Frank Lavelle, Peter Vickery, Bo Yu, and Sudhan Banik

Applied Research Associates, Inc.

Raleigh, NC

(919) 582-3350

HAZUS Coastal Storm Surge Model

HAZUS User Conference

Indianapolis

August 24, 2010

2

Project Objectives

Implement a storm surge and wave hazard modeling capability in HAZUS-MH by coupling and integrating existing, publicly available models

Develop a new capability for combining currently available HAZUS-MH wind-only and flood-only loss estimates into an overall estimate of combined coastal wind and flood losses for a single hurricane event

3

Hurricane Wind Field Model

Goal is to use a single, consistent hurricane wind field model to drive: Storm surge (SLOSH)

Waves (SWAN)

Wind damage (Existing HAZUS Hurricane Model)

Options SLOSH Wind Field Model (NWS 48, 1992)

• Assumed wind speed profile:

ARA Wind Field Model (Vickery et al., 2009)• Assumed pressure profile:

• Wind field equations are numerically solved for the vertically averaged horizontal velocity, V, over open water and open land for 14,040 combinations of Δp, RMW, B (Holland, 1980), and translation speed

4

C-MANFCMP

ASOS

Buoy

Available Surface Wind Measurements

(1) ASOS Towers (Airports)(2) FCMP Towers (Mobile)(3) C-MAN Stations (Coastal)(4) Buoy Stations (Offshore)

Surface Wind Measuring Systems

5

Hurricane Wind Field Summary: Modeled vs. Measured 10-min. Wind Speeds

(Hurricanes Isabel, Ivan, Katrina, Ike & Gustav)ARA-TRK-SLOSH-WD:

y = 1.0505x, R² = 0.5674

ARA-TRK-ARA-WD: y = 1.0234x, R² = 0.7262

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Mod

eled

Mea

n W

ind

Spe

ed (m

ph)

Observed Mean Wind Speed (mph)

ARA-TRK-SLOSH-WD

ARA-TRK-ARA-WD

Linear (ARA-TRK-SLOSH-WD)

Linear (ARA-TRK-ARA-WD)

6

Incorporation of SLOSH Storm Surge Model into HAZUS

SLOSH produces reasonably accurate estimates of surge and runs quickly

Emergency management community is familiar with and comfortable with SLOSH

SLOSH does not include waves or tide • Waves to be modeled in HAZUS using SWAN

• Tide treated approximately as additive term

7

SLOSH Model Coupled with HAZUS Wind Field Model

• Wind field model used in HAZUS has been coupled into SLOSH

• Enables consistent modeling of damage and losses induced by wind and coastal flooding

8

Storm Tide RMS Analysis: Five HurricanesMean Std mean RMS mean RMS

0-3 3338 1.3 0.8 0.2 0.8 0.4 1.0

3-6 1575 4.3 0.9 -1.3 1.8 0.0 1.1

6-9 500 6.7 0.7 -3.3 3.8 -1.0 1.8

all 5413 2.7 2.0 -0.6 1.6 0.1 1.1

0-3 544 2.1 0.9 -0.4 1.9 0.1 1.5

3-6 1083 4.0 0.7 -0.9 1.2 -0.3 0.8

6-9 52 6.5 0.2 0.8 1.1 0.2 0.6

all 1679 3.5 1.3 -0.7 1.4 -0.2 1.1

0-3 65 2.8 0.1 1.1 1.1 1.3 1.4

3-6 357 4.2 0.7 0.5 1.0 0.8 1.3

6-9 30 7.0 0.8 -0.9 1.3 0.5 0.6

all 452 4.2 1.1 0.5 1.0 0.9 1.2

0-3 7085 1.7 0.7 0.6 1.6 0.9 1.8

3-6 5436 4.2 0.8 -0.7 1.8 -0.1 1.2

6-9 2366 7.3 0.9 -2.2 3.1 -1.9 2.3

9-12 993 10.5 0.9 -5.3 5.4 -4.0 4.0

12-15 560 13.3 0.8 -6.4 6.5 -5.2 5.2

all 16440 4.3 3.1 -0.8 2.6 -0.3 2.1

0-3 963 2.0 0.8 2.9 4.4 3.2 4.4

3-6 5429 4.9 0.8 -1.5 3.1 -1.2 3.1

6-9 11235 7.4 0.8 -1.3 3.0 -0.8 2.6

9-12 7871 10.3 0.8 -0.2 3.3 -0.5 3.1

12-15 3147 13.2 0.9 0.6 2.0 -0.4 1.7

15-18 766 15.6 0.5 0.1 2.2 -1.0 2.1

18-21 4 18.3 0.6 -6.3 6.3 -6.8 6.8

all 29415 8.4 3.1 -0.7 3.0 -0.6 2.8

SLOSH-Obs ARA-Obs Hurricane Unit

Isabel 2003

(ft NAVD)

Ike 2008

(ft NAVD)

Surge Range

Numer Data

Obs

Ivan 2004

Katrina 2005

Gustav 2008

(ft NGVD)

(ft NAVD)

(ft NGVD)

9

Storm Tide Summary

SLOSH model runs with ARA wind field result in lower overall mean and RMS errors for 4 of 5 validation events• Only exception is Hurricane Katrina, for which we have only one complete

record tide gauge record and three partial records

Decision is to use SLOSH storm tide model with ARA wind field model• Better overall results

• Ensures consistency between HAZUS wind loss model and HAZUS coastal surge methodology

10

Wave Modeling Objectives

Hazard modeling• Include wave stresses in storm surge model

• Wave set-up increases still water depths produced by SLOSH

Damage modeling• Near-Term: Determination of V-zone and Coastal A-zone (CA-zone) 3 ft < Wave height V-zone

1.5 ft < Wave height < 3 ft CA-zone (use V-zone damage functions)

Wave height < 1.5 ft A-zone

• Longer-Term: Supports move towards direct use of wave height in damage modeling

11

Grids Used in SWAN Runs

-120 -110 -100 -90 -80 -70 -60 -500

5

10

15

20

25

30

35

40

45

50

SLOSH grid

Coarse grid boundary

12

Significant Wave Heights: Katrina, New Orleans Basin

0

1

2

3

4

5

6

8/25/2005 0:00 8/27/2005 0:00 8/29/2005 0:00 8/31/2005 0:00

Sign

ifica

nt W

ave

heig

ht (

m)

Time

Buoy: 42007

Observed

SLOSH_grid_No BC

SLOSH_grid_WW3_BC

SLOSH_grid_SWAN_BC

0

1

2

3

4

5

6

7

8

9

10

8/25/2005 0:00 8/27/2005 0:00 8/29/2005 0:00 8/31/2005 0:00

Sign

ifica

nt W

ave

heig

ht (

m)

Time

Buoy: 42039

Observed

SLOSH_grid_No BC

SLOSH_grid_WW3_ BC

SLOSH_grid_SWAN_BC

-1

1

3

5

7

9

11

13

15

8/25/2005 0:00 8/27/2005 0:00 8/29/2005 0:00 8/31/2005 0:00

Sign

ifica

nt W

ave

heig

ht (

m)

Time

Buoy: 42040

Observed

SLOSH_Grid_No BC

SLOSH_grid_WW3_BC

SLOSH_grid_SWAN_BC

-94 -92 -90 -88 -86 -84

26

27

28

29

30

31

42039

42040

42007

Gulf of Mexico

13

Significant Wave Heights: Ike, Galveston Basin

0

1

2

3

4

5

6

7

8

9/11/2008 0:00 9/12/2008 0:00 9/13/2008 0:00 9/14/2008 0:00

Sign

ifica

nt W

ave

heig

ht (

m)

Time

Observed

SLOSH_grid_No BC

SLOSH_grid_SWAN_BC

Buoy: 42019

0

1

2

3

4

5

6

7

9/11/2008 0:00 9/12/2008 0:00 9/13/2008 0:00 9/14/2008 0:00

Sign

ifica

nt W

ave

heig

ht (

m)

Time

Observed

SLOSH_grid_No BC

SLOSH_grid_SWAN_BC

Buoy: 42035

-98 -97 -96 -95 -94 -93 -92 -9126

27

28

29

30

31

42019

42035

Gulf of Mexico

14

Overland Waves

Use existing 1-D transects and simplified WHAFIS methodology implemented in HAZUS coastal flood model

Where each transect intersects the coastline, use the modeled significant wave height from SWAN to estimate the controlling wave height, Hc = min(0.78 ds, 1.6 Hs) where ds = still water depth at the coast line

Wave crest elevation = SWEL + 0.7 Hc

Neglect• Wave regeneration and wave dissipation

• Wave run-up and dune erosion

Interpolate between transects to develop flood depth grid

Use V-zone damage functions where Hc ≥ 1.5 ft

15

Hurricane Ike: USGS SSS-TX-GAL-001 Gauge Location

16

Before and After Hurricane Ike

17

Hurricane Ike USGS SSS-TX-GAL-001 Gauge

~ 6 feet

Observations are instantaneous samples at 1 minute intervals

18

Hurricane Ike: USGS SSS-TX-GAL-002 Gauge Location

Transect

19

12

12.5

13

13.5

14

9/13/08 12:00 AM 9/13/08 2:00 AM 9/13/08 4:00 AM 9/13/08 6:00 AM

Wat

er E

leva

tion

(ft

NA

VD

88)

Local Time (CDT)

Hurricane Ike USGS SSS-TX-GAL-002 Gauge

~ 0.3 feet

20

Elevation Profile Along the GAL-002 Transect

-15

-10

-5

0

5

10

15

0 1000 2000 3000 4000 5000 6000 7000 8000

Elev

atio

n (f

t)

Distance from starting point of a Transect (ft)

21

WHAFIS vs. HAZUS Results: Controlling Wave Height

-Hsig=2.0 m at coastline-SWEL=12.0 ft (assumed to be 100-year RP)-All of the results from HAZUS except first point are “instantaneous” depth limited waves

0

2

4

6

8

10

12

0 1000 2000 3000 4000 5000 6000 7000 8000

Cont

rolli

ng W

ave

Hei

ght

(ft)

Distance from starting point of a Transect (ft)

WHAFIS

HAZUS

HAZUS_DL

Depth-LimitedWave with noRegenerationand no Dissipation

22

Coupled Surge and Wave Modeling

SLOSH and SWAN codes have been coupled together

Each code is advanced in 15 minute steps• SLOSH is run first to update water elevations SWAN uses water elevations produced by SLOSH

Result is larger modeled wave heights in areas where waves are depth-limited

• SWAN is run to update wave stresses Wave stresses are added to wind stress in SLOSH

Result is increased modeled storm surge due to wave setup

23

Coupled Storm Tide for Hurricane Ike (2008): Galveston Bay Basin

Difference of Peak Storm Tide (ft)

(coupling – no coupling)

24

Modeled Coupled Storm Tide vs. Observations

25

SLOSH+SWAN Two-Way Coupling Wave Results

26

Study Regions Spanning Multiple SLOSH Basins

27

Hurricane Katrina: Multi-Basin Approach

28

Hurricane Katrina: Maximum Storm Surge (ft. NAVD)

29

Hurricane Katrina: Maximum Significant Wave Height (ft)

30

Combined Wind and Flood Loss Approach

Use existing HAZUS methodologies to compute the “flood-only” and “wind-only” losses

Use USACE New Orleans District (NOD) methodology to apportion HAZUS flood-only building losses to building sub-assemblies

Use HAZUS wind loss methodology to apportion HAZUS wind-only building losses to building sub-assemblies

Sum losses by sub-assemblies: Assume wind and flood losses within a sub-assembly are independent

Cap combined sub-assembly loss at total replacement value of the sub-assembly

Populate combined wind and flood loss matrix

31

Combined Wind and Flood Loss Example

Building• Single family, one-story house (no garage)

• Flood characteristics No basement

• Wind characteristics Wood frame, gable roof shape, shingle roof covering

Medium roof deck attachment (8d nails @ 6/12 spacing)

Strapped roof-to-wall connection

No opening protection, no secondary water resistance

Hazard• Flood: Still water, short duration (1 day or less), saltwater flooding,

negligible waves

• Wind: Suburban surface roughness (z0=0.35 m)

32

Allocation of Flood-Only Losses (NOD Methodology)

“Foundation” includes site work, footings, and slab

“Roof Covering” includes flashing, roofing paper, and shingles

“Roof Framing” includes roof trusses (or rafters) and sheathing

“Exterior Wall” includes siding, insulation, windows, and exterior doors

“Interiors” includes drywall, trim, paint, interior doors, floor coverings, cabinets, counter tops, HVAC, plumbing, and electrical

Building Loss Foundation Roof Covering Roof Framing Exterior Walls Interiors10% 0.0% 0.0% 0.0% 1.0% 9.0%20% 0.0% 0.0% 0.0% 2.5% 17.5%30% 0.0% 0.0% 0.0% 6.7% 23.3%40% 0.0% 0.0% 0.0% 9.6% 30.4%50% 0.0% 1.2% 0.2% 11.2% 37.5%60% 0.0% 1.4% 0.2% 13.4% 44.9%70% 0.0% 1.7% 0.3% 15.7% 52.4%80% 0.0% 1.9% 0.3% 17.9% 59.9%90% 0.0% 2.1% 0.3% 20.1% 67.4%

33

Allocation of Wind-Only Losses (HAZUS Methodology)1 Story, Wood Frame, Gable, 8d@6/12, Straps, No Shutters, No SWR, No Garage, z0=0.03m

“Foundation” includes site work, footings, and slab

“Roof Covering” includes flashing, roofing paper, and shingles

“Roof Framing” includes roof trusses (or rafters) and sheathing

“Exterior Wall” includes siding, insulation, windows, and exterior doors

“Interiors” includes drywall, trim, paint, interior doors, floor coverings, cabinets, counter tops, HVAC, plumbing, and electrical

Building Loss Foundation Roof Covering Roof Framing Exterior Walls Interiors10% 0.0% 4.3% 0.0% 0.8% 4.9%20% 0.0% 4.7% 0.0% 1.5% 13.8%30% 0.0% 4.7% 0.0% 2.3% 23.0%40% 0.0% 4.8% 0.0% 2.9% 32.4%50% 0.0% 4.8% 0.0% 3.0% 42.2%60% 0.0% 4.9% 0.0% 3.8% 51.3%70% 0.0% 4.9% 0.1% 4.9% 60.1%80% 0.0% 5.2% 0.3% 14.3% 60.2%90% 0.0% 5.2% 0.8% 23.8% 60.2%

34

Combined Losses

Assume wind and flood losses within a sub-assembly are independent Ci = Wi + Fi – Wi*Fi i=1,5

Cap the combined sub-assembly loss at the replacement value of the sub-assembly Ci ≤ Ri i=1,5

Add the sub-assembly losses C = ∑ Ci

35

Combined Overall Loss Method (Without Sub-Assemblies)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%0% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

10% 10% 19.0% 28.0% 37.0% 46.0% 55.0% 64.0% 73.0% 82.0% 91.0% 100%20% 20% 28.0% 36.0% 44.0% 52.0% 60.0% 68.0% 76.0% 84.0% 92.0% 100%30% 30% 37.0% 44.0% 51.0% 58.0% 65.0% 72.0% 79.0% 86.0% 93.0% 100%40% 40% 46.0% 52.0% 58.0% 64.0% 70.0% 76.0% 82.0% 88.0% 94.0% 100%50% 50% 55.0% 60.0% 65.0% 70.0% 75.0% 80.0% 85.0% 90.0% 95.0% 100%60% 60% 64.0% 68.0% 72.0% 76.0% 80.0% 84.0% 88.0% 92.0% 96.0% 100%70% 70% 73.0% 76.0% 79.0% 82.0% 85.0% 88.0% 91.0% 94.0% 97.0% 100%80% 80% 82.0% 84.0% 86.0% 88.0% 90.0% 92.0% 94.0% 96.0% 98.0% 100%90% 90% 91.0% 92.0% 93.0% 94.0% 95.0% 96.0% 97.0% 98.0% 99.0% 100%

100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%

Wind-Only Building Loss

Floo

d-O

nly

Build

ing

Loss

C = W + F – W*F

36

Differences

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%

10% 0% 0.5% 0.7% 0.9% 1.1% 1.2% 1.3% 1.5% 2.4% 3.3% 0%20% 0% 1.1% 1.5% 1.9% 2.3% 2.5% 2.9% 3.4% 5.1% 6.9% 0%30% 0% 1.8% 2.7% 3.5% 4.3% 5.0% 5.8% 6.7% 9.0% 7.0% 0%40% 0% 2.4% 3.7% 4.8% 5.9% 6.9% 8.0% 9.2% 12.0% 6.0% 0%50% 0% 3.0% 4.6% 6.1% 7.5% 8.8% 10.3% 11.9% 10.0% 5.0% 0%60% 0% 3.6% 5.5% 7.3% 9.0% 10.6% 12.4% 12.0% 8.0% 4.0% 0%70% 0% 4.2% 6.4% 8.5% 10.5% 12.3% 12.0% 9.0% 6.0% 3.0% 0%80% 0% 4.8% 7.4% 9.7% 12.0% 10.0% 8.0% 6.0% 4.0% 2.0% 0%90% 0% 5.4% 8.0% 7.0% 6.0% 5.0% 4.0% 3.0% 2.0% 1.0% 0%

100% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0%

Floo

d-O

nly

Build

ing

Loss

Wind-Only Building Loss

37

Combined Wind and Flood Loss Methodology

Compatible with existing wind-only and flood-only loss methodologies

Losses combined at the building sub-assembly loss level

Addresses order in which losses accumulate• Wind and flood losses are not independent Wind Top-down

Flood Bottom-up

Makes use of available sub-assembly loss data• HAZUS wind loss simulation data

• USACE NOD flood loss expert opinion

Relative contributions of foundation and exterior wall sub-assembly flood losses relative to interiors is higher when wave action is present (V-zone or CA-zone)

38

HAZUS Coastal Storm Surge Methodology Summary

Development of coastal surge methodology is nearing completion Links existing HAZUS Hurricane and Coastal Flood models

Uses a single hurricane wind field model to drive storm surge (SLOSH), waves (SWAN), and wind damage (HAZUS Hurricane)

Surge and wave models are coupled

Combined loss methodology implemented to combine wind-only and flood-only losses across five building sub-assemblies

Functional prototype to be completed by end of September

End-to-end hurricane wind and flood scenario analysis capability in HAZUS-MH Maintenance Release 6 (March 2011)