Brackish water , sometimes termed brack water , is water occurring in a natural environment that has more salinity than freshwater , but not as much as seawater . It may result from mixing seawater (salt water) and fresh water together, as in estuaries , or it may occur in brackish fossil aquifers . The word comes from the Middle Dutch root brak . Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming . Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it can be damaging to the environment (see article on shrimp farms ).
41-647: Sullivans Cove is on the River Derwent adjacent to the Hobart City Centre in Tasmania . It was the site of initial European settlement in the area, and the location of the earlier components of the Port of Hobart . The cove was the initial landing site of what is now the city of Hobart . It was founded on 21 February 1804 by Lieutenant Governor David Collins , who travelled to the shore via what
82-601: A freshwater river in the Central Highlands at Lake St Clair , descending over 700 metres (2,300 ft) across a distance of more than 200 kilometres (120 mi). At the settlement of New Norfolk in the Derwent Valley its waters become brackish , flowing through Hobart , the capital city of Tasmania, its seawater estuary eventually empties into Storm Bay and the Tasman Sea . Historically,
123-629: A natural defense against hurricane and tsunami damage in particular. The Sundarbans and Bhitarkanika Mangroves are two of the large mangrove forests in the world, both on the coast of the Bay of Bengal . Some seas and lakes are brackish. The Baltic Sea is a brackish sea adjoining the North Sea . Originally the Eridanos river system prior to the Pleistocene , since then it has been flooded by
164-476: A range of salinity regimes and is not considered a precisely defined condition. It is characteristic of many brackish surface waters that their salinity can vary considerably over space or time. Water with a salt concentration greater than 30‰ is considered saline . See the salinity table from the Misplaced Pages salinity article . Brackish water condition commonly occurs when fresh water meets seawater. In fact,
205-512: A significant portion of Hobart's water needs. The river is also crucial for recreation, supporting activities such as boating, fishing, and leisure along its banks. Additionally, it facilitates marine transportation and various industrial activities, playing a central role in Tasmania's economy and lifestyle. The upper part of the river was named after the River Derwent, Cumbria by British Commodore John Hayes who explored it in 1793. The name
246-535: A species only found in deep water in the Baltic, while pike are confined to the less saline surface waters. The Caspian Sea is the world's largest lake and contains brackish water with a salinity about one-third that of normal seawater. The Caspian is famous for its peculiar animal fauna, including one of the few non-marine seals (the Caspian seal ) and the great sturgeons , a major source of caviar . Hudson Bay
287-471: A vacant lot and the Mawson's Huts replica were proposed to be redeveloped into a Civic Square. 42°53′07″S 147°20′04″E / 42.88528°S 147.33444°E / -42.88528; 147.33444 Derwent River, Tasmania The River Derwent , also known as timtumili minanya in palawa kani , is a significant river and tidal estuary in Tasmania, Australia . It begins its journey as
328-490: Is Brythonic Celtic for "valley thick with oaks". Matthew Flinders placed the name "Derwent River" on all of the river. The name "River Derwent" was officially endorsed on 20 May 1959. The River Derwent valley was inhabited by the Mouheneener people for at least 8,000 years before British settlement. Evidence of their occupation is found in many middens along the banks of the river. The first European to chart
369-555: Is a brackish marginal sea of the Arctic Ocean , it remains brackish due its limited connections to the open ocean, very high levels freshwater surface runoff input from the large Hudson Bay drainage basin , and low rate of evaporation due to being completely covered in ice for over half the year. In the Black Sea the surface water is brackish with an average salinity of about 17–18 parts per thousand compared to 30 to 40 for
410-422: Is very low and the fish fauna consists predominantly of freshwater species such as roach , dace , carp , perch , and pike . The Thames Estuary becomes brackish between Battersea and Gravesend , and the diversity of freshwater fish species present is smaller, primarily roach and dace; euryhaline marine species such as flounder , European seabass , mullet , and smelt become much more common. Further east,
451-543: The Hobart City Hall Axis. The designs were not for construction. With the change in the cove's primary activity from a freight port to tourism and recreational uses, many of the sheds in the area have been either re-purposed or replaced – notably, all buildings keep the former gabled roof architecture. These buildings include: Additional development in the immediate area include a $ 100m redevelopment of Parliament Square , behind Parliament House . In 2015,
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#1732772076904492-406: The crab-eating frog , Fejervarya cancrivora (formerly Rana cancrivora ). Mangroves represent important nesting sites for numerous birds groups such as herons, storks, spoonbills, ibises, kingfishers, shorebirds and seabirds. Although often plagued with mosquitoes and other insects that make them unpleasant for humans, mangrove swamps are very important buffer zones between land and sea, and are
533-571: The Arts building is based on Hunter Street. A serviced apartment building, ZeroDavey , drew some criticism for its blue Davey Street facade, though it has some sandstone to blend in with the Hunter Street warehouses. During 2004 there has also been discussions about a proposal for a tourist tram from Sullivans Cove to the CBD, and possibly to North Hobart . An international design competition
574-518: The Colonies. By 1916, several piers had been constructed: from north to south: In 1933, the Argyle Street and Elizabeth Street Piers were replaced with a single concrete-reinforced structure at Elizabeth Street Pier. In 1947 there was a proposal to replace Queens and Kings Pier with an extra wide pier, but this was never realised. In 1948, Ocean Pier was destroyed by a fire. Kings Pier
615-780: The Derwent is the 113,000-tonne (111,000-long-ton), 61-metre (200 ft) high, ocean liner Diamond Princess , which made her first visit in January 2006. At points in its lower reaches the river is nearly 3 kilometres (1.9 mi) wide, and as such is the widest river in Tasmania. The Derwent estuary contains dozens of white sandy beaches, many of which are staples of local activity within Hobart suburbs and include Bellerive Beach , Blackmans Bay Beach , Howrah Beach , Nutgrove Beach , Lords Beach , Long Beach , Taroona Beach , Hinsby Beach , Kingston Beach and Windermere Beach. Until
656-419: The Derwent, preys on not only the fish eggs, but also on the sea squirts ( ascidians ) that help to form the substrate that the fish spawn on. Several bridges connect the western shore (the more heavily populated side of the river) to the eastern shore of Hobart – in the greater Hobart area, these include the five lane Tasman Bridge , near the CBD, just north of the port; the four lane Bowen Bridge ; and
697-490: The Meadowbank, Cluny, Repulse, Catagunya, Wayatinah, Liapootah and King William lakes or lagoons. The Upper Derwent is affected by agricultural run-off, particularly from land clearing and forestry. The Lower Derwent suffers from high levels of toxic heavy metal contamination in sediments. The Tasmanian Government -backed Derwent Estuary Program has commented that the levels of mercury , lead , zinc and cadmium in
738-484: The North Sea but still receives so much freshwater from the adjacent lands that the water is brackish. As seawater is denser, the water in the Baltic is stratified, with seawater at the bottom and freshwater at the top. Limited mixing occurs because of the lack of tides and storms, with the result that the fish fauna at the surface is freshwater in composition while that lower down is more marine. Cod are an example of
779-457: The banks of the Derwent were covered by forests and frequented by Aboriginal Tasmanians . With the arrival of European settlers, the area saw agricultural development and the construction of dams for hydro-electricity generation during the 20th century. Today, the Derwent's catchment area is characterised by agriculture , forestry , and hydropower generation. It serves as a vital source of water for irrigation and urban supply, notably providing
820-535: The construction of several hydro-electric dams between 1934 and 1968, the river was prone to flooding. Now there are more than twenty dams and reservoirs used for the generation of hydro-electricity on the Derwent and its tributaries, including the Clyde , Dee , Jordan , Nive , Ouse , Plenty and Styx rivers. Seven lakes have been formed by damming the Derwent and the Nive rivers for hydroelectric purposes and include
861-659: The mean annual flow is 90 cubic metres per second (3,200 cu ft/s). The large estuary forms the Port of the City of Hobart – the deepest sheltered harbour in the Southern Hemisphere . Some past guests of the port include HMS Beagle in February 1836, carrying Charles Darwin ; the USS ; Enterprise ; USS John C. Stennis and USS Missouri . The largest vessel to ever travel
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#1732772076904902-467: The most extensive brackish water habitats worldwide are estuaries , where a river meets the sea. The River Thames flowing through London is a classic river estuary. The town of Teddington a few miles west of London marks the boundary between the tidal and non-tidal parts of the Thames, although it is still considered a freshwater river about as far east as Battersea insofar as the average salinity
943-626: The most northerly crossing is at Derwent Bridge , before the river reaches its source of Lake St Clair . At the Derwent Bridge crossing, the flow of the river is generally narrow enough to be stepped across. The river is the subject of the multimedia performance "Falling Mountain" (2005 Mountain Festival), a reference to the mountain in the Cradle Mountain-Lake St Clair National Park from which
984-549: The oceans. The deep, anoxic water of the Black Sea originates from warm, salty water of the Mediterranean . Lake Texoma , a reservoir on the border between the U.S. states of Texas and Oklahoma , is a rare example of a brackish lake that is neither part of an endorheic basin nor a direct arm of the ocean, though its salinity is considerably lower than that of the other bodies of water mentioned here. The reservoir
1025-431: The pens the farmed fish are kept in. Another important brackish water habitat is the mangrove swamp or mangal . Many, though not all, mangrove swamps fringe estuaries and lagoons where the salinity changes with each tide. Among the most specialised residents of mangrove forests are mudskippers , fish that forage for food on land, and archer fish , perch-like fish that "spit" at insects and other small animals living in
1066-436: The river during months in winter and spring when their migration takes place. Some females even started using calm waters of the river as a safe ground for giving birth to their calves and would stay over following weeks after disappearance of almost 200 years due to being wiped out by intense whaling activities. In the winter months of 2014, humpback whales and a minke whale (being the first confirmed record of this species in
1107-439: The river exceed national guidelines. In 2015 the program recommended against consuming shellfish and cautioned against consuming fish in general. Nutrient levels in the Derwent between 2010 and 2015 increased in the upper estuary (between Bridgewater and New Norfolk) where there had been algal blooms . A large proportion of toxic heavy metal contamination stems from legacy pollution caused by major industries that discharge into
1148-639: The river including Nyrstar Hobart , a historic smelter establish at Lutana in 1916, and the Norske Skog Boyer paper mill at Boyer which opened in 1941. The Derwent adjoins or flows through the Pittwater–Orielton Lagoon , Interlaken Lakeside Reserve and Goulds Lagoon, all wetlands of significance protected under the Ramsar Convention . In recent years, southern right whales finally started making appearance in
1189-425: The river rises. The Derwent is mentioned in the song, Mt Wellington Reverie by Australian band, Augie March . Hobart is located in the foothills of Mount Wellington . Brackish Technically, brackish water contains between 0.5 and 30 grams of salt per litre—more often expressed as 0.5 to 30 parts per thousand (‰), which is a specific gravity of between 1.0004 and 1.0226. Thus, brackish covers
1230-472: The river was Bruni d'Entrecasteaux , who named it the Rivière du Nord in 1793. Later that same year, John Hayes explored the river and named it after the River Derwent , which runs past his birthplace of Bridekirk , Cumberland . When first explored by Europeans, the lower parts of the valley were clad in thick she-oak forests, remnants of which remain in various parts of the lower foreshore. There
1271-710: The river) have been recorded feeding in the River Derwent for the first time since the whaling days of the 1800s. The rare spotted handfish ( Brachionichthys hirsutus ), whose only habitat is in the Derwent estuary and surrounds, was the first marine fish to be listed as critically endangered in the IUCN Red List , in 1996. The fish is threatened by the Northern Pacific seastar's invasion into southern Australian waters . The Northern Pacific seastar ( Asterias amurensis ), now firmly established in
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1312-500: The river. This type of ecological succession from freshwater to marine ecosystem is typical of river estuaries. River estuaries form important staging points during the migration of anadromous and catadromous fish species, such as salmon , shad and eels , giving them time to form social groups and to adjust to the changes in salinity. Salmon are anadromous, meaning they live in the sea but ascend rivers to spawn; eels are catadromous, living in rivers and streams, but returning to
1353-412: The salinity increases and the freshwater fish species are completely replaced by euryhaline marine ones, until the river reaches Gravesend, at which point conditions become fully marine and the fish fauna resembles that of the adjacent North Sea and includes both euryhaline and stenohaline marine species. A similar pattern of replacement can be observed with the aquatic plants and invertebrates living in
1394-727: The sea to breed. Besides the species that migrate through estuaries, there are many other fish that use them as "nursery grounds" for spawning or as places young fish can feed and grow before moving elsewhere. Herring and plaice are two commercially important species that use the Thames Estuary for this purpose. Estuaries are also commonly used as fishing grounds and as places for fish farming or ranching. For example, Atlantic salmon farms are often located in estuaries, although this has caused controversy, because in doing so, fish farmers expose migrating wild fish to large numbers of external parasites such as sea lice that escape from
1435-420: The trees, knocking them into the water where they can be eaten. Like estuaries, mangrove swamps are extremely important breeding grounds for many fish, with species such as snappers , halfbeaks , and tarpon spawning or maturing among them. Besides fish, numerous other animals use mangroves, including such species as the saltwater crocodile , American crocodile , proboscis monkey , diamondback terrapin , and
1476-684: The two lane Bridgewater Bridge and Causeway . Until 1964 the Derwent was crossed by the unique Hobart Bridge , a floating concrete structure just upstream from where the Tasman Bridge now stands. Travelling further north from the Bridgewater crossing, the next crossing point is the Blair Street Bridge at New Norfolk , slightly north of the point where the Derwent reverts from seawater to fresh water , Bushy Park , Upper Meadowbank Lake , Lake Repulse Road, Wayatinah , and
1517-669: Was a thriving whaling industry until the 1840s when the industry rapidly declined due to over-exploitation. Formed by the confluence of the Narcissus and Cuvier rivers within Lake St Clair , the Derwent flows generally southeast over a distance of 187 kilometres (116 mi) to New Norfolk and the estuary portion extends a further 52 kilometres (32 mi) out to the Tasman Sea. Flows average in range from 50 to 140 cubic metres per second (1,800 to 4,900 cu ft/s) and
1558-519: Was created by the damming of the Red River of the South , which (along with several of its tributaries) receives large amounts of salt from natural seepage from buried deposits in the upstream region. The salinity is high enough that striped bass , a fish normally found only in salt water, has self-sustaining populations in the lake. Brackish water is being used by humans in many different sectors. It
1599-418: Was demolished and replaced with a marina for commercial and private craft, around 1970. This marina increased in size in 2003. Sullivans Cove holds large historical and sentimental value for the city. The cove area itself is now known as Macquarie Wharf and serves as the main port for the city. Many of the original buildings along the esplanade are still standing. The University of Tasmania 's School of
1640-469: Was held for the Hobart waterfront in 2006. It attracted 280 entries from over 50 countries. Three winners were announced on January 26, 2007, including entries by Jeppe Aagaard Andersen, Preston Lane Architects and Tony Caro Architecture. Many proposals indicated a return to the Hobart Rivulet as a canal on its original alignment at Constitution Dock , with a civic and reconciliation space linking
1681-522: Was then a rocky island named Hunter Island. The connection to the shore was developed and is now known as Hunter Street. The island now has a building directly above it. Although the first European settlement in the state was further up the river at Risdon Cove by John Bowen a year earlier, that settlement was abandoned and relocated to join the Sullivans Cove settlers. Collins named Sullivans Cove after John Sullivan, Permanent Under Secretary to