Scientists are using a remote-controlled miniature speedboat to gauge river flows in New Zealand's rivers, including those in the Bay of Plenty.

NIWA principal technician Wayne McGrath says the two metre long Q-boat to measure river flow, which is crucial for measuring river water quantity.

The Q-boat.

He says power companies, regional councils and New Zealanders that use rivers for recreation need to know what the river flows, and levels, are.

'The Q-boat is the only one of its type in the country and our scientists have embraced it.”

NIWA's Rotorua, Dunedin and Hamilton branches are the latest to use this technology.

Owning this piece of equipment has recently enabled the NIWA Rotorua and Hamilton staff to secure a contract to measure river flows at sites operated by the Waikato Regional Council.

The Q-boat has an Acoustic Doppler Current Profiler (ADCP).

This sonar system produces a record of water current velocities, width and depths.

The ADCP sits snugly inside the waterproof miniature speed boat.

One person operates the boat from the safety of the riverbank using a remote control.

The river flow data is transferred directly to a laptop computer via enhanced Bluetooth communications.

A second scientist operates the computer.

To measure river flow and river height, the scientists do two things.

'We have a staff-gauge in the river, it's like a ruler in the water, which provides NIWA with a quick and easy visual indicator of the river's water level,” says Wayne.

'The Q-boat measures the flow, and the relationship between that measurement and the river's water level gives a relationship know as a 'rating' for the river.”