Eastern CFRAM Study HA09 Hydrology Report IBE0600Rp0016 rpsgroup.com/ireland Eastern CFRAM Study HA09 Hydrology Report DOCUMENT CONTROL SHEET Client OPW Project Title Eastern CFRAM Study Document Title IBE0600Rp0016_HA09_Hydrology Report_F03 Document No. IBE0600Rp0016 DCS TOC Text List of Tables List of Figures No. of This Document Appendices Comprises 1 1 1 1 1 5 Rev. Status Author(s) Reviewed By Approved By Office of Origin Issue Date B. Quigley D01 Draft M. Brian G. Glasgow Belfast 10/04/2013 U. Mandal B. Quigley D02 Draft M. Brian G. Glasgow Belfast 29/04/2013 U. Mandal B. Quigley F01 Draft Final M. Brian G. Glasgow Belfast 03/09/2013 U. Mandal B. Quigley F02 Draft Final M. Brian G. Glasgow Belfast 14/08/2015 U. Mandal B. Quigley F03 Final B. Quigley G. Glasgow Belfast 29/04/2016 U. Mandal rpsgroup.com/ireland Copyright Copyright - Office of Public Works. All rights reserved. No part of this report may be copied or reproduced by any means without prior written permission from the Office of Public Works. Legal Disclaimer This report is subject to the limitations and warranties contained in the contract between the commissioning party (Office of Public Works) and RPS Group Ireland rpsgroup.com/ireland Eastern CFRAM Study HA09 Hydrology Report – FINAL TABLE OF CONTENTS LIST OF FIGURES ................................................................................................................................. IV LIST OF TABLES .................................................................................................................................. VI ABBREVIATIONS .................................................................................................................................. IX 1 INTRODUCTION ................................................................................................................................ 1 1.1 OBJECTIVE OF THIS HYDROLOGY REPORT ........................................................................ 3 1.2 SUMMARY OF THE AVAILABLE DATA .................................................................................. 4 1.2.1 Summary of Available Hydrometric Data ................................................................4 1.2.2 Additional Simulated Flow Data ..............................................................................5 1.2.3 Summary of Available Meteorological Data ............................................................ 7 1.2.4 Rainfall Radar .........................................................................................................9 1.2.5 Historic Flood Frequency Analysis ........................................................................10 2 METHODOLOGY REVIEW .............................................................................................................. 11 2.1 HYDROLOGICAL ANALYSIS .............................................................................................. 11 2.2 METEOROLOGICAL ANALYSIS ......................................................................................... 12 2.3 DESIGN FLOW ESTIMATION ............................................................................................ 12 2.3.1 Index Flood Flow Estimation .................................................................................12 2.3.2 Growth Curve / Factor Development ....................................................................14 2.3.3 Design Flow Hydrographs .....................................................................................14 2.4 HYDROLOGY PROCESS REVIEW ..................................................................................... 15 2.5 ALTERNATIVE APPROACHES REQUIRED WITHIN HA09 ..................................................... 18 2.5.1 Integrated Drainage Network / Watercourse Model and Direct Application of Design Rainfall Events ...................................................................19 2.6 CATCHMENT BOUNDARY REVIEW .................................................................................... 20 3 HYDROMETRIC GAUGE STATION RATING REVIEWS ............................................................... 21 3.1 METHODOLOGY ............................................................................................................. 21 3.2 RATING REVIEW RESULTS .............................................................................................. 22 3.3 IMPACT OF RATING REVIEWS ON HYDROLOGICAL ANALYSIS ............................................. 23 4 INDEX FLOOD FLOW ESTIMATION .............................................................................................. 27 4.1 MODEL 1 – SANTRY ....................................................................................................... 29 4.2 MODEL 2A – BALDONNEL .............................................................................................. 31 4.3 MODEL 2B – LUCAN TO CHAPELIZOD .............................................................................. 34 4.4 MODEL 2C – LOWER LIFFEY ........................................................................................... 37 4.5 MODEL 2D – CAMAC ...................................................................................................... 39 4.6 MODEL 2E – PODDLE ..................................................................................................... 43 4.7 MODEL 3A – LEIXLIP ...................................................................................................... 45 4.8 MODEL 3B – HAZELHATCH / CELBRIDGE ......................................................................... 48 4.9 MODEL 4 – MAYNOOTH .................................................................................................. 53 4.10 MODEL 5 – KILCOCK ...................................................................................................... 56 IBE0600Rp00016 i Rev F03 Eastern CFRAM Study HA09 Hydrology Report – FINAL 4.11 MODEL 6A – CLANE ....................................................................................................... 58 4.12 MODEL 6B – NAAS ......................................................................................................... 60 4.13 MODEL 7 – TURNINGS / KILLEENMORE (MORELL) ............................................................ 64 4.14 MODEL 8 – NEWBRIDGE ................................................................................................. 67 4.15 MODEL 9 – BLESSINGTON .............................................................................................. 70 4.16 INDEX FLOOD FLOW CONFIDENCE LIMITS ........................................................................ 72 4.16.1 Gauged Qmed .........................................................................................................72 4.16.2 Ungauged Qmed .....................................................................................................74 5 FLOOD FREQUENCY ANALYSIS AND GROWTH CURVE DEVELOPMENT ............................. 75 5.1 OBJECTIVE AND SCOPE .................................................................................................. 75 5.2 METHODOLOGY ............................................................................................................. 75 5.2.1 Selection of Statistical Distribution ........................................................................75 5.2.2 Forming a Pooling Region and Groups .................................................................75 5.2.3 Growth Curve Development ..................................................................................75 5.2.4 Limitations in the FEH and FSU Studies ...............................................................76 5.3 DATA AND STATISTICAL PROPERTIES .............................................................................. 76 5.3.1 Flood Data .............................................................................................................76 5.3.2 Pooling Region Catchment Physiographic and Climatic Characteristic Data ................................................................................................81 5.3.3 Statistical Properties of the AMAX series .............................................................83 5.4 STATISTICAL DISTRIBUTION ............................................................................................ 84 5.5 GROWTH CURVE ESTIMATION POINTS ............................................................................ 85 5.6 POOLING REGION AND GROUP FOR GROWTH CURVE ESTIMATION ................................... 88 5.6.1 Pooling Region ......................................................................................................88 5.6.2 Pooling Group .......................................................................................................88 5.7 GROWTH CURVE ESTIMATION ........................................................................................ 89 5.7.1 Choice of Growth Curve Distributions ...................................................................89 5.7.2 Estimation of Growth Curves ................................................................................89 5.7.3 Examination of Growth Curve Shape ....................................................................91 5.7.4 Recommended Growth Curve Distribution for the River Liffey and Santry River Catchments ......................................................................................95 5.8 RATIONALISATION OF GROWTH CURVES ........................................................................