USAF Floodplain Area Analyses

Shannon Voggesser – Environmental GIS Program Manager, Center for Environmental Management of Military Lands

Asma Hanif – Engineering Research Manager, Department of Civil & Environmental Engineering

Creating a comprehensive dataset for use in future planning and assessments

U.S. Naval Air Station Key West – Boca Chica Field. Flooding after Hurricane Irma. Source: U.S. AF photo by SSgt.Chris Drzazgowski

Assessment• CSU/CEMML tasked with populating the USAF environmental GIS floodplain area data layer with data obtained from

FEMA as directed by AFI 32-7064– Found many bases did not have a FEMA floodplain map that could be utilized

• Assessment results of the FEMA floodplain GIS data for 81 CONUS installations and select GSUs: – 10 USAF installations have flood maps that are considered current (updated within the last 5 years by FEMA)

– 23 USAF installations are missing FEMA flood maps (entire or partial)

– 48 USAF installations have floodplain data that is considered outdated

– 7 USAF installation’s flood maps have not been updated in more than 30 years

Airmen from the 821st Contingency Response Group setup tent city at Tyndall AFB after Hurricane Michael. Source: U.S. AF photo by Tech. Sgt. Liliana Moreno

Impacts

Tyndall AFB Hurricane Recovery

• 1200 buildings/structures impacted at a value of $4.3 to $4.9 billion

• $700 million has already authorized

• Developing and updating flood maps through FEMA is lengthy (typically 3-5 years)– If a flood map is not assessed/updated with the 5 year period, the level of flood risk is considered “unknown”

• Flooding is the costliest disaster in the United States

Offutt AFB Flood Recovery

• 202 structures/buildings impacted; $272.2 million for Milcon repair projects

• $650 million total for recovery efforts

Defense Secretary Mark T. Esper and his wife Leah Esper tour flood damaged infrastructure during a visit to STRATCOM Headquarters at Offutt AFB. Source: DoD photo by Army Staff Sgt. Nicole Mejia

Tyndall AFB air traffic control tower amid debris after Hurricane Michael. Source: U.S. AF photo by Tech. Sgt. Liliana Moreno

Develop and Obtain High Quality Data

Sophisticated 2D Modeling

FEMA Approved Models & Methods

Updated & Accurate Flood Maps

The CSU/CEMML Approach

High Quality Data - LiDAROpen source USDA data is displayed on top for each installation and the higher quality USAF LiDAR data is displayed on the right

High Quality Data – Land CoverOpen source NLCD data (30m resolution) is displayed on top for each installation and the higher quality CSU-CEMML developed data(0.3m resolution) is displayed on the right

2D vs. 1D Floodplain Modeling• FEMA flood maps are generally generated using 1D simulations

• Stream networks are rarely straight and uni-directional with relatively shallow slopes

• CSU utilizes 2D modeling since 2D models provide a more realistic simulation of stream networks

• 2D models are more stable and less subjective to assumptions

• 2D models provide more accurate representations of:– Flow Distribution and Depth, Water Surface Elevation, Velocity Distribution and Magnitude and Shear Stress

Example 2D simulation of a stream network

FEMA Review

• According to the latest congressional testimony, FEMA faces a significant challenge in keeping flood maps current (Thomas Frank, ClimateWire, Feb 2020)

• CSU collaborated with FEMA’s National Program Leaders to submit CSU’s models for FEMA’s review

• FEMA has provided a memo endorsing the CSU-generated maps, models and methodology utilized

Keesler AFB: As Hurricane Katrina struck the base, rising waters swallowed cars parked along streets. Source: U.S Air Force photo

CSU/CEMML and FEMA Floodplain Comparison

CSU/CEMML and FEMA Floodplain Comparison

FEMA vs. CSU: Comprehensive list of improvements

Flood Modeling Including Stormwater InfrastructureAnalysis at Offutt AFB

• A FEMA flood map has never been created for Offutt AFB

• An analysis for flood modeling with and without incorporating Stormwater Infrastructure (SWI) was conducted

• A defined area of interest (AOI) was selected

• Surface flood analyses without incorporating SWI is common practice among the industry and FEMA

• Incorporating SWI into surface flood models further improves the accuracy and reliability of the results

• The addition of sub-surface SWI simulation accounts for water drainage that can cause a redistribution of the flood water during a storm event

• Flood waters from the northern and central areas of AOI are diverted more towards the south and out of the AOI, due to SWI

• Additional areas outside of the AOI (south and east) were included in this assessment

• Not a true representation of the final flood map

Flood Modeling Including Stormwater InfrastructureAnalysis at Offutt AFB

CSU/CEMML Progress To-Date

• The CSU surface floodplain modeling include stream overflow analyses, precipitation modeling for low lying areas and wetlands areas and coastal floodplain areas due to storm surges

• The outputs include the floodplain area (flood maps), flood depths, maximum flood velocity, maximum shear stress and an animation of the flood simulation to provide insight for planning purposes

• These assessments do not currently include the incorporation of sub-surface SWI

Installation Name FEMA Map Status FEMA Map Date1 Beale AFB Outdated 2/18/20112 Shaw AFB Outdated 2/16/20073 JB Andrews Does not include areas inside the base 9/16/20164 Moody AFB Outdated 5/5/19785 Buckley AFB Outdated 8/16/19956 Altus AFB Outdated 7/19/20057 JBSA - Camp Bullis Outdated 9/29/20108 JBSA - Fort Sam Houston Outdated 9/29/20109 JBSA - Lackland AFB Outdated 9/29/201010 Columbus AFB Outdated 2/18/201111 McConnell AFB No FEMA Map N/A12 Hurlburt Field Outdated 7/18/198513 Tyndall AFB Outdated 6/2/2009

Completed CSU Modeled Flood Maps

CSU/CEMML work continues…

FY2020– Phase One: Cape Canaveral, Eglin AFB, MacDill AFB, Minot AFB, JB Anacostia-

Bolling and Patrick AFB

– Phase Two: Barksdale AFB, JBCHS (Charleston AFB and North Auxiliary Field), JBLE (Fort Eustis and Langley AFB), Keesler AFB, and Seymour Johnson AFB

– Phase Three: Dover AFB (main installation), Maxwell-Gunter AFB, Robins AFB, Scott AFB, Grand Forks AFB, and Sheppard AFB

– Phase Four: Davis-Monthan AFB, Eareckson AS, Edwards AFB, Joint Base Elmendorf-Richardson, Laughlin AFB, and Luke AFB

• There are still 52 CONUS USAF installations that do not have any current flood maps for installation planning

Pararescueman from the 48th Rescue Squadron scans the ground over southern Florida. Source: U.S. AF photo by SSgt. Ryan Callaghan

Thank you

Contact Info:

Shannon VoggesserShannon.Voggesser@colostate.edu

To access floodplain reports, story maps and data: https://maps.af.mil/geoportal/apps/sites/#/environmental/pages/enhanced-floodplains

Asma HanifAsma.Hanif@colostate.edu

Hurricane Irma. Source: NASA Photo