PROJECT ALERT NOTICE (GA NC SC) 09/30/2024 USGS SAWSC response to post-Hurricane Helene flooding

Date: Mon, 30 Sep 2024 21:46:06 EDT

Summary: The USGS South Atlantic Water Science Center (SAWSC) continued post-storm field operations for sites safely accessible following the catastrophic flooding arising from the passage of Hurricane Helene across Georgia, South Carolina, and North Carolina on September 26-27, 2024.

ERRATA statement for the 09/29/2024 Project Alert: "Of the 81 sites serviced by the Asheville Field Office, gage heights following the storm exceeded the current ratings." is CORRECTED to say: "Of the 81 sites serviced by the Asheville Field Office, approximately 60 sites had observed peak gage heights that exceeded the current ratings following the storm runoff."

(1) All personnel in the SAWSC Asheville Field Office region as well as 2 Raleigh Field Office crews (or 4 hydrologic technicians) currently in the Asheville area were again accounted for in this morning's USGS EARS alert. EARS alerts will be continued for the Asheville office, and alerts will again be sent to other field offices where home power outages are reportedly still in effect for some USGS SAWSC personnel (Asheville, Tifton, Columbia, Savannah).

(2) The SAWSC Data program continued to develop post-storm field response plans for western NC under the oversight of the USGS Southeast Regional Office due to the continuing (a) search and rescue operations still underway combined with (b) damaged infrastructure and continuing lack of widespread available services (vehicle fuels, food, safe water, lodging arrangements that otherwise need to be available first for the local populations).

(3) A total of 17 crews were dispatched today from the Tifton (1), Savannah (1), Columbia (4), Norcross (3), Charlotte (3), and Asheville (5) Field Offices to continue various tasks ranging from obtaining high-flow measurements and completing repairs and needed equipment checks and verifications for streamgages that were inundated (but not destroyed). As of today, stage-discharge ratings have been extended at 29 streamgages, and indirect measurements will be required to compute the peak discharges at approximately 30 streamgages where direct measurements could not safely be obtained during this runoff event. USGS field crews are being supported by other USGS personnel who are working behind the scenes to inventory damaged equipment, extend and review/analyzed extended ratings, and to support the database with notifications and banners related to the on-going status of the network.

(4) The Charlotte Field Office and Duke Energy have been in continual communication with each other as Duke Energy has been releasing historic amounts of flow through its series of reservoirs in the Catawba and Wateree River basin across both North Carolina and South Carolina.

(5) Peak gage heights at a number of USGS streamgages appeared to have exceeded the levels observed during the July 1916 flood across western NC. In post-storm flooding following Hurricane Helene, the provisional peak gage height observed at USGS Sta. 03451500 French Broad River at Asheville was 24.67 feet recorded on 09/27/2024 at 05:30 PM, exceeding the previous record maximum peak stage of 23.10 feet during the 1916 event by a little more than 1.5 feet. Continuous discharge records at this streamgage date back to October 1895, making it one of the oldest USGS streamgages east of the Mississippi River.