Float your boat! Scientists use hi-tech miniature Q-boat to measure river flows

Scientists are using a remote-controlled miniature speedboat to gauge New Zealand river flows. It's red and cute, and just two metres long. They call it a Q-boat.

Flow is crucial for measuring river water quantity. Power companies, regional councils, and New Zealanders who 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," says NIWA Principal Technician Wayne McGrath, "and our scientists have embraced it." NIWA's Dunedin, Rotorua and Hamilton branches are the latest to use this technology.

NIWA Rotorua and Hamilton staff are now using the Q-boat to measure river flows at sites operated by the Waikato Regional Council.

Onboard the Q-boat is 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. River flow data are transferred directly to a laptop computer via enhanced Bluetooth communications. A second scientist operates the computer.

The Q-boat is more accurate than using traditional methods for gauging river flow and "the results are instant," says McGrath.

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 McGrath.

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

Waikato Regional Council Environmental Monitoring Programme Manager Jim Price says, "It is also much safer as staff no longer have to stand on road bridges to get these measurements."

The Q-boat was initially tested in the South Island, on the Clutha, Pomahaka and Taieri Rivers.

This work was funded by the Ministry of Science and Innovation.

Julie Proud and Q-boat in use at NIWA’s Motu River flow site Photo by Eddie Bowman