Murray River
The Murray River is a river in Southeastern Australia. It is Australia's longest river, having an extent of. Its tributaries include five of the next six longest rivers of Australia. Together with that of the Murray, the catchments of these rivers form the Murray–Darling basin, which covers about one-seventh the area of Australia. It is widely considered Australia's most important irrigated region.
The Murray rises in the Australian Alps, draining the western side of Australia's highest mountains, then meanders northwest across Australia's inland plains, forming the border between the states of New South Wales and Victoria as it flows into South Australia. From an east–west direction it turns south at Morgan for its final, reaching the eastern edge of Lake Alexandrina, which fluctuates in salinity. The water then flows through several channels around Hindmarsh Island and Mundoo Island. There it is joined by lagoon water from The Coorong to the south-east before emptying into Encounter Bay through the Murray Mouth, east of Goolwa South. Despite discharging considerable volumes of water at times, particularly before the advent of large-scale river regulation, the waters at the Murray Mouth are almost invariably slow and shallow.
, the Murray River system received 58 per cent of its natural flow; the figure varies considerably.
The border between Victoria and New South Wales lies along the top of the southern or left bank of
the Murray River.
Geography
The Murray forms part of the long combined Murray–Darling river system that drains most of the inland of Victoria, New South Wales and the southern part of Queensland. The Murray carries only a small fraction of the water of comparably sized rivers in other parts of the world, and with great annual variability of its flow. It has dried up completely during extreme droughts on three occasions since official record-keeping began. More often, a sandbar formed at the mouth and stopped the flow.The Murray is the border between New South Wales and Victoria – specifically at the top of the left bank. In a 1980 judgement, the High Court of Australia ruled on the question as to which state had jurisdiction in the unlawful death of a man who was fishing by the river's edge on the Victorian side of the river. This boundary definition can be ambiguous, since the river changes its course over time, and some of the river banks have been modified.
For west of the line of longitude 141°E, the border is between Victoria and South Australia, in the middle of the river. The discrepancy was caused during the 1840s, when the border was originally surveyed, by an east–west miscalculation of 3.72 kilometres, and led to a long-running boundary dispute. West of this sector, the Murray is entirely within the state of South Australia.
Major settlements
Major settlements along the course of the river, from its source to the Southern Ocean, and their populations from the 2016 Australian census are as follows.Tributaries
River life
The Murray and its tributaries support a variety of river life adapted to its vagaries. This includes native fish such as the famous Murray cod, trout cod, golden perch, Macquarie perch, silver perch, eel-tailed catfish, Australian smelt and western carp gudgeon, as well as other aquatic species such as the Murray short-necked turtle, broad-clawed yabbies and the large-clawed Macrobrachium shrimp, in addition to aquatic species more widely distributed through Southeastern Australia such as common long-necked turtles, common yabbies, the small claw-less paratya shrimp, water rats and platypus. The Murray crayfish, an endangered species, was able to increase its numbers thanks to scientists. The Murray also supports fringeing corridors and forests of the river red gum.The health of the Murray has declined significantly since European settlement, particularly through regulation of its flows. Extreme droughts between 2000 and 2007 put significant stress on river red gum forests, leading to mounting concern over their long-term survival. The Murray has also flooded on occasion. The most significant was the flood of 1956: lasting for up to six months, it inundated many towns on its lower reaches in South Australia.
Ancient history
Lake Bungunnia
Between 2.5 and 0.5 million years ago, the Murray terminated in a vast freshwater lake – Lake Bungunnia – formed by earth movements that blocked the river near Swan Reach. At its maximum extent, Lake Bungunnia covered, extending to near the Menindee Lakes in the north and to near Boundary Bend in the south. The draining of Lake Bungunnia occurred approximately 600,000 years ago.Deep clays deposited by the lake are evident in cliffs around Chowilla in South Australia. Considerably higher rainfall would have been required to keep such a lake full; the draining of Lake Bungunnia appears to have marked the end of a wet phase in the history of the Murray–Darling Basin and the onset of widespread arid conditions similar to today. A species of Neoceratodus lungfish existed in Lake Bungunnia; today Neoceratodus lungfish are only found in several Queensland rivers.
Cadell Fault and formation of the Barmah red gum forests
The noted Barmah River red gum forests owe their existence to the Cadell Fault. About 25,000 years ago, displacement occurred along this fault, raising its eastern edge, which runs north–south, above the floodplain. This created a complex series of events. A section of the original Murray River channel immediately behind the fault was rendered abandoned. The Goulburn River was dammed by the southern end of the fault to create a natural lake.The Murray River flowed to the north around the Cadell Fault, creating the channel of the Edward River which exists today and through which much of the Murray's waters still flow. Then the natural dam on the Goulburn River failed, the lake drained, and the Murray changed its course to the south and started to flow through the smaller Goulburn River channel, creating "The Barmah Choke" and "The Narrows", before entering into the proper Murray River channel again.
The primary result of the Cadell Fault – that the west-flowing water of the Murray River strikes the north–south fault and diverts both north and south around the fault in the two main channels in addition to a fan of small streams, and regularly floods a large amount of low-lying country in the area. These conditions are perfect for river red gums, which rapidly formed forests in the area. Thus the displacement of the Cadell Fault 25,000 BP led directly to the formation of the famous Barmah river red gum forests.
The Barmah Choke and The Narrows restrict the amount of water that can travel down this part of the Murray. In times of flood and high irrigation flows the majority of the water, in addition to flooding the red gum forests, actually travels through the Edward River channel. The Murray has not had enough flow power to naturally enlarge The Barmah Choke and The Narrows to increase the amount of water they can carry.
The Cadell Fault is quite noticeable as a continuous, low, earthen embankment as one drives into Barmah from the west, although to the untrained eye it may appear man-made.
File:Confluence of Murray & Darling Rivers, Wentworth, NSW, 9.7.2007.jpg|thumb|center|750px|The confluence of the Darling and Murray Rivers at Wentworth, New South Wales
Murray mouth
The Murray Mouth is the point at which the Murray River empties into the sea, and the interaction between its shallow, shifting and variable currents and the open sea can be complex and unpredictable. During the peak period of Murray River commerce, it presented a major impediment to the passage of goods and produce between Adelaide and the Murray settlements, and many vessels foundered or were wrecked there.Since the early 2000s, dredging machines have operated at the Murray Mouth for 24 hours a day, moving sand from the channel to maintain a minimal flow from the sea and into the Coorong's lagoon system. Without the dredging, the mouth would silt up and close, cutting the supply of fresh sea-water into the Coorong National Park, which would then warm up, stagnate and die.
Mythology
Being one of the major river systems on one of the driest continents on Earth, the Murray has significant cultural relevance to Aboriginal Australians. According to the people of Lake Alexandrina, the Murray was created by the tracks of the Great Ancestor, Ngurunderi, as he pursued Pondi, the Murray Cod. The chase originated in the interior of New South Wales. Ngurunderi pursued the fish on rafts made from red gums and continually launched spears at his target. But Pondi was a wily prey and carved a weaving path, carving out the river's various tributaries. Ngurunderi was forced to beach his rafts, and often create new ones as he changed from reach to reach of the river.At Kobathatang, Ngurunderi finally got lucky and struck Pondi in the tail with a spear. However, the shock to the fish was so great it launched him forward in a straight line to a place called Peindjalang, near Tailem Bend. Eager to rectify his failure to catch his prey, the hunter and his two wives hurried on, and took positions high on the cliff on which Tailem Bend now stands. They sprung an ambush on Pondi only to fail again. Ngurunderi set off in pursuit again but lost his prey as Pondi dived into Lake Alexandrina. Ngurunderi and the women settled on the shore, only to suffer bad luck with fishing, being plagued by a water fiend known as Muldjewangk. They later moved to a more suitable spot at the site of present-day Ashville. The twin summits of Mount Misery are said to be the remnants of his rafts; they are known as Lalangengall or the two watercraft.
This story of a hunter pursuing a Murray cod that carved out the Murray persists in numerous forms in various language groups that inhabit the enormous area spanned by the Murray system. The Wotojobaluk people of Victoria tell of Totyerguil from the area now known as Swan Hill, who ran out of spears while chasing Otchtout the cod.