Water, water everywhere – but not enough
university-of-waikato
Wed Jul 22 2009 12:00:00 GMT+1200 (New Zealand Standard Time)
Water, water everywhere – but not enough
Wednesday, 22 July 2009, 2:17 pm
Press Release: University of Waikato
Media Release
July 22, 2009
Water, water everywhere – but not enough in the Whanganui
There’s continuing controversy over the loss of water from the Whanganui River due to the Tongariro Power Scheme at the southern end of Lake Taupo. Part of that scheme takes water from the Whanganui headwaters and discharges it into Lake Taupo through the Tokaanu power station. This increases the water available to Mighty River hydropower stations on the Waikato River, but at the expense of decreasing Whanganui water flows downstream of the diversions – particularly in summer.
But now a University of Waikato science student has come up with a possible solution: a 20 kilometre long tunnel which would take water from Lake Taupo after it’s been through Tokaanu and return it to the Whanganui River.
That way, summer river levels in the Whanganui could be maintained, and Genesis Energy, which runs the Tongariro Power Scheme, could continue to meet its water use obligations while generating more energy.
To simulate the effect of such a tunnel, honours student Tehnuka Ilanko carried out a ten week summer research project under the supervision of Associate Professor Earl Bardsley.
“I like maths and hydrology and this combined both of those,” says Ilanko. “I learnt a lot about programming in a short time – I had to teach myself how to write code. By loading water intake from the main feeder rivers and then measuring outputs of used water from Tokaanu power station, I could then calculate how much water would need to be diverted via the tunnel to maintain Whanganui summer levels.”
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And according to Ilanko such a scheme would work – though she’s aware it’s unlikely to happen. “It was enjoyable and satisfying to find out that by crunching the numbers and generating graphs that such a scheme would work,” she says.
“Tehnuka did the simulations, and as far as we can tell it almost balances out overall in terms of national good – we’d lose a net power output of just 2.7 MW which could easily be made up by a couple of windmills,” says Dr Bardsley, who devised the project. “However, the impact of the diversion would be significant for Mighty River Power’s hydropower stations on the Waikato River – they would lose around 16 MW during summer.”
Dr Bardsley says while the project was devised purely as a student exercise and wasn’t part of a Genesis investigation, it gave Ilanko hands-on experience of a research environment in a real-world context. “There was a lot for her to get her head around – optimisation and simulation, issues of water rights, and the contracts under which the Tongariro Power Scheme operates – there’s pages and pages of definitions.”
Ilanko was one of 70 students to win a University of Waikato Summer Research Scholarship, worth up to $4,000. Applications for the 2009-10 scheme will open shortly.
ends
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