This International Standard specifies methods for determining the velocity and cross-sectional area of water flowing in open channels and for calculating the discharge employing point velocity measurement devices. It covers methods using rotating element Current Meters, Acoustic Doppler Velocimeters (ADV), Acoustic Doppler Velocity Profiler (ADVP) – Stationary method, Surface Velocity measurement including floats and other surface velocity systems. Although some general procedures are discussed, it does not describe in detail how to use or deploy these systems. For detailed procedures, reference should be made to guidelines from instrument manufacturers and appropriate public agencies.