Analysis and Inundation Mapping of the April–May 2011 Flood at Selected Locations in Northern and Eastern Arkansas and Southern Missouri 2013 U.S. Geological Survey, Westerman, D.A., Merriman, K.R., De Lanois, J.L., and Berenbrock, Charles, 2013, Analysis and inundation mapping of the April-May 2011 flood at selected locations in northern and eastern Arkansas and southern Missouri: U.S. Geological Survey Scientific Investigations Report 2013-5148, 44 p. (Available at usgs.gov/sir/2013/5148/.) ABSTRACT: Precipitation that fell from April 19 through May 3, 2011, resulted in widespread flooding across northern and eastern Arkansas and southern Missouri. The first storm produced a total of approximately 16 inches of precipitation over an 8-day period, and the following storms produced as much as 12 inches of precipitation over a 2-day period. Moderate to major flooding occurred quickly along many streams within Arkansas and Missouri (including the Black, Cache, Illinois, St. Francis, and White Rivers) at levels that had not been seen since the historic 1927 floods. The 2011 flood claimed an estimated 21 lives in Arkansas and Missouri, and damage caused by the flooding resulted in a Federal Disaster Declaration for 59 Arkansas counties that received Federal or State assistance. To further the goal of documenting and understanding floods, the U.S. Geological Survey, in cooperation with the Federal Emergency Management Agency, the U.S. Army Corps of Engineers-Little Rock and Memphis Districts, and Arkansas Natural Resources Commission, conducted a study to summarize meteorological and hydrological conditions before the flood; computed flood-peak magnitudes for 39 streamgages; estimated annual exceedance probabilities for 37 of those streamgages; determined the joint probabilities for 11 streamgages paired to the Mississippi River at Helena, Arkansas, which refers to the probability that locations on two paired streams simultaneously experience floods of a magnitude greater than or equal to a given annual exceedance probability; collected high-water marks; constructed flood-peak inundation maps showing maximum flood extent and water depths; and summarized flood damages and effects. For the period of record used in this report, peak-of-record stage occurred at 24 of the 39 streamgages, and peak-of-record streamflow occurred at 13 of the 30 streamgages where streamflow was determined. Annual exceedance probabilities were estimated to be less than 0.5 percent at three streamgages. The joint probability values for streamgages paired with the Mississippi River at Helena, Ark., streamgage indicate a low probability of concurrent flooding with the paired streamgages. The inundation maps show the flood-peak extent and water depth of flooding for two stream reaches on the White River and two on the Black River; the vicinities of the communities of Holly Grove and Cotton Plant, Ark.; a reach of the White River that included the crossing of Interstate 40 north of De Valls Bluff, Ark.; and the Tailwaters of Beaver Dam, near Eureka Springs, Ark., Table Rock Dam, near Branson, Mo., and Bulls Shoals Dam, near Flippin, Ark. The data and inundation maps can be used for flood response, recovery, and planning efforts by Federal, State, and local agencies. DISCLAIMERS: This report is in the public domain, permission must be secured from the individual copyright owners to reproduce any copyrighted material contained within this report. Users of these data should acknowledge the U.S. Geological Survey as the source of the data. Although the flood-inundation maps represent the boundaries of inundated areas with a distinct line, some uncertainty is associated with these maps. The flood boundaries shown were estimated on the basis of gage heights (water-surface elevations) at selected streamgages and collected high-water marks. Water-surface elevations along the stream reaches were estimated assuming unobstructed flow, and using streamflows and hydrologic conditions anticipated at the streamgage. The accuracy of the floodwater extent portrayed on these maps will vary with the accuracy of the digital elevation model used to simulate the land surface. Inundated areas and depths are only an estimate of flooding that occurred during the April-May 2011 flooding event in northern and eastern Arkansas and southern Missouri. Because unique meteorological and hydrological conditions preceded this flood, these inundation maps should not be used for navigation, regulatory, permitting, or other legal purposes. These maps are to be used as an estimated flood-peak surface for a specific flooding event. The USGS provides these maps "as-is" for a quick reference, emergency planning tool but assumes no legal liability or responsibility resulting from the use of this information. CONTENTS: 00Readme.txt metadata.met Datafiles: This report consists of a report with 10 map figures. Each figure has data files, and the single metadata file pertains to all of the maps. SIR5148_Shapefiles.zip The shapefiles are as follows: fig_7_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_8_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_9_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_10_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_11_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_12_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_13_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_14_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_15_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) fig_16_inundation_extent (.shp/.dbf/.prj/.sbn/.sbx/.shx) Extent_of_lidar (.shp/.dbf/.prj/.sbn/.sbx/.shx) High_water_marks (.shp/.dbf/.prj/.sbn/.sbx/.shx) Limits_of_the_study_area (.shp/.dbf/.prj/.sbn/.sbx/.shx) Streamgages (.shp/.dbf/.prj/.sbn/.sbx/.shx) SIR5148_Rasters.zip The depth raster values are in feet and the files are as follows: fig_7_dem fig_8_dem fig_9_dem fig_10_dem fig_11_dem fig_12_dem fig_13_dem fig_15_dem fig_7_lidar fig_8_lidar fig_9_lidar fig_10_lidar fig_14_lidar fig_15_lidar fig_16_lidar SIR5148_kmz (folder) SIR5148_kmz.zip DATA UNCERTAINTY: Two different forms of elevation data were used in this study. Where available, high-resolution lidar raster data were used as the elevation dataset. In some areas where lidar data were not available, a lower resolution 10-meter raster Digital Elevation Model (DEM) was used and or mosaicked with the lidar raster data in adjoining areas. The DEM data have less horizontal and vertical accuracy compared to the lidar raster data; therefore, the uncertainty is greater in areas where inundation maps were derived from DEM data. Inundation depths derived from lidar were displayed in the report at a finer resolution than those generated from the DEM. The depth values derived from the DEM data had a minimum uncertainty corresponding to half the maximum contour interval for the area of interest. Also, water depths in the stream channel for all areas were estimated because neither DEM nor the traditional infrared lidar can penetrate water. Listed below are the maximum contour intervals associated with the DEM for each figure. This information has been included in the attribute table for each of the respective extent shapefiles in the "contour" field for reference. fig 7: 5 foot contour interval fig 8: 5 foot contour interval fig 9: 10 foot contour interval fig 10: 10 foot contour interval fig 11: 5 foot contour interval fig 12: 5 foot contour interval fig 13: 5 foot contour interval fig 15: 20 foot contour interval The high-resolution lidar raster data has a 2-foot contour accuracy. Figures 14 and 16 used lidar only. See Table 3 of the report for specific sources and resolution for the digital elevation models (DEMs) used for inundation mapping. Some simplification of inundation extent polygons was necessary in order for the KML files to display properly; therefore, polygons may not be identical to the shapefiles. INSTRUCTIONS AND DOCUMENTATION FOR U.S. GEOLOGICAL SURVEY SCIENTIFIC INVESTIGATIONS REPORT 2013-5148 To access the data: The data files can be downloaded via the web from http://pubs.usgs.gov/sir/SIR5148.The main product is a Portable Document Format (.pdf) report which requires Adobe Acrobat for viewing. Acrobat software runs on a variety of systems and is available for download free of charge from Adobe at http://www.adobe.com. To access the .kmz files in this report, download and install Google Earth free of charge at http://www.google.com/earth/index.htm. Launch Google Earth, click the file menu, and choose open. Locate and select the .kmz file on your computer. References to non-U.S. Department of the Interior (DOI) products do not constitute an endorsement by the DOI. By viewing the Google Maps API on this web site the user agrees to these terms (terms found at: http://code.google.com/apis/maps/terms.html) of Service set forth by Google. Software Recommended: Adobe Acrobat (6.x, 7.x, or 8.x), Adobe Acrobat Pro (6.x, 7.x, or 8.x), or the free Adobe Reader (8.x or 10.x), 10.x is preferred. ArcGIS 10.0 is also preferred; however older versions may also work.