Lake Alexandrina (South Australia)
The Lake Alexandrina is a lake in the south of the Australian state of South Australia. It is located about 100 km southeast of Adelaide and is connected to the Indian Ocean.
The Lake Alexandrina is located north of Encounter Bay and east of the Fleurieu Peninsula. The Murray River is the largest river flowing into the lake. There is also the Bremer River, the Angas River and the Finniss River. All these rivers rise on the eastern slopes of the southern Mount Lofty Ranges. The lake is shallow and at its southwest end, there are many islands.
In the town of Goolwa Lake Alexandrina is connected to the ocean; this place is called the Murray estuary. At low water levels in the rivers this connection, however, is closed by a sandbar. Previously expressed the tide and southwest storms sea water into the lake. Today, however, only fresh water in Lake Alexandrina is because a number of surge barriers between the islands along the Murray estuary were installed. Thus, the lake needed an annual influx of at least 1 billion cubic meters of water to compensate for evaporation losses.
Although the lake was connected to the sea, fresh and salt water did not mix almost; 95 % of the time, it contained only fresh water. The influx of salt water from the sea resulted in only small transverse and longitudinal mixing. Hindmarsh Iceland (east of Goolwa ) is the largest island in the world with fresh water on one side and salt water on the other side. Through a small channel of Lake Alexandrina is connected on the south side with the smaller Lake Albert.
The lake was named after the later to become Queen Victoria, niece and successor of King William IV, who was called in her youth, Princess Alexandrina, named. After the coronation of Victoria, there were some voices that suggested the renaming of the lake in Lake Victoria, but this idea could not prevail.
In the myths of the aborigines of the lake is inhabited by a monster called Muldjewangk.
The Lake Alexandrina offers a number of waterfowl habitat, including some species of migratory birds from the northern hemisphere. Pelicans, black swans, and a number of other birds live on insects, plants and the water of the lake. For example, these are wrens, garden fantails, swallows and ravens. Birds of prey, such as eagles and hawks, are often seen above the water and the adjacent shore areas. Turtles live in the lake, lizards and snakes are found on the shore.
Occurring species of insects, dragonflies, moths and a number of butterflies and a large number of beetles. In the lake there are also fresh-water fish, such as carp. The earth around the lake are low in organic carbon compounds, but the barley and other cereals grow well there. Dry soil there is on the south shores of Lake Albert and in certain areas around Lake Alexandrina.
In 2008, the water levels in Lake Alexandrina and Lake Albert declined to such an extent that large amounts of sulfuric acid formed on earth. The earth at the bottom of the lake are usually rich in natural iron sulfide. If they are exposed to the air intake, as this can be done in large periods of drought, the sulfides are oxidized and forms sulfuric acid. Today the flood weirs prevent the ingress of sea water that has been stopped in any drought since the ice age this process. It has upriver proposed the construction of a weir at Pomanda Iceland to protect drinking water supplies, in the event that it should be necessary to open the flood weirs.
The journalist Edward Wilson, who visited the lake in the 1850s, described him as follows:
" The Lake Alexandrina is the most beautiful freshwater lake that I have ever seen. He really looked so wonderful from, emerged as a stiff breeze, the waves brought forth that could make one seasick, so I almost could not believe it was a freshwater lake. However, this is precisely the case. He is forty or fifty miles long, around the twelve or fifteen miles wide, and its banks disappeared in the distance until they entirely invisible, were in the way we know it only from the sea. The lake is fed almost entirely by Murray and remains the marshy ponds, of which I have spoken, which unfortunately draws from the otherwise magnificent phenomena of this wonderful water surface from. "