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If It Keeps on Rainin,evee s o n o rea
Kiran Chinnayakanahalli, PhD
Raulina Wojtkiewicz
1CONFIDENTIAL 2014 AIR WORLDWIDE
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AGENDA
- Why is AIR developing a US Flood Model?
-
- Challenges of modeling flood- How do we do it?
- How do we model hazard?
- How do we estimate loss?
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WHY IS AIR DEVELOPING A US FLOOD MODEL?
Presidential Declarations for Flood Disasters
(1964-2011)
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FLOODING IS A MAJOR CONTRIBUTOR TO
ECONOMIC LOSSES
1) The Great Flood, 1993 ($25 B)
In the US, floods causes more than $5 billion in damageseach year
,
3) Gulf Coast Flooding, 1995 ($5.5 B)
4) Pacific Northwest, 1996-97 ($6 B)44 5
8 95) Red River Flood, 1997 ($2 B)
6) Texas Flood, 1998 ($1.3 B)
7) Northeast Flood, 2006 ($1 B)
12
108) Midwest Flooding, 2008 ($10 B)
9) Rhode Island Flooding, 2010 ($1.5 B)
10) Tennessee Flooding, 2010 ($2.3 B)3
6 11
11) Lower Mississippi River Flood, 2011($7.5 B)
Source: Economic Losses from
4CONFIDENTIAL 2014 AIR WORLDWIDE
National Weather Service
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ALL MODELING APPROACHES ARE NOT EQUAL
Modeling Approach Pros Cons
Historic event footprints - Understandable- Discrete
- Deterministic, does not produceEP curve
- -
Actuarial or based on trendinghistorical losses - Simple- Inexpensive - Deterministic, does not produceEP curve- NO off-plain component- Need lar e sam le of ast losses
Return period flood maps (e.g.,FEMA maps in U.S.)
- Estimates risk at location- Easy to apply to
underwriting andaccumulation
- Deterministic, does not produceEP curve
- NO off-plain component- Inconsistent mapping methods
Probabilistic models based onriver gauging station data
- Stream flow gauge data iseasily obtained
- Easily derived historicalevent foot rints
- Physical data requirements high- Incomplete view of runoff
generation- NO off- lain com onent
AIRs event-based, fullyprobabilistic model developedfrom precipitation and runoffmodels
- Scientifically mostadvanced
- Provides a full occurrenceand aggregate EP curve
- Length of time to develop model- Physical data requirements are
high- Computational requirements high
5CONFIDENTIAL 2014 AIR WORLDWIDE
for portfolios
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CHALLENGES OF MODELING FLOOD
- The hazard model should have realistic spatial and temporal patterns of precipitation at suitable scale
spatial distribution of soil saturation accounting of lakes and reservoir attenuation
- location of flood defense structures and their design capacities
effects of customized flood defense
spatial distribution of off-floodplain losses
- Data intensive
- Computationally demanding
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MODEL FOR US FLOOD COVERS MORE THAN
2,000,000 KILOMETERS OF RIVER NETWORK
18 major river basins in theconti uous US
Every stream draining 10 km2
ormore
2.
2.2 M km of total streams
About 8,000 river gauges used forca ra on
Over 4 M river cross-sections,roughly spaced every 500 m
30-m NED DTM* used for flooddepth estimation
7CONFIDENTIAL 2014 AIR WORLDWIDE
*NED DTM National Elevation Dataset - Digital Terrain Model
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AIR USES SIMILAR FRAMEWORK ACROSS
DIFFERENT PERILS
HAZARD
Model
Dama e
EVENT CATALOG
-
Hazard
Assessment ENGINEERING
Event Definition
Estimation
Flood
amage
EstimationContract
LossCalculations
Flood Routing
Runoff Generation
Snowmelt Flood Mapping
Exposure
Information
Large Scale
Precipitation
Downscaling
Model
Policy
ConditionsRegionalFF
X-sectional
Cutline
8CONFIDENTIAL 2014 AIR WORLDWIDE
a a o g Analysis Generation
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COMPONENTS OF A FLOOD MODEL
1. Hydrology
- Precipitation- Precipitation into
runoff components Storage in soil, snow pack etc
- Flows in river
2. Hydraulics
- Mechanics of flow- How water overflows banks
- Mapping of flood zone
9CONFIDENTIAL 2014 AIR WORLDWIDE
Illustration adopted from http://www.metrofieldguide.com/the-hydrologic-cycle/
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SIMULATING REALISTIC PRECIPITATION IS CENTRAL
TO GENERATING A STOCHASTIC CATALOG
HAZARD
Model
Dama e
EVENT CATALOG
-
Hazard
Assessment ENGINEERING
Event Definition
Estimation
Flood
amage
EstimationContract
LossCalculations
Flood Routing
Runoff Generation
Snowmelt Flood Mapping
Exposure
Information
Large Scale
Precipitation
Downscaling
Model
Policy
ConditionsRegionalFF
X-sectional
Cutline
10CONFIDENTIAL 2014 AIR WORLDWIDE
a a o g Analysis Generation
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AIRS INNOVATIVE SOLUTION TO PRECIPITATION
SIMULATION: COUPLING GCM AND NWP MODELS
1. Couple Global Circulation Models (GCM) at globalscale with a mesoscale Numerical Weather Prediction
(NWP) models at regional scale to provide coherentlarge-scale patterns
.realistically simulate small scale features
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AIRS DOWNSCALING APPROACH YIELDS REALISTIC
LOOKING PRECIPITATION PATTERNS
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RUNOFF MODULE TRANSFORMS THE
PRECIPITATION INTO FLOWS
HAZARD
Model
Dama e
EVENT CATALOG
-
Hazard
Assessment ENGINEERING
Event Definition
Estimation
Flood
amage
EstimationContract
Loss
Calculations
Flood Routing
Runoff Generation
Snowmelt Flood Mapping
Exposure
Information
Large Scale
Precipitation
Downscaling
Model
Policy
ConditionsRegionalFF
X-sectional
Cutline
13CONFIDENTIAL 2014 AIR WORLDWIDE
a a o g Analysis Generation
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AIR USES A WELL ESTABLISHED APPROACH
FOR ITS RUNOFF GENERATION MODULE
Nonlinear runoffeneration for realistic
Precipitation (P)
soil saturation Continuous water
balance tracksantecedent conditionsbefore a storm
Effects of snowmelt isaccounted
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EVENTS ARE DEFINED BASED ON TEMPORAL
AND SPATIAL SIGNATURE OF HIGH FLOWS
HAZARD
Model
Dama e
EVENT CATALOG
-
Hazard
Assessment ENGINEERING
Event Definition
Estimation
Flood
amage
EstimationContract
Loss
Calculations
Flood Routing
Runoff Generation
Snowmelt Flood Mapping
Exposure
Information
Large Scale
Precipitation
Downscaling
Model
Policy
ConditionsRegionalFF
X-sectional
Cutline
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a a o g Analysis Generation
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FLOWS ARE CLASSIFIED BASED ON PEAK
FLOW TIMING AND RELATIVE POSITION
Based on similarities between flow attributes (spatial andtemporal), they are grouped into different clusters
Each cluster is then named as an event
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Each color represents an event
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HYDRAULIC MODEL TRANSFORMS THE FLOWS
TO DEPTHS AND MAPS THE FLOOD ZONE
HAZARD
Model
Dama e
EVENT CATALOG
-
Hazard
Assessment ENGINEERING
Event Definition
Estimation
Flood
amage
EstimationContract
Loss
Calculations
Flood Routing
Runoff Generation
Snowmelt Flood Mapping
Exposure
Information
Large Scale
Precipitation
Downscaling
Model
Policy
ConditionsRegionalFF
X-sectional
Cutline
17CONFIDENTIAL 2014 AIR WORLDWIDE
a a o g Analysis Generation
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THE HYDRAULIC MODEL DETERMINES THE
EXTENT OF FLOOD
Flows at each link is converted to depth at every cross section
2D mapping methodology than converts the depths into flood
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AIR VALIDATES AND BENCHMARKS ITS
RESULTS AT EVERY STAGE
100-Year FEMA 100-Year AIR
AIR hazard ma s are
based on the latest flow andterrain data
produced using consistentmethods for the entire country
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VULNERABILITY MODULE TRANSLATES
FLOODING INTO DAMAGE ESTIMATES
HAZARD
Model
Dama e
EVENT CATALOG
-
Hazard
Assessment ENGINEERING
Estimation
Runoff Generation
Flood
amage
EstimationContract
Loss
Calculations
Event Definition Flood Mapping
Exposure
Information
Large Scale
Precipitation
Downscaling
Model
Policy
ConditionsRegionalFF
X-sectional
Cutline
20CONFIDENTIAL 2014 AIR WORLDWIDE
a a o g Analysis Generation
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THE AIR INLAND FLOOD MODEL INCLUDES SEPARATE DAMAGE
FUNCTIONS FOR MODELING ON- AND OFF-FLOODPLAIN LOSSES
On-plain
damage
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AIR USES COMPONENT-BASED APPROACH TO ESTIMATE
DAMAGEABILITY FOR ALL LINES OF BUSINESS
Building is divided into key flood vulnerable components
Each component vulnerability is aggregated using componentcost breakdown to determine the overall building vulnerability
Building and Component Damage Functions for a
80%
100%
ag
eRatio
Retail Shop
40%
60%
MeanDa
Building StructureServices
0%
20%
0.00 1.00 2.00 3.00Flood Depth
Fixtures and Fittings
22CONFIDENTIAL 2014 AIR WORLDWIDE
Building Structure Services
Fixtures and Fittings Overall Building Coverage
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THE AIR INLAND FLOOD MODEL INCLUDES SEPARATE DAMAGE
FUNCTIONS FOR MODELING ON- AND OFF-FLOODPLAIN LOSSES
On-plain Off-plain
damage damage
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OFF-PLAIN FLOOD VULNERABILITY INCORPORATES SURFACE RUNOFF
AND PROXIMITY TO THE NEAREST DRAINAGE SYSTEM
Relative
Runoff
Surve of the 2011 Flood Event IL
50%
Type of Flooding f romExcessive Overland Flow
Relative
Elevation
10%
20%
30%
24CONFIDENTIAL 2014 AIR WORLDWIDE
SanitaryBackup
Seepage SumpPump
failure
Streetand Yard
flooding
Streetflooding
Yardflooding
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SECONDARY MODIFIERS PLAY A KEY ROLE IN
LOSS ESTIMATE ACCURACY IN THE MODEL
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DAMAGE FUNCTIONS CREATED TO ACCOUNT FOR OCCUPANCY,
PRESENCE OF BASEMENTS, HEIGHT AND CONSTRUCTION MATERIAL
Basements are very-
vu nera e o oo ng
since they are closerto under round water
Building Damage Function
No Basement
sources
Basement
Unknown
cellar also increasesthe risk for contents
damage -2 -1 0 1
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AIR SOFTWARE USERS CAN ENTER A SECONDARY
MODIFIER THAT SPECIFIES FOUNDATION TYPES
Build ing detail based Modifiers
Foundation 0 = Unknown/default= asonry asemen
2 = Concrete basement
4 = Crawl space cripple wall5 = Crawl space masonry6 = Post & pier
=
Crawlspace
Foundation
8 = Mat / slab9 = Pile10 = No basement
11 = Engineering foundation12 = Crawlspace - raised (wood)
Basement Levels 0 = Unknown/Default1,2,3= Any positive integral level of basement
Piles
Foundation
Basement FinishType
0 = Unknown1 = Unfinished basement used for storagepurposes2 = Finished basement used for dwelling
ur oses
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FLOOD DESIGN REGULATIONS ARE CONSIDERED IN
ESTIMATING VULNERABILITY OF THE STRUCTURES
Without Flood Regulations
PRE-FIRMFlood Regulations
POST-FIRM
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CUSTOMIZED SECONDARY MODIFIERS ALLOW
FOR IMPROVED LOSS ESTIMATES
Elevation/Hazard modif iers
Custom Elevation (CE) Elevation in feet0 = UnknownUser input value (positive/negative) to override AIR's DTM
Base Flood Elevation (BFE) BFE elevation pertinent to the location from FEMA's FIRM maps which is the "water surfaceelevation corresponding to a flood having a 1% probability of being equaled or exceeded ina given year"= n nown
First Floor Height (FFH) Height in feet above grade of the first floor in the building0 = Unknown
FFH
CE
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COMMERCIAL BUILDING UTILITIES AND SERVICES TYPICALLY LOCATED
ON LOWER FLOORS ARE HIGHLY SUSCEPTIBLE TO FLOOD DAMAGE
Positioning of services such aselectrical equipment increase the
e oo o oss
Cleanup measures lead toncrease us ness n errup oncosts
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THE MODEL WILL INCORPORATE A SECONDARY MODIFIER
THAT SPECIFIES SERVICES AND CONTENT LOCATION
Content and Building Based Modifiers
Service Equipment Protection 0 = Unknown flood protection1 = Protected for flood by being elevated and/or flood proofing2 = Unprotected for flood not elevated and not flood proofed
Content Vulnerability 0 = Unknown1 = Low (a large fraction of the contents are resistant to water damage)2 = Moderate (typical fraction of contents are resistant to water damage e.g. single familyhomes etc.3 = High (low fraction of contents are resistant to water damage e.g. grocery stores,restaurants etc.)4 = Very High (almost no contents are resistant to water damage)
31CONFIDENTIAL 2014 AIR WORLDWIDE
Example of protected ground-level equipment
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AIR TAKES A PROBABILISTIC APPROACH TO
MODELING FLOOD DEFENSES
Data sourcesFEMA Levee Accreditation Map
USACE National LeveeDatabase
USGS National HydrologicDataset
Available levee data 14,000miles
Total National estimate byUSACE > 100,000 miles
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USERS CAN ENTER A SECONDARY MODIFIER THAT
SPECIFIES CUSTOMIZED FLOOD PROTECTION
The secondary modifier Custom Flood Protection enables users to setup site-specific custom flood protection
Without Custom Flood Protection: Levee Overflow
Custom Flood Protection (height of the structure)
33CONFIDENTIAL 2014 AIR WORLDWIDE
S OS S ( ) S
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INDUSTRY EXPOSURE DATABASE (IED) ENABLES AIR
TO VALIDATE THE MODEL AT AN INDUSTRY LEVEL
Data sources NFIP insured losses
nsure osses
National Weather Serviceeconomic losses
a ms a a rom ac ware
Low
34CONFIDENTIAL 2014 AIR WORLDWIDE
NFIP PCSCopyright: 2013 EsriCopyright: 2013 Esri
High
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CONCLUSIONS
AIR US Flood Model will be released in 2014 Event-based fully probabilistic model developed from precipitation
and runoff models
US Flood Model is suitable for underwriting and portfoliomanagement applications
State of the art precipitation model and non-linear runoffgeneration approach to simulate realistic flood events at a finer
resolution for more accurate loss estimates AIRs US flood model accounts for on- and off-floodplain losses to
yield the most realistic view of risk
Secondary modifiers, including custom flood protection features
allow users to correctly model exposures
35CONFIDENTIAL 2014 AIR WORLDWIDE
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Q&A
Modeling Approach Pros Cons
Historic event footprints - Understandable- Discrete
- Deterministic, does not produceEP curve
- -
Actuarial or based on trending
historical losses
- Simple
- Inexpensive
- Deterministic, does not produce
EP curve- NO off plain component- Need lar e sam le of ast losses
Return period flood maps (e.g.,FEMA maps in U.S.)
- Estimates risk at location- Easy to apply to
underwriting andaccumulation
- Deterministic, does not produceEP curve
- NO off plain component- Inconsistent mapping methods
Probabilistic models based onriver gauging station data
- Stream flow gauge data iseasily obtained
- Easily derived historicalevent foot rints
- Physical data requirements high- Incomplete view of runoff
generation- NO off lain com onent
AIRs event-based, fullyprobabilistic model developedfrom precipitation and runoffmodels
- Scientifically mostadvanced
- Provides a full occurrenceand aggregate EP curve
- Length of time to develop model- Physical data requirements are
high- Computational requirements high
36CONFIDENTIAL 2014 AIR WORLDWIDE
for portfolios
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