Geospatial datasets for the flood-inundation study of Joachim Creek, De Soto, Missouri, 2018

Digital flood-inundation maps for a 6.7-mile reach of Joachim Creek, De Soto, Missouri, were created by the U.S. Geological Survey (USGS) in cooperation with the city of De Soto, Missouri. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science web site 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 USGS streamgage 07019500 on Joachim Creek at De Soto, Missouri. Near-real-time stages at this streamgage may be obtained on the internet from the USGS National Water Information System at https://waterdata.usgs.gov/ or the National Weather Service Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/, which also forecasts flood hydrographs at this site Flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The model was calibrated by using current stage-discharge measurements at the USGS streamgage 07019500 on Joachim Creek at De Soto, Missouri, and documented high-water marks from the flood of April 18, 2013. The hydraulic model was then used to compute 10 water-surface profiles for flood stages at 1-foot (ft) intervals referenced to the streamgage datum and ranging from 8 ft, or near bankfull, to 17 ft, which exceeds the stage that corresponds to the estimated 0.2-percent annual exceedance probability flood (500-year recurrence interval).The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging [lidar] data) having a 1-ft vertical accuracy and 3.28-ft horizontal resolution) to delineate the area flooded at each water level. The availability of these maps, along with internet information regarding current stage from the USGS streamgage and forecasted high-flow stages from the National Weather Service 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 post flood recovery efforts.