Gilbert F. White Gilbert F. White National Flood Policy National Flood Policy Forum Forum Reducing Flood Reducing Flood Losses: Losses: Is the 1% chance Is the 1% chance flood standard flood standard sufficient? sufficient? Lawrence W. Olinger, Lawrence W. Olinger, P.E., P.E., Dewberry Dewberry Doug Plasencia, P.E., CFM Doug Plasencia, P.E., CFM Michael Baker Corp Michael Baker Corp B.G. Gerald Galloway, B.G. Gerald Galloway, Ph.D., P.E., Ph.D., P.E., Titan and Titan and University of Maryland University of Maryland
Transcript
Gilbert F. WhiteGilbert F. WhiteNational Flood Policy National Flood Policy ForumForumReducing Flood Losses: Reducing Flood Losses: Is the 1% chance Is the 1% chance flood standard sufficient?flood standard sufficient?
Lawrence W. Olinger, P.E., Lawrence W. Olinger, P.E., DewberryDewberryDoug Plasencia, P.E., CFMDoug Plasencia, P.E., CFMMichael Baker CorpMichael Baker CorpB.G. Gerald Galloway, Ph.D., P.E., B.G. Gerald Galloway, Ph.D., P.E., Titan and University of MarylandTitan and University of Maryland
Gilbert F. WhiteGilbert F. WhiteNational Flood Policy ForumNational Flood Policy Forum
• Reducing Flood Losses: Is the 1% chance Reducing Flood Losses: Is the 1% chance flood standard sufficient?flood standard sufficient?
• Where we have beenWhere we have been• Where we areWhere we are• Where we need to goWhere we need to go
• September 21-22, 2004, at the National September 21-22, 2004, at the National Academies, Washington D.C.Academies, Washington D.C.
• 80+ Attendees80+ Attendees
Forum (Cont’d)Forum (Cont’d)
Effectiveness of the standard has never been Effectiveness of the standard has never been thoroughly evaluatedthoroughly evaluated• Floods getting bigger, causing greater damageFloods getting bigger, causing greater damage
• Nationwide flood losses continue to riseNationwide flood losses continue to rise
• Mapped flooding does not match actual eventsMapped flooding does not match actual events
• Numerous localities use a higher level of Numerous localities use a higher level of protection reduce their flood losses protection reduce their flood losses
• Advanced technology calls into question clinging Advanced technology calls into question clinging to a standard designed in an earlier era to a standard designed in an earlier era
Forum (Cont’d)Forum (Cont’d)
Enhance policies and programs Enhance policies and programs associated with the existing 1% associated with the existing 1% standard. Most needed:standard. Most needed:Integrate protection of natural Integrate protection of natural
resources and functions;resources and functions;Communicating flood risk, “in or Communicating flood risk, “in or
out”;out”;Use future-conditions hydrology; andUse future-conditions hydrology; andEstablishing a new levee standard.Establishing a new levee standard.
Forum (Cont’d)Forum (Cont’d)
Floodplain Management Progress based Floodplain Management Progress based on the 1% Annual Chance Floodon the 1% Annual Chance Flood Satisfies our social needs for uniformity, Satisfies our social needs for uniformity,
administrative ease, and a baseline for equity.administrative ease, and a baseline for equity.
Well institutionalized, supported by a body of Well institutionalized, supported by a body of case law, and integrated into federal, state, and case law, and integrated into federal, state, and local floodplain management initiatives. local floodplain management initiatives.
Flood hazards are Flood hazards are being managedbeing managed..
Homes and other buildings constructed since Homes and other buildings constructed since regulations began are safer, sustain less damageregulations began are safer, sustain less damage
Forum (Cont’d)Forum (Cont’d)
Floodplain Management Progress based on Floodplain Management Progress based on the 1% Annual Chance Floodthe 1% Annual Chance Flood Development is clustered just outside the 1% boundary.Development is clustered just outside the 1% boundary.
Grey area of uncertainty surrounds calculation of Grey area of uncertainty surrounds calculation of floodprone zone. floodprone zone.
1% standard not linked to other water programs, e.g. 1% standard not linked to other water programs, e.g. water quality.water quality.
Term 1% chance flood is problematic for Term 1% chance flood is problematic for communications.communications.
1% standard in inadequate for levees.1% standard in inadequate for levees.
Forum (Cont’d)Forum (Cont’d)THE SUCCESS OF THE FORUM IS DUE TO THE THE SUCCESS OF THE FORUM IS DUE TO THE DEDICATION AND DILIGENCE OF NUMEROUS DEDICATION AND DILIGENCE OF NUMEROUS
PEOPLE AND ORGANIZATIONSPEOPLE AND ORGANIZATIONS
PLANNING TEAMPLANNING TEAMLarry Olinger, ASFPM Foundation President, DewberryLarry Olinger, ASFPM Foundation President, Dewberry
Urbanizing watersheds lead to Urbanizing watersheds lead to increased flood damageincreased flood damage
Action →Action → Establish a uniform Establish a uniform method and associated management method and associated management techniques for using future techniques for using future conditionsconditions within a watershed. within a watershed.
Floodplain development affects Floodplain development affects natural resourcesnatural resources
Action →Action → Determine what effect the 1% Determine what effect the 1% standard and associated practices have had standard and associated practices have had on the protection of natural functions and on the protection of natural functions and resources of floodplains.resources of floodplains.
Understanding flood risk can reduce Understanding flood risk can reduce flood losses flood losses
Action Action →→ More effective techniques are More effective techniques are needed to better communicate to the public needed to better communicate to the public and to decision makers the meaning of the and to decision makers the meaning of the probability of flooding, the flood risk, damage probability of flooding, the flood risk, damage that can be expected damage, the impacts of that can be expected damage, the impacts of changing conditions in watersheds, and other changing conditions in watersheds, and other issues.issues.
Inadequate hydrologic Inadequate hydrologic data and techniques lead to data and techniques lead to
incorrect projections of flood levelsincorrect projections of flood levels
Action →Hydrologic research is needed on at least three fronts.Action →Hydrologic research is needed on at least three fronts.
((1) to improve algorithms and methods for rainfall/runoff 1) to improve algorithms and methods for rainfall/runoff modeling for traditional flood-related applications and also modeling for traditional flood-related applications and also for the special hazards such as moveable bed streams, for the special hazards such as moveable bed streams, alluvial fans, subsidence-prone regions, and closed basin alluvial fans, subsidence-prone regions, and closed basin lakes.lakes.
(2) to determine the applicability of the Bulletin 17B guidelines (2) to determine the applicability of the Bulletin 17B guidelines for flood flow frequencies. for flood flow frequencies.
(3) to estimate flood frequencies for watersheds that are subject (3) to estimate flood frequencies for watersheds that are subject to rapid growth and urbanization and/or those that have to rapid growth and urbanization and/or those that have
flood control dams, levees, or channel works in placeflood control dams, levees, or channel works in place..
Benefits and costs of using the 1% Benefits and costs of using the 1% standard are unknownstandard are unknown
Action →Action → Dollar figures or other quantified Dollar figures or other quantified expressions are needed to describe the expressions are needed to describe the economic costs and benefits that have economic costs and benefits that have accrued from using the 1% annual chance accrued from using the 1% annual chance flood standard.flood standard.
Evaluation of the 1% standard would show Evaluation of the 1% standard would show whether it is effectivewhether it is effective
Action →Action → Both the accuracy and Both the accuracy and effectiveness of the 1% annual chance effectiveness of the 1% annual chance standard needs to be measured in specific standard needs to be measured in specific riverine and coastal situations.riverine and coastal situations.
Levee failures lead to catastrophic Levee failures lead to catastrophic damagedamage
Action →Action → The role of levees in floodplain The role of levees in floodplain management should be explored thoroughly, management should be explored thoroughly, particularly with regard to the 1% standard. particularly with regard to the 1% standard. Uniform procedures need to be developed for Uniform procedures need to be developed for certifying levees as being capable of certifying levees as being capable of providing a specified level of protection.providing a specified level of protection.
Coastal A zone regulations result in Coastal A zone regulations result in large damage large damage
Action →Action → Coastal A-zone designations on Coastal A-zone designations on Flood Insurance Rate Maps need to be Flood Insurance Rate Maps need to be revised, along with associated development revised, along with associated development standards.standards.
Flood predictions without good stream gage Flood predictions without good stream gage data often lead to unprotected structures and data often lead to unprotected structures and
poor flood warningspoor flood warnings
Action →Action → More and better stream gage data More and better stream gage data is essential to the determination of the depth, is essential to the determination of the depth, extent, and onset of future floods. extent, and onset of future floods.
Forum (Cont’d)Forum (Cont’d)
Approaches to Floodplain ManagementApproaches to Floodplain Management Bring the 1%Standard Approach up to 1%Bring the 1%Standard Approach up to 1%
Enhance the 1% ApproachEnhance the 1% Approach
Apply A Two-tiered StandardApply A Two-tiered Standard
Use A Vertical StandardUse A Vertical Standard
Apply a Benefit/Cost Model (Risk Based)Apply a Benefit/Cost Model (Risk Based)
Take an Incentive Based ApproachTake an Incentive Based Approach
