Drone technology captures river changes

Charlotte Milne is studying toward a Master of Science in Geography.

Charlotte Milne at Hapuku River

“I have loved nature and rivers since I was a kid. I was three years old when I asked my grandmother ‘how did the hills get there?’ and by the time I was five I was telling everyone I was going to be a geographer when I grew up.

"I specialise in rivers because they are perhaps the most intriguing feature in New Zealand’s dynamic landscape. Not only are rivers complex and beautiful, they have a deep importance in our culture.

“While the 2016 Kaikoura earthquake was devastating, it created unique opportunities for new and exciting studies. My research is based in the Hapuku River, a large gravel river just outside Kaikoura township. Following the earthquake, a landslide dam formed at the top of the river and created a lake that posed a flood risk.

“Over the last few years the lake has drained and the dam has started to release pulses of of course sediment downstream. As a result, the river bed levels have risen significantly. My research is focussed on assessing how the gravel sizes, organisation and river bed levels are changing over time to get a sense of how the pulse material will change the river’s sedimentology.

I urge new researchers in the field of environmental science to pick study
areas that fascinate them and questions that they are desperate to answer. Then your postgraduate research will become an amazing opportunity to fully submerge yourself in something that you love.

Charlotte Milne

“I enjoy being based in such an exciting and relevant field site, surrounded by other stimulating projects. I use state-of-the-art, high-resolution drone technology and Structure from motion (SfM) modelling to assess these alterations. Understanding the sedimentology of my study site will help predict future adjustments in the river and inform management practices for geomorphic, habitat and hazard purposes in Kaikoura.

“When I’m in the field in Kaikoura I'm flying drones, taking photographs and collecting information on the river’s sediment. I access remote sections of the river by helicopter, and I get to see the river from its source in the Kaikoura ranges, all the way down to where it drains at the coast.

“There’s no question that drone technology has started a revolution in geographical research, taking it to levels that were unimaginable 20 years ago, but with that we have to also increase our ability to analyse and critique the new high-resolution data. I’ve seen far more change in the Hapuku River’s sedimentology over a six month period than I had anticipated, so I have to question the rapid rates at which the sediment pulse may be migrating, and the degree of change it might cause.

“Lots of unforeseen problems have come up, but that’s the nature of my research. It’s definitely an adaptive and iterative project. I’ve approached these issues using different pathways to achieve the same end goal, and by ensuring I have lots of data to test different methods on. I’ve learnt that there is no one correct way to go about geospatial analysis!

“When I’m at university I’m mainly processing data, building models from my drone footage and mapping the changes seen at my site. Otherwise, I’m delving into the literature to understand what other experts in the field have found in their research.

“I love the facilities that are available to us in the new Science building, along with the strong sense of community we have especially within the School of Environment. Travelling into the field creates strong friendships with fellow students and gives you the chance to really get to know the academics at the university. This has really opened my eyes to some of the exciting opportunities that are available in the academic field of geography.

“Being a teaching assistant (TA) is my favourite part of being a postgraduate student at the University of Auckland. I love sharing my experience and knowledge with undergraduate students, and helping them with their own research projects. I especially enjoy teaching first and second-year students, meeting new students and hearing about their passion for geography.

“I urge new researchers in the field of environmental science to pick study areas that fascinate them and questions that they are desperate to answer. Then your postgraduate research will become an amazing opportunity to fully submerge yourself in something that you love."

Charlotte has a BSc with a double major in Geography and Earth Sciences. Her Masters supervisors are Dr Jon Tunnicliffe, Senior Lecturer at the School of Environment, and Professor Gary Brierley