Lake Alexandrina (South Australia)
Encyclopedia
Lake Alexandrina is a lake
in South Australia
adjacent to the coast of the Southern Ocean
, about 100 kilometres south-east of Adelaide
.
, niece and successor of King William IV
of Great Britain and Ireland. When the princess ascended the throne and took the name Queen Victoria there was some talk of changing the name of the lake to Lake Victoria, but the idea was dropped.
and east of Fleurieu Peninsula
. The Murray River
is the major river to flow into Lake Alexandrina. Others include the Bremer
, Angas
, and Finniss Rivers, all from the eastern side of the southern Mount Lofty Ranges
. The lake is shallow and contains a number of islands near the southern end.
The lake empties into the sea near Goolwa
(the channel is known as the Murray Mouth
), but when the river flow is low the entrance is often blocked by a sand-bar. Originally subjected to tidal and storm inflows of seawater the lake is now maintained as fresh water by a series
of barrage
s across the islands near the Murray Mouth. This has produced an annual requirement for more than 1 million megalitres of fresh water to replace losses from evaporation that once came from sea water.
Though connected to the ocean historically the fresh and salt water flows mixed very little, with the lake area remaining fresh over 95% of the time with normal river inflow. Salt water inflows from the ocean would result in relatively little mixing of fresh and salt water, either vertically in the water column or laterally across the flow stream. Hindmarsh Island
is reputed to be the largest island in the world with salt water on one side and fresh water on the other. Lake Alexandrina is connected by a narrow channel to the smaller Lake Albert to the south-east.
known as the Muldjewangk
.
Edward Wilson
, visiting the lake in the 1850s described it as follows:"Lake Alexandrina is the finest sheet of fresh water I ever saw. Indeed so formidable did it look, with a stiff wind blowing up quite a sufficient swell to make one seasick, that I could scarcely believe it to be fresh. Such is the fact however. It is forty or fifty miles long by twelve or fifteen wide and the shores around it receded into the dim distance until they become invisible, in the way which we are accustomed only with ideas of salt water. Supplied almost entirely by the Murray, the whole lake retains the muddy tinge of which I have spoken, and this sadly detracts from the otherwise beautiful appearances of this magnificent sheet of water."
In 2008, water levels in Lake Alexandrina and Lake Albert
became so low that large quantities of acid sulphate soils threatened to form. The soils on the lake beds are naturally rich in iron sulfides. When exposed to the air, such as may occur in a time of severe drought, the sulfides oxidize, producing sulfuric acid. The barrages
now prevent seawater inflows that have prevented this phenomenon in every drought since the last ice age. A weir has been proposed near Pomanda Island
to protect upriver water supplies should it become necessary to open the barrages.
wader
s, or shorebirds, which breed in northern Asia and Alaska. It forms part of the 1300 km2 Lakes Alexandrina and Albert Important Bird Area
(IBA), identified as such by BirdLife International
because it regularly supports critically endangered
Orange-bellied Parrot
s, endangered Australasian Bittern
s, vulnerable
Fairy Tern
s, as well as over 1% of the world populations of Cape Barren Geese
, Australian Shelduck
s, Great Cormorant
s and Sharp-tailed Sandpiper
s.
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
adjacent to the coast of the Southern Ocean
Southern Ocean
The Southern Ocean comprises the southernmost waters of the World Ocean, generally taken to be south of 60°S latitude and encircling Antarctica. It is usually regarded as the fourth-largest of the five principal oceanic divisions...
, about 100 kilometres south-east of Adelaide
Adelaide
Adelaide is the capital city of South Australia and the fifth-largest city in Australia. Adelaide has an estimated population of more than 1.2 million...
.
Name
The lake was named after Princess AlexandrinaVictoria of the United Kingdom
Victoria was the monarch of the United Kingdom of Great Britain and Ireland from 20 June 1837 until her death. From 1 May 1876, she used the additional title of Empress of India....
, niece and successor of King William IV
William IV of the United Kingdom
William IV was King of the United Kingdom of Great Britain and Ireland and of Hanover from 26 June 1830 until his death...
of Great Britain and Ireland. When the princess ascended the throne and took the name Queen Victoria there was some talk of changing the name of the lake to Lake Victoria, but the idea was dropped.
Description
Lake Alexandrina is located north of Encounter BayEncounter Bay
Encounter Bay is located on the south central coast of South Australia, some 100 km south of Adelaide, South Australia. It is named after the encounter on 8 April 1802 between Matthew Flinders and Nicolas Baudin, both of whom were charting the Australian coastline for their respective countries...
and east of Fleurieu Peninsula
Fleurieu Peninsula
The Fleurieu Peninsula is a peninsula located south of Adelaide in South Australia, Australia. It was named after the French explorer and hydrographer Charles Pierre Claret de Fleurieu by the French explorer Nicolas Baudin as he mapped the south coast of Australia in 1802.Towns of interest in the...
. The Murray River
Murray River
The Murray River is Australia's longest river. At in length, the Murray rises in the Australian Alps, draining the western side of Australia's highest mountains and, for most of its length, meanders across Australia's inland plains, forming the border between New South Wales and Victoria as it...
is the major river to flow into Lake Alexandrina. Others include the Bremer
Bremer River (South Australia)
The Bremer River is a river in South Australia that rises on the eastern side of the Mount Lofty Ranges at an altitude of 431 metres and drains into Lake Alexandrina at the lower end of the Murray-Darling Basin...
, Angas
River Angas
The River Angas is a small river rising on the eastern side of the Mount Lofty Ranges in South Australia. Its headwaters are near Macclesfield and it flows generally southward through Strathalbyn, emptying into Lake Alexandrina near the town of Milang....
, and Finniss Rivers, all from the eastern side of the southern Mount Lofty Ranges
Mount Lofty Ranges
The Mount Lofty Ranges are the range of mountains just to the east of Adelaide in South Australia.-Location and description:The Mount Lofty Ranges stretch from the southernmost point of the Fleurieu Peninsula at Cape Jervis northwards for over before petering out north of Peterborough...
. The lake is shallow and contains a number of islands near the southern end.
The lake empties into the sea near Goolwa
Goolwa, South Australia
Goolwa is a historic river port on the Murray River near the Murray Mouth in South Australia, and joined by a bridge to Hindmarsh Island. The name "Goolwa" means "elbow" in Ngarrindjeri, the local Aboriginal language....
(the channel is known as the Murray Mouth
Murray Mouth
Murray Mouth is the point at which the River Murray meets the southern Southern Ocean. The Murray Mouth's location is changeable. Historical records show that the channel out to sea moves along the sand dunes over time...
), but when the river flow is low the entrance is often blocked by a sand-bar. Originally subjected to tidal and storm inflows of seawater the lake is now maintained as fresh water by a series
Goolwa Barrages
The Goolwa Barrages comprise five barrage structures in the channels linking Lake Alexandrina to the mouth of the River Murray and the Coorong in Australia...
of barrage
Barrage (tidal)
A barrage is an artificial obstruction at the mouth of a tidal watercourse.-Purpose:The common primary functions of a barrage are:* Increase the depth of a river * Maintain a separation between fresh and salt water...
s across the islands near the Murray Mouth. This has produced an annual requirement for more than 1 million megalitres of fresh water to replace losses from evaporation that once came from sea water.
Though connected to the ocean historically the fresh and salt water flows mixed very little, with the lake area remaining fresh over 95% of the time with normal river inflow. Salt water inflows from the ocean would result in relatively little mixing of fresh and salt water, either vertically in the water column or laterally across the flow stream. Hindmarsh Island
Hindmarsh Island
Hindmarsh Island is an island in the lower Murray River near the town of Goolwa, South Australia. Located on the Fleurieu Peninsula, it is a popular tourist destination, which has increased in popularity since the Hindmarsh Island bridge was opened in 2001...
is reputed to be the largest island in the world with salt water on one side and fresh water on the other. Lake Alexandrina is connected by a narrow channel to the smaller Lake Albert to the south-east.
History
In the Australian Aboriginal Dreamtime the lake was inhabited by a monsterMonster
A monster is any fictional creature, usually found in legends or horror fiction, that is somewhat hideous and may produce physical harm or mental fear by either its appearance or its actions...
known as the Muldjewangk
Muldjewangk
The Muldjewangk is a water-creature in Australian Aboriginal mythology that inhabited the Murray River, particularly Lake Alexandrina. It was used as a deterrent for Aboriginal children who wished to play near the riverside after dark. Sometimes they are portrayed as evil merfolk , or times as a...
.
Edward Wilson
Edward Wilson (journalist)
Edward Wilson was an English Australian journalist and philanthropist.Wilson was born at Hampstead, London. He was educated at a private school and then entered a business house at Manchester. He went to London and in 1842 emigrated to Australia...
, visiting the lake in the 1850s described it as follows:"Lake Alexandrina is the finest sheet of fresh water I ever saw. Indeed so formidable did it look, with a stiff wind blowing up quite a sufficient swell to make one seasick, that I could scarcely believe it to be fresh. Such is the fact however. It is forty or fifty miles long by twelve or fifteen wide and the shores around it receded into the dim distance until they become invisible, in the way which we are accustomed only with ideas of salt water. Supplied almost entirely by the Murray, the whole lake retains the muddy tinge of which I have spoken, and this sadly detracts from the otherwise beautiful appearances of this magnificent sheet of water."
In 2008, water levels in Lake Alexandrina and Lake Albert
Lake Albert (South Australia)
Lake Albert is a notionally fresh water lake near the mouth of the Murray River. It is filled by water flowing in from Lake Alexandrina at its mouth near Narrung. It is separated on the south by the Narrung Peninsula from the salt-water Coorong. The only major town on the lake is Meningie...
became so low that large quantities of acid sulphate soils threatened to form. The soils on the lake beds are naturally rich in iron sulfides. When exposed to the air, such as may occur in a time of severe drought, the sulfides oxidize, producing sulfuric acid. The barrages
Goolwa Barrages
The Goolwa Barrages comprise five barrage structures in the channels linking Lake Alexandrina to the mouth of the River Murray and the Coorong in Australia...
now prevent seawater inflows that have prevented this phenomenon in every drought since the last ice age. A weir has been proposed near Pomanda Island
Pomanda Island
Pomanda Island is a low-lying 34 Ha island within Lake Alexandrina, located 87 km southeast of Adelaide and 12 km south of Wellington, South Australia....
to protect upriver water supplies should it become necessary to open the barrages.
Environment
Turtles live in the lake, with lizards and snakes present along the shoreline. Insect species include dragon flies, a range of moths and butterflies and large numbers of beetles (coleoptera). Freshwater fish inhabit the lake, including the introduced European carp. The soils around the lake are relatively low in organic carbon although good barley and vegetable crops may be produced. Non-wetting soils are present along the south eastern bounds of Lake Albert and in areas around Lake Alexandrina.Birds
The lake is a habitat for many species of waterbird, including migratoryBird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
wader
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
s, or shorebirds, which breed in northern Asia and Alaska. It forms part of the 1300 km2 Lakes Alexandrina and Albert Important Bird Area
Important Bird Area
An Important Bird Area is an area recognized as being globally important habitat for the conservation of bird populations. Currently there are about 10,000 IBAs worldwide. The program was developed and sites are identified by BirdLife International...
(IBA), identified as such by BirdLife International
BirdLife International
BirdLife International is a global Partnership of conservation organisations that strives to conserve birds, their habitats and global biodiversity, working with people towards sustainability in the use of natural resources...
because it regularly supports critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
Orange-bellied Parrot
Orange-bellied Parrot
The Orange-bellied Parrot is a small broad-tailed parrot endemic to southern Australia, and one of only two species of parrot which migrate. The adult male is distinguished by its bright grass-green upperparts, yellow underparts and orange belly patch. The adult female and juvenile are duller...
s, endangered Australasian Bittern
Australasian Bittern
The Australasian Bittern , also known as the Brown Bittern, is found in south-western and south-eastern Australia, Tasmania, New Zealand, New Caledonia and Ouvea. Populations in Australia and New Zealand have declined in the 20th century.It is a large bittern, patterned and streaked brown, buff...
s, vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
Fairy Tern
Fairy Tern
The Fairy Tern is a small tern which occurs in the southwestern Pacific.There are three subspecies:* Australian Fairy Tern, Sterna nereis nereis - breeds in Australia...
s, as well as over 1% of the world populations of Cape Barren Geese
Cape Barren Goose
The Cape Barren Goose is a large goose resident in southern Australia. The species is named for Cape Barren Island, where specimens were first sighted by European explorers.-Taxonomy:...
, Australian Shelduck
Australian Shelduck
The Australian Shelduck, Tadorna tadornoides, is a shelduck, a group of large goose-like birds which are part of the bird family Anatidae, which also includes the swans, geese and ducks. The Anatidae article should be referred to for an overview of this group of birds.This is a bird which breeds...
s, Great Cormorant
Great Cormorant
The Great Cormorant , known as the Great Black Cormorant across the Northern Hemisphere, the Black Cormorant in Australia and the Black Shag further south in New Zealand, is a widespread member of the cormorant family of seabirds...
s and Sharp-tailed Sandpiper
Sharp-tailed Sandpiper
The Sharp-tailed Sandpiper, Calidris acuminata is a small wader.- Taxonomy :More recently, a review of new data has indicated that this bird should perhaps better be placed into the genus Philomachus- as P...
s.