Monday, January 4, 2010

Grandiose and not-so-Grandiose Water Supply Schemes for Australia


and Not-so-Grandiose,

schemes for water supply in Australia.

1. The need.

The amount of Rainfall on the Australian continent is not increasing. In fact, the general consensus of global climate models is that it’s decreasing slightly. The population of Australia is increasing, and seems unlikely to peak in the near future. People need both water and food, and food needs water.

Let’s look at the population trend in more detail.

Australia’s population is increasing slightly faster than linearly. In future a worst case so far as water supply is concerned would be exponential growth. On the other hand, Australia’s total fertility rate is hovering around the 1.8 children per mother rate, which is below sustainability levels. So if total fertility rate were the only factor controlling Australia’s population then the population would peak in about 50 years and start to decline after that. But when migration into Australia is taken into account, the population certainly won’t peak in 50 years.

The water usage by each Australian depends on both direct usage, and usage by food. The direct usage may decline slightly as, for example, gardens get smaller and washing machines become more efficient, but overall the usage per head of population can only drop slightly. Let’s trade this off against the faster than linear growth of population to say that over the next 50 and 100 years the need for water will grow linearly with time.

It will be immediately clear that, as present water supplies are struggling to keep pace with demand now, they are going to be totally inadequate in 50 years time, and even worse in 100 years time.

2. Three old grandiose schemes

The past is not short of grandiose schemes for solving Australia’s water supply problems. I’ll mention just three of the worst here.

2.1. Piping snowballs from Antarctica.

Many years ago a patent was granted on the topic of piping snowballs from Antarctica to Australia as a way of overcoming Australia’s water supply needs.

This scheme fails primarily because Australia is not near Antarctica. The mining operations required for mining ice in Antarctica are not too excessive, but the distance from the nearest point of Antarctica to Tasmania is more than that from Melbourne to Cape York. Salt water freezes at a lower temperature than fresh water so any water piped from Antarctica to Australia runs the risk of freezing en route. The low precipitation rate in Antarctica is not an immediate problem because there is plenty of water ice stored there.

2.2. Building a mountain range through the middle of Australia.

The centre of the USA is much wetter than the centre of Australia. A main reason for this is the presence of the rocky mountains. The rocky mountains in the centre west of the USA are high enough to enhance precipitation there and lead to a permanent supply of fresh water in rivers through the centre of the continent. The Andes have a similar role in South America. Africa has no such high western range and has similar water supply problems to Australia. So the scheme is to build a range of mountains down the western side of Australia to catch the rain and direct it inland.

This scheme fails primarily because of the cost required to build mountains that high. Only a tiny percentage of the cost would be recoverable through mined byproducts.

2.3. Implementing a water trading scheme for farmers.

Rather than increasing the supply of water, induce farmers to fight each other over a progressively more expensive and dwindling resource.

This has so many negative aspects that it is difficult to state them all. It would lead to losses in time, effort and money to an ever-growing beaurocracy that essentially does nothing. It would lead to the generation of a number of fat-cat middlemen who make a profit off water trading at the expense of the farming community. And it would lead to a reduction in food and clothing production even as the need for food and clothing is increasing. This would be a complete disaster in the long term, with losses in export earnings and massive food price hikes because of the food shortages. In short, it would destroy Australia’s economy.

3. What to do with the centre of Australia?

Australia has a surplus of salt lakes. It has a far larger area of salt lakes than fresh water lakes. Let’s consider Lake Eyre. Could it be turned into a freshwater lake or an inland sea? The answer to both is “yes”. After considering both possibilities, I’ve come to the conclusion that turning it into an inland sea would be best.

To make Lake Eyre into an inland sea would be fairly easy. Construct a sea level shipping channel from the tip of Spencer’s Gulf through Lake Torrens to Lake Eyre. This is an old river bed. The dry salt pan of Lake Torrens would disappear, but would be flushed out with seawater first to remove the salt. Evaporation would remove water from the new Lake Eyre, but this would be refilled by seawater from Spencer’s Gulf. Occasional flushing of excessive salt out by rain and with the help of tides would keep the salt level in Lake Eyre stable. The ongoing maintenance cost would be negligible.

An advantage of making Lake Eyre and inland sea would be that it would remain a mecca for wildlife permanently, rather than on rare occasions. The stability of level would allow permanent colonisation by fish and birds, molluscs and arthropods, as well as providing a beach line along which towns could be built.

What has this to do with water supply? Nothing. But once settled, there are other rivers and lakes nearby that could be flushed out and used as sources and storages of fresh water for local use.

The alternative of turning Lake Eyre into a freshwater lake would rely on pumping the water out to the sea (via Lake Torrens) whenever it gets too salty. This would turn both Lake Eyre and lake Torrens into freshwater lakes, and could be used to supply Adelaide and surrounds with fresh water. But as a source of fresh water it would be very ephemeral unless extra steps were taken to reduce evaporation and/or infiltration. There would also be the cost involved in pumping water from Lake Eyre to Lake Torrens, and across the Yorke Peninsula.

4. Moving Australia’s population.

Rather than moving Australia’s water from where it is to where it is needed, move Australia’s population from where it is to where the water is. This scheme is quite feasible, and cheap. All that really needs to be done is to provide infrastructure (road, rail, air, flood protection, good harbours) and the people will come. Soils tend to be poor in regions were Australia has an excess of water, but by good management and appropriate crops that can be rectified. A practical aim would be to allow for a population exceeding 5 million north of latitude S18° with a hundred years.

5. Directing water from the North of Australia down to the South East and South West.

The lowest cost version of this that I’m aware of was proposed by Rex Macintosh. Start with the Flinders River. The Flinders River begins in the Great Dividing Range near Hughenden. It transports a massive volume of water to the Gulf of Carpentaria in the wet season each year. It has an absolutely massive catchment area in a part of the continent with very high rainfall.

Capture some of that water and pump it to a high place on the Great Dividing Range. Then use a channel and gravity to direct water down the Great Dividing Range to where it can be used for coastal uses and for refilling the Murray-Darling Basin. One relatively cheap and simple version takes the channel from near Hughenden along the range to Lake Galilee (presently a salt lake) and from there to Lake Maraboon (a dam on the Nogoa R.) and from there to near Taroom on the Dawson R., from which it could be directed either across the range to the Condamine R. (which feeds the Darling) or east to the coastal area around Brisbane.

Another version is the Bradfield Scheme. Original documents can be found in the Australian National Museum in Canberra. From memory, it involves connections from two rivers, one of which may be the Flinders R. and the other the Burdekin R. across into the Thompson R. which feeds water into Lake Eyre.

A variant on the Bradfield Scheme is to take the water to the east of the Thompson R., on the western flank of the Great Dividing Range, down to the Warrego R. or Paroo R. to feed into the Murray-Darling system.

There has been a recent proposal to feed water down from the Kimberley region to Perth.

6. SE Coast road, rail and pipeline link.

It used to be that people driving between Sydney and Melbourne had the choice of going via the Hume or Princes Highway. These days, nobody would consider the Princes Highway if time were a factor. The road between Nowra and Eden is very poor. By the same token, the railway through the coastal towns between Nowra and Orbost doesn’t even exist.

I strongly suggest a joint road, high-speed rail and water pipeline link from Sydney to Melbourne via the coast. The high speed rail would have something like fourteen intermediate stops between Sydney and Melbourne. The water pipeline would extend from Nowra to (or below) the Thompson Dam linking the two major cities. This would allow the pipeline to be linked in later to any further water sources developed between The Shoalhaven R. and Thompson R. Water could flow either way along the pipeline, allowing for water-balancing operations between Sydney and Melbourne.

Later, the pipeline could be extended to Brisbane to pick up any future water sources on the North Coast of NSW and/or to Adelaide to help to overcome water restrictions there.

7. Greater use of desalinated seawater.

Dubai is a city with a large population that is growing rapidly. Dubai is also a city in a desert with no water supply from rivers, but Dubai has no water supply problem. Why? The reason is desalination. Practically all the water for Dubai, and for nearby Abu Dhabi, comes from seawater desalination. The desalination plants installed in Australia, by comparison, are tiny.

Let me also digress slightly into the topic of water quality and cost. Farms in Australia get water at roughly one tenth of the cost of cities. The difference in cost is solely due to quality. The catchments for city water are protected, and the water is ensured free from contamination all the way from the catchments to the tap. Desalinated water is also of extremely high quality, and hence is suitable as a source of city water, but not as a source of water for farms.

So one option is to get ALL Australia’s city drinking water from seawater desalination. The resulting power costs would be large but not excessive. This would free up a lot of extra water for farm use. In addition, the catchments for this farm water would no longer need such strict protection and so could be opened up as recreational areas. An immediate gain would be the diversion of water currently held in Warragamba Dam into the Lachlan and/or Macquarie Rivers, significantly easing the water problems of the Murray-Darling. From Brisbane the gain would be to the Condamine R., and from Melbourne the gain would be to the Goulburn R.

8. Making Sydney Harbour a fresh water lake. A not-so-grandiose scheme.

Have you by any chance noticed traffic congestion on the Sydney Harbour Bridge and Bradfield Highway? A new road crossing of Sydney Harbour is desperately needed to ease the congestion. Plans were drawn up many years ago for a new bridge at Cremorne, and at least one Sydney engineer has suggested a crossing between Bradley’s Head and Point Piper.

Note that Sydney does not rely on cargo traffic through the heads, that the heads are very close together, and that Sydney Harbour holds a lot of water. So let’s build a weir across the heads of Sydney Harbour. An allowance would be made for small craft to pass through. Sydney Harbour would then fill with fresh water, and by putting a water purification plant on the foreshore, the water supply for Sydney would be assured for a long time.

Compared with the grandiose schemes mentioned above, this option is very very inexpensive. A bridge over the weir connecting the heads would also go a long way towards solving the Harbour Bridge traffic problem. The one and only disadvantage of putting a weir across Sydney Harbour would be that it would raise the water level in the Harbour by about a metre, which is not too great a rise to cope with.

Once successful, proposals may come forward for turning some other lakes adjoining the ocean into freshwater lakes.

9. Melbourne 1985.

In 1985, a report came out evaluating options to overcome the problem of water shortages in Melbourne. The report found three high priority low cost sources of water - all equally good - and nothing else was anywhere close to as good. One was a site on the Snowy R. below the intersection with the Delgate R. One was on the Goulburn R. The third I don’t remember clearly, but was on either the Mitchell R. or Macalister R.

To give you some idea of the potential of these sites, most of the Snowy Mountains Scheme runs of less than 20% of the catchment area of the Snowy R. With the Snowy below Delegate, we’re talking about more like 60% of the catchment area.

None of the three were implemented, and very little has been done in the past 25 years in Victoria. East Gippsland is still subject to unwanted flooding.

10. North Coast NSW.

There isn’t a single reservoir of any significant size between Sydney and the Queensland border. There isn’t even any significant groundwater usage. This is so bad as to be criminal. Rainfall intensities are high, unwanted flooding is common, and nothing significant is being done about it.

The two rivers with greatest potential on the north coast of NSW are the Hunter and its tributary the Goulburn, and the Clarence and its tributary the Nymboida. In both cases the lower reaches are unsuitable for reservoir construction because of the amount of farmland and number of homes involved. For example, there’s a geologically beautiful dam site just below the Clarence - Nymboida junction, but it’s impossible because it would flood too many farms.

Upper reaches of some rivers are off limits because of reserves such as the “Wild Rivers” park and the reserve on Guy Faulkes R. In addition, the New England plateau slopes gently to the west, which limits the size of catchment areas. But dozens of good sites for small water supply (and hydroelectricity) reservoirs remain. These are individually not very large, but could be linked together into a water supply exceeding that of the South Coast of NSW.

Water captured on the upper tributaries of the Clarence R could easily be redirected through a few tunnels across the McPherson range to the Gold Coast, up onto the plateau for Toowoomba, down to Coffs Harbour and places further south along the coast, or through the Great Dividing Range to the Dumaresq R which feeds the Murray-Darling system.

11. Water farming.

One financial alternative to the purchasing of large plots of land for the siting of reservoirs is “water farming”. In water farming a rural landowner gets paid for the water on his land as if it was a cash crop. The value of the amount of water extracted from a reservoir for water supply or hydroelectric purposes is apportioned between the landowners who own the land on which the reservoir sits.

12. Flood harvesting.

This brilliant idea is so feasible that it has already been implemented in at least one location in Australia, but could be applied successfully at hundreds if not thousands of locations all around the country. I’m not sure that I can describe it properly, but let me try.

The first part of the basic idea is to catch only floodwater from a river system, and not all of that. This would be done by putting an inlet or inlets above the level of normal flow. Each inlet would be small, they could be made so small as to be essentially invisible. Each inlet would have a screen at the top to keep out unwanted animals, plants and/or boulders.

The concept is to get a water supply that is completely environmentally friendly, not overly expensive, and doesn’t require the building of any extra reservoirs. Instead, pre-existing reservoirs that are running at only a percentage of their full level would be filled up. Currently, by far the majority of reservoirs in Australia are well below their full level.

Once water enters the inlet, it could be transported to the pre-existing reservoir using a trough, pipe or tunnel. One simple case I can think of would be like an ag-drain or a stormwater drain, a buried pipe with slits along the top for water to enter. This water would then drain under the action of gravity to the pre-existing reservoir. There are many possible arrangements. All they need in common is to have an inlet above the normal water flow level that can only be reached under flood conditions or when the water level is otherwise exceptionally high.

The system would be especially suitable for creeks that have too small a catchment area to warrant the construction of a reservoir. There are plenty of creeks like this, such as those running between the Cataract, Cordeaux and Avon reservoirs inland from Wollongong.

Normal creek and river flows are unaffected by this scheme. A system could even be set to aid rather than interfere with that dangerous sport white-water rafting, so would even be suitable for the “Wild Rivers” park.

13. Prize for best solution to Australia’s water supply problem.

Every engineering project of any significance since the invention of the wheel has had to cope with protesters. People protest for a wide variety of reasons, and it’s never possible to deal with them all. But it did occur to me that “democracy” in its original form was actually government by the people, and the people who would govern at any particular time were chosen by lottery. What if the solution of Australia’s water supply problems was opened up to the public? Any person or organisation would be permitted and in fact encouraged to find a solution. The whole thing could be opened up to competition with significant prize money at the end of it.

The entrants to the competition, and any other member of the public who wants, would be given copies of appropriate data predicted 50 and 100 years into the future. This would include maps of rainfall, maps of water loss through evaporation, water loss through infiltration, water loss through transpiration and growth of native plants. It would show maps of water demand for drinking water and farm use. It would include a map of topography. And a map of environmental sensitivity and land use. All these maps would be very detailed and in a format readable by any geographic information system (GIS) software. Additional information would include costing for reservoir construction, land purchase, pipelines, channels, other ways of shipping water, desalination, as well as engineering data.

Judging of the competition would be by public vote after technical assessment by a wide-ranging panel of experts. The technical assessment would ensure that the entries satisfy the criteria of not fudging the figures.

One way in which this would help is that opinionated members of the public would end up protesting in favour of a particular solution, whichever one they happen to favour, rather than protesting against everything - when tends to be the norm.