# Calculating weighted estimates of peak streamflow statistics

March 27, 2012

According to the Federal guidelines for flood-frequency estimation, the uncertainty of peak streamflow statistics, such as the 1-percent annual exceedance probability (AEP) flow at a streamgage, can be reduced by combining the at-site estimate with the regional regression estimate to obtain a weighted estimate of the flow statistic. The procedure assumes the estimates are independent, which is reasonable in most practical situations. The purpose of this publication is to describe and make available a method for calculating a weighted estimate from the uncertainty or variance of the two independent estimates.

## Citation Information

Publication Year 2012 Calculating weighted estimates of peak streamflow statistics 10.3133/fs20123038 Timothy A. Cohn, Charles Berenbrock, Julie E. Kiang, Robert R. Mason, Report USGS Numbered Series Fact Sheet 2012-3038 fs20123038 USGS Publications Warehouse National Center