The information gathered by the hydrology team is crucial to many. It helps Environment Canterbury to sustainably manage the overall water resource that’s available for irrigation, environmental values and recreation. It provides important data for staff in planning, consenting, surface water quality and enforcement, as well as for external stakeholders, such as farmers, recreational users of rivers and science and conservation bodies.
Hydrological information also helps create essential rainfall runoff models and flood forecasting models – which are very important for flood warning systems for landowners and civil defence.
His 4WD driving skills are impressive
Making it safely to the 155 river and lake sites monitored around Canterbury is a big part of the job. Owen and his colleagues often travel in pairs and the vehicles are equipped with safety gear and radio transmitters. For the remote sites in the hill country this can mean off-roading through some tricky countryside.
“If there’s been a lot of wind or rain, I’ll check in with the landowner before heading out – a tree across a track could muck up the whole trip. This year, the ground has been sodden and we’ve seen lots of change to some of the tracks, with washouts and fords. We’ve all undertaken 4WD training and have a lot of experience as well to help calculate risk.”
The main piece of kit for the Ecan hydrologists is a SonTek FlowTracker. It may look low-tech (like a sheep crook with EFTPOS) but it’s actually very clever and collects all measurements digitally for the hydrologists to download once back in the office. The FlowTracker (worth at least $17k each) is an acoustic doppler velocimeter and works by using ultrasonic sound waves which bounce off the particles in the water to help calculate the velocity, and therefore flow, of the water.
The meter alone doesn’t do the job though – Owen needs to plot a course across the river stopping at least 20 times to take depth and distance measurements as well. These together will give you the flow.
“It usually takes about 20 minutes but sometimes it can take up to an hour. We were up at Asbhurton SH1 the other week and it took about an hour as the river was so braided and took so long to get across.”
The team also have some special remote-controlled boats – definitely not toys – that they can use when the water is too deep to wade across. They only have a few of these, due to their significant cost, but they are already proving their worth in those tricky spots.
He needs proper wet weather gear (ie. not an umbrella)
If you’re a hydrologist you need to be confident in the water and be equipped with the right gear. This becomes apparent as Owen braces against the force of the Ashburton River as he painstakingly completes his river flow monitoring across its width at the North Ashburton site.
Owen wears a life jacket and GPS spot tracker and also relies on his partner to throw him a safety rope if he gets into trouble. He has also undertaken extensive water safety training.
“I checked the fixed reading in the office earlier and it was 9 cumecs (cubic metres per second) but now it’s reading 11.9 cumecs,” he reports on making it safely back to the bank. “Around 10-12 cumecs is where it gets a bit tougher for us to do manually so we might use the boat instead.”
A chainsaw comes in useful
No two monitoring stations are alike
No two monitoring stations are alike. They all have their quirks and were built at different times. Most have a locked cabin or box which contains the fixed water monitor gauge, log book and use radio transmitter, cell phone or satellite for communication. The latter come in useful during flood events, when hydrology staff are often out in the field, checking river levels in person and reporting any faults with meters.
Owen’s favourite monitoring sites are at alpine locations, such as North Rakaia and Macauley at Tekapo.
“Turtons Saddle at the top of the Rakaia really is my favourite spot in the whole world.”