USACE team collecting Hurricane Helene flood data to build resiliency into community planning and response

NASHVILLE, Tenn. (Oct. 23, 2024) – Data collection teams are documenting flood information that will help hydraulic engineers with the U.S. Army Corps of Engineers understand the impacts of Hurricane Helene to enhance flood risk resiliency for the affected communities.

Nearly 20 USACE Nashville District employees are supporting the mission to collect high-water marks. A high-water mark is a line or threshold that indicates the highest point or elevation that water reaches during a flood. Field teams are currently marking and surveying high-water indicators, such as mud lines, debris accumulations, and seed lines on buildings, trees and other surfaces in flood-impacted areas of East Tennessee in Carter, Cocke, Greene, Johnson, Unicoi, and Washington Counties. The team is heading to impacted areas of North Carolina and Virginia next to continue collecting high-water marks.

Why does USACE collect flood data?

High-water marks are important data as they are used to improve flood risk management models, guide future infrastructure projects designed to mitigate the impacts of natural disasters and improve early warning systems and evacuation protocols.

“Technically speaking, the data will be used to calibrate and validate hydraulic and hydrologic models,” said Kelley Peck, Nashville District Water Resources Section chief. “This ensures that floodplain information is accurate for city planners, homeowners, and emergency responders.”

The processed high-water mark data is compiled into a database for USACE and its local, state and federal partners. Collected information plays a key role in interagency coordination and support for flood risk management, infrastructure planning, and emergency response. This process is time sensitive, as high-water marks can quickly fade, be washed away with subsequent rain events, or be inadvertently removed during cleanup efforts. Therefore, immediate action is essential to maintain the accuracy and usability of the data.

What is involved with the mission?

The mission requires experienced personnel to efficiently plan operations, canvass evidence of high-water marks, and survey elevation data. The teams consist of office and field personnel from all backgrounds, including engineering, surveying, planning, and natural resource management.

Office personnel begin by coordinating with other agencies to maximize resources and share best practices. Geospatial specialists utilize post-flood drone imagery and cross-agency data to catalog areas most impacted and areas of need.

When field personnel visit flood-impacted areas they carefully photograph and document each high-water mark, the type of surface it is on, and the quality of the mark, among other details. Professional land surveyors note the precise location and elevation of each mark using Global Positioning System (GPS) devices and survey-grade equipment, tied to known benchmarks for accuracy. The public can easily identify USACE field teams collecting data in impacted areas wearing Corps of Engineers apparel and/or reflective safety vests.

When field collection is complete, the teams process data, perform quality reviews, and catalog supporting documentation such as pictures and field notes. The data is processed into maps, models, and geo-databases. A report documenting the precipitation event, the collection effort and the flood impacts is developed for historical reference.

How can the public help?

Gathering data in the aftermath of a flood requires a thorough and comprehensive effort to document detailed, reliable data about the flood’s peak. This process can also include input from those who experienced the flood firsthand, as the public possesses critical information that can help supplement data in areas where the USACE may lack coverage.

To obtain first-hand accounts of the impacts, USACE encourages the public to help by providing any data, such as photos, videos, and/or personal accounts, of floodwater levels during Hurricane Helene.

To provide input and submit the requested information, simply scan the QR Code available with this article, or e-mail [email protected] .

“Your input can greatly aid our efforts,” Peck stressed. “We encourage you to share this information with us to assist in refining our flood risk management models, and, in turn, improve our ability to plan and respond for future storm events.”

Eye-opening assignment

The USACE high-water mark team has been out several weeks surveying flood damages in counties and communities along the Pigeon, French Broad, and Nolichucky Rivers in East Tennessee.

Rebby Midkiff, civil engineer in the USACE Nashville District Water Resources Section Hydraulics and Hydrology Branch, said she surveyed high-water marks for five days, visiting 10-25 sites per day. She encountered a range of damage levels, from minor to absolute.

Midkiff shared that she met a mother and daughter who had to be rescued from their home with a swift water raft as the Pigeon River flooded almost every home in their neighborhood. She also met a Vietnam veteran whose home was completely washed away by the Nolichucky River, along with about 10 of his neighbors’ homes.

“He was living in his truck at the site of his former home,” Midkiff said. “And then, we came across many homes, businesses, and churches, which were at least temporarily abandoned, and we could only hope that the former residents had evacuated in time.”

Alex Fenili, professional land surveyor with the USACE Nashville District Civil Site and Survey Section’s Civil and Geotechnics Branch, said he traversed tens of miles surveying high-water marks along the front lines of Hurricane Helene. Despite the devastation and destruction, he couldn’t help but be amazed by how people had high spirits although they had lost everything. He also couldn’t believe the sheer power and destruction that the flood waters unleashed.

“It was a very eye-opening and humbling experience for me,” Fenili said. “To be a part of this mission was an honor and one I will never forget.”

Mark Veasey, civil engineer with the USACE Nashville District Water Resources Section Hydraulics and Hydrology Branch, said he heard first-hand accounts and saw the immense damage and impact of the storm. Seeing residents that lost all their possessions and the overwhelming debris material spanning miles across streams is a sight that motivated him to collect the data that will help with future disaster planning and early warning development.

“Being able to participate in the high-water mark collection allowed me to assist, in a small way now, and most valuably, listen to the people share their stories,” Veasey said. “Hearing people share that they have lost so much but are so kind and open with us, gives me perspective on my personal life and how much I take for granted.”

Veasey said the high-water mark’s data that the team is collecting is important for the affected areas.

Public Law 84-99 provides authority for USACE to undertake emergency response operations including flood response, rehabilitation, preparedness, and technical assistance. Data collection serves to advance preparedness.

Story by Lee Roberts. The public can obtain news, updates and information from the U.S. Army Corps of Engineers Nashville District on the district’s website at?https://www.lrd.usace.army.mil/About/Districts/Nashville-District/ , on Facebook at?www.facebook.com/nashvillecorps ?and on X (formerly Twitter) at?www.x.com/nashvillecorps . Follow us on LinkedIn for the latest Nashville District employment and contracting opportunities at?https://www.dhirubhai.net/company/u-s-army-corps-of-engineers-nashville-district .