ISO 1070:1992

The method is suitable for use under somewhat special conditions when direct measurement of discharge by more accurate methods is not possible. It can be used with reasonable accuracy in open channels having stable boundaries, bed and sides (e.g. rock), in lined channels and in channels with relatively coarse material. In other cases it is subject to large uncertainties, and it is not suitable for use in very large channels, channels with very flat surface slopes and high sediment load or channnels having significant curvature.