Hydro-Logic is now part of Hydro International.

Flow Derivation & Uncertainty

Stage discharge and velocity indexing techniques are of critical importance for obtaining accurate flow measurement. Stage-discharge relationships enable the conversion of observed water level measurements to flows where there is a consistent control feature such as a weir or stable river channel. Velocity index techniques are used where no direct relationship exists between stage and flow. Velocity index techniques are required at sites where acoustic velocity meters or radar instruments are installed.

We have undertaken the design, operation and audit of numerous flow monitoring sites. In doing this we have developed and reviewed numerous stage-discharge relationships and velocity index ratings for open channels, informal controls and formal structures. We are also able to complement these techniques with rating extension throughout the full flow range using simple hydraulic analyses and 1D / 2D modelling techniques, as appropriate.

Uncertainty analysis is a means of gaining a better understanding of the quality of hydrometric data and the potential consequences for reliable decision making. We undertake uncertainty analysis for a wide range of flow measurement techniques. Hydro-Logic Services Senior Consultant, Stewart Child, was a key contributor to the Hydrometric Uncertainty Guide (HUG), the joint European and International Standard that defines the approach to uncertainty estimation in hydrometry.

Further information about each of these topics can be found in the sections below:

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