Alaska Section, AWRA, Northern-Region Brown-Bag Meetings

December 29, 2017

Do the 2016 USGS Flood-Peak Regression Equations Systematically Over- or Under-Estimate Flood-Peak Discharge?

Arctic Hydrologic Consultants

James W. Aldrich, P.H., P.E., Arctic Hydrologic Consultants, Fairbanks, Alaska
Phone: (907) 479-2582, Email:

For more than 40 years, the USGS flood-peak regression equations have been used to design bridges, culverts and flood control measures at ungaged sites throughout Alaska. Updated approximately every 10 years, as our flood-peak database increased, the equations have provided an increasingly more accurate method of estimating flood-peak magnitude and frequency at ungaged sites. Although the equations are easy to use, there are important concepts that the users should understand regarding the development of the equations. Additionally, in 2016 a significantly different approach was taken in the development of the equations. This presentation will discuss some of the basic concepts that users of the regression equations should understand as well as present the results from a test of the new equations to determine if they systematically over- or under-estimate flood-peak discharge.

Select Presentation Figures

Figure 1. 2016 USGS Regression Equations

Figure 2. Use of the 2016 USGS Regression Equations on the North Slope, Former Region 7

Figure 3. What Options are Available for Region 7? 2003 USGS Regression Equations?

Figure 4. 50-Year Flood Peaks Predicted with 2016 USGS Equations