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Environment group Friends of Awa Matakanakana (FOAM) have begun trials of light beam sensors to monitor the health of the Matakana River, which if successful will be considered for use throughout the Auckland region and the rest of the world.
The instruments measure turbidity – or the amount of suspended sediment in the water. High turbidity is associated with reduced use of the river for recreation and the decline of fish, bird and plant species.
The Matakana River is one of the largest tributaries of the Matakana Estuary and FOAM says it appears to carry large quantities of detrimental sediment, though currently there is a dearth of environmental data on the river – something FOAM hopes the sensors will help correct.
Data is recorded by the sensors every 12 minutes and transmitted online so that data can be monitored by FOAM via a website.
FOAM spokesperson Martin Evans says the group hopes to use the data to deduce key pieces of information such as what is a normal level of sediment for the Matakana River, what events trigger an increased level of sediment, identify long-term trends and track the progress of catchment-wide restoration works.
Martin says that the trial is still in its early stages, but analysis of the level of turbidity during storm events suggests that when the ground is relatively dry, sediment production is related to river flow rate, rather than being generated by runoff flowing into the river.
FOAM is conducting the trials in conjunction with Auckland Council’s Healthy Waters department and Pukekohe-based sensor maker Quadbeam Technologies. It is also working in partnership with art business Metalbird, who are providing the internet connection for the sensors free of charge.
Quadbeam spokesperson Emma Ford says the sensors were originally developed for the dairy industry to monitor milk fluids. However, following the death of thousands of cockles in the Long Bay-Okura Marine Reserve, Quadbeam engineers began looking at ways to adapt the sensors to monitor sediment harming marine life.
She says the Phathom sensors in the Matakana River are among the first to be deployed in a natural environment.
This creates challenges since engineers have to contend with natural growths, such as algae, which impede the effectiveness of the sensors. Such problems don’t occur in the dairy industry where the environment for milk processing is more controlled.
Emma says Quadbeam is experimenting with the use of air jet cleaners and wipers to remove the growth material from the sensors.
If trials such as the one in the Matakana River prove successful, then the New Zealand technology will likely be deployed around the world to help in the effort to clean up other rivers and streams.
