Andrew P. Dunn Timothy D. Straub Adam E. Manaster 20200813 vector digital data (polyline) Reston, Virginia U.S. Geological Survey https://doi.org/10.5066/P99L14DN Andrew P. Dunn Timothy D. Straub Adam E. Manaster 2020 document SIR 2020-5074 Dunn, A.P., Straub, T.D., Manaster, A.E., 2020, Flood-Inundation Maps for the Little Calumet River from Lansing to South Holland, IL, 2020: U.S. Geological Survey Scientific Investigations Report 2020-5074, XX p. https://doi.org/10.3133/sir20205074 Digital flood-inundation maps for about an 8-mile reach of the Little Calumet River, Illinois, were created by the U.S. Geological Survey (USGS) in cooperation with the U.S. Army Corps of Engineers. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Program website at https://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 three USGS streamgages: Little Calumet River at South Holland, Illinois (USGS station 05536290); Little Calumet River at Munster, Indiana (USGS station 05536195); and Thorn Creek at Thornton, Illinois (USGS station 05536275). Near-real-time stages at these streamgages may be obtained on the internet from the USGS National Water Information System at https://doi.org/10.5066/F7P55KJN or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at https://water.weather.gov/ahps/, which also forecasts flood hydrographs at this site. Flood profiles were computed for the stream reaches using a one-dimensional unsteady flow step-backwater hydraulic model. The model performance was evaluated using historical streamflow measurements and the most current stage-discharge relations at the USGS streamgages at Little Calumet River at South Holland, Illinois; Little Calumet River at Munster, Indiana; and Thorn Creek at Thornton, Illinois. The model was used to compute 24 water-surface profiles at 1-foot intervals referenced to the streamgage datum and ranging from bankfull to about the 0.2-percent annual-exceedance probability flood (500-year recurrence interval flood). The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging data having a 0.6-foot vertical accuracy and a 2-foot horizontal resolution) to delineate the area flooded at each water level. Breach shapefiles were included in this study to determine the extent of flooding if the river breached a levee in the nearby vicinity. The resultant flooding area is deemed the ‘area of uncertainty’ in the flood-inundation maps. The availability of these maps, along with internet information regarding current stage from USGS streamgages and forecasted high-flow stages from the NWS, will provide emergency management personnel and residents with information that is critical for flood-response activities such as evacuations and road closures, as well as for postflood recovery efforts. This dataset was created to support the development of flood-peak inundation maps for documenting the extent of flooding at various elevations along a reach of the Little Calumet River in northeastern Illinois. A GIS application was used to produce a plane representing the flood-peak water surface. The application duplicates the water-surface-elevation data from cross-section points across the flood plain perpendicular to the direction of the flood flow. Elevations between water-surface points on the cross-sections are proportional interpolations of the water-surface-elevation data and were positioned to generate a flood surface sloping with the water flow. A raster surface was created with the data points using a spline interpolation method, forming the estimated flood surface. A flood-depth grid was made by subtracting the DEM from the flood surface. The flood-peak inundation areas are available in a GIS format, polyline shapefile, that provides extent of the flood peak for each stage level. This format allows the GIS data to be overlain on maps and aerial photographs and to be used for various GIS applications. For more information on data processing and checking procedures, see the full report at https://doi.org/10.3133/sir20205074. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, as well as in ArcGIS format, this metadata file may include some ArcGIS-specific terminology. 20200422 ground condition Complete N/A -87.61280 -87.52040 41.62440 41.56210 none flood river/stream flood-inundation maps flooded area geospatial analysis USGS Metadata Identifier USGS:5ec58ae882ce476925ebbbf5 none Lansing, South Holland, Calumet City Illinois Little Calumet River None. This dataset is provided by USGS as a public service. Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. The flood boundaries shown were estimated based on water stages at the USGS streamflow-gaging stations Little Calumet River at South Holland, Illinois (USGS station 05536290), Little Calumet River at Munster, Indiana (USGS station 05536195), unsteady-state hydraulic modeling (assuming unobstructed flow), and a digital elevation model. The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing on January 2018. Unique meteorological factors (timing and distribution of storm) could cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations from the water surface elevations and inundation boundaries shown here. Additional areas may be flooded due to unanticipated backwater from major tributaries along the main stem or from localized debris- or ice-jams. Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. Although USGS intends to make this server available 24 hours a day, seven days a week, timely delivery of data and products from this server through the Internet is not guaranteed. 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. If this series of flood inundation maps will be used in conjunction with National Weather Service (NWS) river forecasts, the user should be aware of additional uncertainties which may be inherent or factored into NWS forecast procedures. The NWS uses river forecast models to estimate the quantity and timing of water flowing through selected river reaches in the United States. These forecast models (1) estimate the amount of runoff generated by a precipitation event, (2) compute how the water will move downstream, and (3) predict the flow and stage (water surface elevation) for the river at a given location (AHPS forecast point) throughout the forecast period (every six hours and 3 to 5 days out in many locations). For more information on AHPS forecasts, please see: http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf . US Geological Survey, Central Midwest Water Science Center mailing and physical address

405 N. Goodwin Avenue

Urbana IL 61801 (217) 328-8747 Microsoft Windows 10 Version 1511 (Build 10586.1478); ESRI ArcCatalog 10.4.1 Attributes for water surface elevation were input from the HEC-RAS model output data table. No formal logical consistency tests were performed. This dataset is complete; there are no planned revisions or updates at this time. Used cross-section data points from surveyed data, accurate to the datum of the survey. Flood inundation extent was manually checked by sampling the digital elevation model (DEM) adjacent to water-surface elevations. This check was done to verify that DEM elevations greater than the water-surface elevation were not in the flood inundation polygon and elevations less than the water-surface elevation were within the flood inundation polygon. Used cross-section data points from surveyed data, accurate to the datum of the survey. Flood inundation extent was manually checked by sampling the digital elevation model (DEM) adjacent to water-surface elevations. This check was done to verify that DEM elevations greater than the water-surface elevation were not in the flood inundation polygon and elevations less than the water-surface elevation were within the flood inundation polygon. Vertical accuracy to the input Lidar DEM dataset. A GIS application was used to produce a plane representing the flood-peak water surface. The application duplicates the water-surface-elevation data from cross-section points of the hydraulic model across the flood plain perpendicular to the direction of the flood flow. Elevations between high-water marks, or water-surface points on the cross-sections are proportional interpolations of the water-surface-elevation data and were positioned to generate a flood surface sloping with the water flow. A raster surface was created with the data points using a spline interpolation method, forming the estimated flood surface. A flood-depth grid was made by subtracting the DEM from the flood surface raster. 201711 Vector String 24 Mercator 0.0 0.0 0.0 0.0 coordinate pair 1.0 1.0 meters D_WGS_1984 WGS_1984 6378137.000000 298.257224 North American Vertical Datum of 1988 0.000100 feet Attribute values Flood-Inundation Maps for the Little Calumet River from Lansing to South Holland, Illinois, 2020, station IDs 05536195, 05536195 lcalumeil and lcalumeil_breach shapefile attribute table U.S. Geological Survey FID Internal feature number. ESRI N/A Shape Feature geometry. ESRI Coordinates defining the features. STAGE_1 USGS stage height associated with the area for USGS station 05536290, in feet. U.S. Geological Survey 10.32 24.32 Feet ELEV_1 NAVD88 elevation that correlates with the stage for USGS station 05536290, in feet. U.S. Geological Survey 585 599 Feet USGSID_1 USGS station ID number (05536290) U.S. Geological Survey N/A STAGE_2 USGS stage height associated with the area for USGS station 05536195, in feet. U.S. Geological Survey 8.61 19.61 Feet ELEV_2 NAVD88 elevation that correlates with the stage for USGS station 05536195, in feet. U.S. Geological Survey 589 600 Feet USGSID_2 USGS station ID number (05536195) U.S. Geological Survey N/A PROFILE A unique code consisting of a number (2, 5, 25, 50, 100, or 500), which corresponds to a __-year recurrence interval flood, followed by 'p' (for 'profile'), two numerical digits to differentiate between various stages/elevations, and '_il' (which denotes Illinois). Producer Defined N/A GRIDID A dimensionless integer between 1-24 corresponding to the various stages/elevations. Producer Defined 1 24 N/A Each entity corresponds to an estimated flood extent area for 24 water-surface profiles at 1-foot (ft) intervals referenced to the streamgage data and ranging from bankfull to about the 0.2-percent annual-exceedance probability flood (500-year recurrence interval flood). US Geological Survey, Central Midwest Water Science Center mailing and physical address

405 N. Broadway Avenue

Urbana IL 61801 (217) 328-8747 Downloadable Data Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of this data, software, or related materials. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This coverage may be redistributed if it is not edited and is properly referenced. The flood boundaries shown were estimated based on water stages/streamflows at the USGS streamflow-gaging stations Little Calumet River at South Holland, Illinois (USGS station 05536290), Little Calumet River at Munster, Indiana (USGS station 05536195), unsteady-state hydraulic modeling (assuming unobstructed flow), and a digital elevation model. The hydraulic model reflects the land-cover characteristics and any bridge, dam, levee, or other hydraulic structures existing on January 2018. Unique meteorological factors (timing and distribution of storm) could cause actual streamflows along the modeled reach to vary from those assumed during a flood, which may lead to deviations from the water surface elevations and inundation boundaries shown here. Additional areas may be flooded due to unanticipated backwater from major tributaries along the main stem or from localized debris- or ice-jams. Inundated areas shown should not be used for navigation, regulatory, permitting, or other legal purposes. Although USGS intends to make this server available 24 hours a day, seven days a week, timely delivery of data and products from this server through the Internet is not guaranteed. 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. If this series of flood inundation maps will be used in conjunction with National Weather Service (NWS) river forecasts, the user should be aware of additional uncertainties which may be inherent or factored into NWS forecast procedures. The NWS uses river forecast models to estimate the quantity and timing of water flowing through selected river reaches in the United States. These forecast models (1) estimate the amount of runoff generated by a precipitation event, (2) compute how the water will move downstream, and (3) predict the flow and stage (water surface elevation) for the river at a given location (AHPS forecast point) throughout the forecast period (every six hours and 3 to 5 days out in many locations). For more information on AHPS forecasts, please see: http://water.weather.gov/ahps/pcpn_and_river_forecasting.pdf. shapefile 0.989 https://doi.org/10.5066/P99L14DN none Data are supplied in ArcINFO format. Format compatibility is the user's responsibility. 20220927 2018 US Geological Survey Ask USGS - Water Webserver Team mailing address

507 National Center

Reston Virginia 20192 USA 1-888-275-8747 (1-888-ASK-USGS) amanaster@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 local time ESRI Metadata Profile