SWRBD CFRAM Study Inception Report - Unit of Management 20 September 2013 Office of Public Works SWRBD296235 IWECFRAM CCW StudyR005 C 296235/IWE/CCW/R005/C February 2013 Inception Report - Unit of Management 20 September 2013 Office of Public Works Jonathan Swift Street Trim Co. Meath Mott MacDonald, 5 Eastgate Avenue, Eastgate, Little Island, Cork, Co Cork, Ireland T +353 (0)21 4809 800 F +353 (0)21 4809 801, W www.mottmac.com SWRBD CFRAM Study Issue and Revision Record Revision Date Originator Checker Approver De scription A May 2012 M. Piggott B. O’Connor F. McGivern Initial Issue T. Donovan B November 2012 M. Piggott B. O’Connor F. McGivern Revised Issue T. Donovan C February 2013 M. Piggott B. O’Connor F. McGivern Revised Issue A. Lambe D September 2013 T. Donovan B. O’Connor F. McGivern Revised Issue Please read carefully the following statements and conditions of use of the data, contained in this report. 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It should not be shown to other parties without consent from us and from the party which commissioned it. Mott MacDonald, 5 Eastgate Avenue, Eastgate, Little Island, Cork, Co Cork, Ireland T +353 (0)21 4809 800 F +353 (0)21 4809 801, W www.mottmac.com SWRBD CFRAM Study Content Chapter Title Page 1. Introduction 1 1.1 Aims and Objectives _________________________________________________________________ 1 1.2 Description of the South Western Study Area ______________________________________________ 2 1.3 Unit of Management 20 _______________________________________________________________ 4 1.4 Areas for Further Assessment _________________________________________________________ 4 1.5 SW CFRAMs Project Delivery __________________________________________________________ 4 2. Detailed Methodology 6 2.1 Data Collection _____________________________________________________________________ 6 2.2 Hydrometric Data ___________________________________________________________________ 6 2.3 Meteorological Data _________________________________________________________________ 7 2.4 Coastal Data _______________________________________________________________________ 7 2.5 Survey Data (including LIDAR & IFSAR) _________________________________________________ 7 2.6 Environmental Data _________________________________________________________________ 8 2.7 Receptor Data _____________________________________________________________________ 10 2.8 Flood Event Data __________________________________________________________________ 12 2.9 Flood Defence Asset Data ___________________________________________________________ 12 2.10 Outstanding Data __________________________________________________________________ 13 2.11 Unavailable Data ___________________________________________________________________ 13 3. Survey Requirements 14 3.1 River Channel Survey _______________________________________________________________ 14 3.2 Floodplain Survey __________________________________________________________________ 15 3.3 Flood Defence Asset Condition Survey _________________________________________________ 15 3.4 Property Level Survey _______________________________________________________________ 17 4. Preliminary Hydrological Assessment 18 4.1 Hydrometric Data Review ____________________________________________________________ 18 4.2 Meteorological Data Review __________________________________________________________ 20 4.3 Coastal Data Review _______________________________________________________________ 22 4.4 Physical Catchment Descriptor Review _________________________________________________ 23 4.5 Historical Flood Events ______________________________________________________________ 24 4.5.1 Review of Historical Flood Data _______________________________________________________ 24 4.5.2 Historical Flood Event Summaries _____________________________________________________ 27 4.5.3 Selection of Calibration/Verification Events ______________________________________________ 29 4.6 Flooding Mechanisms _______________________________________________________________ 30 5. Detailed Method Statement 31 5.1 Flood Risk Review Approach _________________________________________________________ 31 5.1.1 Site Visits ________________________________________________________________________ 31 5.1.2 Flooding History ___________________________________________________________________ 31 5.1.3 Flood Risk Review Report____________________________________________________________ 31 5.2 Survey Approach __________________________________________________________________ 31 5.2.1 Channel and Structure Survey ________________________________________________________ 31 5.2.2 Defence Asset Condition Survey ______________________________________________________ 31 296235/IWE/CCW/R005/D 296235-IWE-CCW-R005-D HA20 SWRBD CFRAM Study 5.3 Hydrology Approach ________________________________________________________________ 32 5.3.1 Overview _________________________________________________________________________ 32 5.3.2 HEP Conceptualisation ______________________________________________________________ 34 5.3.3 Rating Review _____________________________________________________________________ 35 5.3.4 Approach for Gauged Fluvial Locations _________________________________________________ 36 5.3.5 Approach for Ungauged Fluvial Locations _______________________________________________ 38 5.3.6 Approach for Tidal Locations _________________________________________________________ 39 5.3.7 Future Scenarios ___________________________________________________________________ 41 5.4 Hydraulic Analysis Approach _________________________________________________________ 42 5.5 Flood Risk Assessment (FRA) ________________________________________________________ 46 5.5.1 Social Risk _______________________________________________________________________ 46 5.5.2 Risk to the Environment _____________________________________________________________ 46 5.5.3 Risk to Cultural Heritage _____________________________________________________________ 46 5.5.4 Risk to the Economy ________________________________________________________________ 47 5.5.5 Indicators of Vulnerability ____________________________________________________________ 47 5.5.6 Risk Assessments __________________________________________________________________ 47 5.6 Strategic Environmental Assessment (SEA) ______________________________________________ 47 5.6.1 Phase I Screening Assessment _______________________________________________________ 47 5.6.2 Phase II Constraint and SEA Scoping Study _____________________________________________ 48 5.6.3 Phase III Option Appraisal Study ______________________________________________________ 48 5.6.4 Phase IV SEA Report _______________________________________________________________ 49 5.6.5 Phase V Update of SEA Report _______________________________________________________ 49 5.6.6 Production of the SEA Statement ______________________________________________________