new data that is automatically pooled or requested by the operator. In addition, this service will be configured to stream radar data and meteorological predictions; • This automated FFS data service will fetch and aggregate the data in a format suitable for the General Import and Validation Modules. • The FFS service will also automatically transport and store the data, as they become available on a secure web (ftp) location; • The General Import Module of FFS will be configured to be able to read the data from this secure web (ftp) location.
River gages data (Ascii .r files)
Rain gages data (Ascii .r files) General Telem. PCs locations import module
Radar images (1,0 x 1,0 grid) Validation module Database
Meteo forecast data (hdf5 format) Secure web location
Other data data monitoringHydroNET service
Figure 7.6 Configuration of the FFS for data streaming for existing data sources and telemetry process.
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Figure 7.7 Example of data import task configuration file of the FFS.
The following minimum information is required from the OPW / DCC in order to configure the data import properly: • For each data source, an overview of the time series that need to be imported. Each time series is mapped to the location used in the FFS user interface. • For each data source, an overview of the units for the used parameters, for example in [m] for the water levels. • For each data source, an overview of the validation labels that can be used to set the pre- defined validation labels in FFS.
In summary, by setting up and configuring FFS data service and the Import Data workflow services, the FFS will be able to: 1. Operate using the data obtained from the above described existing telemetry process where the data is directed and stored onto a PC hard drive folders and where this data is directed and stored onto a secure web (ftp) location; 2. Automatically update its data import workflow every time new pooled or transmitted data is directed and stored onto a PC hard drive folder and where this data is directed and stored onto a secure web (ftp) location.
Optionally, an envisaged more efficient telemetry process can be setup by OPW, DCC, ESB and EPA. In summary, this telemetry process is expected to operate in the following way: • Real-time rain and river gauge data will be frequently retrieved and stored on a Web / FTP server or web database service (e.g. WISKI system). • This data will be made available and accessible via a secure Web site location.
The proposed FFS can then be configured in order to be able to use the envisaged telemetry process in the following way (Fig. 7.7): • FileCollect services will be configured to securely monitor the Web/FTP server (WISKI data service) for any new data that is automatically pooled or requested by the operator. In
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addition, this service can be configured to stream and process radar data and meteorological predictions (if requested) with time series extraction for the specified locations. The processed radar-generated rainfall data and the meteorological prediction data will be stored on the FTP location as well. • Automated service can fetch and aggregate the data from the FTP server in any data format suitable for the General Import Module of FFS. • Additional service can also be configured to transport and store the data on a backup (shadow) FTP server location (hosted by OPW, ESB, DCC or other potential operator or service provider). • The General Import Module of FFS is configured to be able to read the data from the data streams, pass the data to the Validation Module (labelling and interpolating missing data) and interact with the FFS Database.
Web/FTP server River gages data (data streams)
Rain gages data General WISKI service (data streams) import module
Radar images Validation module Database (1,0 x 1,0 grid) (data fused)
Meteo forecast data (hdf5 format)
Other data data HydroNET monitoring services
Figure 7.8 Configuration of the FFS for data streaming for more efficient telemetry process.
7.4 REQUIRED HARDWARE AND SOFTWARE INFRASTRUCTURE
Taking into account the key requirements of an FFS and the existing and envisaged telemetry process for data streaming and importing, the following hardware client-server architecture is proposed as a basis for the implementation of the FFS (Fig.7.8). At the server side, the following hardware is needed: • FTP server for storing and managing the raw and pre-processed data; • Database and application server for installation of the FFS software including the central database; • Modelling server dedicated for running the modules and services controlling the forecasting models (in automated and /or manual modes); • Web server for publishing the results, providing secure web-based access to the generated HTML reports and communicating the flood warnings. In order to send SMS warning
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messages to the specified list of operators / decision makers, a separate SMS hardware module should be attached to the Web server.
At the client side, as standard PC desktop and laptop computers are already available, no additional hardware is required.
The software architecture of the FFS is schematically presented in Fig.7.9, where the FFS system can be configured in a client-server mode.
Server side Client side
Database and FTP server Application server
• Telemetry data •Radar data •Meteo forecasts WEB server
Central database
Backup
1. Operational Modelling GUI server 2. Browser
Figure 7.9 Proposed hardware client - server architecture of the FFS.
reports FFT Web server Web Viewer forecasting services Services data streams FFT Controller Operator Client
models
Central Local data Database
Server side Client side
Figure 7.10 Client-server setup of the FFS.
In this client-server configuration mode, FFS is requiring a central database and all workflows and tasks are controlled by so-called Services Controller module. All users of the system running the FFS Client will be required to login in a secured way. The configured tasks will be started and managed by the Services Controller which is dispatching those to so-called “Forecasting Services”. In this way the computational processes on the user side are minimal.
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Additionally, a web server is configured. The data on the Web server is kept up-to-date by the FFS web services and interactive HTML reports and GUI are generated by the Services Controller module. A SMS Text hardware box linked to the Web server can be configured for sending SMS text notifications.
In order to allow proper speed and robustness of the proposed FFS software architecture, it is highly advisable that the Database and the Forecasting Services are running on different server systems, as proposed in Fig. 7.8.
7.5 CHARACTERISTICS OF THE PROPOSED FFS
The main functions of the proposed FFS and its components can be summarised as: • Import and management of telemetry data, including radar data and (ensemble) precipitation forecasts (when requested so). • Pre-processing of the imported data, validation labelling, interpolation and data storage. • Data visualisation and presentation in dynamic thematic maps, graphs and tables. • Coupling and simulation with forecasting models: NAM, Mike 11, Isis or others. • Presentation of the measured and forecasted data in a light GIS environment (operational GUI) • Storage and management of the measured and forecasted data in a central database. • Web-based access, reporting and provision of web-based access to forecasting reports. • Communication and dissemination of the flood warnings. • Administrative configuration of the FFS.
It is important to stress that the FFS can be implemented and configured as a Service Oriented Architecture (Fig. 7.10). Using this framework the FFS can be developed in a modular way such that different modules (functionalities) can be easily replaced by new or updated modules.
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Figure 7.11 FFS based on a Service Oriented Architecture using WCF (Windows Communication Foundation). FFS services are registered in the Windows services registry.
The main modules that can be implemented and configured as out-of-box FFS solution are: • FFS Client (HC): This is the Graphical User Interface for the operators / forecasters / users. Using this HC the operators can access and manage all functionalities of the FFS. • Web Viewer (WV): The FFS generates HTML forecasting reports that can be published via the Web server and accessed with the Web Viewer, typically an Internet browser. • FFS Services Controller (SC): This module is the ‘brain’ of the FFS. SC is keeping track of the real time and also starts on pre-defined timestamps (e.g. every hour) all tasks that needs to be carried out by the Forecasting Services. All FFS Clients must login in the SC to be able to retrieve the (new) telemetry data and forecasts. In case the operator / forecaster wish on- demand to execute a new forecast or scenario, this can be done via the FFS Client. The HC sends this request to the SC. The SC looks for availability of the Forecasting Services and passes the request for execution. The SC keeps track of the status of the tasks execution and as soon as the forecasts are ready it sends back the results to the FFS Client. These tasks are known as ‘workflows’. • FFS Forecasting Services (FS): FSs are executing the requests from the SC. Typically several FS can be configured. Main tasks are: o import the telemetry data, radar data and meteorological predictions; o interface and execute the 3rd party hydrological and hydrodynamic models; o send back the forecasted results; o generate HTML and Web GUI reports. • FFS Central Database (CB): The SC controls and manages not only the FS but also the central database. In the CB all necessary information will be stored. Automated backup of the CB is ensured on a daily / weekly basis. • Admin Interface (AI): The Services Controller can be configured by the Admin Interface. Only defined administrators will have access to this module. For example, the AI one can define the frequency of the automated tasks execution of certain workflows and setup the key configuration settings (configuration file); The Services Controller of the FFS always works to Greenwich Mean Time (GMT), or in CET which is equal to the GMT+1 hour. The presentation of the results at the user side is always in the actual winter or summer time (including BST) and this is configurable via the local XML configuration files. The key summary of the workflows that can be configured for the FFS are:
• HNArchive_Scheduled automated backup procedure • Database_Maintenance automated compression of the data • HNExport_Web generate HTML reports • HNFile_Collect imports telemetry data and radar / meteo data • Model_Performance determines the accuracy of the forecasted model results • HNNAM _Forecast makes the forecasts with the NAM model
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• HNMIKE_Forecast makes the forecasts with the Mike11 /21 model • HNModels_ Historical updates models with historical data
The workflows can be setup with different time stamps and intervals, as presented in Table 7.1.
Table 7.1 Example of initial configuration of the key FFS workflows.
Workflow Time interval Start time (CET) HNArchive_Scheduled 24 hours 01:00 HNDatabase_Maintenance 24 hours 02:00 HNImport_Data 15 min 00:00 HNNAM _Forecast 60 min 00:30 HNModels _Historical 24 hours 04:00 HNMIKE_Forecast 30 min 00:30 HNModel_Performance 1440 min 12:00
Some of the workflows, such as HNExport_Web are only run when certain conditions (triggers) are met. For example, HNExport_Web can run if a new forecast (from the models) is available. The scheduling of the workflows can be configured in such a way that there is always a new up-to-date forecast when the operator / forecaster starts his / her working day (e.g. 09:00). This is schematically illustrated in the Fig.7.11 below.
24:00 23:00 24:00
03:00 02:00 03:00
06:00 05:00 06:00
09:00 08:00 09:00 pull telemetry data start forecasting 12:00 11:00 12:00 office start time initial frc ready 15:00 14:00 15:00
18:00 17:00 18:00
21:00 20:00 21:00
24:00 23:00 24:00
SC time OClient OClient (GMT) winter time summer time
Figure 7 Schematic illustration of the scheduling and different time stamps.
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When clients login on the Services Controller, they can retrieve the most recent data and forecast information. Activities and tasks scheduled in the workflows with fixed intervals are executed automatically. The FFS Client can manually invoke tasks (data import and forecasts) that are passed to the queue managed by the Services Controller.
7.5.1 Number of FFS clients The FFS can be configured in a way that a large number of clients (FFS Clients) can run simultaneously. The performance of the system is usually tested and optimised (database operations) during the testing phase. In principle there is no limitation to the number of clients that can simultaneously access the Services Controller of the FFS but for larger numbers, performance tests need to be carried out along with optimisation of the synchronisation process between the central database and the FFS Clients.
7.5.2 Presentation of the FFS results The FFS is able to present the telemetry data and the forecasting results from the Liffey forecasting models implemented initially in the Eastern CFRAM project: NAM and Mike 11. The following presentation tools can be implemented and configured:
1. Graphical and tabular presentation of the forecasted results from hydrological / hydrodynamic models for the water levels and the discharges at the desired locations.
Mallow
Figure 7.12 Example of possible graphical and tabular presentation for selected station.
2. The GUI Client of the FFS can display an interactive map of the River Liffey Catchment area with thematic presentation of the river and rain gauging stations. By selecting certain stations, the result form the telemetry data and the forecast results can be displayed in graphical (hydrograph) form and tabular forms.
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Figure 7.13 Example of interactive location map and hydrograph presentation of the water levels (measured and forecasted) graphical presentation for a selected station: left thin client, right web-based interface.
3. The GUI Client can also be configured in such a way to be able to show the attributes for each station on the thematic map. By hovering the mouse at a particular station, the operator / forecaster can see the actual available data and forecast information for that station. The availability of real-time data and forecasts are mapped using customer-defined symbols and “traffic lights” concept (red - no data available, yellow- recent data available and green-up-to- date data available). When data from river or rain gauges cannot be telemetered in real-time, then the stations will change their symbols using colour coding (e.g. grey). In addition, using the Transformation Module aggregation of data (mean and accumulation) for the water levels, river discharges and precipitation data is available in order to display the last telemetered value, values for 15 min, 30 min, 60 min, 6, 12 and 24 hours accordingly.
Figure 7.14 Example of thematic mapping of attribute information (data and forecasts) for a particular station.
4. The FFS can be configured to display user-defined ‘trigger values’ for both the water level and the flows, which are visible on the time series graphs. The configurations settings are stored Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL
within XML formats (or in the database) and can be edited graphically with an XML editor. The threshold utility will automatically monitor the threshold values for both observed and forecasted time series. In case threshold values are crossed, several actions can be taken such as red “traffic lights” on the thematic maps, indicators when hydrographs are crossing the threshold values and for how long. Events can be triggered to the SC (e.g. communication events) in both cases when crossing the threshold values upwards and downwards. The choice of actions to be taken when threshold values are crossed is left to be discussed and agreed with the client.
Figure 7.15 Example of hydrographs showing the different threshold values for water levels and discharges at a particular station (left) and threshold setting interface (right).
5. For monitoring and logging the tasks that are executed in certain workflows by the Services Controller (at the sever side) a Log Viewer is available in the FFS Client (at the client side, Fig 7.16). For coupling with external forecasting modules, the log file includes module diagnostics exchange where users can see and debug the eventual error messages generated from running the external models (see next section).
Figure 7.16 Log file management, with easy-to-use user interface for filtering logs on application type, user, urgency etc.
7.5.3 Third Party hydrologic and hydrodynamic models implemented in FFS Initially, as part of the Eastern CFRAM modelling activities, the following forecasting models can be made operational within the FFS:
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1. The NAM models forecasting flows at the Liffey hydrometric stations as boundary upstream conditions based on meteorological data and antecedent conditions within the catchments; 2. The Mike 11 hydrodynamic model for the River Liffey, forecasting water levels and flows at the defined hydrometric stations and HEPs; The process of coupling these two external models is schematically illustrated in Fig.7.17. For the forecasting models which are Open MI compliant (www.openmi.org), the process of model coupling can be simplified.
Workflow NAM_Forecast
General Adapter
Open MI interface files
Pre-processing Model Adapter Post-processing (e.g. for NAM)
Model Model Input f iles Output
(data) execute files (data)
External Model (e.g. NAM)
Figure 7.17 Schematic interaction between FFS and the external forecasting models.
Both model connectors for the NAM and Mike 11 can be developed quite quickly since they are OpenMI compliant.
The process of coupling with the external 3rd party forecasting models can be summarised as follows: • The configured tasks of the FFS workflow (e.g. NAM_Forecast) will execute the General Adapter, which is a standard module; • The General Adapter imports and exports the data files following a standard published format and executes the Model Adapter; • The Model Adapter (to be configured) contains routines for pre-processing (input adapter), execution and post-processing (output adapter) the data (model files) required to run the forecasting model (e.g. NAM); • The General Adapter monitors, reports and exchange any errors with the Model Adapter during this execution process via a diagnostic file written in the XML format;
7.5.4 Data management in FFS The central database stores all necessary data for the FFS. The Services Controller module manages the central database through the set of preconfigured workflows as previously described. Automated
IBE0600Rp0010 56 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL backup of the CB is made on a daily / weekly basis. Key data stored in the central database are the FFS time series which can in the following four formats: • 0D: scalar data; • 1D: vector data and longitudinal profile data; • 2D: grid data; • 2D: polygon data.
The time series data are available from two sources: i) external such as the telemetered data, radar data and meteorological predictions; and ii) internal such as the simulated and post-processed data. In relation to the time stamp, the time series data are labelled in two categories: i) historical data (continuous in time); and ii) forecasting data (characterised by its starting time). Internally, the time series data are handled by the Time Series component. The key characteristics of the time series data to be managed in the FFS are: • Station Id: defining the mapping of the times series to the location on the map. • Variable Id: data parameter (water level, rain, flow, temperature etc.). • Start date • Time step interval • Data Count: number of data elements in the time series • Key: unique identifier of the time series • Compression State: indicates the state of the time series data (compressed or uncompressed) • Flags: data labels per time step, indicating state of the data (raw, validated, missing, interpolated, etc.)
The Flood Forecasting System can be configured to essentially manage the following application critical data: 1. The telemetry data using both the existing and envisaged telemetric process as described previously. 2. Meteorological predictions (including forecasted rainfall data) provided by external data provider such as Met Éireann. FFS data streaming component is configured to pre-process this data and extract time series of rainfall necessary for the grids covering the River Liffey Catchment area. In addition, this service is configured to stream and process radar data. The processed radar rainfall data and the meteorological (EPS) prediction data will be stored on the FTP location as well. Automated FFS data service will fetch and aggregate the data from the FTP server in a format suitable for use in other modules of the FFS. This data is used to feed the forecasting models in order to produce an ensemble forecast for both water levels and flows (Fig. 7.18).
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Figure 7.18 Example of an ensemble forecast produced by the FFS.
3. The FFS can be configured to manage a minimum of data inputs (i.e. rainfall stations, river gauges, radar data and meteorological predictions and future data streaming services such as WISKI). The maximum number of data inputs in most FFS is based on the underlying database architecture and mostly sufficient (e.g. 10000 data inputs). 4. The FFS uses the Services Controller and the configured workflows to manage all external inputs and outputs into the 3rd party forecasting models, i.e. initially the NAM and Mike 11 models as described above. This includes the operation with the real-time rainfall and river levels input telemetry data. 5. For interpolation and transformation of the internal and the external time series, both Interpolation and Transformation Modules are to be configured. The Interpolation Module interpolates missing data at desired locations or interpolation in time and includes several interpolation methods (linear, block, default value and extrapolation). This can be done automatically or manually editing the data by the user. The Transformation Module is configured to allow execution of pre-defined transformation functions such as arithmetic functions, catchment and sub-catchment value averaging (e.g. averaging rain over the sub- catchments), data aggregation, equidistant transformations and rule-based transformations. The Time Series component of the FFS Client can be configured to alert the user when such interpolation or transformation of the data occurs. 6. The time series sets in the proposed FFS can be configured for use of different time-stamp and time intervals, taking into account the nature of the data, the time zone and the current system time.
7.5.5 ‘Trigger Value’ Settings and Communication
The FFS can be configured to manage user-defined ‘trigger values’ for both the water level and the flows at each hydrometric station. The configuration settings are stored in the database and can be edited graphically with the FFS editor. This configuration file offers a possibility to: - Enter a warning text to be sent to multiple mobile phone numbers in case thresholds are crossed.
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- Manage the set of mobile phone numbers. - Enter warning text to be sent to multiple e-mail accounts. - Manage the list of e-mail accounts for dissemination (using different e-mail servers). - Enter the format in which the forecasts will be communicated. For example: 17:02:2012 23:15, water level at Newbridge is 2.56 [m] and flow is 185 [m3/s].
The threshold service automatically monitors the threshold values for both, observed and forecasted time series. In case threshold values are crossed, several actions can be taken, such as red “traffic lights” on the thematic maps, indicators when hydrographs are crossing the threshold values and for how long. Events can be triggered to the SC (e.g. communication events) in both cases when crossing the threshold values upwards and downwards. The choice of actions to be taken when threshold values are crossed is left to be discussed and agreed with the client.
7.5.6 Quality Assurance and Testing of FFS The testing of the FFS is done in two phases: a Factory Acceptance Test (FAT) phase and a Site Acceptance Test (SAT) phase. Prior to both tests, a detailed list of tests and acceptance criteria is prepared (the test protocol) which is to be approved by the client. Using this test protocol the functionality of the software will be systematically tested in a predefined sequence during the FAT and the SAT. The effectiveness of both calibration and testing of the FFS will benefit greatly from the input of organisations with direct knowledge and day to day management responsibilities for the catchment, particularly ESB and DCC, and it is envisaged that such organisations will provide input at the testing stage.
The FAT takes place on the development systems at the premises of HydroLogic / RPS, in the presence of members of the project team and the client. After the FAT, a list is compiled with remaining items that have to be fixed prior to installation at the premises of the client. The SAT takes place on the hardware of the client after installation and configuration of the FFS. The SAT is the final test of the FFS.
7.5.7 Requirements for Effective Flood Warning The reliable flood forecasts produced by the FFS for the River Liffey must be efficiently and effectively disseminated via a Flood Warning Service. A primary aim of a flood warning service is to reduce risk to life and damage to the economy, the environment and society. This is achieved by providing those at risk, service providers, Response Authorities and Agencies with the opportunity to take mitigating actions, such as evacuating people, provision of clear flood evacuation paths and information, erecting defences, operating river or reservoir control structures, moving possessions to safe places, and shutting down infrastructure at risk. Recipients of warnings generally fall into one of three categories: (1) the public at risk, (2) Response Authorities and Agencies, and (3) other service providers such as water, energy and telecoms utilities. This document does not cover the requirements and organisational arrangement of the principal responsible agencies and authorities to enable effective flood warning services. Those requirements were analysed on a strategic level and well elaborated in
IBE0600Rp0010 59 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL the “Strategic Review of Options for Flood Forecasting and Flood Warning in Ireland, Stage I and Stage II Report” conducted by JBA Consultants (2011).
7.5.8 Training Programme Usually after the development and the implementation of the released version of the FFS, the project team delivers 2 days training to the staff from the involved Local Authorities and the OPW staff. The scope of the 2 days training is dedicated to the introduction, configuration and operation of the FFS for the operators / forecasters. In addition, a third day training in the advanced configuration for the FFS tool for IT administrators is organised onsite.
7.5.9 Basic Maintenance, Hosting and Support for the FFS Several options are usually considered for basic maintenance and support of the FFS, including hosting solutions options: - The continuous basic maintenance and support is provided in the form of a helpdesk, through a Site Level Agreement (SLA); - Maintenance support – upgrade of the FFS software components used to implement and configure the FFS. This support is provided by the HydroLogic staff in-situ in Ireland. - Maintenance support – upgrade of the hardware and software infrastructure used for the FFS. This support can be provided by the IT hardware suppliers or in the form of a hosted solution by HydroLogic in a Data Centre in Ireland.
7.6 ECONOMIC ANALYSIS
7.6.1 Cost Assessment of the proposed FFS In order to assess the initial implementation costs for FFS of River Liffey, a simplified budget calculation is provided in Table 7.2 and Table 7.3.
Table 7.2 Budget breakdown for implementing a FFS for Liffey River.
Item Cost (euro)
FFS configuration and integration (time effort) 150 000 Onsite work and travel costs 8 500 FFS prototype version delivery and testing onsite (in Ireland) 5 000 Final version delivery and commissioning (in Ireland) 5 000 Reporting and other costs 3 000 Basic hardware infrastructure for the FFS 20 000 Maintenance and support SLA per year (basic price) 7 000
TOTAL ex. VAT 198 500
Optional FFS hosting at a secure Data Centre in Ireland
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Hosting services (per year) 15 000
Table 7.3 Overview of the software licenses costs.
Item Cost (euro) Cost (euro) per year for 3 years
FFS license (corporate with unlimited use) - first year license 21 000 14 500 cost and following years only maintenance costs 22.5% Microsoft Business Server license (corporate) 3 000 5 500
The total implementation costs of the FFS which includes implementation services and software licenses for the first year are estimated at about €225,000, with annual operating costs of €27,000 without including a core team of 2 FTEs needed to operate the system.
Once the FFS for Liffey is implemented and operational, the FFS can be extended to include the Tolka River and the Dodder River as well. Estimated implementation costs (including support for the 1st year) in order to include both rivers with their own FFSs additionally are approximately 120,000-140,000 Euro.
7.6.2 Assessing the Benefits from the FFS Different methodologies exist to assess the potential financial benefits from implementing FFS and flood warning. Most of the methodologies are based on the Source-Pathway-Receptor-Consequence model, initially developed during the FloodSite EU integrated project, depicted in Fig. 7.19.
Source (e.g. rainfall, wind, waves, ground water)
Pathway (e.g. flood plain inundation, overtopping, overf low)
Receptor (e.g. people, property, environment, infrastructure)
Consequence (harm) (e.g. loss of life, material damage, cultural loss, environmental degradation)
Figure 7.19 Source-Pathway-Receptor-Consequence model.
Some of the methodologies in UK, The Netherlands and Germany are using multi-criteria analysis to assess the tangible and intangible benefits of flood forecasting and warning. The Scottish and Northern Ireland Forum for Environmental Research (SNIFFER) has commissioned a multi-phase project to look at the cost-benefit of flood forecasting and warning. Currently phases 1, 2 and 3 are
IBE0600Rp0010 61 RevF01 Eastern CFRAM Study Liffey Flood Controls and Flood Forecasting System Option – FINAL completed. Phase 1 recognised that the current traditional models underestimate the benefits, particularly those that might accrue as a result of reducing injury or loss of life and reducing transport and vital utility disruption. It demonstrated that a Multi-Criteria Approach (MCA) has the potential to fill this gap, though data deficiencies essential to apply the full model need to be addressed. In Phase 2 of the SNIFFER project, a MCA GIS-based tool was used to assess the tangible and intangible benefits of flood warning for 9 pilot studies selected in England, Scotland and Wales. Finally, in Phase 3 of the project the impact on the critical infrastructure into the MCM method was included. The SNIFFER project Phases 2 and 3 outputs are an excellent template and relevant to Ireland for assessing the potential benefits of the FFS. The shortcomings are the data requirements for its successful application.
The recently finalised report “Strategic Review of Options for Flood Forecasting and Flood Warning in Ireland” by JBA (March 2011) summarises the proposed methodology for estimation of benefits due to flood forecasting and warning in Ireland on a strategic level, which takes into account: i) benefits from moving possessions; (ii) benefits from operational activities; (iii) benefits from implementing flood resilience measures; (iv) benefits from asset operations including erection of temporary and demountable defences and (v) agricultural benefits. Furthermore example computations for fluvial and tidal flooding for different flood depths (0.2-0.3 [m] and 0.5-0.6 [m) are carried out, clearly indicating potential benefits of implementing flood forecasting and warning system on a wide scale in Ireland. However, since the analysis of the potential benefits was carried out on a strategic level, there is no detailed information regarding potential benefits of implementing FFS for the River Liffey and the wider Dublin City area.
Based on the flooding reports in Ireland, discussion with OPW and previous studies, it is estimated the damages from fluvial flooding in the River Liffey within the wider Dublin area are approximately €15-20 million for an event of Annual Exceedance Probability (AEP) of 0.01 (1 in 100 years event). For example, the damage from the fluvial flooding in November 2009 caused by a rainfall of 35 [mm] in 6 [hours] equated to around a 1 in 10 year event, or AEP of 0.10. The flood damage in Dublin was estimated at around €350k and over the total middle and lower Liffey catchment amounted to more than €1m not counting the flooding at Sallins. Pluvial, groundwater and urban water and drainage asset failure flooding damages would add to this total. Due to the scarcity of this data and also the uncertainty of the effectiveness and response made to flood warnings, it is difficult to quantify how much the provision of an effective FFS would reduce these damages.
Our estimate using data from The Netherlands, UK, Germany, France and FFS from other countries, where effectiveness of the FFS is between 10-30%, is that this could be at least €2-4 million of average damages benefits. A simplified computation of the cost-benefit analysis is provided in Table 7.4.
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Table 7.4 Example of cost-benefit analysis.
Probability of Cumulative Design Return Exceeding Average Damage Annual damage for Discounted Value of Damage (€) flood in Average Damage Period Years Probability for Interval interval (€) 50 year scheme (€) Interval (€)
1 1 0 € 10,000.00 0.5 € 5,000.00 € 5,000.00 € 111,707.36 2 0.5 € 20,000.00 € 60,000.00 0.3 € 18,000.00 € 23,000.00 € 513,853.86 5 0.2 € 100,000.00 € 550,000.00 0.1 € 55,000.00 € 78,000.00 € 1,742,634.82 10 0.1 € 1,000,000.00 € 2,500,000.00 0.06 € 150,000.00 € 228,000.00 € 5,093,855.62 25 0.04 € 4,000,000.00 € 6,000,000.00 0.02 € 120,000.00 € 348,000.00 € 7,774,832.26 50 0.02 € 8,000,000.00 € 12,000,000.00 0.01 € 120,000.00 € 468,000.00 € 10,455,808.90 100 0.01 € 16,000,000.00
n x ⎛ ⎛ 1 ⎞ ⎞ Net Present Value = ⎜(1+ r) − ⎟ ⎜ ⎜ ⎟ ⎟ r ⎝ ⎝1+ r ⎠ ⎠
x - cumulative average damage r - 0.04 (Irish Treasury’s Test Discount Rate) (the projected life of the scheme – 50 n - 49 years)
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The Average Annual Damage (AAD) computed in Table 7.4 amounts to 468,000 Euro and is larger than the implementation costs of the FFS for the River Liffey which amounts to 225,000 Euro, as estimated in Table 7.3. The damages are a preliminary estimate based on a typical profile up to €1M for a 0.1 AEP event (as per 2009 estimate), €16M for a 0.01 AEP event and experience from other countries.
7.6.3 Preliminary Net Present Value Analysis In order to further assess the economic value of a flood forecasting system over time, a preliminary analysis of the Net Present Value (NPV) was considered compared to a ‘do nothing’ scenario. The analysis was carried out for a 20 year time period based on the Environment Agency’s ‘Supporting Spreadsheet to the Economic Appraisal for a Flood or Coastal Erosion Risk Management Project’. It must be stressed that such a preliminary analysis requires a number of assumptions to be made and the results are therefore to be treated as indicative of the potential benefits of such a scheme and not as a full cost benefit analysis. This analysis may be further developed through the CFRAMS options appraisal and cost benefit analysis. The NPV analysis is based on the following assumptions:
1. The typical damage profile discussed above.
2. A test discount rate of 4% per annum.
3. Full time employee costs are not considered as it is assumed this would fall within existing operator budgets.
4. No flood protection is provided above the 1 in 100 year event (e.g. measures such as demountable barriers are designed to 1 in 100 year level then overtopped)
5. Threshold flood event is constant for all damages.
6. 30% effectiveness of the FFS
The analysis indicates a potential Net Present Value of a FFS at €1.3M and a benefit cost ratio (BCR) of 2.36 over 20 years (for full details see Appendix D). As a sensitivity analysis if the FFS is only 10% effective then the Net Present Value drops to € -0.2M with a benefit cost ratio (BCR) of 0.8 over 20 years. Results of this preliminary analysis suggest the economic case is highly dependent on the effectiveness of the system but should an effective system be implemented the economic benefits alone are potentially high.
7.6.4 Other Considerations The benefits of a flood forecasting and warning system for the River Liffey are far wider than the saving of potential damages to households and businesses through reliable forecasts and effective and timely warnings. It has been well recognised and established in Europe that floods are essentially a social business. Many practitioners and researchers would claim that because of the current
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- Avoidance of loss of human life and anxiety; - Avoidance of the loss of cultural personal capital; - Avoidance of the feeling of insecurity of living in flood prone areas.
It is thus essential that any adopted tools and models for the evaluation and the assessment of the consequence of flooding are essentially focused very much on the receptors and the risk to human life. In order to reduce the risk to life it is necessary to better understand the causes of loss of life in floods in order to pinpoint where, when and how loss of life is more likely to occur and what kind of interventions, including flood warnings, may be effective to eliminate or reduce serious injuries and fatalities.
Thus, any cost-benefit analysis of a potential FFS for the River Liffey will be improved significantly by consideration of the social aspects of flooding.
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8 SUMMARY AND CONCLUSIONS
8.1 CONCLUSIONS
This report analysed the potential to develop and implement an effective FFS option for the identified AFAs within the Eastern CFRAM study area; in particular HA09, the Liffey Catchment and the wider Dublin City area. This analysis serves as one of the inputs to the potential flood risk management options in the Preliminary Options Report. The main conclusions are summarised as:
The analysis work undertaken within this part of the Eastern CFRAM Study has clearly indicated that the development and implementation of a FFS for the Liffey Catchment (part of HA09) is a viable and cost-beneficial option. Integrating this system in a nation-wide FFS (service) will further strengthen the business case for such a flood risk management option. The main potential benefits of FFS are summarised as: o Reduction in risk to life or injury o Reduction in business impact & losses o Reduction in residential impact & losses o Reduction in social and environmental impacts (e.g. social and environmental stress, concerns, insurance premiums) o Improved hydrometric gauge network o Improved use of (calibrated) radar data at the Dublin Airport o Potential optimisation of flood management measures such as operation of dams and sluices o Improved emergency response
With respect to the Liffey controls, the provision of real-time information on flooding using a FFS especially focused on the middle and lower Liffey inundation areas, coupled with the existing flood operation and control rules of the Liffey reservoirs, can potentially bring improvements in flood risk management and mitigation for the River Liffey and Dublin City in particular. The FFS can also serve as a decision support tool to run and compare different scenarios (joint probability events) that can plausibly occur in the Liffey catchment and adjust the Liffey reservoirs control rules to avoid superposition of hydrographs in the middle and lower part of the Liffey catchment areas. In order to study these scenarios and potentially further optimise the Liffey reservoirs control rules, the availability of a calibrated hydrodynamic model of the River Liffey is essential. At this stage, without availability of additional real-time information (additional telemetered rain and river gauges), we cannot provide any recommendation for improvement of the existing Liffey control rules.
A preliminary economic analysis indicates that the average damages from fluvial flooding in the River Liffey and the Dublin wider area is approximately €15-20 million for the Annual Exceedance Probability of 0.01 (1 in 100 years event). Pluvial, groundwater and urban water and drainage
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asset failure flooding damages will add to this total. Due to the scarcity of this data and also the uncertainty of the effectiveness and response made to flood warnings, it is difficult to quantify how much the provision of an effective FFS would reduce these damages. Our estimate using data from The Netherlands, UK, Germany, France and FFS from other countries, where effectiveness of the FFS is between 10-30%, is that this could be at least €2-4 million of savings in terms of average damages.
The key success factors for implementing the described FFS are summarised as: - Operational use of the Doppler radar system at Dublin airport operated by Met Éireann will increase the lead-time of forecasts and the quality of the precipitation data (spatio-temporal variability). In particular this link to real-time rainfall measurements can significantly improve insight to the expected runoffs and improve model forecasts through the provision of real time high quality (spatial and temporal) input data to drive the hydrological and hydrodynamic models. - Availability of an optimised telemetry network of rain gauges and hydrometric flow / water level recorders is essential for accurate and reliable forecasts and for producing longer lead-times. The minimum data required for calibration and real time model updating of the FFS used to warn the general public should be: o Rain Gauges – At least one telemetered hourly rain gauge (but preferably up to four) to calibrate in real time the radar data to drive local rainfall runoff models. The number of gauges required depends on several factors, with accuracy generally increasing with coverage. o Hydrometric Gauges – A minimum of one river level gauge at, or near to, the identified risk areas. This is required to calibrate forecasting models and correct their predictions in real time. In large river systems such as the Liffey Catchment, it is recommended to have several river gauges upstream of the risk area to allow calibration of network sub-components and real time updating of predictions (data assimilation techniques). - Hydrological and hydrodynamic models running frequently (on a daily or sub-daily basis), with the frequency increased (to hourly forecasts) pending a flood event. - A vital component of a successful FFS is the existence of a central body (agency) to make decisions and issue clear warnings in flood emergency situations. Due to the complexity of such situations, additional tools need to be implemented to aid authorities during emergency events. - FFS must also be comprehensible and accessible to all stakeholders to gain credibility. - The need for common assessment to review the performance of the FFS which can identify any operational problems with the system in order to improve the reliability of the forecasts. o Review and simulate historical flooding events (FFS hindcasting model); o Testing the FFS for a range of design flood events; o Using statistically significant calibration data to improve the reliability of the FFS; o Incorporating feedback and learning loops into the FFS
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The set-up cost of developing and implementing the FFS and warning service for fluvial and coastal flooding in the Liffey Catchment, by integrating existing river (Eastern CFRAM Study: NAM and Mike 11 hydrologic and hydrodynamic models) and coastal models (Triton coastal FFS) and available data streams, has been estimated to €225,000 with annual operating costs of €27,000 excluding a core team of 2 FTEs. This FFS can be easily integrated in a national flood forecasting and warning service that would be cost-beneficial.
8.2 TOWARDS INTEGRATED FLOOD FORECASTING AND WARNINGS SYSTEM FOR DUBLIN CITY
Currently Dublin City Council is at the end of a four-year programme (2008-2012) to make the capital a flood resilient city. The Flood Resilient City (FRC) project is an EU-funded project supporting local authorities in eight cities in North-West Europe to combat flooding in urban areas and exchange information on best practice. It builds on the previous EU-funded SAFER (Strategies and Actions for Flood Emergency Risk Management) project, an outcome of which was the establishment of an operational coastal (tidal surge) early warning system for Dublin. An umbrella project, the Dublin Flood Initiative, was rolled out with the aim of creating an integrated flood protection strategy for the city, which also looks into an integrated flood forecasting and warning system that includes risk from coastal flooding, fluvial (river) flooding and pluvial (monster rain) flooding.
Clearly the implementation and rollout of a FFS for the Dublin Rivers Liffey, Tolka and Dodder is of significant importance in implementing an integrated flood forecasting and warning system as one of the key options for proactive flood risk management. This report outlined a potential blueprint of FFS for the River Liffey using existing available data streams (with strong emphasis to extend the River Liffey hydrometric stations) that can be implemented as a viable option. The development, implementation and roll-out out of such integrated flood forecasting and warning system for the Dublin city and the other AFAs is significantly driven and high priority for the currently ongoing nation-wide CFRAM Programme managed by OPW.
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References
Flood Emergency Response Planning –'A Guide to Flood Emergencies' and 'Draft Protocol for Multi- Agency Response to Flood Emergencies' (Major Emergency Management Project Team – Department of Environment, Heritage and Local Government).
Environmental Protection Agency (2010). Report on Hydrometric Activities undertaken by Environmental Protection Agency from 21 Nov 2009 to 3 Dec 2009. EPA Dublin.
European Commission, (2007) Directive on the Assessment and Management of Flood Risk, 2007/60/EC, European Commission.
Holleman I., (2007) Determining weather radar antenna pointing using signals detected from the sun at low antenna elevations. J. Tech. 24, 476-483.
Huuskonen A., 2001, A method for monitoring the calibration and pointing accuracy of a radar network. 31st AMS Conf. on Radar Meteorology, 29–31.
Irish Flood Warning Service website (University College Cork, 2009).
Lee CFRAM Study – Draft Catchment Flood Risk Management Plan (Halcrow, 2010).
Meetings and discussions with OPW, ESB, Met Éireann and DCC conducted in June 2011 (appx C).
Office of Public Works (2004) Report of the Flood Policy Review Group [online] http://www.opw.ie/en/media/Report of the Flood Policy Review Group.pdf (Accessed march 2012).
Office of Public Works / Department of the Environment, Heritage & Local Government (2008a). A Guide to Flood Emergencies, A Framework for Major Emergency Management, Working Draft, Guidance Document 11.
Office of Public Works / Department of the Environment, Heritage & Local Government (2008b) Multi- Agency Protocol, A Framework for Major Emergency Management, Working Draft, Multi-Agency Protocol (10).
Office of Public Works (2009a) Storm Surge Forecasting, Period 1: Evaluation Report. Report by RPS, IBE0057_Eval/Period1_R01 CR.
Office of Public Works (2010a) National Flood Risk Assessment and Management Programme, Catchment-Based Flood Risk Management (CFRAM) Studies, Stage 1 Tender Documents: Project Brief, 2149/RP/002/F May
Office of Public Works (2010b) Lee Catchment Flood Risk Assessment and Management Study CFRAMS, Draft Catchment Flood Risk Management Plan, Office Public Works, Cork City Council, and Cork Country Council.
Office of Public Works (2010c). Report on the November 2009 Floods, OPW.
Office of Public Works (2010d) Storm Surge Forecast for Irish Water, Validation of MIKE 21 Flow Model FRM on Linux, Final Report, OPW.
Operational Programmes: Flood Relief Schemes (OPW website).
Reviews of the November 2009 flooding in Ireland (in particular Eastern CFRAM Study HA09 Inception Report, RPS).
River Dodder Catchment Flood Risk Management Plan (RPS, 2011).
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RPS (2010a) Storm Surge Forecasting 2009/2010, Period 2: Evaluation Report, Office of Public Works.
RPS (2010b) Irish Coastal Protection Strategy Study, Phase 2 - Strategic Assessment of Coastal Flooding and Erosion Extents, South East Coast, Dalkey Island to Carnsore Point Pilot Area, Work Packages 2, 3 & 4A, Final Technical Report, IBE0104/June, Office of Public Works.
RPS (2010c) Irish Coastal Protection Strategy Study, Phase 3 - Strategic Assessment of Coastal Flooding and Erosion Extents, North East Coast, Dalkey Island to Omeath, Work Packages 2, 3 & 4A, Final Technical Report, IBE0071/June, Office of Public Works.
RPS & HydroLogic (2012). Analysis of the Dublin Radar Data for the Dodder Catchment (Stage 1 – Final report, IBE0600Rp0007).
Strategic Review of the Hydro-Meteorological Monitoring Programme for Ireland (JBA Consulting, 2008).
Strategic Review of Options for Flood Forecasting and Flood Warning in Ireland, Stage I and Stage II Report. JBA Consultants (2011).
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APPENDIX A HYDROMETRIC GAUGING STATIONS AND THE OPERATING AUTHORITIES
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Record Type (i.e. Level Flow BODY Data WATERBODY CATCHMENT COUNTY NUMBER NAME DATA TELEMETRY 15min, extracted Data Data RESPONSIBLE Received chart etc.) (Y/N) (Y/N) Dept. Marine & LIFFEY Liffey Dublin 09015 ISLANDBRIDGE WEIR Water Level Only No Chart Data Y N Y Natural Resource IRISH SEA Dublin 09062 HOWTH Water Level Only No Dublin City Council DODDER Liffey Dublin 09010 WALDRON'S BRIDGE Water Level and Flow Yes Chart & 15 min Y Y Y TOLKA Tolka Dublin 09019 DRUMCONDRA Water Level and Flow No Chart Data Y N Y DODDER Liffey Dublin 09023 BOHERNABREENA No Data Recorded No 15 min TOLKA Tolka Dublin 09037 BOTANIC GARDENS Water Level and Flow Yes datalogger Y Y Y FLUME 1 EFFLUENT STR. Coastal08 Dublin 09051 RINGSEND STW Staff Gauge Site No FLUME 2 EFFLUENT STR. Coastal08 Dublin 09052 RINGSEND STW Staff Gauge Site No S.O 1 EFFLUENT STR. Coastal08 Dublin 09053 RINGSEND STW Staff Gauge Site No S.O. 2 EFFLUENT STR. Coastal08 Dublin 09054 RINGSEND STW Staff Gauge Site No Mayne‐ 15 min SANTRY Santry‐Coastal Dublin 09102 CADBURY'S Water Level and Flow Yes datalogger Y Y Y 15 min DODDER Liffey Dublin 09103 GLENASMOLE Water Level and Flow Yes datalogger Y N Y 15 min TOLKA Tolka Dublin 09104 FINGLAS WEIR Water Level and Flow Yes datalogger Y N Y Dublin Port Company SEA Dublin 09064 DUBLIN NORTH WALL Water Level Only No Dún Laoghaire Port Company IRISH SEA Dublin 09061 DUN LAOGHAIRE Water Level Only No Dún Laoghaire ‐ Rathdown Council SLANG Liffey Dublin 09011 FRANKFORT Water Level and Flow Yes Chart & 15 min Y Y Y ESB LIFFEY Liffey Kildare 09006 CELBRIDGE Water Level and Flow No Chart Y Y Y LIFFEY Liffey Kildare 09007 GOLDEN FALLS Water Level and Flow No Chart Data Y Y Y LIFFEY Liffey Kildare 09013 STRAFFAN D/S Water Level and Flow No UPPER LIFFEY Liffey Wicklow 09014 BALLYWARD Water Level and Flow No Chart Data Y Y Y KINGS [LIFFEY] Liffey Wicklow 09017 LOCKSTOWN BR. Staff Gauge Site No LIFFEY Liffey Dublin 09022 LEIXLIP POWER STATION Water Level and Flow No Chart & 15 min Y Y Y LIFFEY HEADRACE CH. Liffey Kildare 09032 POLLAPHOUCA Water Level Only No Chart & 15 min Y Y Y LIFFEY Liffey Kildare 09033 LEINSTER AQUEDUCT No
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LIFFEY Liffey Kildare 09034 STRAFFAN U/S Water Level and Flow No Chart & Roll Data POOLBEG POWER COOLING WATER Dublin 09055 STATION No LIFFEY Liffey Wicklow 09056 BURGAGE BR. Water Level and Flow No Chart Data Fingal County Mayne‐ Council SANTRY STREAM Santry‐Coastal Dublin 09004 SANTRY Staff Gauge Site No Kildare County LIFFEY Liffey Kildare 09008 OSBERSTOWN Staff Gauge Site No Council LIFFEY Liffey Dublin 09012 LEIXLIP BR. Staff Gauge Site No STREAM Liffey Kildare 09016 ARTHURSTOWN Water Level and Flow No Chart Data Y Y Y 15 min MORELL Liffey Kildare 09024 MORELL BRIDGE Water Level and Flow NO datalogger Y N Y LEMONSTOWN STREAM Liffey Kildare 09038 LONGSTONE Staff Gauge Site No LIFFEY Liffey Kildare 09039 LA TOUCHE BRIDGE Staff Gauge Site No 15 min KILCULLEN STREAM Liffey Kildare 09040 NICHOLASTOWN Water Level and Flow No datalogger Y Y Y AWILLYINISH STREAM Liffey Kildare 09041 CARRAGH RLY. BR. Staff Gauge Site No 15 min NAAS STREAM Liffey Kildare 09042 OSBERSTOWN HOUSE Water Level and Flow No datalogger Y Y Y LIFFEY Liffey Kildare 09043 MILLICENT BR. Staff Gauge Site No 15 min MORELL Liffey Kildare 09044 KERDIFFSTOWN HOUSE Water Level and Flow Yes datalogger Y Y Y MORELL Liffey Kildare 09045 GRAND CANAL BRIDGE No Chart Data Y Y Y PAINESTOWN Liffey Kildare 09046 PAINESTOWN BRIDGE Staff Gauge Site No 15 min PAINESTOWN Liffey Kildare 09047 BARONRATH Water Level and Flow Yes datalogger Y Y Y 15 min RYEWATER Liffey Kildare 09048 ANNE'S BRIDGE Water Level and Flow No datalogger Y Y Y 15 min LYREEN Liffey Kildare 09049 MAYNOOTH Water Level and Flow Yes datalogger Y Y Y INFLUENT STREAM Liffey Dublin 09050 LEIXLIP S.W. Water Level Only No Chart Data Y N Y Marine Institute DODDER Liffey Dublin 09060 BALLSBRIDGE Water Level Only No IRISH SEA Dublin 09063 NORTH BANK LIGHT Water Level Only No IRISH SEA Dublin 09065 KISH BANK Water Level Only No LIFFEY Dublin 09066 O'MORE BR. Water Level Only No Meath County TOLKA Tolka Meath 09003 CLONEE Staff Gauge Site No
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Council TOLKA Tolka Meath 09018 BATTERSTOWN Staff Gauge Site No Office of Public RYEWATER Liffey Kildare 09001 LEIXLIP Water Level and Flow Yes Chart & 15 min Y Y Y Works MORELL Liffey Kildare 09036 KERDIFFSTOWN Water Level Only Yes South Dublin GRIFFEEN Liffey Dublin 09002 LUCAN Water Level and Flow No Inequal intervals Y Y Y County Council CAMMOCK Liffey Dublin 09005 CLONDALKIN Water Level and Flow No Chart Data Y Y Y OWENDOHER Liffey Dublin 09009 WILLBROOK ROAD Water Level and Flow Yes Chart & 15 min Y Y Y PIPERSTOWN Liffey Dublin 09021 GLASSAMUCKY Water Level and Flow NO Chart Data Y Y Y 15 min HARTWELL RIVER Liffey Kildare 09027 BROGUESTOWN Water Level and Flow NO datalogger Y Y Y KILL RIVER Liffey Kildare 09028 KILL WEST Staff Gauge Site No KILL Liffey Kildare 09029 RATHGORRAGH Staff Gauge Site No HARTWELL Liffey Kildare 09030 TOBERTON WEIR Staff Gauge Site No 15 min CAMMOCK Liffey Dublin 09035 KILLEEN ROAD Water Level and Flow No datalogger Y Y Y LANSDOWNE VALLEY CAMMOCK Liffey Dublin 09101 PARK Flow Measurements No Wicklow County SHANKILL Liffey Wicklow 09020 CLOGHLEAGH Flow Measurements NO Council BALLINAGEE Liffey Wicklow 09025 BALLINAGEE BR. Flow Measurements No Chart Data Y Y Y ANNALECKA BROOK Liffey Wicklow 09026 ANNALECKA BR. Water Level and Flow NO Chart Data Y Y Y KINGS [LIFFEY] Liffey Wicklow 09057 BAWNOGE Staff Gauge Site No KINGS [LIFFEY] Liffey Wicklow 09058 OAKWOOD Staff Gauge Site No GLENREEMORE BROOK Liffey Wicklow 09059 KNOCKNAROOSE Staff Gauge Site No
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APPENDIX B ANALYSIS OF THE RIVER LIFFEY RECENT FLOODINGS
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APPENDIX C DISCUSSION TOPICS WITH KEY STAKEHOLDERS
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Discussion Topics during the meetings with ESB, Met Éireann, Dublin City Council and OPW
The following items in relation to the FFS were discussed: o Background of the Eastern CFRAM project; o Regulations and Guidelines for control of the River Liffey – discussion on how the current system for flood control at the Liffey dams work (managed by the Hydro Control Centre); o Discussion of the Liffey reservoirs operation rules; o Availability of telemetry data on based on which decisions are made; o Available and planned telemetry system; o Usage of radar and meteorological information in the neighbourhood catchments; o Organisation aspects of a potential FFS; o General availability of hydrometric gauges and information; o Coastal Flood Forecasting and Warning at DCC: o Overview of the Triton system; o Aims and objectives of development a Dublin City FFS; o Incorporating Triton system into an Integral FFS; o Ongoing projects and initiatives; o Current usage of meteorological ensemble forecasts and radar data; o Existing telemetry network and envisaged network operated by DCC o Availability of historical flooding information for the River Liffey; o Flood defences assets; o Availability of GIS datasets that are relevant for FFS: urban water courses, culverts, etc. o Other topics.
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