In the July 2019 issue of the Australasian Hydrographer, the article Automatic Discharge Measurement of Lowland Weedy Streams provided an overview on the Rising Bubble Method (RBM) and the progress in developing a practical RBM tool to improve the reliable measurement of water flowing in lowland weedy streams. This work is part of an MBIE Envirolink Tools project we are carrying out in collaboration with regional councils.

As previously outlined, conventional methods for continuous flow monitoring require a surrogate (water level) translated to discharge using a rating curve. The presence of aquatic vegetation makes this relationship insensitive and unstable, often resulting in ‘difficult-to-impossible’ measurement. In principle the Rising Bubble Method (RBM) involves releasing ‘precision’ air bubbles from a streambed to enable direct calculation of Total Discharge Q.

In this follow-up article we share some of the results from recent field trials that we carried out near Napier with Hawke’s Bay Regional Council (HBRC) staff.