Hydraulic modeling and flood-inundation mapping for the Huron River and Ore Lake Tributary, Livingston County, Michigan

Digital flood-inundation maps for an 8-mile (mi) reach of the Huron River near Hamburg, Michigan (station number 04172000), from downstream of Rickett Road to Strawberry Lake, were created by the U.S. Geological Survey (USGS), in cooperation with Green Oak and Hamburg Townships, Michigan, and the U.S. Army Corps of Engineers. The flood-inundation maps also include a 1.16-mi reach of the Ore Lake Tributary until it joins the Huron River, approximately 2.22 mi downstream of Rickett Road. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science website at http://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 on the Huron River near Hamburg, Michigan (station number 04172000). Near real-time stages at this streamgage may be obtained on the Internet from the USGS National Water Information System at http://waterdata.usgs.gov/ or the National Weather Service (NWS) Advanced Hydrologic Prediction Service at http:/water.weather.gov/ahps/. The NWS Advanced Hydrologic Prediction Service also provides forecasted flood hydrographs at this website.

Flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The hydraulic model was calibrated by using the current stage-discharge relation at the Huron River near Hamburg, Mich., streamgage and was calibrated to water levels determined with stage sensors (pressure transducers) temporarily deployed along the stream reach. The hydraulic model was used to compute a set of water-surface profiles for flood stages ranging from 7.0 to 10.5 feet (ft). This range represents stages just above 6.0 (bankfull) to 2.04 ft above the maximum recorded stage at the USGS streamgage on the Huron River near Hamburg, Mich. (station number 04172000). The computed water-surface profiles were then combined with a Geographic Information System digital elevation model (derived from light detection and ranging [lidar] data having a 0.49-ft vertical accuracy and 3.8-ft horizontal resolution) to delineate the area flooded at each water level.

The availability of these maps, along with Internet information regarding current stage and forecasted high-flow stages from the NWS, will provide emergency management personnel and residents with information critical for flood-response activities such as evacuations, road closures, and postflood recovery efforts.