The Potential of BLE Data - lfma.memberclicks.net · •Identification and publication of information floodplain areas within 5 years NFIP History 8 | LFMA Annual Conference | The

How Communities Can Use This

Product to Enhance Their Floodplain

Management Program

The Potential of BLE Data

• 4.5-7.5 billion to provide flood mapping for

entire country

• $116 - $275 million to maintain accurate

and up-to-date flood maps annually

Flood Management State of the Union

2 | LFMA Annual Conference | The Potential of BLE Data April 4, 2019

• Investment would drive down costs and suffering

and provide better tools for managing flood risk

• Costs affect individuals and businesses,

communities, states, and the federal government

• All taxpayers pay for consequences of flooding


• Climate change

• Population growth

• US population has doubled since 1950 (161 million to

320 million)

• Projected to be over 380 billion in 2030 and 450

billion in 2050

Reasons for Increase Costs?


0

100,000,000

200,000,000

300,000,000

400,000,000

500,000,000

1750 1800 1850 1900 1950 2000 2050 2100

US Population

Total Population Increase Poly. (Total Population)

• Maps won’t prevent flood from

occurring

• Essential tool in avoiding or minimizing

the damage to property, loss of life, and

communicating flood risk

Benefits of Flood Mapping


• Without accurate flood maps local officials face

serious difficulties

• Guiding development away from hazardous areas

• Ensuring that development in or near the hazard area

is properly built and protected

• If potential flood prone area is not mapped

community has no tool to guide development

• 1997 – FEMA conducted a benefit-cost analysis

showing benefit to taxpayers of over $2 for every

$1 invested in flood mapping

• Buildings constructed in compliance with NFIP

building standards suffer 80% less damage

annually

Benefits of Flood Mapping (cont.)


Purpose of Flood Maps


Flood Hazard Information

Determine Flood Insurance Rates

Development Regulations

Flood Preparations for

those at Risk

Establish Zoning, Land Use, and

Building Standards

Infrastructure and Transportation

Planning

Flood Warning, Evacuation, and Emer. Management Planning

Flood Mitigation Loss Reduction

• 1968 Flood Insurance Act called for:

• Identification and publication of

information floodplain areas within 5 years

NFIP History


• Establishment of flood-risk zones in all such areas

to be completed over a 15-year period following

passage of act

• Incorrect Assumption: Once initial flood maps were

published – no need for updating or republishing

• Early 2000s FEMA recognized

• Planned mapping had not been completed

• Flood map inventory started to become outdated

NFIP History (cont.)


• Map Modernization (2004-2009): Goal to convert

nations paper maps to digital

• RiskMAP (2009-present): Lessons learned

• Providing only flood hazard boundaries perpetuates

the concept that flood risk in an “in” or “out”

proposition and doesn’t convey flood risks

• Effectiveness of communication with communities

during mapping process


• $1.5 billion in avoided damages every year for

buildings constructed in compliance with NFIP

standards

• 22,000 communities participate in NFIP (317 In

LA)

• 5.5 million flood insurance policy holders

(501,851 In LA)

• Digital platform for flood maps and can be

integrated into federal, state, and local systems

NFIP Results



CNMS in Louisiana

CNMS in Louisiana


• 13 Parishes are

unmodernized

• Over 17,000 stream

miles non-NVUE

compliant

• https://msc.fema.gov/

cnms/

https://msc.fema.gov/cnms/

*ASFPM estimates between $4.5 – $7.5 billion dollars is

needed to accomplish these goals

What Remains to be Done?


Complete Mapping for Communities without Maps

Update Communities with Maps but Incomplete Data

Update Communities to Reflect Changed Conditions

1

2

3

• Efficiencies in mapping using better technology

• Leveraging state and locally collected elevation

data

• Incenting better cost sharing overall

• Streamlining the geospatial processes and

management of data for flood mapping

• Increasing the flood insurance policy fee to

provide additional funds for flood mapping

Cost Savings


What is Base Level Engineering?


Base Level Engineering (BLE)


Terrain

High resolution LiDAR (QL2 or better) data

required for BLE analysis

Hydraulics

Will the stream in question be able to

convey all the stormwater and runoff, and how

high will water get

Hydrology

What volume of water and when will the runoff

reach the stream

Floodplain Mapping

What areas of a community will be inundated based on engineering

analysis?

BLE Focus Areas


BLE Models are Scalable


BLE Products


• Hydraulic Engineering Models10%, 4%, 2%, 1%, 1%+, 1%-, 0.2%

• Estimated Flood Extents10%, 1%, and 0.2%

• Estimated Water Surface Grids1% and 0.2%

• Estimated Flood Depth Grids1% and 0.2%

• Additional Purchased (R6)• Hazus – Level 2 Analysis

• Point file (Choke Points, Survey Support, and Update Areas)

• Base Level Engineering Report

• Other datasets can be produced, modeling is available

BLE - Best Available Data


• The BLE results may be used in areas where no flood

hazard information is shown on your FIRM.

• Where BLE is similar OR more conservative it may be used

to provide Estimated Base Flood Elevations to residents

• Where BLE is smaller than current FIRM, BLE should NOT

be used to provide Estimated Base Flood Elevations

• BLE data complements FIRMs where they exist and current

flood coverage is minimal

• BLE information can be adopted and used as Best Available

Information by locals without a FIRM or Ordinance update

1. Estimating BFE

2. Engineering assessment for project

impact/permitting

3. Emergency management and disaster

response

4. Capital improvement planning and

infrastructure

5. Informing elevation certificates and LOMA

applications

BLE – Top 5 Uses at the Local Level


BLE Online Viewer


• Region 6 is currently

reformatting data for

upload to the viewer

• Ability to download

models and datasets

directly from the viewer

• Generate reports for

specific

points/addresses with

estimated depth of

flooding and estimated

BFEhttps://webapps.usgs.gov/infrm/estbfe/

https://webapps.usgs.gov/infrm/estbfe/

• LaSalle and West

Feliciana moving

forward with BLE

data

• West Carroll Parish

has paper Flood

Information Guide

(FIG) as alternative

for BFE

determination in

Zone A

BLE Use in Louisiana


LaSalle Parish


• Little Watershed BLE

Completed in 2017

• Moved to Phase 2

• 30 miles Limited Detail

• 140 miles Approximate

• Incorporated 678 miles of

BLE

LaSalle Parish

BLE Study compared to Limited Detail Study


LaSalle Parish

BLE – Before/After cleanup in sample 12 square-mile watershed


West Feliciana Parish


• West Feliciana Parish maps

dated 1979, not modernized

• Bayou Sarah Thompson BLE

completed in 2016

• Discovery completed in 2017

• West Feliciana Parish currently

using BLE for permitting and

BFE determinations

• Moved to Phase 2:

• 232 miles of limited detail

study

• 200 miles of BLE/Zone A to

be incorporated in FIRMs

• BLE results in City

of Denham Springs

showed drastic

reduction in flood

risk

• Urbanized areas or

areas with complex

H&H conditions may

not be accurately

captured

BLE Cautionary Tale


• Acadia

• Allen

• Ascension

• Avoyelles

• Catahoula

• Concordia

• East Feliciana

• Evangeline

• Jackson

• Livingston

• Rapides

• St. James

• St. John the

Baptist

• St. Helena

• St. Landry

• St. Mary

• Tangipahoa

• Winn

Upcoming CTP BLE Workshops


Late Summer/Early Fall

• FEMA Region 6 Resources

http://riskmap6.com/Resources.aspx

• CNMS Viewer and NVUE Report Generator


• BLE Viewer


Links and Resources


http://riskmap6.com/Resources.aspx



Questions?


Jake Lesue, PE, CFMSenior Project [email protected]

Seth Bradley, PEProject [email protected]

Documents

The Potential of BLE Data - lfma.memberclicks.net · •Identification and publication of information floodplain areas within 5 years NFIP History 8 | LFMA Annual Conference | The