Corps Collects High-Water Mark Data From Helene Flooding

While many people aid in response and recovery after a natural disaster, a team from the Nashville Engineer District hopes its technical assistance in areas flooded during Hurricane Helene could help prepare for future floods.

Kelley Peck, the Nashville Engineer District’s Water Resources Section chief, is leading a team collecting flood high-water mark data in Tennessee, North Carolina and Virginia. 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.

“This data is very important in order to enhance resiliency for these communities that are now rebuilding,” Peck said.

The data must be collected soon after floodwaters recede, as high-water marks can quickly fade, be washed away with subsequent rain events or be inadvertently removed during cleanup efforts.

Data is being collected in coordination with the U.S. Geological Survey, the Tennessee Valley Authority and state and local emergency managers.

“Once the data collection is complete, we will compile this into a database and combine it into a formal report to be able to share it with our local, state and federal partners,” Peck said.

The database and report may be used to update flood risk management models, assess dam safety, focus emergency responders’ efforts and assist community planners and homeowners in rebuilding, Peck said. It could also be used in planning for construction and rehabilitation of river-related infrastructure projects.

The inland flooding following Hurricane Helene was an outlier for the Appalachian region, with the last local storm of such impact occurring in 1916, when the flow of the Tennessee River and its tributaries was uncontrolled by modern infrastructure. Thus, the storm provided a rare opportunity for hydrologists and other scientists to measure modern flood impact in this region.

Peck’s team includes 15 to 20 people actively working on the mission at any one time, she said. That includes engineers, surveyors, planners and those involved in natural resource management.

Geospatial specialists use post-flood drone imagery and information already collected by other agencies to catalog areas that were most impacted by flooding. Field personnel then visit those sites, carefully photographing and documenting 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 systems (GPS) devices and survey-grade equipment, tied to known benchmarks for accuracy.

The public can identify the field teams collecting data in impacted areas by their Corps of Engineers apparel and/or reflective safety vests. The team has concluded its work in Tennessee and Virginia and has moved on to North Carolina, where work is expected to wrap up around Thanksgiving. The final report is expected in the first quarter of 2025.

The data collected will be especially helpful in areas where river and stream gages were lost during the flood, Peck said. It could prove valuable in helping scientists to understand the volume and force of the flooding where other data does not exist. Additionally, she said, the U.S. Geological Survey can use the data to determine where best to place gages in the future.

Eye-Opening Assignment

Rebby Midkiff, civil engineer in the Nashville District Water Resources Section’s Hydraulics and Hydrology Branch, said she surveyed high-water marks for five days, visiting 10 to 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 by 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 Nashville District’s Civil Site and Survey Section’s Civil and Geotechnics Branch, said he traversed tens of miles surveying high-water marks. 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 Nashville District Water Resources Section’s Hydraulics and Hydrology Branch, said he heard first-hand accounts and saw the immense damage and impact of the storm. Seeing residents who 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 data the team is collecting is important for the affected areas.

“Being able to help, inform and protect communities from floods is what I value most as a water resources engineer working for USACE,” Veasey added.

Public’s Help Needed

The team is also relying on information provided by those in flooded areas and is asking for additional information to be submitted online.

“We need the community’s input,” Peck said. “They’ve experienced it. They know themselves how high the flood water got, and in areas where we may not be collecting, we need their input, their photos, their personal stories. All of that can help us in helping them in the future.”

Information may be emailed to nashville.waterresources@usace.army.mil.

Peck said she is grateful for the information already received and for those who have spoken to Corps of Engineers data collectors in the field, often while simultaneously dealing with enormous loss.

“My team starts every engagement with compassion and a goal of listening to all those affected by Hurricane Helene, acknowledging the immense challenges and emotional toll this disaster has placed on families and communities,” Peck said. “Although they’re going through a traumatic experience, community members have been open with team members in the field, sharing their experiences and acknowledging the importance of this data-gathering effort to mitigate disaster risk in the future.”

Nashville Engineer District public affairs specialist Lee Roberts contributed to this report.

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Featured photo caption: Cara Brown (left) and Mark Veasey survey Hurricane Helene flood impacts Ocober 11 in Newport, Tenn. By collecting accurate measurements of flood levels and their impact, the Corps of Engineers is building a foundation for more effective planning and response to future weather events. (Photo by Michael Krneta/Nashville Engineer District)