Reducing Flood Losses: Reevaluating the 1% Flood Standard

1. Gilbert F. WhiteNational Flood Policy ForumReducing Flood Losses: Is the 1% chance flood standard sufficient?Lawrence W. Olinger, P.E., DewberryDoug Plasencia, P.E., CFMMichael Baker CorpB.G. Gerald Galloway, Ph.D., P.E., Titan and University of Maryland

2. Gilbert F. WhiteNational Flood Policy Forum • Reducing Flood Losses: Is the 1% chance flood standard sufficient? • Where we have been • Where we are • Where we need to go • September 21-22, 2004, at the National Academies, Washington D.C. • 80+ Attendees

3. Forum (Cont’d) Effectiveness of the standard has never been thoroughly evaluated • Floods getting bigger, causing greater damage • Nationwide flood losses continue to rise • Mapped flooding does not match actual events • Numerous localities use a higher level of protection reduce their flood losses • Advanced technology calls into question clinging to a standard designed in an earlier era

4. Forum (Cont’d) Enhance policies and programs associated with the existing 1% standard. Most needed: • Integrate protection of natural resources and functions; • Communicating flood risk, “in or out”; • Use future-conditions hydrology; and • Establishing a new levee standard.

5. Forum (Cont’d) Floodplain Management Progress based on the 1% Annual Chance Flood • Satisfies our social needs for uniformity, administrative ease, and a baseline for equity. • Well institutionalized, supported by a body of case law, and integrated into federal, state, and local floodplain management initiatives. • Flood hazards are being managed. • Homes and other buildings constructed since regulations began are safer, sustain less damage

6. Forum (Cont’d) Floodplain Management Progress based on the 1% Annual Chance Flood • Development is clustered just outside the 1% boundary. • Grey area of uncertainty surrounds calculation of floodprone zone. • 1% standard not linked to other water programs, e.g. water quality. • Term 1% chance flood is problematic for communications. • 1% standard in inadequate for levees.

7. Forum (Cont’d) THE SUCCESS OF THE FORUM IS DUE TO THE DEDICATION AND DILIGENCE OF NUMEROUS PEOPLE AND ORGANIZATIONS PLANNING TEAM Larry Olinger, ASFPM Foundation President, Dewberry Larry Larson, ASFPM Executive Director Michael Armstrong, ICF Consulting Gerald Galloway, Titan Corporation Jacquelyn Monday, JLM Associates, Inc. Doug Plasencia, Michael Baker Corp. Ed Thomas, Michael Baker Corp. Diane Brown, ASFPM Administrator

8. Forum (Cont’d) Speakers Chad Berginnis, Ohio Department of Natural Resources Dennis S. Mileti, University of Colorado David Ford, David Ford Consulting Engineers, Inc. Cooperative Support Disasters Roundtable William Hooke, American Meteorological Society William A. Anderson, The National Academies

9. ASFPM Foundation AMEC Earth and Environmental Dewberry Flood Master Barriers, Inc. Michael Baker Corp. National Lenders’ Insurance Council PBS&J Shodeen, Inc. SmartVENT Titan Corporation URS Corporation Watershed Concepts Forum Sponsors

10. Urbanizing watersheds lead to increased flood damage Action → Establish a uniform method and associated management techniques for using future conditions within a watershed.

11. Floodplain development affects natural resources Action → Determine what effect the 1% standard and associated practices have had on the protection of natural functions and resources of floodplains.

12. Understanding flood risk can reduce flood losses Action → More effective techniques are needed to better communicate to the public and to decision makers the meaning of the probability of flooding, the flood risk, damage that can be expected damage, the impacts of changing conditions in watersheds, and other issues.

13. Inadequate hydrologic data and techniques lead to incorrect projections of flood levels Action →Hydrologic research is needed on at least three fronts. (1) to improve algorithms and methods for rainfall/runoff modeling for traditional flood-related applications and also for the special hazards such as moveable bed streams, alluvial fans, subsidence-prone regions, and closed basin lakes. (2) to determine the applicability of the Bulletin 17B guidelines for flood flow frequencies. (3) to estimate flood frequencies for watersheds that are subject to rapid growth and urbanization and/or those that have flood control dams, levees, or channel works in place.

14. Benefits and costs of using the 1% standard are unknown Action →Dollar figures or other quantified expressions are needed to describe the economic costs and benefits that have accrued from using the 1% annual chance flood standard.

15. Evaluation of the 1% standard would show whether it is effective Action → Both the accuracy and effectiveness of the 1% annual chance standard needs to be measured in specific riverine and coastal situations.

16. Levee failures lead to catastrophic damage Action → The role of levees in floodplain management should be explored thoroughly, particularly with regard to the 1% standard. Uniform procedures need to be developed for certifying levees as being capable of providing a specified level of protection.

17. Coastal A zone regulations result in large damage Action → Coastal A-zone designations on Flood Insurance Rate Maps need to be revised, along with associated development standards.

18. Flood predictions without good stream gage data often lead to unprotected structures and poor flood warnings Action → More and better stream gage data is essential to the determination of the depth, extent, and onset of future floods.

19. Forum (Cont’d) Approaches to Floodplain Management • Bring the 1%Standard Approach up to 1% • Enhance the 1% Approach • Apply A Two-tiered Standard • Use A Vertical Standard • Apply a Benefit/Cost Model (Risk Based) • Take an Incentive Based Approach

20. The End Thank You