appendix c risk assessment data

APPENDICES 2017 City of Alabaster Floodplain Management Plan

C-1

Appendix C

Risk Assessment Data


C-2


C-3

App. C – Risk Assessment Data

1.0 Summary of Vulnerability and Impacts 2.0 HAZUS-MH: Flood Global Risk Report

1.0 Summary of Vulnerability and Impacts

Tables C-2 and C-3 summarize the City of Alabaster’s vulnerability to flooding

and other natural hazards, according to the methodology developed by the Shelby

County Hazard Mitigation Committee. These tables are an abridged version, based

upon the comparable Tables 6.6 and 6.7 found in chapter 6 of the 2016 Shelby County

Multi-Hazard, Multi-Jurisdictional Mitigation Plan prepared under the Committee’s

direction. Tables C-2 and C-3 include a summary of all hazards identified in Chapter 4

Risk Assessment in Section 4.2 of this Alabaster plan, except for dam and levee failures,

which were not addressed in the County plan.

To summarize and quantify the impacts and risks associated with the various

hazards, the Shelby County Hazard Mitigation Committee designed its own rating

methodology. Their methodology relies on the Committee’s qualitative assessment of

historical and anecdotal data, community input, and historic and projected hazard

events. This assessment is based upon the hazard ratings assigned by the Shelby

County’s Hazard Mitigation Committee described in Table C-1 below.

Table C-1 Hazards Rating Table

Category 0 1 2 3 4 5

Fatalities and Injuries

0 Fatalities

or Injuries

< 3 Fatalities

or Injuries

4 to 14

Fatalities or

Injuries

15 to 49

Fatalities or

Injuries

50 to 99

Fatalities or

Injuries

>100

Fatalities or

Injuries

Economic Loss

No Loss Less than

$500K cost From $500K

to $2.9Mil cost

From $3Mil

to $7.9Mil

cost

From $8Mil to

$19.9Mil cost

More than

$20Mil cost

Area Impacted

Local No

Evacuation Local minimal

evacuation

Local some

evacuation

1 mile some

evacuation

1 mile high

evacuation

>3 mile and

evacuation

Probability of Occurrence

Once Every

100+ Years Once every 36

to 99 years

Once every 10

to 35 years

Once every 4

to 9 years

Once every 1

to 3 years

More than

once a year

Repetitive Loss

< 3 3 to 10 11 to 24 25 to 49 50 to 99 > 100

Source: 2016 Shelby County Multi-Hazard, Multi-Jurisdictional Mitigation Plan

The Shelby County Hazard Mitigation Committee developed the historic and

future hazard profile vulnerability assessment summary tables (Tables C-2 and C-3)

using the above Hazards Rating Table (Table C-1) by assigning a value (1 through 5) for

each category. In addition, fatalities and injuries were assigned a weighting factor of 3,


C-4

and economic loss was assigned a weighting factor of 2. Table C-2 “Summary of

Historic Hazards and Community Impacts” below provides an assessment of the present

risk due to hazard events. A brief summary of future impacts of hazard events can be

found in Table C-3 “Summary of Future Hazards and Community Impacts.” Each of

tables prioritizes the overall risk and threat of the 13 hazards, according to their

vulnerability scores.

Table C-2. Summary of Historic Hazards and Community Impacts

Hazard

Hazard Status Hazard Profile Vulnerability

Index

Risk/Threat

Fata

lity

an

d In

jury

Eco

no

mic

Lo

ss

Exte

nt

of

Imp

act

Pro

bab

ilit

y o

f

Occu

rren

ce

Rep

eti

tive L

oss

Vu

lnera

bilit

y S

co

re

Pri

ori

ty

High Wind High/High 15 10 2 5 5 37 1

Urban Fires Moderate/Moderate 12 10 1 5 3 31 2

Flooding Moderate/High 6 8 2 4 3 23 3

Wildfires Moderate/Moderate 0 8 2 5 5 20 4

Extreme Temperature Moderate/Minimal 6 8 0 3 2 13 5

Hail Moderate/Minimal 6 4 0 5 1 16 7

Ice/Snow Storm Moderate/Moderate 6 4 1 4 1 16 6

Lightning Moderate/Low 6 2 0 3 2 13 8

Drought Moderate/Slight 0 4 0 3 2 9 9

Land Subsidence Moderate/Minimal 0 2 0 4 1 5 10

Landslides/Mudslides Low/Minimal 0 0 0 3 0 3 11

Earthquake Low/Moderate 0 0 0 1 0 1 12

Tsunami Low/Low 0 0 0 0 0 0 13


Note: Dam and levee failures were not considered in the 2016 Shelby County Multi-Hazard, Multi-Jurisdictional Mitigation

Plan vulnerability assessment.


C-5

Table C-3. Summary of Future Hazards and Community Impacts

Hazard

Hazard Status Hazard Profile Vulnerability

Index

Risk/Threat

Fata

lity

an

d In

jury

Eco

no

mic

Lo

ss

Exte

nt

of

Imp

act

Pro

bab

ilit

y o

f

Occu

rren

ce

Rep

eti

tive L

oss

Vu

lnera

bilit

y S

co

re

Pri

ori

ty

High Wind High/High 15 10 2 5 5 37 1

Flooding High/High 9 8 3 4 5 29 2

Urban Fires - 9 8 2 5 4 28 3

Earthquake High/Moderate 9 10 5 1 0 25 4

Wildfires - 6 6 3 5 4 24 5

Ice/Snow Storm Low/Moderate 6 4 1 4 2 17 6

Lightning - 6 4 0 3 2 15 7

Extreme Temperature High/Moderate 6 2 1 3 2 14 8

Hail Moderate/Moderate 3 4 0 5 1 13 9

Drought Low/Low 0 4 0 3 3 10 10

Land Subsidence Low/ Moderate 0 2 1 4 1 8 11

Landslides/Mudslides Low/ Moderate 0 2 1 3 1 7 12

Tsunami - 0 0 0 0 0 0 13


Note: Dam and levee failures were not considered in the 2016 Shelby County Multi-Hazard, Multi-Jurisdictional Mitigation

Plan vulnerability assessment.


C-6

2.0 HAZUS-MH: Flood Global Risk Report

FEMA’s HAZUS-MH risk assessment software was used to estimate losses due

to flooding for the City of Alabaster study area. The results of the modeled flood

scenario are included in the following Flood Global Risk Report generated from HAZUS-

MH, which have been integrated into this plan in Chapter 4. Risk Assessment.

Hazus-MH: Flood Global Risk Report

Region Name:

Flood Scenario:

Print Date: Friday, September 29, 2017

AlabasterFlood

scenario3

Disclaimer:This version of Hazus utilizes 2010 Census Data.

Totals only reflect data for those census tracts/blocks included in the user's study region.

The estimates of social and economic impacts contained in this report were produced using Hazus loss estimation methodology software

which is based on current scientific and engineering knowledge. There are uncertainties inherent in any loss estimation technique.

Therefore, there may be significant differences between the modeled results contained in this report and the actual social and economic

losses following a specific Flood. These results can be improved by using enhanced inventory data and flood hazard information.

Table of Contents

Section Page #

General Description of the Region

Building Inventory

4

3

General Building Stock

Essential Facility Inventory

Flood Scenario Parameters

5

Building Damage

7General Building Stock

Essential Facilities Damage

Induced Flood Damage

9

Debris Generation

Social Impact

Shelter Requirements

Economic Loss

10

Building-Related Losses

Appendix A: County Listing for the Region

Appendix B: Regional Population and Building Value Data

15

16

6

10

12

Page 2 of 16Flood Global Risk Report

General Description of the Region

Hazus is a regional multi-hazard loss estimation model that was developed by the Federal Emergency

Management Agency (FEMA) and the National Institute of Building Sciences (NIBS). The primary purpose of

Hazus is to provide a methodology and software application to develop multi -hazard losses at a regional

scale. These loss estimates would be used primarily by local, state and regional officials to plan and

stimulate efforts to reduce risks from multi-hazards and to prepare for emergency response and recovery.

The flood loss estimates provided in this report were based on a region that included 1 county(ies) from the

following state(s):

Alabama-

Note:

Appendix A contains a complete listing of the counties contained in the region .

The geographical size of the region is 43 square miles and contains 853 census blocks. The region contains

over 14 thousand households and has a total population of 39,975 people (2010 Census Bureau data). The

distribution of population by State and County for the study region is provided in Appendix B .

There are an estimated 15,585 buildings in the region with a total building replacement value (excluding contents)

of 4,489 million dollars (2010 dollars). Approximately 93.85% of the buildings (and 85.60% of the building value)

are associated with residential housing.


General Building Stock

Hazus estimates that there are 15,585 buildings in the region which have an aggregate total replacement value

of 4,489 million (2014 dollars). Table 1 and Table 2 present the relative distribution of the value with respect to

the general occupancies by Study Region and Scenario respectively. Appendix B provides a general

distribution of the building value by State and County.

Building Inventory

Occupancy Exposure ($1000) Percent of Total

Table 1

Building Exposure by Occupancy Type for the Study Region

3,842,433Residential 85.6%

Commercial 431,912 9.6%

Industrial 126,507 2.8%

Agricultural 8,839 0.2%

Religion 46,499 1.0%

Government 4,109 0.1%

Education 28,673 0.6%

Total 4,488,972 100.0%

Residential $3,842,433Commercial $431,912Industiral $126,507Agricultural $8,839Religion $46,499Government $4,109Education $28,673

Total: $4,488,972

Building Exposure by Occupancy Type for the Study Region($1000's)


Occupancy Exposure ($1000) Percent of Total

Table 2

Building Exposure by Occupancy Type for the Scenario

906,656Residential 75.9%

Commercial 222,142 18.6%

Industrial 37,892 3.2%

Agricultural 4,211 0.4%

Religion 13,146 1.1%

Government 3,381 0.3%

Education 7,279 0.6%

Total 1,194,707 100.0%

Residential $906,656Commercial $222,142Industrial $37,892Agricultural $4,211Religion $13,146Government $3,381Education $7,279

Total: $1,194,707

Building Exposure by Occupancy Type for the Scenario ($1000's)

Essential Facility Inventory

For essential facilities, there are 1 hospitals in the region with a total bed capacity of 228 beds.

There are 7 schools, 1 fire station, 1 police station and no emergency operation centers.


Flood Scenario Parameters

Hazus used the following set of information to define the flood parameters for the flood loss estimate provided

in this report.

Scenario Name:

Return Period Analyzed:

Analysis Options Analyzed:

scenario3

Study Region Name: AlabasterFlood

100

No What-Ifs

Study Region Overview Map

Illustrating scenario flood extent, as well as exposed essential facilities and total exposure


Building Damage

General Building Stock Damage

Hazus estimates that about 318 buildings will be at least moderately damaged. This is over 62% of the total

number of buildings in the scenario. There are an estimated 4 buildings that will be completely destroyed. The

definition of the ‘damage states’ is provided in Volume 1: Chapter 5 of the Hazus Flood Technical Manual.

Table 3 below summarizes the expected damage by general occupancy for the buildings in the region. Table 4

summarizes the expected damage by general building type.

Total Economic Loss (1 dot = $300K) Overview Map


Table 3: Expected Building Damage by Occupancy

1-10 41-5031-4021-3011-20

Occupancy (%)Count Count (%) Count (%) Count (%) Count (%)

Substantially

Count (%)

Agriculture 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00

Commercial 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00

Education 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00

Government 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00

Industrial 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00

Religion 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.00 0.00

Residential 134 167 74 57 16 4 29.65 36.95 16.37 12.61 3.54 0.88

Total 134 167 74 57 16 4

Damage Level 1-10 134Damage Level 11-20 167Damage Level 21-30 74Damage Level 31-40 57Damage Level 41-50 16Substantially 4

Total: 452

Counts By Damage Level


Table 4: Expected Building Damage by Building Type

Building

Type

1-10 41-5031-4021-3011-20

(%)Count Count (%) Count (%) Count (%) Count (%)

Substantially

Count (%)

Concrete 0 0 0 0 0 0 0 0 0 0 0 0

ManufHousing 0 0 1 0 0 3 0 0 25 0 0 75

Masonry 3 4 0 0 0 0 43 57 0 0 0 0

Steel 0 0 0 0 0 0 0 0 0 0 0 0

Wood 132 163 73 57 16 1 30 37 17 13 4 0


Before the flood analyzed in this scenario, the region had 228 hospital beds available for use. On the day of the

scenario flood event, the model estimates that 228 hospital beds are available in the region.

Essential Facility Damage

Table 5: Expected Damage to Essential Facilities

Classification Loss of Use

# Facilities

At Least

SubstantialAt Least

ModerateTotal

1Fire Stations 0 0 0

1Hospitals 0 0 0

1Police Stations 0 0 0

7Schools 2 0 2

If this report displays all zeros or is blank, two possibilities can explain this.

(1) None of your facilities were flooded. This can be checked by mapping the inventory data on the depth grid.

(2) The analysis was not run. This can be tested by checking the run box on the Analysis Menu and seeing if a message box

asks you to replace the existing results.


Induced Flood Damage

Debris Generation

Hazus estimates the amount of debris that will be generated by the flood. The model breaks debris into

three general categories: 1) Finishes (dry wall, insulation, etc.), 2) Structural (wood, brick, etc.) and 3)

Foundations (concrete slab, concrete block, rebar, etc.). This distinction is made because of the different

types of material handling equipment required to handle the debris.

Analysis has not been performed for this Scenario.


Social Impact

Shelter Requirements

Hazus estimates the number of households that are expected to be displaced from their homes due to

the flood and the associated potential evacuation. Hazus also estimates those displaced people that will

require accommodations in temporary public shelters. The model estimates 831 households will be

displaced due to the flood. Displacement includes households evacuated from within or very near to the

inundated area. Of these, 2,184 people (out of a total population of 39,975) will seek temporary shelter in

public shelters.

0 400 800 1200 1600 2000 2400

2,184

831

Persons Seeking ShelterDisplaced Households

Displaced Households/Persons Seeking Short Term Public Shelter


Economic Loss

The total economic loss estimated for the flood is 98.83 million dollars, which represents 8.27 % of the total

replacement value of the scenario buildings.

Building-Related Losses

The building losses are broken into two categories: direct building losses and business interruption losses. The

direct building losses are the estimated costs to repair or replace the damage caused to the building and its

contents. The business interruption losses are the losses associated with inability to operate a business

because of the damage sustained during the flood. Business interruption losses also include the temporary

living expenses for those people displaced from their homes because of the flood.

47.46 47.46 47.46 47.46

The total building-related losses were 98.16 million dollars. 1% of the estimated losses were related to the

business interruption of the region. The residential occupancies made up 48.02% of the total loss. Table 6 below

provides a summary of the losses associated with the building damage.


Table 6: Building-Related Economic Loss Estimates

(Millions of dollars)

Total OthersIndustrialCommercialResidentialAreaCategory

Building Loss

Building 29.95 8.42 3.39 0.84 42.60

Content 17.40 23.34 7.85 5.26 53.84

Inventory 0.00 0.52 1.18 0.02 1.72

Subtotal 47.35 32.28 12.42 6.12 98.16

Business Interruption

Income 0.00 0.17 0.00 0.02 0.19

Relocation 0.09 0.03 0.00 0.01 0.13

Rental Income 0.02 0.02 0.00 0.00 0.04

Wage 0.00 0.15 0.00 0.16 0.31

Subtotal 0.11 0.37 0.00 0.19 0.67

ALL Total 47.46 32.65 12.42 6.31 98.83

Residential $47Commercial $33Industrial $12Other $6

Total: $99

Losses by Occupancy Types ($M)


Appendix A: County Listing for the Region

Alabama

- Shelby


Appendix B: Regional Population and Building Value Data

ResidentialPopulation

Building Value (thousands of dollars)

Non-Residential Total

Alabama

3,842,433Shelby 39,975 646,539 4,488,972

Total 39,975 3,842,433 646,539 4,488,972

Total Study Region 39,975 3,842,433 646,539 4,488,972


appendix c risk assessment data

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