ASFPM Conference – May Shifting Our Focus from Maps to Risk William L. Coulbourne, P.E. Applied Technology Council (ATC)

ASFPM Conference – May Topics of Discussion  Background  Proposed modifications to our current approaches to floodplain management  Flood design information must include risk  Risk must reflect probability of the event  Need to consider mitigation measures in addition to elevation  All flood insurance is not equal  Conclusions and Recommendations

ASFPM Conference – May Background  Last 20 years we’ve experienced many major flood events  1993 – Midwest floods  1997 – Red River floods – ND/MN  2005 – Hurricane Katrina  2008 – Midwest floods  2008 – Hurricane Ike  2009 – Red River floods  NFIP has over 20,000 participating communities and 5.5 million policies  Represents $1 trillion in exposure  NFIP program is $19 billion in debt

ASFPM Conference – May Background  Current mitigation to reduce losses is really just:  Elevation  Relocation  There are currently many ways to “ignore” the property location  LOMR – remove the land from the floodplain  Levee – protected by a manmade structure  Adjacent to a ‘100-year’ floodplain and you are out  Live in a house built pre-FIRM, you’re subsidized

ASFPM Conference – May Background (and the smell test)  Mapping standards require flood plain delineations to 1/10 th ft. and then are shown on maps drawn to 1:600 – 1:700 scale (from paper titled: Demonstrating Floodplain Uncertainty Using Flood Probability Maps)  How much sense does that make?  Width of the boundary line could be 25 ft.  Conclusion I draw is the current strategy is not working

ASFPM Conference – May Considerations for the Program  Flood design must include risk – now the risk is “read” as all the same everywhere in the flood plain  Risk must reflect the probability of the event  The only feasible mitigation solution is elevation above the ‘design event’ – need more options  All flood insurance must be actuarial and represent the risk

ASFPM Conference – May Flood Design Must Include Risk  Risk = probability x consequences  Low risk = high probability x low consequences  High risk = low probability x high consequences  Not all development in the flood plain is equal (unequal consequences to the community)

ASFPM Conference – May Generic plot of risk

ASFPM Conference – May Possible Risk Levels  Very High Risk:  Property in coastal high hazard area  Economic impact is great if damaged  Affects more than 50,000 people  Recovery would require more than 3 mos.  Property is behind flood protection barrier not inspected within last 5 years  Iconic buildings could be flooded  Flood depths could exceed 5 ft, velocities 5 fps

ASFPM Conference – May Possible Risk Levels  High Risk:  Flood protection barrier inspected within last 5 years  Flood depths could be 3 ft but not likely to exceed 5 ft.  Important buildings could be impacted but community has plan for continued operations  Population affected 10,000 – 50,000

ASFPM Conference – May Possible Risk Levels  Moderate Risk:  Last floodplain study less than 2 years old  Flood depth will not exceed 3 ft.  Population affected less than 10,000  Property might be on fill and thus cut off by floods  No community-important buildings affected

ASFPM Conference – May Possible Risk Levels  Low Risk:  Property outside mapped flood plain  Flood depth less than 2 ft.  No property is isolated by flooding  Population affected less than 5,000  No community-important buildings affected

ASFPM Conference – May Example – Cedar Rapids, IA 2008

ASFPM Conference – May Example – Cedar Rapids, IA 2008 Very High Risk High Risk

ASFPM Conference – May Risk Must Reflect Probability  It seems that many floods in last few years are exceeding the mapped probability (1% annual chance)  Maybe these floods are not really 1% annual events but something greater  Maybe our standard is to low (Dutch – 10,000-yr recurrence interval)  Continued development in/near floodplains will continue to increase flood probabilities (always changing condition)

ASFPM Conference – May Need Options to Elevation  Elevate to what elevation?  100-year event?  500-year event?  Engineer to resist floods  Perhaps elevation is not economically feasible – but actuarial flood rates are feasible  Dry floodproofing?  Wet floodproofing?

ASFPM Conference – May Stop Encouraging Development  Areas behind flood protection structures should be classified High Risk  Properties elevated within the designated floodplain are “not out of the floodplain”  Some places should be no build areas – coastal high hazard areas, floodways, areas where flood velocity > 5 fps  Properties within flood boundaries are either insured or do not receive federal assistance if damaged

ASFPM Conference – May Floodplain or not?

ASFPM Conference – May All Flood Insurance is not Equal  Premiums should be based on risk – not just elevation +/- BFE or in/out of 100-yr floodplain  Premiums should be higher when closer to the flood source  Premiums should account for installed mitigation measures of all sorts

ASFPM Conference – May Conclusions & Recommendations  Making a shift from maps to risk-based floodplain approach will not be easy or fast  Making a shift is imperative if we ever need for this program to be self-sufficient  Must broaden the pool of flood insurance contributors at the same time that the basis changes to risk  Must have insurance be actuarial at the same time the basis changes to risk

Questions?