Metro Flood Preparedness

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US ARMY CORPS OF ENGINEERS                                                    BUILDING STRONG®

                                                                           FACT SHEET

                                                                       (As of August 2012)

AUTHORIZATION: Section 22 of the 1974 Water Resources and Development Act (WRDA), Planning Assistance to States, (PAS).

TYPE OF PROJECT: Flood Risk Management

LOCATION: Nashville, Tenn.

CONGRESSIONAL INTEREST:  Jim Cooper (TN-05), Alexander (TN), Corker (TN)

NON-FEDERAL SPONSOR: City of Nashville, Tenn.

BACKGROUND:

·  As a result of the May flood, Metro Nashville is partnering with the Corps to develop flood inundation models and tools for 6 streams in the county.  The streams include the Cumberland and Harpeth Rivers and Mill, Browns, Whites and Richland Creeks.  The majority of the population impacted by the flood and all of the loss of life was associated with these streams.  Three of the streams, the Cumberland River, Mill and Richland Creeks had good existing models and just need updating.  The Harpeth River, Whites and Browns Creeks have models that are 20 to 30 years old using old technology.  They have been totally redone.  In addition to the modeling, tools that enable the city to better predict what is likely to occur under different flooding scenarios have been completed.  With these tools, Metro will know exactly what is flooded at various flood stages on the Cumberland and Harpeth Rivers and be able to predict what could flood on the smaller streams when certain amounts of rain occur.  The USGS and NWS are also working on this project.  The USGS has added new gages and is updating rating curves for the existing gages.  NWS is working on additional forecasting for specific creeks and updating flood alerts levels and actions. Phase 2 of the study includes Real Time Simulation (RTS) modeling for the 6 streams discussed above.

·  The modeling will be able to incorporate real time observed data, NEXRAD radar, NWS rainfall predictions to predict inundated areas and depths.  The models can be used to simulate the impacts from different rainfall scenarios and will be available to both Metro and the National Weather Service.  Phase 2 also includes updating frequency and flow data to turn over to FEMA who will use the date to update the Flood Insurance Maps in Davidson County.  The updated products will also be used to evaluate alternatives on 3 of the streams.  About 122 miles of streams have been updated.

·  Four future phases will be initiated as federal and local funding become available.  An additional 150 miles of stream need to be updated and included in the RTS-SAFE tools

IMPORTANCE: Updating the FIS will help better define floodplains and reduce future flood risk.  Providing better tools for decision makers and emergency responders will also reduce flood risk.

STATUS:

·  Phase 1 completed May 2011

·  Phase 2 Initiated July 2011 and scheduled to be complete in October 2012

·  Phase 3 has not been initiated

BUDGET ($): Estimated project costs are shown below. 

                                                     Note¹ – PAS studies are cost shared 50/50

SCHEDULE:

FY2011 Completed Work:  Phase 1 products included inundation layers and modeling for the Cumberland and Harpeth Rivers and Mill, Richland, Whites, and Browns Creeks. 

FY2012 Scheduled Work:  Phase 2 work included developing predictive Real Time Simulation Modeling (HEC-RTS) for the 6 streams discussed above.  Updated frequency and hydrologic analyses for Richland, Whites and Browns Creeks, incorporation of new LIDAR data, and Flood Insurance Studies (FIS) model development were also included.  32 miles of tributary streams were added to the Whites Creek FIS data and about 27 miles to the Harpeth River data.  Lastly, the hydraulic and economic impact of potential flood damage reduction alternatives are being evaluated at a preliminary level for Richland, Whites and Browns Creeks. 

FY2013 Scheduled Work: Initiate Phase 3 which will include Dry, Gibson, and Manskers Creeks

Completion:  Work is estimated to be completed in 2015.

For more information regarding Nashville Flood Preparedness Studies, contact Sue Ferguson, CELRN-PM, phone: (615) 736-7192, email:  sue.l.ferguson@usace.army.mil.