Unit 4 Damage-Frequency Assessmentflghc.org/ppt/2014/Training Sessions/TS20 Benefit List...

Unit 4. Damage Frequency Assessment 4-1-1

Unit 4

Damage-Frequency

Assessment

Unit 4. Damage Frequency Assessment -24-2

Unit 4 Objectives

Identify when to use the DFA module

List the hazards when the DFA

module can be used

Identify the sources of documentation

necessary to successfully complete a

DFA BCA

Accurately complete a DFA BCA

using a pre-defined case study

Unit 4. Damage Frequency Assessment 4-3

When to use the DFA Module

When any of the following situations apply:

Mitigating risk to non-buildings:

Utilities

Roads

Infrastructure

Mitigating risk to buildings, but structure or hazard data are unavailable


DFA Module Overview

The Flood Module runs on data and probabilities; for the

DFA Module, users provide all of the data needed to

calculate the BCA

Like it sounds, the user-input data is attaching damage

values to the frequency (recurrence intervals) of actual

historic events

Users must provide post-project effectiveness values; this

is done for you in the Flood Module

The Tool calculates before-project damages and

subtracts the after-project damages


DFA Module Overview (cont.)

Requires some assumptions and sound engineering

judgment, especially for after-project effectiveness

DFA provides flexibility and can be used for a wide range

of hazards and project types

If recurrence intervals from historic events are unknown,

the Tool can calculate recurrence intervals for you


DFA Hazard Types

The DFA module can

be used for a variety of

hazards including:

Snow/ice storm

Earthquake

Tsunami

Unit 4. Damage Frequency Assessment 4-7-7

Landslides and Mudflows

Landslides and mudflows are

different from other hazards

because there is seldom data for

recurrence

Typically requires acquisition,

relocation, or stabilization of

buildings, roads, and other

facilities


Landslides and Mudflows (cont.)

Methodologies:

Slope failure is imminent

Projects with an annual rate of erosion

Contact the BCA Helpline for guidance on how to calculate


DFA Requirements

1. Typical analyses use documented historical damages/losses from two or more hazard events of known frequencies from:

FEMA Project Worksheets/Damage Survey Reports,

Insurance or repair records, or

Newspaper articles citing other credible sources

2. Typical analyses use documented frequencies associated with each hazard event based on:

Comparison of observed flood elevations or discharges to FIS,

stream gauge or tide gauge data

Documented data from a credible source to estimate

frequencies

The unknown frequency calculator with supporting

documentation when the requirements are met


DFA Key Data Inputs and BCA Documentation


DFA Documentation

The DFA Module requires documentation of the following key

data:

Value of Services (Roads/Utilities)

Loss of Service Durations

Historical Damages

Loss Event Frequencies

Residual Damages/Losses (Project Effectiveness)

Other documentation


Value of Services (Roads)

The number of one-way trips, and additional detour time and

mileage to calculate an economic benefit.

Documentation:

Traffic counts from a reliable source

Detour time estimates and distance with maps

Other sources – For smaller subdivision roads where

traffic counts are unavailable, one-way trips may be

estimated using the TRB Highway Capacity Manual or

other recognized sources


Roads/Bridges - Examples


Value of Services (Utilities)

The number of people impacted by the loss of service is multiplied by a FEMA

standard economic value for the service, then multiplied by the number of days

of service loss

Recommended documentation:

Projects that prevent loss of service to the entire community can use

the current community population

Projects that benefit a portion of a community or people outside a

community need documentation from the utility showing the number

of accounts. An adjustment to determine the number of people may

be needed.

FEMA Project Worksheets

News article that links the event to the outage duration


Value of Services (Public Buildings)

The annual budget for a public facility like a hospital, school, or

government building is used to calculate an economic value based on

the duration (in days) of service loss


Copy of the annual budget for the actual facility being

mitigated

This could be multiple departments in one building or one

building our of a larger entity like a school district

Letter from someone competent to provide the annual budget

value


Historical Event Damages/Losses


FEMA Project Worksheets/Damage Survey Reports

Insurance claims, BureauNet, damage repair records, or data

from the State/local agency, local government

Newspaper accounts citing credible sources (other than

homeowner accounts)

High water marks tied to depth-damage function damages

Other documentation


Historical Event Frequencies


Frequencies linked to documented FIS data

U.S. Geological Society (USGS) stream gauge data or

National Oceanic and Atmospheric Administration (NOAA) tide

gauge data

Copies of engineering/technical expert reports

Use the unknown frequency calculator with supporting

documentation when requirements are met


Analysis Period

The “window of time” through which the frequency of

damaging events are seen in DFA

Most often based on the date of construction

Must be a minimum of 10 years

Can be adjusted with appropriate documentation for

reasons like altered hydrology, complete reconstruction, or

a 50-year analysis duration is acceptable if the date of

construction is unknown for roads and rural electric lines


Analysis Period Documentation

Documentation must come

from a competent source:

Floodplain map change correspondence

Rapid development photographs

Engineering reports

Other sources

BEFORE

AFTER


Unknown Frequency Calculator: Requirements

The unknown frequency calculator can only be used when the following requirements are met:

1. Minimum of three hazard events occurring in different years where either:

The frequencies/RIs of all events are unknown, or

The frequencies/RIs of up to two events are known and have total inflated values that exceed the total inflated values of all the other unknown frequency/RI events

2. Period of record based on the age of the structure or a minimum of 10 years; whichever is greater

3. No other way to tie historical events to known frequencies/RIs


Unknown Frequency Calculator: Documentation


Three historical events of unknown frequency

Date of construction (needed for the period of record)

Sources of documentation may include:

Insurance claims, damage repair records, technical reports,

data from the State/local agency, local government, etc.

Extraordinary claims require extraordinary documentation!


Project Effectiveness

Elements to documenting project effectiveness:

Keep in mind that nearly all mitigation projects have some

residual risk/damages

Some projects will not completely eliminate damages after

mitigation, but will reduce damages by a certain percentage

Consult with the mitigation project designer to determine the

level of effectiveness

Assume damages after mitigation occur once the level of

effectiveness frequency is reached


Summary: Documenting DFA Data

Methods to derive data from documented events:

Interpolation between known data points (but not by extrapolating above or below known data points)

Calculate estimates based on “typical values” such as:

Examples of good and bad documentation for each of the key DFA inputs are provided on the slides that follow.

FEMA Depth-Damage functions for buildings,

contents, and displacement costs

Damage functions or relationships from other credible

sources


DFA Documentation: Value of Services (Roads/Utilities)

Acceptable Documentation

DOT traffic counts and detour

time estimates with maps

(roads)

Local utility company data

indicating number of

impacted accounts (utilities)

Unacceptable Documentation

“Ballpark” estimates of traffic

counts/detour times without

maps (roads)

Population/census data not

correlated to utility service area

(utilities)

For FEMA standard values for services, refer to FEMA’s

BCA Toolkit


DFA Documentation: Historical Damage Event Costs/Losses


FEMA Project

Worksheets/DSRs

Insurance or damage repair

records from DOT, DPW, utility

company

Damages estimated based on

FEMA standard values


Extrapolated damages or

service losses

Road and utility maintenance

costs not tied to damage events

Newspaper articles that do not

cite credible sources (i.e., other

than homeowner accounts)


DFA Documentation: Historical Damage Event Frequencies


Frequencies linked to

documented FIS data

USGS stream gauge data or

NOAA data

Copies of engineering/

technical expert reports

Using the unknown frequency

calculator with supporting

documentation


Assuming all recurring damages

occur at the 1-year frequency

Extrapolated event frequencies

Using the unknown frequency

calculator with no explanation or

supporting documentation


DFA Documentation: After-Mitigation Damages/Losses


Engineering or technical

report

A detailed project scope that

clearly indicates the level of

effectiveness

Plans or specifications


Assuming no damages occur

after mitigation for non-

acquisition projects

Poorly-defined project scopes

with no clear level of

effectiveness

Remember most mitigation projects do not eliminate

all future damages (except acquisition)


BCA Software

Case Study 1


Add a new

structure

Select the

State and

county from

the drop-

down menu

Overview of DFA BCA Tool


Add a new

project

Organization

is

subapplicant

POC is the

person who

can answer

questions

about the

project



Add the

structure to

the project



Select

Damage

Frequency

Assessment

to begin the

mitigation

project

analysis




Select from

multiple

hazard

types for

proposed

project

Enter

damage

information



Enter the

project useful

life

Select Yes for:

Do you have a

detailed Scope

of Work?

Easy-to-use

cost estimation

framework

provided


Overview of DFA Tool

What forms of documentation

would you provide in this

area of the module?



Select loss

of function

type

Software

auto-

populates

total value

of the

service per

day



Select type

of service

Enter utility

data



Input data for:

Year built

Updated FEMA

BCA inflation

calculator

incorporated

Can add or

delete columns

for specific

damages



Damages after

mitigation auto-

populated

Input data for:

Return

Interval

Downtime

(days)

Can attach

documentation

directly into the

software



Summary of

benefits and

costs

BCR value

Select Save

and Go Back to

change values

used in the

analysis


Check on Learning Activity& Case Study

Purpose of Activities

To review the DFA topics covered in

this unit.


Conclusion

FEMA Damage-Frequency Assessment

Remember: It is always about risk, regardless of the hazard

Good mitigation projects address high- risk situations

Poor mitigation projects address low- risk situations

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