Paleoflood Investigations to Improve Flood-Frequency Estimates for Eastern Colorado
Study Area: Eastern Colorado and Adjacent States
Period of Project: July 2013 - September 2015
Project Number: RE00FCU
Project Chief: Michael Kohn, P.E.
Cooperator: Colorado Department of Transportation
Reliable peak-streamflow information is critical for the proper design of stream-related infrastructure, such as bridges and dams, and floodplain inundation maps. At gaged sites, where sufficient long-term streamflow data have been collected, statistics can be obtained from available publications, by an analysis of available data in the U.S. Geological Survey (USGS) National Water Information System, or other sources of flood information. Estimates also are needed at ungaged sites, however, where no site-specific streamflow data are available. Large areas with few streamflow gages having short periods of record have caused large uncertainties in the regional-regression equations used to estimate peak streamflow. Additional flood information may improve the reliability of the regional-regression equations in the Plains hydrologic region of eastern Colorado. A total of 188 streamgages, with a combined total of 6,536 years of record and an average of approximately 35 years of record per streamgage, was used to develop the peak-streamflow equations. In addition, paleoflood data was documented at 41 streamgages and 3 streamgages had previously collected paleoflood data for a total of 44 streamgages with paleoflood or non-exceedance bound data.
- Compile systematic flood data available at USGS, Colorado Division of Water Resources, and Nebraska Department of Natural Resources streamgages through water year 2013 (October 1, 2012 through September 31, 2013) in eastern Colorado and adjacent States.
- Collect paleoflood data at streamgages to supplement the systematic flood data.
- Perform flood-frequency analysis at each streamgage following guidelines outlined in Advisory Committee on Water Data, Bulletin 17C, (England, 2015)
- Provide updated regional peak-streamflow equations for eastern Colorado and update USGS StreamStats program with new equations.