Flood-inundation maps for the Meramec River at Valley Park and at Fenton, Missouri, 2017

Abstract

For more information on the USGS-the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment-visit https://www.usgs.gov or call 1-888-ASK-USGS.For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov.Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.Suggested citation: Dietsch, B.J., and Sappington, J.N., 2017, Flood-inundation DatumVertical coordinate information is referenced to (1) stage, the height above an arbitrary datum established at a streamgage, and (2) elevation, the height above the North American Vertical Datum of 1988 (NAVD 88).Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). vi AcknowledgmentsThe authors wish to thank the U.S. Army Corps of Engineers St. Louis District and the Metropolitan St. Louis Sewer District for funding the operation and maintenance of the streamgages used for this study. Special thanks are given to the National Weather Service for their continued support of the U.S. Geological Survey flood-inundation mapping program. Flood-Inundation Maps for the Meramec River at Valley Park and at Fenton, Missouri, 2017By Benjamin J. Dietsch and Jacob N. Sappington AbstractTwo sets of digital flood-inundation map libraries that spanned a combined 16.7-mile reach of the Meramec River that extends upstream from Valley Park, Missouri, to downstream from Fenton, Mo., were created by the U.S. Geological Survey (USGS) in cooperation with the U.S. Army Corps of Engineers, St. Louis Metropolitan Sewer District, Missouri Department of Transportation, Missouri American Water, and Federal Emergency Management Agency Region 7. The floodinundation maps, which can be accessed through the USGS Flood Inundation Mapping Science website at https://water. usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the cooperative USGS streamgages on the Meramec River at Valley Park, Mo., (USGS station number 07019130) and the Meramec River at Fenton, Mo. (USGS station number 07019210). Near-real-time stage data at these streamgages may be obtained from the USGS National Water Information System at https://waterdata.usgs.gov/nwis or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/, which also forecasts flood hydrographs at these sites (listed as NWS sites vllm7 and fnnm7, respectively).Flood profiles were computed for the stream reaches by means of a calibrated one-dimensional step-backwater hydraulic model. The model was calibrated using a stage-discharge relation at the Meramec River near Eureka streamgage ...

Flood-inundation maps of the Meramec River from Eureka to Arnold, Missouri, 2018

“…The 17-ft stage at station 07019000, the 11-ft stage at station 07019130 (previously '27" 403.84 1904, 1905, 1915, 1916, 1922-present 46. 11 (449.95 Dietsch and Sappington, 2017), the 22-ft stage at station 07019210, and the 22-ft stage at station 07019300 are stages defined by the NWS as the "action stage" or that stage that, when reached by a rising stream, requires the NWS or a partner to take some type of mitigation action in preparation for possible substantial hydrologic activity (National Weather Service, 2018b). The maximum stage at each streamgage for the estimated flood-inundation maps exceeds the "major flood stage" as defined by the NWS (31 ft at station 07019000, 25 ft at station 07019130, 32 ft at station 07019210, and 38 ft at station 07019300), exceeds the maximum recorded stage at the streamgages, and is the stage that corresponds to a flow rate of about 227,000 cubic feet per second (ft 3 /s) at the cooperative USGS streamgage for the Meramec River near Eureka, Mo.…”

“…Flood-inundation maps were produced for the sections of the Valley Park reach and the Fenton reach in 2017 (Dietsch and Sappington, 2017). The maps produced for the 2017 report represent conditions in which the Mississippi River was assumed to be at or near a stage corresponding to median annual flow.…”

“…The flood-inundation profiles for the Valley Park and Fenton reaches generated in Dietsch and Sappington (2017) were simulated with a downstream boundary condition corresponding to a Mississippi River stage at or near median flow and, therefore, assumed no substantial backwater effect from the Mississippi River. For this report, additional unsteady hydraulic-modeling simulations were run using the calibrated model and constant Mississippi River water-surface elevations to determine the effects of elevated Mississippi River conditions on the lower Meramec River.…”

“…Water-surface profiles were generated by Dietsch and Sappington (2017) for a total of 44 stages at 1-ft intervals between 11 ft and 54 ft for the Valley Park reach (which included USGS station 07019130) as referenced to the local streamgage datum, and these stages correspond to elevations of 402.1 ft and 445.1 ft above NAVD 88, respectively. Water-surface profiles were generated for Mississippi River condition stage equivalents of 26 ft, 30 ft, 34 ft, 38 ft, 42 ft, 46 ft, and 50 ft and used with water-surface profiles generated by Dietsch and Sappington (2017), which corresponded to the Mississippi River condition stage equivalent of 14 ft, for a total of 192 Mississippi River conditions and stages at 1-ft intervals ranging from 22 ft to 51 ft as referenced to the local streamgage datum for the Fenton reach (which includes USGS station 07019210), and these stages correspond to Table 4. Stage and water-surface elevations simulated at reference streamgages used in study.…”