Workshop on Probabilistic Flood Hazard Assessment

The U.S. Nuclear Regulatory Commission's Offices of Nuclear Regulatory Research, Nuclear Reactor Regulation, and New Reactors in cooperation with Federal agency partners: U.S. Department of Energy; Federal Energy Regulatory Commission; U.S. Army Corps of Engineers; U.S. Bureau of Reclamation; and U.S. Geological Survey organized and conducted a "Workshop on Probabilistic Flood Hazard Assessment (PFHA)" at NRC headquarters auditorium, Rockville, Maryland, January 29 – 31, 2013. This research workshop provided a venue for the sharing of information on probabilistic flood hazard assessments of extreme natural and human-related events (i.e., annual exceedance probabilities much less than 2.0 E-3 per year) among the Federal community. The organizing committee chose the session topics, presenters and panelists.

The workshop objectives were to:

• assess, discuss, and inform participants on, the state-of-the-practice for extreme flood assessments within a risk context with the following objectives;
• facilitate the sharing of information between both Federal agencies and other interested parties to bridge the current state-of-knowledge between extreme flood assessments and risk assessments of critical infrastructures;
• seek ideas and insights on possible ways to develop a PFHA for use in probabilistic risk assessments (PRA);
• identify potential components of flood-causing mechanisms that lend themselves to probabilistic analysis and warrant further study (i.e., computer-generated storm events);
• establish realistic plans for coordination of PFHA research studies as the follow-up to the workshop observations and insights; and
• develop plans for a cooperative research strategy on PFHA for the workshop partners.

The technical focus was to:

• understand flood assessment needs of the participating Federal agencies with respect to the evaluation of critical industry infrastructure;
• leverage the flood hazard risk assessment studies performed to date to assess the applicability and practicality of using probabilistic approaches for extreme flood hazard assessments within a risk framework;
• discuss research or other activities needed to address identified gaps or challenges in the use of PFHA for extreme flood assessments within PRA; and
• determine how these PFHA approaches and methods can be best utilized in conjunction with more traditional deterministic approaches.

Related Documents

• Final Program of the Federal Workshop on Probabilistic Flood Hazard Assessment (PFHA)
• Public Meeting Summary
• Panel 1: Federal Agencies' Interests and Needs in PFHA
  • Introduction – Nilesh Chokshi and Mark Blackburn
  • Commissioner George Apostolakis – Importance of Risk-Informed, Performance Based Regulations
  • US Nuclear Regulatory Commission (USNRC) Staff Needs In PFHA – Fernando Ferrante
  • Transferable Methods from Seismic Hazard – Annie Kammerer
  • Bureau of Reclamation Dam Safety Program – John England
  • FERC'S Need for PFHA – David Lord
  • Status of ANS 2.31, "Determining Design Basis On-Site Flooding Caused by Precipitation at Nuclear Facility Sites" – John Stevenson
  • ANS-2.8 Working Group Status, "Determining External Flood Hazards for Nuclear Facilities" – Yan Gao and Ray Schneider
• Panel 2: State-of-the-Practice in Identifying and Quantifying Extreme Flood Hazards
  • Overview and History of Flood Frequency in the United States – Will Thomas
  • Extreme Flood Frequency Analysis Concepts, Philosophy and Strategies – Jery Stedinger
  • Quantitative Paleoflood Hydrology – Jim O'Connor
  • USACE Methods for Quantifying Extreme Flood Hazards – Doug Clemetson
  • Hydrologic Hazard Curve Methods for Dam Safety – John England
• Panel 3: Extreme Precipitation Evens
  • Introduction – John England and Chandra Pathak
  • An Observation-Driven Approach to Rainfall and Flood Frequency Analysis Using High-Resolution Radar… – Daniel Wright
  • Regional Precipitation – Frequency Analysis And Extreme Storms Including PMP –Mel Schaefer
  • High-Resolution Numerical Modeling as a Tool to Assess Extreme Precipitation Events – Kelly Mahoney and Jason Caldwell
  • Precipitation Frequency Estimates For The Nation And Extremes – A Perspective – Geoff Bonnin
  • Extreme Precipitation Frequency for Dam Safety and Nuclear Facilities – A Perspective – Victoria Sankovich
• Panel 4: Flood-Induced Dam and Levee Failures
  • Risk-Informed Approach to Flood-Induced Dam and Levee Failures – David Bowles
  • Dutch Approach to Levee Reliability – Timo Schweckendiek
  • Risk-Informed Decision Making Approach for Inflow Design Flood Selection and Accommodation for Dams – Jason Hedien
  • Incorporating Breach Parameter Estimation and Physically-Based Dam Breach Modeling – Tony Wahl
  • Risk Informed Decision Framework for Dam And Levee Safety – David Margo
  • Probabilistic Risk Analysis for Dams – Martin McCann
  • Extreme Flood Frequency Analysis: Practicing Risk Analysis – Jery R. Stedinger
• Panel 5: Tsunamis Flooding
  • Probabilistic Tsunami Hazard Analysis – Hong Kie Thio
  • Recent Advances in PTHA Methodology – Randall LeVeque
  • Geological Perspective on Submarine Landslide Tsunami Probability – Uri ten Brink
  • Modeling Generation and Propagation of Landslide Tsunamis – Patrick Lynett
  • Tsunami Flooding Assessment Using Forecast Tools – Yong Wei
• Panel 6: Riverine Flooding
  • Introduction – Rajiv Prasad and Will Thomas
  • Riverine PFHA for NRC Safety Reviews – Why and How – Rajiv Prasad
  • Flood Frequency of a Regulated River – The Missouri River – Doug Clemetson
  • Stochastic Event Flood Model (SEFM) – Mel Schaefer
  • SEFM Case Study Altus Dam OK – Nicole Novembre
  • Paleoflood Studies and their Application to Reclamation Dam Safety – Ralph Klinger and John England
• Panel 7: Extreme Storm Surge for Coastal Areas
  • Introduction – Don Resio and Ty Wamsley
  • Dutch Approach to Coastal Flood Hazard – Joost Beckers
  • Recent Work and Future Directions in Coastal Surge Modeling and Sea Level Extremes within NOAA – Stephen Gill
  • FEMA's Coastal Flood Hazard Analyses in the Atlantic Ocean and Gulf of Mexico – Tucker Mahoney
  • Modeling System for Applications to Very-Low Probability Events and Flood Response – Ty Wamsley
  • Coastal Inundation Risk Assessment – Jen Irish
• Panel 8: Combined Events Flooding
  • Introduction – David Margo and Joost Beckers
  • Combined Events in External Flooding Evaluation for Nuclear Power Plants – Kit Ng
  • Assessing Levee System Performance Using Existing and Future Risk Analysis Tools – Christopher Dunn
  • Seismic Risk of Co-Located Critical Facilities – Effects of Correlation and Uncertainty – Martin McCann
  • Combined Storm Surge – Riverine Flood Events – Joost Beckers
  • Combining Flood Risks from Snowmelt Rain and Ice – The Platte River in Nebraska – Doug Clemetson
  • Combined Events A Systems Perspective – Patrick Regan
• Panel 9: Summary of Significant Observations, Insights and Identified Opportunities for Collaboration on PFHA
  • Panel 1 – Federal Agencies' Interests and Needs in PFHA
  • Panel 2 – State-of-the-Practice in Identifying and Quantifying Extreme Flood Hazards
  • Panel 3 – Extreme Precipitation Events
  • Panel 4 – Flood-Induced Dam and Levee Failures
  • Panel 5 – Tsunami Flooding
  • Panel 6 – Riverine Flooding
  • Panel 7 – Extreme Storm Surge for Coastal Areas
  • Panel 8 – Combined Events Flooding
  • Panel 9 – Nathan Siu – Personal Comments
• Webcast

Please note that the workshop proceedings are being developed and will be issued as a NUREG/CP report. The proceedings will provide summaries of the presentations, panel discussions, and major observations and insights.