The float method is used in the measurement of streamflow where excessive velocities, depths and floating drift prohibit the use of a current meter. The method consists essentially of observing the time required for a float to traverse a course of known length and noting its position in the channel so that

v = L

t (7.1)

where v is the float velocity (m s−1), L is the distance travelled (m), and t is the time of travel over distance L (s).