Accuracy for H Flumes is listed as 2 to 5% by the U.S. Environmental Protection Agency, while Bos lists the accuracy as 3%.
As with any flume, field installation should expected to experience less accuracy due to factor such as: faulty construction or installation of the flume, improper head measuring location, flowmeter calibration inaccuracies, flowmeter level-to-flow conversion inaccuracies, lateral and longitudinal settling (when flumes used on earthen channels where the installation is exposed to hot / dry and freeze / thaw cycles), and improper conditioning of the incoming flow.
Image: USDA, ARS, Relevance of Pesticide Volatilization
