For over forty thousand years Aborigines were the only people to occupy Australia. Their sustenance was based primarily on hunting and gathering. When European settlers arrived in 1788 they sought to obtain their food from cultivation and grazing which both require greater water supplies. The first part of this paper describes the search by early explorers for an inland sea, the second examines the possibility of enhancing inland water supplies, the third discusses the disastrous effects of some grazing practices in inland Australia, while the fourth examines the possibility of counteracting sea-level rise caused by global warming.
THE SEARCH FOR AN INLAND SEA
The Eromanga Sea
When Australia broke away from Gondwanaland in the Cretaceous period, more than 110 million years ago, the centre of the continent was covered by a vast inland sea. The sea is now known as the Eromanga Sea after the small town in southwest Queensland which is more distant from the coast than any other in Australia (Fig. 1.). Strange creatures inhabited the shallow sea including dinner-plate-sized oysters and long-necked plesiosaurs together with the fearsome predator Kronosaurus queenslandicus. Possibly they lived in the sea to escape land temperatures believed to be 17[degrees]C hotter than today. In the 1930s, a Harvard University team discovered the two-metre long fossilised head of Kronosaurus. They dynamited it out of solid rock and shipped all 4 tons back to the USA where it took 20 years to extricate the skull (Fig. 2.). When the Eromanga Sea started to disappear it left a legacy of opal deposits near the perimeter of the former sea. The opals are found in a narrow band only a few metres deep, but as their occurrence is unpredictable, no major companies are involved in opal mining. Nevertheless hardy entrepreneurs, often living in underground houses, risk their lives searching for the elusive gems in remote mining settlements like Lightning Ridge, White Cliffs, Coober Pedy and Andamooka.
To the surprise of the early mariners who explored Australia's coastline none of them discovered the mouth of any great river. Consequently, explorers including Flinders, Banks, Oxley, Sturt and King, all assumed that rivers flowing inland from the Great Dividing Range must flow towards an Inland Sea (Flannery 1998, 226; Johnson 2001, 21). Sturt searched for the supposed sea commencing from Adelaide, Oxley from Sydney and Leichhardt from Brisbane, the latter's expedition disappearing into the interior never to be seen again. While Oxley was making his abortive inland search in 1827, Thomas Maslen, a former British East India Company employee and an enthusiastic advocate of increased antipodean settlement, published an enticing map which depicted, quite falsely, a vast blue lake in the heart of Australia (Fig. 3.). In 1830, after enduring extreme hardship, Charles Sturt discovered the mouth of Australia's largest river, the Murray, but fourteen years later he was still searching in vain for the Inland Sea (Australian Encyclopaedia 1979, 5:464; Bonython 1971, 1).
The Discovery of Lake Eyre and the Great Artesian Basin
In 1840 Edward John Eyre struggled through parched land and discovered Lake Eyre South--normally an arid, retina-burning salt playa--unaware that he was heading towards the driest portion of the world's driest inhabited continent. The average rainfall at Lake Eyre is less than 150 mm p.a. (six inches) while evaporation rises to a staggering 3500 mm p.a. (11 feet) (Figs. 5a & b.). It's rather like trying to fill up a gas-guzzler without switching off the engine! Moreover the term 'average rainfall' is often meaningless as a short 'wet' year may well be followed by half-a-dozen almost rainless years.
In 1858 B.H. Babbage discovered Lake Eyre North, which was also dry. Burke and Wills commenced a transcontinental crossing from Melbourne to the Gulf of Carpentaria in 1860, and finally brought speculation to the bleak conclusion that no freshwater lake graced our continent's interior, before they perished from starvation on the return journey (Johnson 2001, 75; Murgatroyd 2002, 274). In 1874 J.W. Lewis made a map of most of Lake Eyre (Fig. 6.). It is basically two basins: Lake Eyre North 140 km long and 70 km wide--and Lake Eyre South, less than a quarter that size. The two are connected by a narrow channel, normally dry, known as the Goyder Channel after the first Surveyor-General of South Australia. The Lake Eyre catchment occupies about 20% of Australia in roughly the same location as the ancient Eromanga Sea. The cities of Mount Isa, Broken Hill and Alice Springs lie on its perimeter (Fig. 7.).
In fact it was not entirely true that central Australia was waterless; a huge lake did exist, not on the surface but hidden beneath the arid heart of the continent: the Great Artesian Basin (Fig. 8.). The basin occupies roughly the same area as the Eromanga Sea, the major portion of the water flowing slowly underground from the Great Dividing Range in north Queensland towards South Australia. Kotwicki (1986, 2) postulates that the water takes 3 million years to seep from north to south. In three states bores recover artesian water, sometimes at great depths and high temperatures. There have been suggestions that superheated water 3 km deep could be turned into thermal power and investigations have commenced (Arup 2011). In the past some boreholes were uncapped allowing water to go to waste; today the law requires that they be capped. In a few areas the artesian water flows naturally to the surface where sediments gradually create mounds more than 10m high from which a spring may continue to bubble (Fig. 9.).
The Roxby Downs--Olympic Dam mine is the world's largest uranium mine and is situated 60 km south of Lake Eyre. Since 1982 the mine has been drawing ever increasing quantities of water from the Great Artesian Basin. In order to increase production the owners are considering construction of a sea-water desalination plant in the Spencer Gulf (BHP Billiton 2011, 13).
As the driest of the States, South Australia is reliant on the Murray River for much of its fresh water through two major pipelines running from Murray Bridge to Adelaide and from Morgan to Port Augusta; a smaller pipe continues to Woomera (Badman, Arnold & Bell 1991, 1). Unfortunately much of the Murray's water is extracted before it reaches South Australia. The Commonwealth government is buying back irrigation rights in an endeavour to resuscitate the river.
THE IMPACT OF LAKE EYRE ON PEOPLE
Kotwicki (1986, 50) states that from remote times Aborigines shunned Lake Eyre because of its 'evil influences'. Perhaps this is unsurprising as much of the 'lake' is surrounded by the Simpson, Tirari and Anna Deserts with 30-metre sand dunes, no fresh water, no trees and no shade, where unprepared travellers have perished from thirst. In 1865-66, in order to open up the inland, the South Australian firm Elders imported 120 camels together with their Afghan cameleers (Australian Encyclopaedia 1979, 1:449). Most camel men came from the vicinity of Kabul or Kandahar, while some came from Peshawar--part of Afghanistan until captured by the British in 1893 (Stevens 2002, 2). The South Australian colonial government carefully registered the arrival of every camel, but the Afghans required neither immigration permits nor passports. While some cameleers served three-year contracts and returned home, others lived on in 'Ghan towns' outside Marree, Broken Hill, Cloncurry, Coolgardie, Oodnadatta, Wyndham and other towns, sometimes becoming traders and marrying locals. The Afghans helped build the Overland Telegraph from Adelaide to Darwin and the old Ghan railway. The track laying from Adelaide commenced in 1878 and reached Oodnadatta three years later but it was another 40 years before it was extended to Alice Springs.
Fifty kilometres east of Lake Eyre, on the banks of Cooper Creek, hardy Lutheran missionaries ministered to Aborigines for fifty years, supplying the Aborigines with regular Government rations. One of the mission helpers summed up the lifestyle: "Hot and dry, blazing sky, plenty fly, oh! my eye, close up die." Although no missionaries visited the lake they considered that the great flood of 1906 must have reached it. When the mission was abandoned the Powell family from England bought the 'pastoral' lease sight unseen. After endless droughts they too left in despair.
In 1865 Surveyor-General Goyder set out a line to indicate the northern limit of country safe for crop cultivation. This excluded 80% of South Australia, and became known as the Goyder Line. Tragically for the friable soil there were a few good seasons, the government leased out vast swathes of land and large acres of wheat were planted. For a short period South Australia produced more grain than any other State but when the rains failed a dustbowl was created. While there is no more cultivation north of the Goyder Line, pastoralists still occupy many leases.
In 1922, G.H. Halligan flew over the lake and reported that he'd observed some flooding but he was vilified by less fortunate explorers who disbelieved him (Kotwicki 1986, 50). When Lake Eyre flooded in 1950, Eric Bonython made three attempts to reach it. The first two by motor vehicle failed. For the third, successful, expedition he travelled down Cooper Creek using a boat with an outboard motor and towing a dinghy with spare fuel which was just sufficient for him to reach the lake and return safely (Bonython 1971, 161). In 1964 Sir Malcolm Campbell chose Lake Eyre to set the world land speed record of 648 km/h.
In 1974 there occurred the largest flood ever observed and scientists took the opportunity to make numerous studies of salinity, plankton, botany and geology, and compiled a bathymetric chart of the lake (Fig. 10.). Lake Eyre North was found to have two shallow basins 15 m below sea-level. Contrary to popular legend 'that the lake only fills twice a century' Kotwicki found that some flood water enters Lake Eyre North every few years but only one--in 1974--filled it so completely so that it overflowed into Lake Eyre South. Flood incidents were categorised as follows:
Minor Flooding: Up to 2 m water covering half the lake: once in 3 years.
Major Flooding: Up to 4.5 m water covering all 8,000 [km.sup.2] of the lake: once in 10 years.
Filling: Filling another 50 cm: 2-4 times per century.
Great Filling: More than 5 m water: 2-4 times per millennium.
In terms of volume Kotwicki estimated a maximum of 36 [km.sup.3] once a century (Kotwicki 1986, 63). Littoral debris suggests that the Great Filling of 1974 was exceeded on three occasions in prehistoric times, one of which put 200 [km.sup.3] of water in the lake.
In the major flood of 1984 Lake Eyre South flooded and, for the only time ever recorded, overflowed into Lake Eyre North--taking most of its salt bed with it (Fig. 12.). There was panic that the Ghan railway would be washed away and that vital supplies to Alice Springs would be cut off. Truckloads of rock were rushed in and the railway bed was raised by 1.37 metres. In the nick of time the track was saved (Macdonald 1989). The Marree-Oodnadatta road was flooded, forcing the evacuation of a BBC film crew by rail. Subsequently the old Ghan railway was abandoned beyond Leigh Creek and a new standard-gauge Ghan was built from Tarcoola on the Indian-Pacific rail line to Darwin. In 2009, north Queensland received exceptionally large rainfall and the writer camped on the treeless shore of Lake Eyre North just as the flood waters reached their peak some 300 mm short of overflowing into Lake Eyre South (Fig. 11.). Because the terrain is extraordinarily flat, floods take several months to reach the lake; at the time of writing there are predictions that the 2010 flood will match that of 2009.
ENHANCING WATER SUPPLIES
Filling Lake Eyre
In 1929 Dr John Bradfield, the engineer who built the Sydney Harbour Bridge, proposed a scheme to turn back the Tully River in north Queensland with a view to improving the flow in the Burdekin River and so permanently fill Lake Eyre with fresh water through the Diamantina River. The scheme became known as the Bradfield Scheme and has been furiously debated since then--particularly during the great droughts caused by El Nino. Almost all the rare major floods occur in La Nina years. The original Bradfield Scheme did not include the possible filling of Lake Eyre from the sea but today this possibility is also sometimes referred to as his scheme. The idea of filling Lake Eyre from the sea was raised in the South Australian parliament as early as 1883 but rejected on the grounds that it would take vast amounts of money to dig a 350 km canal. The main arguments against filling Lake Eyre from the sea concern the high cost and uncertain benefit. Nevertheless, if essential, water can be carried long distances. To service the Kalgoorlie gold mines in Western Australia, 22.75 ML of water per day have been piped 554 km since 1903 (Jarvis 1979, 73). Of course water can also be carried by tunnels and canals; nor are canals new: the Pharaohs built one from the Nile to the Red Sea, and China commenced its 700 km Grand Canal in the seventh century. There are some surprisingly long systems:
Length Cross section TUNNELS Built to carry: (km) ([m.sup.2]) Paijanne Tunnel, Finland water 120 16 Orange-Fish, South Africa water 82.8 23 Seikan, Japan trains 53.9 74 Channel Tunnel trains 50.5 2x45+1x18 CERN, France-Switzerland particles 27.0 11-16 Laerdal, Norway motor vehicles 24.5 9x? m CANALS White Sea, Baltic, 1933 small ships 227 3.5 m deep Suez, Egypt, 1869 ships 160 300 m wide Kiel, Germany, 1895 ships 98 42x14 m Panama, 1914 ships 82 33.5x25.9 m PIPELINES Caspian-Mediterranean oil 1,768 1.07 Alyeska, Alaska oil 1,300 1.22
If seawater were to be used to fill Lake Eyre it would have to come from the northern end of Spencer Gulf at Port Augusta. A tunnel would probably have to start near Port Augusta, run for 350 km across the flat plain west of the Flinders Ranges and lie buried at least 100 m below ground level (Fig. 13.). Alternatively water would have to be pumped up to and channelled across Lake Torrens which lies at an altitude of some 33 m above sea-level and runs North-South for 200 km towards Lake Eyre. The day the writer climbed a hillock and photographed his vehicle standing on Lake Torrens, there were no other humans, animals or birds, nor any wind, making it the quietest place he had ever visited (Fig. 14.). Yet another proposal has been to pump seawater to Lake Frome from where it would gravitate into Lake Eyre.
There has long been speculation as to whether a permanently full Lake Eyre would increase surrounding rainfall. In 1981, the head of the Australian Department of Meteorology said that it would do so, while others suspected that it would not, pointing to the Arabian Desert which is surrounded by water (Qld N.P.A. Water Resources Sub-committee, 1981, para.2.1). However, not all of Arabia is desert: as a result of rain received from the southwest monsoon, Oman has pockets of natural vegetation and agriculture (Mansfield 1978, 385).
A check shows that at Marree, the town closest to Lake Eyre, annual rainfall 2 1/2 times greater than the mean was recorded after the major floods of 1950, and again in the three years after the great filling of 1974 (Bureau of Meteorology 2012). The writer has the view that, if water evaporates it must go somewhere. Even if some precipitates in the Flinders or Great Dividing Ranges, it would augment river flow and plant growth. As opinion is divided on what happens when lakes fill up with water, the writer has also examined the reverse: what happens when they dry up.
The Aral Sea and Lake Chad
The Aral Sea in Central Asia used to be seven times the size of Lake Eyre. In order to irrigate cotton, the Soviet Union extracted water from the two rivers that previously filled it. Between 1989 and 2008 the sea lost 95% of its volume--an ecological catastrophe of world significance--and the former sea split into three shallow lakes. The southern two lie in Uzbekistan which has not taken remedial action despite the destruction of its entire fishing industry and a reported decline in surrounding rainfall (Fig. 15.). Lake Aral North lies in Kazakhstan. It too was drying up until the government decided to take remedial action by building a concrete dyke across the channel joining the north and south lakes. Water level rose faster than predicted and there are reports that rainfall has increased (Alles 2011).
Lake Chad lies between Niger, Nigeria, Chad and Cameroon. It used to be 2 1/2 times the size of Lake Eyre. Between 1963 and 2001 the lake lost most of its water and the 20 million people who live nearby are in dire straits (Fig. 16.). The littoral countries cannot agree on a remedy. Nearby rainfall has been measured for a century. The reduction in the lake has lowered surrounding rainfall by about 20% (Tschierschke 2010, 1). It seems reasonable to conclude that if reducing lake water reduces surrounding rainfall, so filling a lake must increase rainfall.
OVERGRAZING NORTH OF THE GOYDER LINE
Cattle and Goats
Anna Creek station claims to be the world's largest cattle station and has long been regarded as an icon of South Australia's pastoral industry. In May 2009 there were no cattle at all in the southern part of the station, and the Roxby Downs newspaper reported that the manager had resigned and was moving to north Australia.
North of the Goyder Line there are hundreds of abandoned homesteads. Though the houses are no longer inhabited, the surrounding land is still grazed when there is a little rainfall. The net result is that when high winds blow across southern Australia, vast clouds of red dust are scattered for thousands of kilometres, blanketing eastern Australia and even depositing red dust in New Zealand.
The Pastoral Board of South Australia, established in 1891, is responsible for monitoring land use north of the Goyder Line. It aims to inspect the 328 pastoral leases, which occupy 70% of northern South Australia, at 14-year intervals but has reported it will not meet this target with current staff numbers (SA Pastoral Board 2008). Cognisant of the continuing drought, it has noted that some properties have reduced or relocated stock while others have embraced tourism or camels. It has also noted the spread of unwanted Buffel grass and dieback in Western Myall trees--a species that can live for 600 years (SA Arid Lands Natural Resource Management Board 2009). However well-intentioned the original Goyder Line, one has to wonder whether any hard-hoofed stock, such as cattle, should be permitted to destroy the fragile residual vegetation. While there are no hard-hoofed sheep north of the dingo-fence because of dingo predation, one pastoral station is trialling goats, which have caused devastation to vegetation in the Western Division of NSW. Historian Charles Bean, wrote "There was not a blade of grass on the earth; but the stock walked over the face of it until it was worked into a hard crust" (Bean 1910, 95). In 1947 in Africa, the catchcry was "After the cattle the sheep; after the sheep the goats; after the goats the desert." Jared Diamond (1997, 398) equates several Australian farming practices to 'mining'. In 2009, former NSW premier Bob Carr likened much of Australia to the Sahara rather than a breadbasket, stating "We resemble North Africa more than North America", echoing the view of Gentilli who in 1972 equated northern South Australia to the Sahara, and Western Queensland to the Punjab (cited in Kotwicki 1986, 12). When, in May 2010, the writer asked former South Australian Premier Dr. John Bannon what future he saw for northern South Australia, other than mining, Bannon pointed to eco-tourism, national parks and Aboriginal usage, but did not mention pastoralism.
It has long been known from petroglyphs that the Sahara was once savannah country with herds of wild animals (Diamond 1997, 390). The Potsdam Institute of Climate Impact Research has shown from carbon dating that the change from savannah to desert was relatively rapid--about 400 years starting 4,000 years ago (Science Daily 1999). Chesterfield and Parsons (1985), showing photos of pasture damage by cattle, state that "nature conservation programs for woodlands might require virtual eradication of all mammalian herbivores, including goats."
In 2009 the writer visited Australia's Arid Zone Botanical Garden at Port Augusta--which is situated near the Goyder Line--and was impressed by the many tree species that have been established in the sandy desert after excluding livestock. The trees, 4 to 10 metres tall, and including Mallee, Mulga, Coolabah, Myall and Wilga, are flourishing, in stark contrast to the surrounding countryside which is almost devoid of vegetation. The garden illustrates what can be done to reclaim a desert. If it could be extended to include areas of arid Australia presently being devastated by livestock, the trees would absorb carbon and help reduce our greenhouse warming footprint.
It is not just cattle, sheep and goats that overgraze Australia's fragile arid environments. Overgrazing by Australia's more than one million feral camels is also a problem, as it is elsewhere. Asher (1986, 198, 278 & 301), who lived among the Arabs of Kordofan in the Sudan for four years, concluded that excessive camel numbers have a devastating effect on vegetation. In the Northern Territory, some camels have been removed by sales or shooting to reduce pastoral damage. The Australian Government 'Caring for our Country' Business Plan 2009-2010 has identified feral camel management as a priority, estimating the damage they cause at $10 million per annum, and proposing that 670,000 camels be removed over four years and 500,000 over the following four (Dept. of Environment 2010).
SAVING COASTAL CITIES FROM SEA LEVEL RISE
The United Nations estimates that there are at least 3,000 low-lying cities imperilled by rising sea-level. Bangkok, Dhaka and Jakarta are already suffering damage. The Intergovernmental Panel on Climate Change estimate a total rise of between 90 and 880 mm by 2011, while CSIRO puts the figure at between 180 and 590 mm (Holper & Torok 2008, 91; Broecker & Kunzig 2008, 166). Would it be possible to ameliorate rising sea-levels by filling the world's great depressions with seawater? The Caspian and Dead Seas, the Qattara Depression in Egypt, the Salton Sea in California, the Assal in Djibouti & Lake Eyre all lie below sea-level.
What is the threat? Most glaciers are in retreat and cause sea-level to rise (Broecker & Kunzig 2008, 166), but by far the greatest threat to coastal inundation is posed by the possible melting of Greenland and Antarctic ice. If the Greenland and West Antarctica icecaps were to melt, sea-level would rise about eleven metres (Holper & Torok 2008, 91). While East Antarctica holds the greatest volume of ice of all it does not seem in danger of melting (Johnston 2005). Several scientists have estimated the volume of ice held in the great ice-caps; these estimates vary considerably. The volumes of sea water that could be absorbed by the great depressions in the following table are also very approximate:
Est. Sea level Area ice vol. rise if Icesheet ([km.sup.2]) ([km.sup.3]) melted (m) Greenland 1,700,000 3,000,000 +7 West Antarctica 1,500,000 3,000.000 +4 to 6 East Antarctica 8,500,000 23,000,000 +55 Possible Total sea level Area Lowest water vol. reduction Depression ([km.sup.2]) elev. (m) ([km.sup.3]) (m) Caspian 400,000 -1,025 78,000 -0.1 * Dead Sea 4,000 -400 600 -0.001 ** Qattara 20,000 -133 1,300 -0.001 ** Lake Eyre 6,216 -15 200 minimal *** * Estimate based on the Caspian's original water level and on Russia increasing water extracted for irrigation. The volume that could be stored if the Caspian were to be filled to mean sea level would be greater but would drown Astrakhan, Baku, etc. ** Estimate assumes a high evaporation rate due to hot climate. *** Estimate based on highest historic flood.
Jordan has examined a proposal to use water from the Red Sea to fill the Dead Sea which has been drying up in recent years; a case perhaps of "rather red than dead"! Israel has considered a proposal to fill the Dead Sea from the Mediterranean (Beyth 2008). There has also been a suggestion that Egypt fill the Qattara and generate hydro-power by channelling water from the Mediterranean down into the depression. While the idea of filling depressions to alleviate sea-level rise might seem far-fetched and expensive, if it were undertaken, the several billion people who live in the 3000 coastal cities at risk could surely be expected to help defray the cost in order to prevent the destruction of their homes. Moreover, while the water in the depressions would become more saline, there is the hope that surrounding arid lands should benefit from increased precipitation. Israel, Kazakhstan and Morocco are already making strides in reducing desertification. Although Australia's Landcare volunteers have done sterling work in planting trees much more remains to be done.
As several thousand coastal cities are in danger of flooding from rising sea levels, consideration should be given to draining sea water into the world's major depressions that lie below sea level. Funding should logically be provided by the cities that would benefit from the resultant reduced risk of flooding. While filling Lake Eyre from the sea would contribute only minutely to sea level reduction and would be costly, filling it with sea water is likely to increase local rainfall, improve vegetation and hence enhance carbon absorption. Vast swathes of northern South Australia and the Western Division of NSW are at severe risk of being turned into desert through overgrazing by cattle, goats and camels. The Australian government should implement its Caring for our Country business plan recommending the culling of a million feral camels over eight years, and state governments should cull goats and prohibit cattle grazing in marginal areas to allow the natural vegetation to regenerate and so prevent desertification.
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Frank Urban 
 Frank Urban, BSc (Witwatersrand) worked as a land surveyor in Southern Rhodesia before studying aerial mapping at the ITC Netherlands. He then moved to NSW where he became director of that state's Central Mapping Authority. Since retiring he has written Ned's Navy and Mapmaker and currently lectures on 'art masters and their times'. Contact: email@example.com