WG F 20 Workshop - Berlin

Transcription

1 WG F 20 Workshop - Berlin THE PLUVIAL PFRA IN IRELAND Mark Adamson Office of Public Works 4 th October, 2016

2 OVERALL APPROACH TO PFRA OVERALL APPROACH Risk Assessment Three-String Approach Historic FRA (What has happened) Predictive FRA (What could happen) Stakeholder Consultation (Local Knowledge) Identification of APSRs Integrate Risk Assessments Identify Significant Risk Identify APSRs Public Consultation

3 HISTORIC PFRA National Flood Data Archive HISTORIC RISK Records of Past Damage / Properties Flooded HISTORIC HAZARD Records of Past Floods HISTORIC RISK CATEGORY (1 4) Degree of Damage / No. Properties Flooded No. of Past Events in Urban Area / Townland

4 CONSULTATION LOCAL AUTHORITIES Two Series of Regional Workshops Data Requests Formal Request for Nominations of APSFRs (Pluvial Risk and Risk from Infrastructure) OTHER DEPTS. / AUTHORITIES

5 PREDICTIVE PFRA FLOOD RISK FUNCTION OF: Probability of a Flood Event (Hazard) Consequences (Degree of Damage in Event of a Flood) 2009: NO NATIONAL FLOOD MAPPING AVAILABLE IN IRELAND ISSUED CONTRACT FOR NATIONAL PLUVIAL SCREENING

6 PREDICTIVE PFRA: PLUVIAL MAPPING MODEL Rapid Flood-Spreading Model H.R. Wallingford Quasi-2D Model Country Divided into 87 Sub-Basins 10m Grid Cells

7 PREDICTIVE PFRA: PLUVIAL MAPPING INPUT DATA National DTM SAR-based DTM 2m, 5m, & 10m Grid Cell Vertical: 0.01m Resolution, 0.5m Absolute RSME Land Use Data: Corine 2000 Soil: FSR Soil Classification Rainfall: FSU 2km Gridded D-D-F Data

8 PREDICTIVE PFRA: PLUVIAL MAPPING METHOD & ASSUMPTIONS Events: 30-yr, 100-yr & 1000-yr 1hr, 3hr, 6hr & 24hr Storm Durations Rainfall: Summer Profile, Areal Reduction Factor Applied Losses: Interception / Depressions: 5mm/hr Rural: 3 8mm/hr Factor of Soil Type Urban: 15mm/hr Derived from Pilot Area Tests Using Infoworks CS Models Depth Threshold for Mapping: 50mm

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11 PREDICTIVE PFRA: PLUVIAL MAPPING BENEFITS Rapid, National Assessment Identification of Areas where More Detailed Assessment may be Required LIMITATIONS DTM Accuracy No Structures Fluvial Drainage Not Incorporated Coastal Boundary Issues Extents Cropped by Fluvial / Coastal Flood Extents for Risk Assessment

12 PREDICTIVE PFRA: RISK RANGE OF RISK CRITERIA INCLUDED Social Economic Environmental Cultural Heritage RECEPTORS / INDICATORS Datasets Meeting Certain Requirements (National, Spatially-Identified, Classified, )

13 PREDICTIVE PFRA: RISK VULNERABILITY CLASSIFICATION FOR A RECEPTOR ASSIGNED AS FUNCTION OF: Importance International National Regional Local Degree of Impact / Damage if Flooded Extreme / Total Loss No / Negligable Impact

14 PREDICTIVE PFRA: RISK E.G., DAMAGE TO MATTERS OF VALUE PROBABLE IMPACT DEGREE OF RECEPTOR IMPORTANCE / DESIGNATION International National Regional Local Total Loss Critical Critical Extreme High Severe Degradation Critical Extreme High Moderate Moderate Damage Extreme High Moderate Low Minor Damage High Moderate Low Low No / Negligible Damage Low** Low Low Low

15 PREDICTIVE PFRA: RISK RISK: PROB. HAZARD * CONSEQUENCES Pluvial Hazard Indicative Mapping for range of sources of flooding 3 Probabilities Consequences Standardised Vulnerability Classifications FLOOD RISK INDEX (FRI) Function of Probability and Vulnerability Consistent Metric Standard Threshold for Significance

16 Vulnerability PREDICTIVE PFRA: RISK Matrix for Flood Risk Index Vulnerability Class Vulnerability Factor Probability of Flood Event 0.1% - Low 1% - Medium 10% - High Low Moderate High Extreme Critical

17 PREDICTIVE PFRA: RISK INDIVIDUAL POINT RECEPTORS Calculate FRI for each Receptor Properties, Power stations, airports, hospitals, etc. FRI = Vulnerability Classification * Probability of Flooding AREAS OF POTENTIALLY SIGNIFICANT FLOOD RISK Cumulative risk within an area Collection of houses, businesses, other receptors Sum FRI within a given area

18 PREDICTIVE PFRA: RISK

19 PLUVIAL PFRA: OUTCOMES PREDICTIVE ASSESSMENT Dublin City: FRI = 11,735 Ennistimmon: 2,508 (One Private Asset) Cork City: 2,418 All Others: < 1,000 CONSULTATION / PAST EVENTS No Significant Pluvial Risk Outside of Dublin Raphoe: Overland Flow into Town APSFRs: Dublin City, Raphoe

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21 WG F 20 Workshop - Berlin THE PLUVIAL PFRA IN IRELAND Mark Adamson Office of Public Works 4 th October, 2016