Assessment of the Performance of Flow Measurement Instruments and Techniques

The last twenty-five years have seen great advances in the instrumentation available for hydrometry and in the procedures and methods for the measurement of discharge. Due to several reasons, this progress has not seen a parallel development of guidance material and standards.

At its Twelfth Session (Geneva, October 2004), the Commission for Hydrology of WMO, having reached a general consensus that information on the appropriate use of this instrumentation and methodologies is direly needed, identified under the priority thematic area "Basic systems (hydrometry and hydraulics)" an activity to develop a proposal and implement a project to assess the performance of flow measurement instruments and techniques against WMO standards.

A small expert team from the Open Panel of CHy Experts (OPACHE) on Basic Systems has developed a proposal, which suggests the implementation of a project with the main objective of making information on standardized test results on hydrometric instrumentation and measurement methodologies available to NHSs by providing a Web site as a forum for exchange of information among interested parties.

An exploratory meeting to further develop the proposal took place in Geneva from 25-27 April 2007. The final report and the PowerPoint presentations given during the meeting can be downloaded here:

• Exploratory meeting on CHy’s Proposal for the Assessment of the Performance of Flow Measurement Instruments and Techniques (Geneva, 25 to 27 April 2007), Final report
• PowerPoint presentations

As a consequence of the meeting, the original proposal was reviewed and at its thirteenth session (Geneva, 4-12 November 2009), the Commission for Hydrology of WMO, through its Resolution 2 (CHy-XIII) – Project for the assessment of the performance of flow measurement instruments and techniques decided to continue the implementation of the project and endorsed its proposed Work Plan.

CHy-XIII also decided to establish a Steering Committee for the project, to provide overall guidance, a role which was given to the Advisory Working Group of CHy and a Management Committee for day-to-day implementation. Please find here the terms of reference of the Management Committee. The first meeting of the Management Committee took place on 18-19 November 2009 in Geneva. The final report of this meeting is available here.

In February 2009, the AWG, on behalf of CHy, decided to adopt the uncertainty analysis framework for flow measurements (developed by the project), based on the Guide to the expression of Uncertainties in Measurements (GUM, 1993). See here for more information

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