Coastal Flood Insurance Studies in Virginia and Climate Change · Coastal Flood Insurance Studies in Virginia and Climate Change US Army Engineer Research and Development Center

Coastal Flood Insurance Studies in Virginia and Climate Change

US Army Engineer Research and Development Center

VFMA Floodplain Management WorkshopOctober 22, 2015

Jeff Gangai

2US Army Engineer Research and Development Center

Why is a Coastal Restudy Needed?

New Guidelines need to be implemented Atlantic Ocean and Gulf of Mexico Guidelines Update (2007) Sheltered Waters Report (2008) PM 50 Limit of Moderate Wave Action (LiMWA) (2008) and new 2013

OG

To update base data such as topographic dataset and aerial imagery to high resolution products and seamless Digital Elevation Model (DEM)

To utilize newer coastal hazard methodologies developed during the FEMA Mississippi Coastal Restudy

To take advantage of higher performance numerical modeling

To take advantage of improvement in GIS technologies to allow for more precise FIRMs


Modern GIS-Integrated FIS Modeling


Technology = Efficiency = Increased Precision

Example, Suffolk County, NY• 1,200 miles of ocean and estuarine shoreline• Existing FIRM = 208 coastal transects• GeoCoastal application allowed 1611 transects for

typical study budget• 670% increase in resolution• Results easier to defend due to detail of analysis


Map Modernization

New digital FIRMs more precisely represent current flood risk

Countywide digital FIRMS –easier to use and update

98% of communities in Region III now have digital FIRMs


Why is a Coastal Restudy Needed?


Region III Coastal Study Timeline

Surge Study Results•Winter 2011

Coastal Hazard Analysis Results•Spring 2012-Summer 2014

Preliminary FIRMs• Summer 2013– Spring 2015

Letter of Final Determination•Spring 2014– Winter 2015

New Effective Coastal FIRMs•Fall 2014 –Summer 2016


Coastal FIS Project Life-cycle


Region III Coastal FIRM Status (Hampton Roads)

Gloucester – 11/19/2014

Newport News– 12/09/2014

Chesapeake, Poquoson – 12/16/2014

Virginia Beach, York – 01/16/2015

Surry – 05/04/2015

Suffolk, Portsmouth – 08/03/2015

Isle of Wight – 12/02/2015 James City/Williamsburg– 12/16/2015 Hampton – 05/16/2016 Norfolk –90-day appeal period ended September 2015 (1 appeal received)

10

FEMA REGION III COASTAL STORM SURGE STUDY

Jeff Hanson, Ph.D.Project Leader

Mike ForteProject Specialist

Presenter

Presentation Notes

Good Afternoon, and Thank you for coming My name is Jeff Hanson With the USACE in Duck For the past 4 years we have been working very hard to prepare this update I am pleased to be able to share the results with you today


FEMA Region III Study Area

• Four states plus District of Columbia

• Five metropolitan areas

• Complex coastal geomorphology

• Delaware River/Bay system- Tidal up to Trenton, NJ- 782 square mile bay- Strategic shipping and military port

• Chesapeake bay - Third largest estuary in world- 11,000 miles of tidal shoreline- Major shipping, seafood and military ports


Storm Surge Study Approach

Storm Surge Modeling

Statistical Analysis completed in order to determine Return

Period

Storm Forcing•Extratropical Wind Fields

•Hurricane Tracks

High-Resolution Bathymetry/Topography

Winds

Water Levels

Waves

10%, 2%, 1% and 0.2% annual chance stillwater elevations


Improvement in Modeling Capabilities

1978 Mesh3-6 mile resolution

2011 Mesh100 ft Minimum Resolution

Current stillwater elevations (SWELs) on FIRMs date back to 1973-1986 (fewupdates made in early-1990s) and were computed using a tidal gage analysisor the Virginia Institute of Marine Sciences (VIMS) model


Modeling System Validation

Validation Storms

Hurricane Isabel (SEP 03)

Hurricane Ernesto (AUG 06)

Extratropical Storm Ida (Nov 09)

Validation Parameters

Tides Hurricane Ernesto (AUG 06)

Wind speed and direction

Water levels

High water marks

Hurricane Isabel September 2003

http://upload.wikimedia.org/wikipedia/commons/7/7f/Hurricane_Isabel_18_sept_2003_1555Z.jpg

http://upload.wikimedia.org/wikipedia/commons/7/7f/Hurricane_Isabel_18_sept_2003_1555Z.jpg


High Water Marks: Hurricanes Isabel and Ernesto

Hurricane Isabel September 2003 Extra-tropical Storm Ida November 2009

Circles depict observed high water marks to same color scale as background surge predictions


Production Run Storms

Extratropical Storms

• 30 Top ranked storms 1975-2009

• Based on water levels at 10 stations

• Careful reanalysis of wind/pressure fields

February 4, 1998 Pressure Field

Tropical Storms

• Record of 20 hurricanes in 60 years insufficient for 100- yr analysis

• 156 Representative events sampled from ASCE 100,000-year synthetic storm set

• A 1-year effort!

• Intensities range from Tropical Storm to Cat 3

• Demonstrated validity with comparisons to historic data

156 Simulated Hurricane

Tracks

17

Tidal Contributions

Average High Tide ElevationMHHW above MSL (m)


Updated SWEL

Hurricanes Extratropicals Combined

Elevation (ft, MSL)

19

Difference between updated and published 100-yr SWELs (ft)

(Updated – published)

Orange: 1-2 ft higherGreen: Less than 1 ft changeBlue: 1-3 ft lower

Hampton Roads Area


Coastal Study Resources - Storm Surge Study

1.1 DEM

Coastal Storm Surge Analysis:Final Report

1.2 Modeling System 1.3 Storm Forcing

3. Final Analysis2. Model Validation

• Methods and results

• Released as formal reports

• Available at http://dodreports.com/

or http://riskmap3.com

http://dodreports.com/

http://riskmap3.com/


Coastal Study Process

FLOODPLAIN BOUNDARY & FLOOD HAZARD ZONE MAPPING

OVERLAND WAVE HEIGHT & RUNUP ANALYSIS

STORM-INDUCED EROSION

FRONTAL DUNE DELINEATION

TRANSECT LAYOUT & FIELD RECONNAISSANCE

STARTING WAVE CONDITION ANALYSIS

STORM SURGE ANALYSIS

TERRAIN PROCESSING


Transect Placement

Transect LayoutCity of Virginia Beach


Overland Wave Hazard Modeling

Storm-induced erosion

•Primary frontal dunes•Erodible bluffs

WHAFIS 4.0

•Profile elevation•1% SWELs•Starting wave conditions•Wave Setup •Obstruction cards (OF, IF,

BU, VE, MG)


Field Reconnaissance

Presenter

Presentation Notes

Update graphics for each County/City, if available


DRAFT

Field Reconnaissance Efforts


Obstructions Ready for Modeling


Erosion Analysis

Dunes:•Dune erosion based on the 540

sqft rule•Dune retreat•Dune removal• Primary Frontal Dune (PFD)

delineation


Primary Frontal Dune Line Drawn Based on Aerial Images and Information Obtained from Field Reconnaissance


Shoreline Protection andWave Runup

Shoreline Protection Structures: Will the shoreline protection structure survive the 1%

event?

Is the structure certified?

Modeling of integral structure vs. fail structure to determine higher hazard

FEMA 2007 Guidelines now requires the use of the 2% runup vs. the mean runup computed prior to 2007

Mild-sloping beaches, bluffs and cliffs

Methods:

•CSHORE 1-D, Runup 2.0, TAW, SPM


Basic Elements of a Coastal Hazard Analysis

Base Flood Elevation on FIRM includes 4 components:

1. Storm surge stillwater elevation (SWEL)

2. Amount of wave setup

3. Wave height above storm surge (stillwater) elevation

4. Wave runup above storm surge elevation (where present)

Determined from storm surge model


Mapping


Limit of Moderate Wave Action (LiMWA)

FEMA Procedure Memorandum No. 50, 2008

At present not a regulatory requirement

No Federal Insurance requirements tied to LiMWA

CRS benefit for communities requiring VE Zone construction standards in areas defined by LiMWA or areas subject to waves greater then 1.5 ft.

FEMA OG No. 13-13 - Updated Guidance for Identification and Mapping of LiMWA (October, 2013)


Coastal Study Resources

FIS Report

Coastal TSDN

FEMA Map Service Center

Website – www.r3coastal.com

www.riskmap3.com

Property Locator Tool

All content transferred to riskmap3.com

http://www.r3coastal.com/


FIS Report

Starting Point of Transect (at shoreline)

Overland Modeling Input Parameters for Transect (at shoreline)


TSDN Data and Report

Detailed methods in Report

County/Citywide stillwater surfaces

(10%, 2%, 1%, & 0.2%) Modeling Geodatabase with published and

mapping transects

•Transect and obstruction GIS layers•Model input parameters and results

CHAMP database/WHAFIS input and output files

Wave runup and overtopping analyses

Mapping Geodatabase

•Floodplain boundaries (1% and 0.2%)•V/A zone boundary•Zone gutters/divisions and labeling


Potential for Ongoing and Future Work

SLR studies

Assessment of flood protection strategies• Design parameters for shoreline protection

structures• Suitability of living shorelines

Boundary conditions for refined regional or local coastal models

Establishment of tailwater conditions for stormwater models

Floodplain mapping changes for Flood Mitigation Efforts (CLOMR and LOMR)


Future Updates to Studies

Coastal Coordinated Needs Management System (CNMS)•Every 5 year evaluate validity of Coastal Study and Mapping on FIRMs Elevation & Bathymetry Data Land Use Modeling Technology Guidelines and Methods Historic Storms Damage Storm Frequency Shoreline Position (Long-term erosion) Water levels (sea level rise/lake level)


Traditional products are regulatory and subject to statutory due-process requirements

Risk MAP products are non-regulatory and are not subject to statutory due-process requirements

Ongoing Work - Additional Risk MAP Products

DFIRM Database

Traditional Regulatory Products Non-Regulatory Products

Presenter

Presentation Notes

Floodplain mapping pre-Risk MAP generated 3 main types of products that all familiar with the DFIRM process have come to know and understand DFIRM Database FIS Report DFIRMs Risk MAP does not seek to replace the FIRM flagship products (FIRM DB, FIS report, and the map itself) – those will still be produced for each study. However, we want to align our new datasets/products with an existing structure and follow the same general model.


Non-Regulatory Coastal Flood Risk Products and Datasets

Flood Risk Products • Flood Risk Report• Flood Risk Database • Flood Risk Map

Flood Risk Datasets• Changes Since Last FIRM • Coastal Depth Grids• Flood Risk Assessment (refined Hazus analysis)• Areas of Mitigation Interest

Flood Risk Products help communities:• Gain a better understanding of flood risk and its potential impact on

communities and individuals • Take proper mitigation actions to reduce this risk


Coastal Increased Inundation Areas

LegendCOASTAL INCREASED INUNDATION

base + 1 foot

base + 2 foot

base + 3 foot

41

State

Change inPopulation

from Baseline

Change inHousing Units

from Baseline

Area withinCoastal SFHA

Change inArea fromBaseline

FLORIDA 1 1 1 1 NEW YORK 2 2 2 14 LOUISIANA 3 3 3 2

NEW JERSEY 4 4 4 9 TEXAS 5 5 5 3

VIRGINIA 7 6 6 6 CALIFORNIA 6 7 7 10

Virginia’s Relative Exposure to SLR

Based on low SLR projectionFEMA Programmatic Environmental Impact Statement

National Rankings –Change in hazard/exposure for 2060 due to SLR


Why is Climate Change important to NFIP? As of October 2013, NFIP currently has:•About 5.6 million policies in force•$1.3 trillion coverage in force•$24 billion debt to U.S. Treasury

Coastal Floodplains expected to increase by up to 55% by 2100 in response to climate change

Number of coastal policies expected to increase by 130%


How is SLR currently treated in NFIP?Directly considered:

BCA Calculations for HMA grants

Indirectly considered:NFIP Contingency Loadings

Long-term coastal erosion, a consequence of long-term SLR, is discussed in detail in FEMA’s Coastal Construction manual

Brief section in Coastal Construction Manual

NFIP Community Rating System (CRS) now gives credit for community efforts to anticipate and take actions that can mitigate adverse impacts from climate change

Insurance rates in V Zones consider generalized effects of long-term coastal erosion

Presenter

Presentation Notes

Pre BW-12, FEMA regulations did not allow inclusion of future conditions in the FIS process (very limited exclusions) In ’07, the GAO recommended FEMA analyze CC on the NFIP, which spurred the national CC study, the PR study, the NC SLRIS Just in case questions are asked regarding last bullet on slide 6: “Insurance rates in our V Zones consider generalized effects of long-term coastal erosion.” V Zone rates were increased close to the maximum allowed per year from about 2001 through 2010 or so (maybe even later—I would have to check with our actuaries). Much of the of the reason for this increase was based on the findings of the 2000 Heinz Center erosion study. In essence, the FEMA actuaries added an erosion loading to the V Zones. Importantly, all V Zones were treated the same, regardless of the local erosion (or accretion) rate.


FEMA and SLR1991 - FEMA Study on Projected Impact of RSLR on NFIP

2007 - GAO instructed FEMA to analyze impacts of climate change on NFIP FEMA National CC Study

2008 – NC Sea Level Rise Impact Study

2009 – FEMA SLR Proof of Concept Study

2012 – Biggert-Waters Flood Insurance Reform Act Ensure that FEMA uses best available climate science, sea level rise and

future development information to access flood risk.

Future implementation pending Technical Mapping Advisory Council

2013-2105 – SLR Proof of Concept/Pilot Studies PR, FL and CA

Presenter

Presentation Notes

1991 study found that the financial impact was not significant, due to annual updates to insurance ratings. Studies may get outdated, but are renewed frequently enough to capture impacts. Recommendations were to monitor the state of the science on SLR and consider adaptation measures to reduce long-term exposure and risk FEMA National CC (A) develop recommendations on how to— (i) ensure that flood insurance rate maps incorporate the best available climate science to assess flood risks; and (ii) ensure that the Federal Emergency Management Agency uses the best available methodology to consider the impact of— (I) the rise in the sea level; and (II) future development on flood risk;


Biggert-Waters Flood Insurance Reform Act of 2012

Section 100216: •Authorizes FEMA to include sea level rise information in FIRM updates•Inclusion of this information on FIRMs will be done in coordination with a Technical

Mapping Advisory Council established in Section 100215

Section 100215: •Establishes TMAC (Technical Mapping Advisory Council)•TMAC will be comprised of members from Federal, State, Local governments, as

well as representatives from various Organizations and Associations•TMAC will be charged in part in developing recommendations to FEMA on how to

incorporate Climate Change data and information into the NFIP

Presenter

Presentation Notes

Overall – In light of BW-12 and pending TMAC recommendations, it is possible that FEMA may produce a SLR advisory layer to assist pro-active communities in building resilience FEMA has funded these studies to learn move on how SLR impacts wave and surge processes in the mapping process, and also to evaluate pilot products We are driving to producing advisory information that will inform FEMA and communities on how base flood elevations will change w/ SLR Homeowner Flood Insurance Affordability Act (HFIAA) is at the White House for signature and this has some impacts on some parts of BW. I don’t have full details here but I don’t want this slide to be outdated by the time you are presenting.


SLR Advisory Layer Concept

Non-regulatory (advisory)

Low incremental production cost

Develop as add-on to Risk MAP studies •Leverage models/data produced by FIS

Convey future changes to coastal flood hazard

Guide long-term planning & adaptation

Develop for pro-active states & communities


SLR Proof of Concept/Pilot Studies Study areas:•Puerto Rico (Caribbean Sea)•San Francisco County, CA (Pacific Ocean)•Hillsborough and Pinellas Counties, FL (Gulf of Mexico)

Goals:•Work closely with coastal communities to produce SLR information for advisory

purposes•Further test whether linear super-position (“bathtub approach”) is adequate for

NFIP flood-mapping purposes•Test and refine approaches for modeling and mapping

Counties selected because:•Willingness to work with FEMA on SLR•Test different coastal environments (different than PR and NC studies) •Leverage ongoing coastal flood studies

Presenter

Presentation Notes

NC study (Atlantic): FEMA funded the study via a grant mandated by a congressional bill, but NC owned and managed the study. There is some controversy regarding SLR curves used.


Questions? Dewberry

• Jeff Gangai, [email protected]

FEMA• Robert Pierson

[email protected]

mailto:[email protected]

mailto:[email protected]

Documents

Coastal Flood Insurance Studies in Virginia and Climate Change · Coastal Flood Insurance Studies in Virginia and Climate Change US Army Engineer Research and Development Center