Reporter: Sally Sara
First Published: 01/04/2007
SALLY SARA: As the drought continues, farmers, politicians and lobby groups are all putting forward their solutions to the 'big dry'. From building more dams to turning rivers around, a number of proposals have hit the headlines. Now the Australian Water Association has released a book which busts the myths and explains some of the ideas surrounding the water debate. Earlier, I spoke with the Association's chief executive Chris Davis. Thanks very much for joining us on Landline.
CHRIS DAVIS: It's a pleasure.
SALLY SARA: To begin with, give us a bit of an overview - how much water do we have and who's using it?
CHRIS DAVIS: The biggest single user is agriculture and that boils down to being irrigation and about 60-70 per cent, depending on the season, goes in irrigation.
SALLY SARA: After that, is it households?
CHRIS DAVIS: Yep, households is next. It's quite interesting. One of the myths that flies around is that industry is the biggest user of water, and that's not the truth. And that's not the case at all. Industry is quite a distant third in some respects.
SALLY SARA: So during time of drought like this, how much does that generate myths and ideas about how we should solve the problem of water solutions?
CHRIS DAVIS: There are quite a few myths that fly around and in the little book we published recently I dealt with about 22. Some of them are definitely in the myths category in that they are very, very fanciful and would never really come to fruition. Others come into the sort of ideas category, where sometimes they could work and other times they wouldn't be practical.
SALLY SARA: Let's run through a few of those ideas. Firstly, building more dams as a solution to the lack of water.
CHRIS DAVIS: Building more dams is not the answer any longer. We have about 501 large dams around Australia and about 1 million - or maybe even 2 million - farm dams. And we built most of those dams in a period between about 1960 and 1980. After building that big rump of dams, the number of good sites that are left is pretty limited. So if a river was worth damming and a site was worth building a dam on, it's pretty much been taken up. So the rate of dam-building has slowed down to a trickle and it probably won't accelerate much at all.
SALLY SARA: I guess dams also store water, they don't create water.
CHRIS DAVIS: That's exactly right. And, unfortunately, a lot of people seem to believe that because you build a dam it will fill with water and, in fact, that often doesn't happen. To add to that challenge, we've got climate change beginning to bite. The west has certainly dropped its rainfall quite dramatically, and there's evidence emerging now that the east coast is suffering a drop in rainfall as well. So building a dam is even less practical than it might have been 20 years ago.
SALLY SARA: Well, one thing that we're not short of is sea water. What about desalination?
CHRIS DAVIS: It's a very interesting proposition. It's got one supreme advantage - it's totally disconnected from rainfall. So, if you're in a drought situation near the coast, you can build desalination and survive.
SALLY SARA: But is it expensive? From what I understand there needs to be lot of force to get that water through the membranes. Is it an expensive option?
CHRIS DAVIS: An interesting comparison that someone gave me the other day was that, if you have a plant like Perth's, that energy is roughly equivalent to one jet-engine on a commuter aircraft - it's 25 megawatts. It's a lot of energy, but it's not the biggest energy-user around. The other thing people don't acknowledge and really should is that you can put water anywhere and in any quality you like, but you pay an energy penalty for doing that. And desal is sometimes not the worst energy user.
SALLY SARA: What about the idea of moving water from the north where there's higher rainfall to bring it back down to the southern areas?
CHRIS DAVIS: It is a possibility and it could be done, and, I suppose, in the heyday of the engineering view of the world - and I trained as a civil engineer many years ago - the engineering philosophy was we harness the forces of nature for the good of mankind, which was very noble but it didn't always work out the way we expected. We now realise that, even if you can build a pipeline, it would chew up so much energy and it would cost so much to build that it's just not cost effective and you'd never recover the cost of the operation through the value of the water.
SALLY SARA: Because water is 'A' very heavy and ‘B’ can create a lot of friction if you're moving it; is that right?
CHRIS DAVIS: That's right, yes. It's not compressible. Gas pipelines, which can traverse thousands of kilometres, transport the gas under high pressure and you can get terrific volumes through the pipe. Water is, as you say, incompressible and very heavy, and it generates a lot of friction. You can enlarge the size of the pipe to lower the friction loss, but then you have to put more capital into building the pipe. So, it's a juggling act between a big pipe that uses a little energy or a small pipe that chews up a lot of energy. But if the distance is large, then you just can't trade it off. So the longest pipeline we've got operating, I think, is the Perth to Kalgoorlie line, which is famous. But that costs a lot to drive and it's not going to be replicated any time soon.
SALLY SARA: What about the idea of moving more farming and agriculture up to the north where the rainfall can be higher?
CHRIS DAVIS: Moving agriculture to the north is a very attractive proposition and, of course, when you look at the maps of where water is in Australia, it's mostly up in the far north with a bit down on the west coast of Tasmania and logically one would think you should take the farming up there. The Ord scheme went off with great energy about 40 years ago and never quite realised its potential. There's several reasons for that. One is that the crops behave differently in the tropical conditions. You've got to get your crop to market, so the transport infrastructure can be quite challenging.
SALLY SARA: I guess one of the other issues too is that, in the north, an area could get 3 or 4 metres of rain, but that rain can fall very quickly or very sporadically.
CHRIS DAVIS: That's exactly right. What happens is you've got monsoonal rainfall when you go far north. You might get 2 metres a year, but it could all happen in a few days. And the engineering challenge of trying to build a dam big enough to store the water and a system that can distribute it is pretty severe.
SALLY SARA: What are some of the stranger ideas and myths that have been put forward as solutions to the current drought?
CHRIS DAVIS: I think my wooden spoon probably would go to the 'drain the sea into Lake Eyre' idea. People look at the map and they see that there's a dry patch in the middle of the south of the centre of Australia and they look at the elevations and they see that it's about 15 metres below sea level, and blind Freddy could tell you that, therefore the sea, if you made a drain, could run in to Lake Eyre and create this wonderful waterhole which would change the climate. But there are a lot of things stacked up against that. One is it is a unique ecosystem, and it's very rich and very varied. If you drain sea water into that, that would destroy that ecosystem entirely. The other one is that there's no evidence that putting sea water next to any land mass has had any impact on its climate. There are several very arid areas with sea water next to them and they don't get any better with rain. It would cost a huge amount to do it and it would do untold damage and the benefits would be questionable. That's the doozey, I would say; that's the worst.
SALLY SARA: Chris Davis from the Australian Water Association, thank you very much for joining us on Landline.
CHRIS DAVIS: It's a pleasure.
Australian Water Association
1300 361 426