BS ISO 18320:2020

This standard BS ISO 18320:2020 Hydrometry. Measurement of liquid flow in open channels. Determination of the stage-discharge relationship is classified in these ICS categories:

• 17.120.20 Flow in open channels

This document specifies methods of determining the stage–d ischarge relationship for gauging stations. It specifies an accuracy for defining the stage–discharge relationship based on a sufficient number of discharge measurements, complete with corresponding stage measurements.

This document considers stable and unstable channels and includes brief descriptions of the effects on the stage–discharge relationship of the transition from inbank to overbank flows, shifting controls, variable backwater and hysteresis. Methods of determining discharge for twin-gauge stations, ultrasonic velocity-measurement stations and other complex rating curves are not described in detail.