Rapid variations of water-surface level in river channels through time, in combination with the occurrence from time to time of overbank flow in flat-bottomed valleys, have promoted intensive study of the discharge relationships and the probability characteristics of peak flow. Stage (depth or height of flow) measurements treat water level: discharge measurements require determinations of velocity through the cross section. Although records of stage respond to frequency analysis, the analysis of magnitude and frequency is preferable wherever stage is affected by progressive scour or fill, and also where channels have been artificially embanked or enlarged or both. The velocity determinations ...(100 of 32811 words)