HAZUS®MH Coastal Flood Hazard Analysis

FATIH C. DOGAN

ABS CONSULTING

ABS Consulting

HAZUS®MH Overview

Standardized, nationally applicable natural hazards loss estimation methodology

Developed by FEMA, under a cooperative agreement with NIBS (www.fema.gov/hazus & www.nibs.org/hazusweb)

GIS (Geographic Information System) based

HAZUS-99 SR2 currently has MapInfo® and ArcView® versions

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HAZUS®MH Components

Next generation HAZUS currently under development

Expanded with multi-hazard methodology for estimating potential losses from wind and flood hazards.

Flood Model (riverine and coastal flooding)

Wind Preview Model (hurricane direct damage only)

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HAZUS®MH

Single user GIS-based software package

Designed for ArcGIS version 8.1.2 with the Spatial Analyst extension

Windows 2000 operating system

Scheduled for release first quarter 2003

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HAZUS®MH Flood Model Results Available formats: maps, tabular, summary

reports Hazard maps – flood depth, erosion depth Building stock loss – structure and contents Lifeline damage – bridges, treatment plants Shelter requirements Indirect economic losses – market sector

recovery Produced for specific return periods, suites

of return periods, or annualized losses Can be exported for use with enterprise GIS

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1. Define Hazard: (Flood Surface-

Land Surface)

2. Define and Overlay Inventory

4. Estimate Losses

3. Determine Damage

HAZUS®MH Flood Model Methodology

Subtract ground surface from flood surface to determine flood depth throughout the study area

Datum

Ground

Elevation

Flood

Elevation

HAZUS®MH Flood Model Hazard Determination

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Pre-storm ground surface from DEM

HAZUS®MH Flood Model Coastal Hazard

Adjust ground surface to account for dune erosion

Calculate flood surface grid through wave height and

runup analyses

Map A and V coastal flood hazard zones

Calculate flood depth grid as flood surface - ground surface

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HAZUS®MH Flood Model User Input

Study region created through HAZUS shell

DEMReturn period to analyzeSelect shoreline(s)Segment and characterize shoreline(s)

Shoreline type100 yr SWEL and wave setup (from an FIS or other

source)

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HAZUS®MH Flood Model Segments & Transects

Segment based on common

characteristics Transects every 1000ft or so

Tr 1-1Tr 1-2

Tr 1-3

Tr 1-4Tr 1-5

Tr 1-0

Segment 1Segment 2

Tr 2-1 Tr 2-2

Tr 2-0Tr 2-3

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Transect Profiles

Query DEM along the transect with an interval of cellsize/ 3

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FEMA Guidelines

Mean Sea Level

Dune reservoir

Stillwater Elevation

Dune Toe

Dune Peak

Ridge Type

Mean Sea Level

Dune PeakDune reservoir

Stillwater Elevation

Dune Toe

Mound Type

(Rear Shoulder)

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FEMA Guidelines (cont.)

Adjustment of profile to approximate post storm eroded profile:Dune RemovalDune Retreat

For a 100-year storm, the frontal dune reservoir should be at least 540sqft (or 20 cubic yards volume per along the shore) to prevent REMOVAL.

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HAZUS®MH Flood Model Estimating Dune Peak and Toe

Dune Peak: The highest point along the transect profile within the first 500ft landward of shoreline.

Dune Toe: The most landward intersection of 10 year SWEL with the transect profile. (must be seaward of peak)

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HAZUS®MH Flood Model Estimating Frontal Dune Reservoir

N-year SWEL: Calculated based on default ratios (Ex: Atlantic 10yr 64%, 50yr 88%, 500yr 123%)

Required reservoir to prevent removal: Based on return period and coastal area (Lake Ontario, other Great Lakes, all other areas)

Res.= 0.7A+B

Mean Sea Level10 yr SWEL

N-yr SWEL

Dune Toe

Dune Peak

A B

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FEMA Removal & Retreat

Dune reservoir

Adjusted Ground Profiles

Original Ground ProfileStillwater Elevation

Dune Toe

Dune Peak

Retreat Removal

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HAZUS®MH Flood Model Coastal Erosion

Mean Sea Level10 yr SWEL

N-yr SWEL

Dune Toe

Dune Peak

1 on 50

No adj. Horizontal 1 on 50 slope

REMOVAL

Dune Toe

1 on 50

Usually removed volume is enough to fill lower areas

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HAZUS®MH Flood Model Coastal Erosion

Mean Sea Level10 yr SWEL

N-yr SWEL

Dune Peak

1 on 40

No adj. Horizontal at toe elev.

1 on 40 slope

RETREAT

Check removed volume against the required reservoir, iterate until close enough.

1 on 1

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Create points with z-value from the eroded transect profile

Interpolate new surface grid which will be used in WHAFIS and Runup calculations to create flood surface grid.

Flood surface- Eroded ground= Flood depth

Subtract eroded ground grid from original ground to get “Erosion Depth Grid”

HAZUS®MH Coastal Erosion

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Long-term erosion – inventory location

Shore protection – erosion susceptibility

Buyout – inventory location

Building codes – first floor elevation/ elevated structures

HAZUS®MH Coastal What-If Scenarios