Assessment of peak discharge uncertainty in the American River basin, California

Flood-discharge data, current-meter and indirect measurements, and stage-discharge relations, the oldest of which dates to the early 1900's, were used to estimate the uncertainty about annual flood peaks in or near the American River Basin at 20 stream-gaging stations operated by the U.S. Geological Survey. The study estimates that, in the study area, most flood peaks that were determined from current-meter measurements have an uncertainty of about plus or minus 3 percent, whereas the peaks that were determined from indirect measurements have an uncertainty ranging from plus or minus 10 to plus or minus 70 percent. The study also determined that the stage-discharge relations that have been developed for most of the sites in the American River Basin are correct.