Spring Flood of 2010 in Nashville, TN A Discussion of Hydraulic Simulation Tools Patrick Dobbs, EIT, CFM patrick.dobbs@amec.com 615-333-0630 AMEC Earth and Environmental 3800 Ezell Road, Suite 100 Nashville, TN 37211

Abstract Today’s available hydraulic simulation tools allow for accurate analysis of major flood events with limited time investment. As a demonstration and case study, this presentation will analyze the weekend of May 1, 2010, when middle Tennessee experienced a record setting rainfall event, over 13 inches in 48 hours. The presentation will primarily highlight HEC-RAS model results through comparison of flood observations to effective flood maps. According to the National Weather Service, the Cumberland River reached a historic crest of 51.86 feet. The Cumberland River had not crested above 50 feet since 1929, which predates the construction of the Old Hickory Lock and Dam, just upstream of Nashville, which is used to detain flood waters. The extent of the HEC-RAS model is a reach of the Cumberland River from Clarksville Pike, upstream to the Old Hickory Lock and Dam. Model outputs will be presented and compared to data from the flood event. Flood locations of interest will be discussed during the presentation; examples include the confluence with the Stones River, Opryland, Riverfront Park, and Metrocenter. Additional discussion will be devoted to collection of data and modeling techniques. The study will review and include data from the USGS, NOAA, TDOT, USACE, and FEMA.

Data Sources for Hydraulic Modeling USGS National Hydrography Dataset Stream Lines The National Map Seamless Server Ground Surface Data USDA Geospatial Data Gateway Aerial Imagery

Tools for Hydraulic Modeling ArcMap Geospatial Analysis Program Geo-RAS Geospatial Tool for Creating HEC-RAS Inputs AFG HEC-RAS Hydraulic Modeling Software

Detailed Studies Approximate Studies Ground Surface Data Study Differences Detailed Studies Approximate Studies Ground Surface Data LiDAR Survey Models Structures Map Results 100yr Floodplain 500yr Floodplain Base Flood Elevations Lettered Cross Sections Floodway Ground Surface Data USGS 10m DEM No Structure Data Map Results 100yr Floodplain