A teenager’s tramping trips with her family have inspired a winning science project at this year’s SciTec competition. 

Hayley Sutherland, 15, said she would sometimes get nervous about crossing rivers as a relatively short person, causing her to wonder how strong a river flow needed to be to tip a person over. 

“I get a lot more nervous crossing rivers just because for a taller person it’s the knee height, but for me it’s like about my thigh,” she said. 

The dilemma formed the basis of her entry into the Marlborough Lines Science and Technology Fair, The Tipping Point, one of more than 270 selected from the region’s schools, with judging last week.

For Sutherland’s project, the Marlborough Girls’ College student asked how strong a river’s flow needed to be to tip over a person attempting to cross. 

“My main question is, when does your hydrodynamic drag force overcome your frictional force and when does that cause you to topple or slide?” Sutherland said. 

Sutherland spoke to several experts for her research, such as hydrology engineering professor Markus Pahlow and physicist Michael Jack, and from Marlborough District Council, environmental monitoring officer Darren Rooney and environmental systems and data analyst Emma Chibnall. 

“I first had to get a kind of basic understanding of river hydraulics to get into all the forces of biomechanics, so that's where Emma helped me with that. 

“[Pahlow] got his whiteboard out and wrote everything down. 

“Darren helped me to formulate all the spreadsheets and stuff for all my statistics. 

“Definitely, without their help, I would have, like, been still quite confused with my project.” 

Her best advice to people crossing rivers was to use tools such as poles to keep equilibrium or link up in groups with the strongest the front and smallest at the back. 

“A lot of trampers misjudge the conditions and crossing and the forces. But really there's so many factors to consider, which makes it so hard to really know when to cross. 

“So just going in groups, and just [make] sure you consider your options before crossing.” 

Sutherland said she planned to enter next year’s fair with another outdoor-based project and hoped to pursue environmental science at the University of Otago. 

Also winning Best in Fair was Patiriella Patterns, a project on New Zealand’s common cushion starfish, Patiriella regularis, by Marlborough Boys’ College students Finn McNabb, year 13, and Oscar Mason, year 12. 

The idea came from an assignment they worked on during a week-long biology camp in Mistletoe Bay.

They looked at whether water depth or distance from the low tide mark affected the number of starfish on the bay’s rocky shore, counting the starfish five times a day, McNabb said. 

But on the day of the SciTec fair, Mason was sick, so McNabb presented their project to the judges alone. 

“You lost half of the team that did half of the work,” McNabb said. 

“So, you have to really understand the other person’s work, which is actually a massive strength to work together and really understand what the other person did independently of you.” 

They found that the starfish was a keystone species with a large effect on its ecosystem. 

But ocean acidification due to climate change was a threat to its foodchain, they said. 

“The more carbon dioxide that that dissolves in the water, it changes the ocean’s chemistry to dissolve some of the barnacle shells which will then kill them, and that’s one of the key food sources of the starfish,” Mason said. 

McNabb said he hoped future biocamp students would continue to count the starfish. 

“If you see a decrease in the Patiriella regularis, we could tell that the Marlborough Sounds is being affected by something,” he said. 

McNabb was looking at attending university in the United States next year, while Mason, who would complete year 13 next year, was still deciding his future studies. 

-LDR is local body journalism co-funded by RNZ and NZ On Air.

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