PROJECT ALERT NOTICE (TN) Localized flooding in middle Tennessee

Date: Mon, 23 Aug 2021 12:37:01 EDT

Summary: Localized flooding in middle Tennessee including the counties of Dickson, Hickman, Humphrey resulted in property damage and loss of life.

Heavy rain over the weekend (Aug. 20th through Aug 22nd) resulted in flash flooding in middle Tennessee near the city of Waverly and included the counties of Dickson, Hickman, and Humphrey. Average rainfall was over 7.5 inches with local areas receiving more than 14 inches.

Small and rural watersheds (approximately 30 square miles) experienced most of the flooding and preliminary annual exceedance probabilities (AEP) indicate a 4% (25-year) flood. The flooding resulted in significant property damage was responsibility for at least 22 lives being lost.

Streamgages are sparse within the impacted watersheds, but at least one real-time gage with a period of record dating back to 1926 (03602500 Piney River at Vernon, TN). Several nonreal-time gages are anticipated to have peak of record, including Trace Creek above Denver (03605555) with a period of record starting in 1964.

The LMGWSC have 2 crews today (8-23) and tomorrow (8-24) to verify peaks at gaging stations, assess only crest stage gages, and begin flagging high water marks for indirect measurements as needed. The LMGWSC anticipate the need to complete at least two indirect measurements. No real-time stations appear to have been damaged and crews will be assessing our crest stage gages over the next week. The USGS is seeking input from FEMA and USACE to help coordinate potential future efforts of documenting the flood event.