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John visits NIWA scientist Roddy Henderson to get an understanding of water in New Zealand. He then meets farmer Craige Mackenzie and finds out why irrigation is important for farmers.

Key content

Key content

Understanding water in New Zealand

Water is the very life force that powers the planet. Kiwis can sometimes take this commodity for granted and assume that there’s plenty to go round, but how do we really know that we have enough? John takes a trip to Canterbury, our biggest consumer of water, to meet NIWA scientist Roddy Henderson who gives him the low down on just how New Zealand is placed for water.

Next up, John heads to a Canterbury dairy farm to meet local farmer Craige Mackenzie to find out about the importance of irrigation. Craige explains to John why he’s got NIWA’s gadgets on his land helping to answer some of the important questions when it comes to water.

To demonstrate the importance of understanding water on a farm, John makes a simple model. John makes clever use of some top soil, rocks, a packet of powdered drink and a watering can to demonstrate the effects of over- and underwatering, which affect both the farmer and environment.

Things to think about

Things to think about

In conjunction with this episode of Ever Wondered?, your students may enjoy these activities.

In this activity, students build a model like John does in part 1 of this episode. The model is called an aquifer. It can be used to look at point sources of pollution (such as fertilisers or pesticides) and non-point sources (such as spills or landfills).
Groundwater contamination

In this activity, students explore and make predictions about some factors that affect soil run-off and ground stability, including gravity, erosion and deforestation.
Water run-off

In this activity, students investigate the issues surrounding water in their local area and relate this knowledge to water issues in other countries.
Water issues

Transcript

Transcript

DR JOHN WATT

Water. It turns the turbines that power our country and it irrigates the fields that power our economy. In New Zealand, we seem to have loads of it. But do we? And can we rely on it being that plentiful in the future?

VOICE-OVER

This week, I’m discovering the answers to these questions by looking into science’s crystal ball, modelling and meeting the very young men revolutionising global irrigation.

But first, I’m off to our biggest water user, Canterbury, where NIWA scientist Roddy Henderson is going to give me the low-down on New Zealand’s water situation.

DR JOHN WATT

So what’s the state of water in New Zealand?

RODDY HENDERSON

Well, on average, we have a lot. We actually have about as much water falling on New Zealand as falls on the whole of Australia, in spite of the difference in our size.

DR JOHN WATT

Tiny size. But it’s not spread evenly?

RODDY HENDERSON

Indeed it isn’t. In the mountains – about 70 or 80 kilometres in that direction – you can get as high as 12 metres in a year. Right here, where we’re standing, about 900 millimetres, and in Christchurch, 600 millimetres.

VOICE-OVER

This uneven distribution of rainfall is largely due to warm, water-laden air from the north-west hitting the mountains where it is pushed upwards and cooled, dropping its cargo in vast quantities, which then rush into the great rivers of the West Coast and the Canterbury Plains.

RODDY HENDERSON

Canterbury is lucky in having major water sources that emerge from the Southern Alps, and the plains themselves are basically the outwash of the set of rivers that cross them, and you know, there’s quite a big distance between the major rivers, and all the space in between is outwash gravel from one or the other.

VOICE-OVER

Agriculture accounts for two-thirds of all of New Zealand’s exports and used an incredible 81% of our freshwater allocations in 2010.

DR JOHN WATT

So our economy clearly needs water to grow and flourish, but how do we know how much water we can safely take?

RODDY HENDERSON

The role of science is to provide the information that allows decision-makers to make decisions based on good data and interpretation.

VOICE-OVER

So I’ve come to a good old Canterbury dairy farm where NIWA have set up the gear that collects this information. But it’s not just the powers that be that want to save water but the farmer as well.

DR JOHN WATT

So Craige, you’ve obviously given up some of your land for the research station. I mean, what do you get out of this?

CRAIGE MACKENZIE

Information’s power. If we haven’t got any information, we are not going to go anywhere. So we’ll be a lot more efficient with our water than what we have been in the past. We can look at graphs and track where the moisture levels are going to in the soil, and then if we need to irrigate because the soil moisture levels are dropping, then we can just put some irrigation on to be able to fulfil that.

DR JOHN WATT

To illustrate the problem that farmers face, I have set up a wee experiment. This here is my miniature field. Up top, we’ve got the nice fertile topsoil, and underneath, the rocky ground. I’ve got a packet of powdered drink which represents my fertiliser. So I put my fertiliser on my fields, put on quite a bit because we need a bit of fertiliser.

And then comes the irrigation, just a little bit. And you can see what happens is that the water draws the fertiliser into the topsoil, feeding and watering the grass. But if I put on too much, give it heaps … oh, it’s going everywhere.

It starts to soak through the topsoil into that rocky ground and as you can see by the colour, taking with it the fertiliser and its nutrients. So instead of fertilising the field, you fertilise the groundwater and the rivers, which is not what you want. It’s not what Craige wants either.

CRAIGE MACKENZIE

Water is one thing but also the other thing is the nutrients we put on.  We pay for both of those so the last thing we want to do is see them disappear out the bottom. So that’s a really good thing. It’s really interesting. Generally, things that are good for the bottom line are also good for the environment.

VOICE-OVER

So over-watering is bad for everyone, and bad management of our water resource can have far-reaching consequences.

RODDY HENDERSON

From a purely selfish perspective from New Zealand’s point of view, the rest of the world and certainly some of our major markets are becoming very particular about the way in which producers treat the environment, and if we aren’t being seen to be careful with our environment, then we are risking our markets.

DR JOHN WATT

So what can we do to manage it better?

RODDY HENDERSON

Well, we need to understand its distribution in space and time, and we have a pretty good handle on that, and then we need to have some modelling capabilities that allow us to predict what will happen under new scenarios, and climate change is one of those.

VOICE-OVER

After the break, we’ll be talking to the guys that use the information that NIWA collects to figure out just how much risk there is to New Zealand and our economy from the dual dangers of floods and droughts.

Go to Part 2

Go to www.biotechlearn.org.nz