17.120.20 - Flow in open channels

This document provides an understanding of the nature of measurement uncertainty and its significance in estimating the "quality" of a measurement or a determination in hydrometry. This document is applicable to flow measurements in natural and man-made channels. Rainfall measurements are not covered.

This document specifies methods of determining the stage?discharge 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 ...view more

This document specifies methods for the measurement of the flow of water in open channels under steady flow conditions using triangular profile weirs. The flow conditions considered are steady flows which are uniquely dependent on the upstream head and non-modular (drowned) flows which depend on downstream as well as upstream levels.

This document gives guidelines for selecting a particular type of flow measuring structure for measuring liquid flow in an open channel. It describes how the individual structures function in simple non-technical terms, and sets out the factors and parameters to take into account in order to make an informed decision on which type of structure to use. Values of the relevant parameters describing the limitations and uncertainty involved in the use of these structures are given in this document. M...view more

This standard describes procedures for determining and verifying the declared values of the noise emitted by household and similar appliances. It applies to all categories of household and similar electrical appliances covered by IEC 60704-1 and all parts of IEC 60704-2, which include particular requirements for special categories of appliances. It applies to appliances being produced in quantity, such as in batches, series or lots, which are manufactured to the same technical specification and ...view more

IEC 60704-3:2019 is available as IEC 60704-3:2019 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 60704-3:2019 describes procedures for determining and verifying the declared values of the noise emitted by household and similar appliances. It applies to all categories of household and similar electrical appliances covered by IEC 60704-1 and all parts of IEC 60704-2, which include particular r...view more

This document specifies a method of determining discharge in open channels from observations of the surface slope and cross-sectional area of the channel. It is applicable to use under special conditions when direct measurement of discharge by typically more accurate methods, such as the velocity-area method, is not possible. Generally, the method can be used to determine discharge a) for a peak flow that left high-water marks along the stream banks, b) for a peak flow that left marks on a serie...view more

This document defines the requirements for the use of rectangular and triangular (V-notch) thin-plate
weirs for the measurement of flow of clear water in open channels under free flow conditions. It includes
the requirements for the use of full-width rectangular thin-plate weirs in submerged (drowned) flow
conditions.

This document describes the establishment and operation of an ultrasonic (transit-time) gauging
station for the continuous measurement of discharge in a river, an open channel or a closed conduit.
It also describes the basic principles on which the method is based, the operation and performance of
associated instrumentation and procedures for commissioning.
It is limited to the “transit time of ultrasonic pulses” technique, and is not applicable to systems that
make use of the “Doppler shif...view more

ISO 18481:2017 specifies a method for the estimation of the sub-critical flow of clear water in a smooth, essentially horizontal channel (or a gently sloping channel), abruptly discontinued at bottom by a hydraulic structure, with a vertical drop and discharging freely. Such an overfall forms a control section and offers a means for the estimation of flow using the end depth measurement method. A wide variety of channel cross-sections with overfall have been studied, but only those which have re...view more

ISO 6416 describes the establishment and operation of an ultrasonic (transit-time) gauging station for the continuous measurement of discharge in a river, an open channel or a closed conduit. It also describes the basic principles on which the method is based, the operation and performance of associated instrumentation and procedures for commissioning.
It is limited to the "transit time of ultrasonic pulses" technique, and is not applicable to systems that make use of the "Doppler shift" or "co...view more

ISO/TR 9210:2017 provides guidelines for discharge measurements in meandering and braided rivers, and from bridges, following the provisions of ISO 748.

ISO 9123:2017 specifies methods for determining stage-fall-discharge relationships for a stream reach where variable backwater occurs either intermittently or continuously. Two gauging stations, a base reference gauge and an auxiliary gauge are required for gauge height measurements. A number of discharge measurements are required in order to calibrate the rating to the accuracy required by this document. The preparation of rating curves is not described in detail in this document. NOTE For a mo...view more

ISO 6416 describes the establishment and operation of an ultrasonic (transit-time) gauging station for the continuous measurement of discharge in a river, an open channel or a closed conduit. It also describes the basic principles on which the method is based, the operation and performance of associated instrumentation and procedures for commissioning. It is limited to the "transit time of ultrasonic pulses" technique, and is not applicable to systems that make use of the "Doppler shift" or "cor...view more

ISO 1438:2017 defines the requirements for the use of rectangular and triangular (V-notch) thin-plate weirs for the measurement of flow of clear water in open channels under free flow conditions. It includes the requirements for the use of full-width rectangular thin-plate weirs in submerged (drowned) flow conditions.

ISO/TR 19234:2016 specifies the requirements for the integration of baffles on the downstream face of triangular profile flow measurement structures to aid the passage of fish.

ISO 6420:2016 specifies methods of determining the position of hydrometric boats based on satellite navigation systems and/or with respect to known points on the banks of rivers, estuaries or lakes. It applies to electronic positioning equipment and conventional surveying techniques.

ISO 24155:2016 specifies the technical requirements that should be considered in designing and operating hydrometric data transmission systems (HDTS) and also the necessary functions of those systems. The scope of HDTS is shown in Annex A.

ISO 29606:2015 specifies requirements for the integration of fishpasses with flow measurement structures. It identifies those fishpasses which have satisfactory hydrometric calibration data and gives methods for computing combined flows and uncertainties. NOTE Flow measurement structures and fishpasses have inherently different hydraulic performance criteria. Flow measurement structures perform better with uniform flow patterns; conversely, fish passage performance is improved by the variability...view more