Everything about Torrens River totally explained
The
River Torrens is the most significant river of the
Adelaide Plains and was one of the reasons for the siting of
Adelaide,
South Australia. It flows from its source in the Adelaide Hills near
Mount Pleasant, across the
Adelaide Plains, past the
central business district and empties into
Gulf St. Vincent at
Henley Beach South. The upper stretches of the river and reservoirs in its
watershed supply a significant part of the city's
water supply. The river's long linear parks and a constructed
lake in the lower stretch are iconic of the city.
At its 1836 discovery an inland bend was chosen as the site of Adelaide and
North Adelaide. The river is named after
Colonel Robert Torrens. At Adelaide, is also known its by native
Kaurna name
Karra wirra-parri. The river and its tributaries are highly variable in flow, and together drain an area of 508 km². They range from sometimes raging torrents, damaging bridges and flooding city areas, to trickles or completely dry in summer. Winter and spring flooding has prompted the construction of flood reduction works. A constructed sea outlet, landscaped linear parks and three holding reservoirs contain peak flow.
The river's flora and fauna have been both deliberately and accidentally impacted since
settlement. Native forests have been cleared, gravel removed for construction and many foreign species introduced. With construction of the linear parks, many species native to the river have been replanted and introduced species controlled as weeds. Since European settlement the river has been a frequently touted
tourist attraction. The river formerly acted as the city’s primary water source and main
sewer, leading to outbreaks of
typhus and
cholera.
Physiography
Due to the faulting in the area creating
grabens, this area is also known as the
Torrens Graben, which is a distinct physiographic section of the larger
South Australian Shatter Belt province, which in turn is part of the larger
West Australian Shield division.
The River Torrens runs largely westward from the Adelaide Hills, through the centre of Adelaide to the
Gulf Saint Vincent. It originates close to the eastern
fault scarp of the
Mount Lofty Ranges, near
Mount Pleasant, approximately
above sea level. It runs predominantly along
faulted north-south ground structures, which were formed over 250 million years ago during the
Paleozoic era then further dislocated during the
Cretaceous and earliest
Tertiary. There is a 400 metre
subsidence along the Para Fault which also affects the rivers flow. This subsidence was formed in the last two million years, after the
Pliocene era.
From its origin to
Birdwood the river follows rolling, relatively level country before entering a hilly section that continues to
Gumeracha. The river then follows
sedimentary rock strata before entering a
gorge after
Cudlee Creek. It flows through the gorge to
Athelstone, passing over the Eden Fault Zone of the
Adelaide Hills face and associated escarpment. After the scarp it flows over sedimentary rocks of varying resistance to
erosion, which has led to interspersed narrows and broad basins. The plains tributaries, known as First to Fifth Creeks, with First being the closest to Adelaide's city-centre and the rest numbered consecutively eastward, were originally named Greenhill, Hallett, Todd, Anstey and Ormsley rivulets respectively. They flow vigorously in winter and spring but are otherwise dry, except for small flows in limited areas upstream. "Moriatta" a
Kaurna word meaning "ever flowing" is now the official name of Fourth Creek. This name has been adapted to
Morialta which is now the name of an
electoral district,
school and the
Morialta Conservation Park through which the creek flows.
First, Second and Third Creeks have been particularly heavily modified. Some sections have been converted to concrete channels; others run through landscaped private gardens and some run in underground pipes. Much of the original vegetation has disappeared from the creeks, particularly those closest to the city. Introduced species including
Olives,
bamboo,
boxthorn,
watsonia and
blackberries have displaced native flora.
Water flow
As discovered by Europeans, the river was a summertime chain of
waterholes bounded by large
gum trees. Flowing through the area where the city of Adelaide is sited the river was sometimes invisible beneath its
gravel stream bed. It frequently
flooded in winter and didn't reach the sea, instead ending at coastal
dunes where its waters created a vast but shallow freshwater
wetlands. These wetlands, known as
The Reedbeds after the dominant vegetation, occupied a large area of the western
Adelaide Plains and was also fed by other waterways.
The river’s catchment area of approximately is the largest of any waterway within the Adelaide region. The upper reaches are used to create a
potable water supply for
metropolitan Adelaide with the river supplying three of Adelaide’s eight reservoirs. The Torrens has a very variable flow leaving early
settlers to use trial and error in determining bridge heights, with many bridges consequently being washed away. Due to the variability of
Adelaide's climate, flow rates can change from a trickle to
flood conditions quickly. On
June 5 1889, prior to major flooding, the flow rate before it entered the suburbs was 0.7 m³/s(
cubic metres per second), rising to 129.1 m³/s, 8 days later.
Since settlement it has repeatedly flooded, sometimes with disastrous consequences. Adelaide's western suburbs were especially prone to flooding due to their location on the river's alluvial fan. As development of Adelaide progressed the amount of rainfall required for flooding decreased and consequent damage increased. Increased
stormwater runoff, modification of the river's banks and other changes all served to exacerbate the problem. Work done by various groups to minimise flooding was often counter productive with the creation of
levees, moving and widening channels and other works simply shifting the flooding elsewhere.
Two early floods were,
18 September 1841 which resulted in two people
drowning while trying to cross the river at
Klemzig, and
22 September 1844, the largest recorded since settlement began, when "Shands' Brewery" was washed away after the river undermined its
foundations. The river ran 9 feet deep over the weir near Thorndon Park Reservoir, 3 feet over the Torrens Lake Weir and 1 foot over the
Morphett Street Bridge. The
Underdale (or Holbrooks) Bridge was destroyed, the Torrens Lake weir's bridge damaged, and the
Felixstow Bridge over the Fourth Creek washed away.
Discovery and naming
The first European sighting of the river was in November 1836 by an exploration party comprising Lieutenant W.G. Field,
John Morphett and
George Strickland Kingston. The river was named "The Yatala" by the party but later renamed by
William Light after
Colonel Robert Torrens, chairman of the South Australian colonisation commissioners.
Much of the river's catchment area is comprised of cleared
farmland with run-off captured in private
dams to sustain farming over Adelaide's dry summer. Combined with the river's use for potable water this has greatly reduced the overall flow especially in the lower river.
Flood mitigation
A flood mitigation bill was passed in 1917 to not only combat the damage floods caused but also the public health risk due to the lack of mains
sewerage in the western suburbs. Popular opinion was to divert the flood waters into their "natural" outlets of the Port and
Patawalonga Rivers. The chief engineer of the department of works favoured a cutting through sand dunes near
Henley Beach; allowing the river an outlet, mitigating floods and preventing silting of the Port River. He also advocated the construction of a reservoir where the
Kangaroo Creek Reservoir is now, to both mitigate floods and provide summer
irrigation water for market gardens. Unfortunately the bill lapsed with no action as
government and
local councils were unwilling to fund the works. The
Millbrook Reservoir opened in 1918 as a summer water source, and flood mitigator if required. A bill was passed in 1923 to enact the earlier plan of cutting through the dunes and adding an upstream regulating weir. Again the bill lapsed due to a lack of commitment from parties on payment.
A major flood in 1931 and another in 1933 lead to the latest in a line of government enquiries. In 1934 the "Parliamentary Standing Committee on Public Works" recommended that an outlet for the river be created to accommodate flows of up to 370 m³/s (
cubic metres per second) (
13,000 ft³/s), covering a 1 in 60 year flood. The work was partly financed by a
Commonwealth Government grant with the
State Government arranging for the balance. The State Government, western and eastern local councils and the
Municipal Tramways Trust shared interest costs. The scheme was enacted in 1935 and largely completed by 1939 with the creation of the "Breakout Creek" channel. The scheme involved diversion of the river at
Lockleys (near
Adelaide Airport), with the original channel blocked and a new channel created to the sea. It remains the only reservoir damming the river rather than being fed from weirs. The "River Torrens Committee" was formed in 1964 to advice the minister of works on; preserving and enhancing the rivers natural beauty, and developing it for recreational uses. The "River Torrens Acquisition Act 1970-72" was passed authorising the purchase of land, in some cases 60 metres back from the top of the river's banks.
By 1980, further development along the riverbanks and removal of levées had reduced the outlets capacity to a 1 in 35 year flood. A study showed that a 1 in 200 year flood would inundate 13,000 properties, so the Kangaroo Creek dam's level was raised, its
spillway modified, the breakout creek channel capacity increased and some bridges reinforced. A development plan was approved in 1981 to purchase land along the length of the river, create a flood mitigating
linear park and also to modify the Kangaroo Creek dam further. The sea outlet was enlarged to a capacity of 410 m³/s which now covered a 1 in 200 year flood. When the
O-Bahn Busway was opened the bridges were designed to cope with this scale of flood, although the two bridges in
St Peters would likely be awash.
Torrens Lake
The 470 megalitre Torrens Lake was created in 1881 with the construction of a weir, landscaping of
Elder park and modification of the river’s bank and surrounds into an English formal park. The lake forms a centrepiece of many Adelaide events and postcard scenes.
Elder Park with its iron
rotunda was opened on
November 28 1882. The Rotunda is a largely
Glasgow built 9 metre high iron bandstand which was funded by Sir Thomas Elder Smith, the park being named after him.
In 1867, prison labour from
Adelaide Gaol was used to build a wooden dam near the site of the current weir. The dam was poorly constructed and almost immediately the Torrens washed it away. Construction of a permanent concrete weir was begun in November 1880 and completed, at a cost of £7,000, in 1881. The sluice gates were closed to begin filling the Torrens Lake on
July 1 1881. At the lake's official opening on July 21 1881 an estimated 40,000, almost the entire population of Adelaide, attended. During the 1889 flood, the weir was overwhelmed, its gates jammed, and in trying to free them the weir's designer John Langdon was crippled. The weir was rebuilt from 1928 to 1929 with its footbridge relocated and the centre section replaced. The gates can now be fully raised and the river allowed to flow unimpeded.
The "Popeye" boats are privately owned recreational
ferries that operate on the lake between Elder Park and the
Adelaide Zoo. The first boat was launched on the Torrens Lake by Gordon Watts in 1935. It was a 25 foot boat, built on the banks of the Torrens to hold up to 20 passengers and named
Popeye 1. Watts purchased a former
Glenelg cruise boat in 1948 and placed it in service as
Popeye 2. Over the next two years three new
jarrah hulled boats were built at
Port Adelaide; carrying 40 passengers each they were numbered
Popeye 3 through
Popeye 5. Trips on the Popeyes from Elder Park to the zoo became a treasured family outing and the boats hosted weddings and other events. In March 1962 Keith Altman, owner of riverside eatery "Jolley's Boathouse", took over the Popeyes and introduced recreational
paddle boats to the river. The Popeyes had a brush with royalty in March 1977 with
Popeye 5 ferrying
Queen Elizabeth II and
Prince Philip followed by a choir in
Popeye 4. Prime Minister
Malcolm Fraser officially launched three new fibreglass models named Popeyes I, II and III in 1982 as the wooden boats' replacements.
Water use
In the early days of Adelaide, the Torrens was used for bathing, stock watering, rubbish disposal, water supply and as a de-facto sewer and drainage sump. This led to a range of health issues until finally, in 1839, when a dysentery outbreak killed 5 children in one day, Governor Gawler forbid bathing, clothes washing and the disposal of animal carcases in the Torrens within 1 mile of town. The quality of the river's water wasn't helped by water supply methods. Carters used to drive water carts into the Torrens to refill. To prevent this the State Government built a facility with steam powered pumps and water storage in 1852, from which the carters then filled.
The "Waterworks Act" of 1856 was passed to enable damming of the upstream Torrens for water supply purposes. The resulting "Water Commission" arranged the following year for foundations to be laid for a water supply weir. Poor construction materials and techniques lead to them being washed away, and the weir not completed. Government then created a Waterworks Department, which started construction of a weir and reservoir in 1859, at Thorndon Park partway through the river’s suburban flow. The weir was completed on
June 4 1860 and the reservoir began supplying piped water in December. The water was captured at the weir, piped for storage to the Thorndon Park Reservoir then to a water tank at Kent Town. Water from Kent Town storage was distributed via a manually controlled water system, unmetered for its first six years. Within six years 20,000 citizens in Adelaide and Port Adelaide were connected to reticulated water from the Torrens. By 1872, the 2840 megalitre
Hope Valley Reservoir in the foothills of the Adelaide Hills was completed as a storage reservoir, supplied via an aqueduct and tunnel.
Public baths were built in 1861 just north of the current
Parliament House. They were supplied with reticulated water from the Torrens and progressively upgraded with the last change a 1940 remodelling including an Olympic size swimming pool and diving tower. The baths were demolished in 1970 to make way for the
Adelaide Festival Centre. The 16,500 megalitre Millbrook Reservoir was constructed high in the Adelaide Hills from 1913 to 1918 submerging the town of Millbrook. An earth bank dam fed by mile long tunnel from a weir on the river at
Gumeracha, its elevation allows gravity supply of water to Adelaide's eastern suburbs.
Bridges
Due to the river's path through the centre of Adelaide, transport necessitated the construction of many bridges. Prior to the bridges all crossings had been via
fords which proved a dangerous practice in spring and winter. The first bridge was one of timber built in 1839 approximately 500 metres west of the current City bridge, but destroyed by floods in September 1844. In 1849 £6000 was allocated to bridge the Torrens. Within four years three wooden bridges had been built and subsequently destroyed in floods.
The
Victoria Bridge extends from Morphett Street and crosses the rail lines from the
Adelaide Railway Station and the river. The first bridge was opened on
June 21 1871,
The
Albert Bridge is adjacent to the
Adelaide Zoo and carries Frome Road over the river. A timber bridge was constructed in 1859, west of the current bridge, and named the
Old Frome Bridge. The
wrought iron structure is made from three parallel, scalloped girders that were manufactured in England. It is long with a
cantilevered span of 60 feet. The bridge is 43 feet wide and originally had a timber deck, which was replaced with concrete in 1922. The bridge is listed on the "City of Adelaide Heritage Register", the "
South Australian Heritage Register" and the "
Register of the National Estate". A complete restoration was finished in 1982, with the bridge now appearing as it did at the 1879 opening.
The
Hackney Bridge was first known as the "Second Company Bridge" as the South Australia Company built it. It was built so that wheat farmers from the northern side could access the South Australian Company's
flour mill which stood where the Hackney Hotel was later built. The current bridge is the third at the same site; in 1845 "Prescott's Crossing" was built as a timber beam bridge, 1860 saw it replaced with a four span, trussed timber bridge and
December 5 1885 with a 126 foot long, 34 foot wide
truss arch bridge.
University Footbridge connects Victoria Drive, at the rear of
University of Adelaide, with Peace Park adjacent to Memorial Drive. The bridge was conceived in 1928 by an engineering
undergraduate at the university and funded with a £26,000 grant from Adelaide City Council. It was designed by university staff under the supervision of Robert Chapman, chief engineer of the
South Australian Railways. Construction was delayed until 1937 due to the economic effects of the
Great Depression. The bridge has an arch spanning 152 ft, 20 ft over the river, and was the first
welded bridge in South Australia. A murder that occurred in the vicinity of the bridge on
10 May 1972 resulted in calls to reform South Australia's laws regarding homosexuality.
University of Adelaide law lecturer
Dr George Duncan was thrown into the river. A plaque on the bridge commemorates his death and the subsequent decriminalisation of homosexuality in South Australia.
Various other bridges have spanned the Torrens including:
