Collaboration After the Storm:Utilizing Post-Disaster Data Collection Efforts to

Update FEMA Flood Maps

Drew Parker, CFMJaime Tyson, GISP, CFM

Agenda

• May 2010 Flood Event

• Hazard Mitigation Technical Assistance Program (HMTAP)

• FEMA High Water Mark (HWM) Collection Priorities

• Collaborating with State and Federal Agencies

• Final HWM Report and further Data Applications

May 2010 Flood Event

May 2010 Flood Event

• NOAA estimated the recurrence interval of the rain event to be 1,000 years by the fact that many locations received 10-20 inches of rain over a 48-hour period.

May 2010 Flood Event

Hazard Mitigation Technical Assistance Program• Capture perishable

data

• Develop and implement mitigation products

• Provide technical assistance, analysis, and reporting

• Share knowledge and information

• Support FEMA grant programs

Hazard Mitigation Technical Assistance Program

• Nashville High Water Mark Task Order– Identify and survey

250 high water marks in Davidson County

– Priority 1: Acquisition Projects

– Priority 2: Six Major Flood Locations

– Priority 3: Added After Field Data Collection Had Begun-Collaborative Effort of AECOM and USACE

Project Kick-Off Meeting

• Occurred within 24 hours of contract award

• Held at AECOM Nashville office

• FEMA Region IV, State of Tennessee, USACE Nashville District, USGS all participated

• USACE high water mark efforts were identified

• Information was quickly exchanged

• FEMA Project avoided duplication of efforts

• 3 AECOM field teams identified and training occurred the same day

HWM – Identification and Survey

HWM – Identification and Survey

• Property Address and location

• Latitude and Longitude coordinates

• Sketch of the HWM location for survey team

• Digital photograph

• Data from field crews was uploaded daily and compiled into a database by a GIS Specialist

FEMA Priority 1 – Acquisition Properties

• 57 FEMA Acquisition Properties– Purchased by METRO using

FEMA Grant Programs– Located in Areas Impacted by

the May 2010 Flood Event

FEMA Priority 1 – Acquisition Properties

FEMA Priority 2 – Six Major Flood Areas

• Cumberland River near Downtown Nashville

• Mill Creek

• Seven Mile Creek

• Boulder Park Drive Area

• Harpeth River

• Interstate 24 / Bell Road Intersection

HWM – Identification and Survey – Priority 2

• AECOM identified 135 high water marks in the six FEMA Priority 2 areas.

Flooding Source CountyNumber of High

Water Marks Surveyed

Mill Creek Davidson 6

Seven Mile Creek Davidson 13

Cumberland River (near Downtown Nashville) Davidson 66

Boulder Park Drive Davidson 4

Harpeth River Davidson 44

Interstate 24 and Bell Road Interchange Davidson 2

HWM – Identification and Survey – Priority 2

HWM – Identification and Survey – Priority 3

• Rather than duplicate efforts, AECOM surveyed 189 additional high water marks identified by the USACE Nashville District.

Flooding Source CountyNumber of High

Water Marks Surveyed

Mill Creek Davidson 40Seven Mile Creek Davidson 10Sorghum Branch Davidson 9

Whittemore Branch Davidson 7Browns Creek Davidson 33Richland Creek Davidson 23

Station Camp Creek Sumner 18East Camp Creek Sumner 5

Whites Creek Davidson 12Town Creek Sumner 11

Mansker Creek Davidson / Sumner 13Owl Creek Williamson 8

HWM – Identification and Survey – Priority 3

Results of Collaboration

• Project was expanded to include HWM collection in both Williamson and Sumner Counties to correspond with FEMA Flood Insurance Study updates.

• Collaborative effort resulted in the collection of 381 high water marks for the same price as 250 high water marks.

USACE HWM Collection• The USACE collected 443 properties on their own, in

addition to the Priority 3 properties on which they collaborated with FEMA and AECOM.

Submittal to FEMA

• Report was submitted to FEMA Region IV within 90 days of project completion.

• Report was shared with the State of Tennessee, USACE Nashville District, and USGS.

Continued Use of Data

• Mitigation Projects & Planning

• Inundation Mapping

• Flood Insurance Study updates

Continued Use of Data - Mitigation Projects & Planning

• Metro invested $127 million in flood mitigation efforts in Davidson county. The bulk of those funds went toward a home-buyout program where the city purchased and demolished 267 flood-prone homes.

• Removal of the homes not only adds storage capacity to the floodplain, but increases the riparian habitat for streams.

BEFORE AFTER

Continued Use of Data• The Nashville district developed Hydrologic Engineering

Center - River Analysis System (HEC-RAS) models to using the high water mark data.

Inundation Mapping• Inundation depth surfaces and inundation boundaries were

developed using the May 2010 flood profiles derived from May 2010 HWM survey data, historic flood data and GIS analysis.

Flood Insurance Study Updates

• USACE models were used to map flooding in Nashville-Davidson County

Potential Future FEMA Non-Regulatory Products

• 10% depth grid

• 1% depth grid

Potential Future FEMA Non-Regulatory Products

• Chance of Flooding in a 30 year Period

Lessons Learned

• GIS is a valuable tool in collecting data in a time sensitive situation

• Early collaboration across State and Federal levels reduces project duplication and maximizes project value

• Collaboration builds relationships for future projects

• Sharing of data allows for multiple uses

Questions?

Drew Parker, CFMDrew.Parker@aecom.com

Jaime Tyson, GISP, CFMJaime.Tyson@aecom.com

1360 Peachtree Street NE Suite 500

Atlanta, GA 30309404.965.9601