Development of Regional Regression Equations to Estimate the Magnitude of Peak Flows for Selected Annual-Exceedance Probabilities in Maine

Science Center Objects

Knowledge of the magnitude and frequency of floods is needed for the effective and safe design of bridges, culverts, and other structures.  This information is also important for flood-plain planning and management. The flood-frequency characteristics for streamgages and regression equations for estimating flood magnitudes at ungaged sites were last developed in 1999 (Hodgkins, 1999).  

New analyses will benefit from 20 additional years of data including many sites with small (< 30 mi2 watersheds) and state of the art methods. 


  1. Calculate magnitude of peak flows for 50-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent Annual Exceedance Probabilities (AEP)  at streamgages in Maine using up-to-date methods and data collected through 2017;
  2. Evaluate peaks flow data in Maine for potential trends over period of record;
  3. Determine basin characteristics that are most important for predicting peak flows in regional-regression equations;
  4. Produce new regional regression equations for estimating the 50-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEP flows at ungaged sites in Maine;
  5. Document the methods and findings in a USGS publication,
  6. Incorporate new estimates and equations into the U.S. Geological Survey (USGS) StreamStats Program  
  7. Concurrently update Streamstats with the newest Maine Lidar, up to date drainage basin delineations at all gages, land up-to-date digital coverages of basin characteristics including a watershed basin delineation (WBD) layer based on new lidar.