Overview of Hurricane Helene
In late September 2024, Hurricane Helene made landfall as a powerful Category 4 storm before weakening as it moved inland. As the remnants tracked into the Southern Appalachia region, the system produced record-breaking rainfall and catastrophic flooding in eastern Tennessee, western North Carolina, and southern Virginia.
Mountainous terrain and already saturated soils amplified the flash flooding, leading to washed-out roads, damaged bridges, power outages, and widespread property and life loss. The storm’s rainfall totals exceeded historical records in several locations, with some rivers cresting far above their previous highs.
USACE Flood Data Collection Mission
Following the storm, the U.S. Army Corps of Engineers (USACE) carried out a high-water mark (HWM) survey to capture precise flood information for post-event analysis.
Survey Summary:
- Area Covered: 19 counties across 3 states (East Tennessee, West North Carolina, South Virginia)
- Scope: 2,587 high-water marks documented across 115 streams
- Purpose: Document peak flood levels for the Hurricane Helene flood event, to support future flood risk management, hydrologic and hydraulic modeling, emergency response planning, and public awareness.
- Time Period of Collection: October 9 – November 23, 2024
What Is High-Water Mark Collection?
High-water marks are visible indicators, such as seed lines, debris lines, or water stains, left on surfaces that show the highest point reached by floodwaters.
Collection Process:
- Identified high-water marks in flood-affected areas
- Photographed each mark for visual documentation
- Recorded notes on the surface type, quality, and surrounding context
- Surveyed each point using GPS and elevation equipment
- Logged the data for processing, quality control review, and mapping
How the Data Was Used
The Hurricane Helene high-water mark dataset supports:
- Flood Model Calibration – Improving accuracy of hydraulic and hydrologic models
- Flood Risk Mapping – Updating flood maps and hazard assessments
- Infrastructure Planning – Informing bridge, road, and critical infrastructure design
- Emergency Management – Enhancing evacuation routes and disaster response plans
- Historical Recordkeeping – Preserving data for long-term scientific and planning use
Where to View and Download the Data
The Hurricane Helene high-water mark dataset, along with comprehensive documentation of the storm and survey, has been made available for public and interagency use.
Available resources include:
- Post-Flood Report – Summarizing the storm impacts, survey methods, results, and applications
- GIS & Microsoft Excel Data Files – Downloadable formats for analysis and mapping
- Interactive Map Viewer – Explore HWM locations, elevations, and descriptions online
- Supporting Documents & Forms – ReadMe files, Metadata, and reference guides for interpreting the dataset
Access the Data & Resources:
Data is publicly available and can be used for non-commercial and governmental applications. The dataset is provided “as-is” with no warranties. Users should verify the accuracy of the data before applying it to decision-making processes.
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