Water-surface profile and flood boundaries for the computed 100-year flood, Lame Deer Creek, Northern Cheyenne Indian Reservation, Montana

Hydrologic and hydraulic evaluations of Lame Deer Creek were made to determine the magnitude of the 100-year flood and the extent of flooding that would occur as the result of this flood. SixtY-six cross sections were Surveyed and 25 cross sections were synthesized along a 9.5-mile reach of Lame Deer Creek. Data from the surveys were used to calculate the water-surface elevation at each cross section using a computer program (WSPRO) developed by the U.S. Geological Survey. The water-surface profile of the computed 100-year flood elevations was then drawn. The profile shows the streambed elevation and the location of the bridge, culverts, and cross sections. The computed 100-year flood elevation at each cross section was used to delineate the width of the flood plain at that section. Flood boundaries between cross sections were interpolated using contour lines on topographic maps.