Flood-inundation maps for an 8-mile reach of Papillion Creek near Offutt Air Force Base, Nebraska, 2022

Abstract

Digital flood-inundation maps for an 8-mile reach of Papillion Creek near Offutt Air Force Base, Nebraska, were created by the U.S. Geological Survey (USGS) in cooperation with the U.S. Air Force, Offutt Air Force Base. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Program website at h ttps://www .usgs.gov/ mission-areas/ water-resources/ science/ flood-inundation-mapping-fim-program, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgages Papillion Creek at Fort Crook, Nebr. (station 06610795), and Papillion Creek at Harlan Lewis Road near La Platte, Nebr. (station 06610798). Near-real-time stages at these streamgages may be obtained from the USGS National Water Information System database at https://doi.org/ 10.5066/ F7P55KJN or from the National Weather Service Advanced Hydrologic Prediction Service at https: //water.we ather.gov/ ahps/ .Flood profiles were computed for the 8-mile stream reach by means of a one-dimensional step-backwater model. The model was calibrated by adjusting roughness coefficients to best represent the current (2022) stage-streamflow relation at the Papillion Creek at Fort Crook (station 06610795) streamgage.The hydraulic model then was used to compute watersurface profiles for 157 scenarios using a combination of stage values in 1-foot (ft) stage intervals that ranged from 27 to 39 ft at the Papillion Creek at Fort Crook (station 06610795) streamgage and from 13.9 to 30.9 ft at the Papillion Creek at Harlan Lewis Road near La Platte (station 06610798) streamgage, as referenced to the local datums. The simulated water-surface profiles then were combined by a geographic information system with a digital elevation model, which had a 3.281-ft grid to delineate the area flooded and water depths at each stage. The availability of these flood-inundation maps, along with information regarding current stage from the USGS streamgages, can provide emergency management personnel and residents with information that is critical for flood response activities and postflood recovery efforts.

Floodwater drainage assessment of Offutt Air Force Base, Nebraska, 2020–22

“…The streamflow resulting in a water-surface elevation of 951.60 ft above NAVD 88 at outfall 10 was determined using the U.S. Army Corps of Engineers Hydrologic Engineering Center-River Analysis System (HEC-RAS) hydraulic model described in Strauch and Hobza (2023). The HEC-RAS hydraulic model (Strauch and Hobza, 2023) was developed to create a series of flood inundation maps that cover about an 8-mi reach of Papillion Creek from its confluence with Big Papillion Creek downstream to its confluence with the Missouri River (fig. 1).…”

“…3). Analysis using a HEC-RAS model (Strauch and Hobza, 2023) indicated that the threshold streamflow associated with a water-surface elevation of 951.60 ft in Papillion Creek at outfall 10 is about 771 ft 3 /s. Flow-duration analysis examined streamflow records at the Papillion Creek at Fort Crook (USGS site 06610795) streamgage, which is about 2.1 mi upstream from outfall 10, from October 1, 2012 to September 30, 2021, and determined that 120 streamflow events exceeded the 771-ft 3 /s streamflow threshold.…”