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The Snowy River is a major river in south-eastern Australia. It originates on the slopes of Mount Kosciuszko, Australia's highest mainland peak, draining the eastern slopes of the Snowy Mountains in New South Wales, before flowing through the Alpine National Park and the Snowy River National Park in Victoria and emptying into Bass Strait.
While the river's course and surroundings have remained almost entirely unchanged, the majority of it being protected by the Snowy River National Park, its flow was drastically reduced in the mid 20th century, to less than 1% (as measured at Jindabyne), after the construction of four large dams (Guthega Dam, Island Bend, Eucumbene Dam, and Jindabyne Dam) and many smaller diversion structures in its headwaters in New South Wales, as part of the Snowy Mountains Scheme.
The river has been immortalised in cultural folklore through the poem The Man from Snowy River, written by Banjo Paterson in 1890, which formed the basis of many subsequent works in film, TV and music theatre.
In New South Wales, the river runs through the Snowy Monaro Regional Council. The tributaries of the Snowy River below Jindabyne include: the Mowamba River, Wullwye Creek, Maclaughlin, Delegate River, Jacobs, Pinch River, Suggan Buggan, Deddick River, Buchan River, Rodger River and Brodribb River rivers. At a pinch point named Hutchings pass, water flows uphill.
In 1986, Jennings and Mabbutt mapped four geomorphic classes in the Snowy River Basin; (i) Australian Alps; (ii) the Monaro Tablelands; (iii) the East Victorian Uplands and (iv) the Gippsland Plains. Each class is physically distinct from one another.
The highest average annual rainfall is recorded in the higher alpine reaches of the Snowy Catchment, with recorded in areas above . The lowest average rainfall is recorded in the rain shadow affected north eastern catchment on the Monaro Plains around Dalgety, with average rain below . The lower eastern sub-catchments are more strongly influenced by coastal rainfall patterns. For example, peak rainfall in the Delegate catchment is strongly influenced by east coast lows, rather than the alpine dominated precipitation patterns in the upper Snowy River catchment. These local variations in rainfall result in distinctly different hydrology in the rivers across the Snowy River catchment.
In the lower reaches of the Snowy River catchment, the larger tributaries have a distinctly different flow regime to the snow melt rivers of the Alps. These tributaries are typically dominated by the winter rainfall and often have peak monthly flows a few months earlier than the snow melt tributaries. The peak monthly flows for these lower Snowy River tributaries occur in June through July. Additionally, the flow regime in the lower tributaries is far more variable and unpredictable.
The bushfires of 2002–03, added to this problem as large amounts of sediment and organic matter were deposited in the river via tributary inflows. This input of sediment lead to the substrate becoming finer.Rose T. (2010) Geomorphic changes in the Snowy River following the stage environmental release. Snowy River Flow Response Monitoring and Modelling. NSW Office of Water This pattern of increased silt in the pools of rivers and streams has been observed across the Snowy Mountains following the bushfires. These bushfires are likely to have a long lasting influence on these waterways.
Larger events are required to start to improve the condition of the river bed. Events of per day will start to move the unconsolidated fine particles of the riverbed.Reinfelds I. and Williams, S. (2008). Hydraulic modelling to estimate threshold discharges for sediment entrainment in the Snowy River, Australia. Snowy River Recovery: Snowy River Flow Response Monitoring, NSW Department of Water and Energy Events between per day are important for conditioning the riffle habitats ( i.e., a type of flowing water habitat).
The current poor condition of the river bed is one of the key factors inhibiting the aquatic fauna typical in a snow melt river.
Large dams can essentially influence downstream water quality via two key mechanisms, either by poor water quality released from the waters of the dam itselfGrowns, I., Reinfelds, I., Williams, S., and Coade, G. (2009).Longitudinal effects of a water supply reservoir (Tallowa Dam) on downstream water quality, substrate and riffle macroinvertebrate assemblages in the Shoalhaven River, Australia. Marine and Freshwater Research 60, 594–606 and reduced mixing of the river water column attributable to lower water velocities leading to anoxic conditions at the bottom of deep river pools.Turner, L. and Erskine, W. D. (2005) Variability in the development, persistence and breakdown of thermal, oxygen and salt stratification on regulated rivers of Southeastern Australia. River Res. Applic. 21: 151–168
The Snowy River is on average 4 °C (7 °F) warmer than the surrounding unregulated snow melt rivers, with a peak difference of up to 8 °C (14 °F). The water temperature in spring appears to be the greatly warmer than the surrounding snow melt rivers.
Stratification can occur between October and March, but typically does not persist for very long in the Snowy River in the Jindabyne Gorge. Breakdown of thermal stratification is frequently driven by the cooling overnight air temperature. This region experiences a very large temperature range between day and night (i.e. diurnal temperature range).
The composition of algae in the free flowing snow melt rivers are typically defined by diatoms. Over 58% of taxa are diatoms, with Fragilaria spp. being the most numerically abundant taxa.
Caenid mayflies (riffles) and oligochaete worms (pool edges) are generally typical of the upland regulated Snowy River. Other studies have also found greater densities of Caenidae mayflies in regulated rivers compared to unregulated rivers. Reduced high flows and constant low flows in the upper Snowy River are likely to have favoured high densities of worms through the buildup of silt and organic matter in the pools. Nichols et al. (2006) and Petts et al. (1993) also found greater densities of segmented worms associated with soft sediments and coarse organic debris in response to river regulation. Chironomids were also numerically dominant in riffles sampled in the regulated Snowy River. This response has been found in many other studies of regulated rivers and has been attributed to an increase of periphytic growth in riffles that increased overall habitat area and food availability.
Conoesucidae caddisflies (riffles), larval and adult elmids (riffles) and Oniscigastridae (pool edges) distinguished the snow melt rivers from regulated Snowy River. Marchant and Hehir (2002) reported that AUSRIVAS models (>50% probability) predicted Conoesucidae and elmids to be present in the upper Snowy River, but these taxa were not found in their study. The greater density of these taxa in snowmelt rivers compared the Snowy River is consistent with river regulation.
Marchant and Hehir attribute the absence of these taxa to dams acting as a barrier to drift and limiting recolonisation of these taxa and not to flow regulation. The upper Snowy River sites are all below the confluence of the Mowamba River which provides a pathway for recolonisation of the Snowy River. Therefore, the reduced flow and altered flow regime is likely to be the primary cause of reduced densities of these taxa in the upper Snowy River rather than the barrier effects of Jindabyne Dam. There is little information on the responses of Oniscigastridae to reduced flows and altered flow regimes, but it is probable that an elevated temperature regime combined with lack of suitable sandy edge habitat has reduced their densities in the Snowy River.
The major differences between the two zones were the low abundance or absence of diadromous migratory fish (except eels) and the greater abundance of short-finned eel and trout in the upper catchment, and the greater abundance of Australian smelt, congolli and long-finned eel below Snowy Falls. These upper and lower Snowy River zone differences were greater than the differences between un-regulated tributary streams and the highly regulated main channel of the Snowy River within either zone. In the upper catchment, river blackfish, brown trout and short-finned eel were more abundant in un-regulated tributaries, whilst long-finned eel and goldfish were more abundant in the regulated upper part of the Snowy River. In the lower zone, eastern gambusia, long-finned eel, Australian smelt, short-finned eel and congolli were all more abundant in Snowy River while common galaxias and short-headed lamprey were more abundant at tributaries.
| Initial wetting of lower benches- old riverbed (Dalgety uplands) |
| Breakdown of thermal stratification (Jindabyne gorge) |
| Movement of fine silt from riverbed and initiating movement in unconsolidated coarse sands up to about 1.9 mm |
| Shear stress velocities across riffles are substantially greater than in pools (riffle maintenance) |
| Passage for Adult Australian Bass (Pinch Falls) |
| Passage for Juvenile Australian Bass (Pinch Falls) |
Further defining of ecological flow thresholds is currently in progress via modelling, field based studies, and flow trials. See Snowy Flow Response Monitoring and Modelling.
The first use of the Snowy River, for the extraction of energy, was by a water-powered flour mill, fed from a low weir across the river at Jindabyne. It was constructed by Stewart Ryrie Jr in 1847, and operated until around 1889.
This period of increased awareness of the impacts of water diversions led to the Snowy Water Inquiry, which looked at options to improve the health of the Snowy River.Pendlebury, P., Erskine, W., Lake, S., Brown, P., Banks, J., Pulsford, I. and Nixon, J. (1996) Expert Panel environmental flow assessment of the Snowy River below Jindabyne Dam. NSW Government The key outcomes of the Snowy Water Inquiry was an initial agreement to increase environmental water releases to the Snowy River below Jindabyne by 15% and the Snowy Montane Rivers.
These series of staged flow targets (up to 28% of mean annual natural discharge) were set for the Snowy River below Jindabyne, with these dependent on water savings in the Murray and Murrumbidgee River catchments. The targets included 15% by 2009 and 21% by 2012.
This stage increased flows from 1% to approximately 4% of mean annual river discharge. Typically an annual release of per year.
Overall the annual volume released remained around 38GL year given the historical record drought.
In November 2010 the first spring snow melt release occurred. This small but important release had a peak discharge of per day, and was sufficient to start to scour the fines sediment from some sections of the bed of the Snowy.
In October 2011, with substantially greater water available a much larger spring snow melt release has occurred i.e. over 19 days. This second and substantially larger release with a peak discharge rate of per day over three days is expected to scour the bed of the river. This releases targeted much larger particles, up to the size of , as the bed of the river is heavily "armoured" and larger flows are required to move these particles to improve the instream habitat of the river. Once the armouring had been removed it is expected the fine sediment would be scoured within the river bed profile.
After Ingram was elected to office, he became instrumental in the three shareholding governments reaching agreement to return of up to 28% ANF of an environmental flow to the Snowy River which was an outcome of the corporatisation of the Snowy Scheme, swinging the Victorian Government to sign the legislation. Although the Victorian, NSW and Federal governments promised that corporatisation would not lead to privatisation, in November 2005 they announced their intention to sell Snowy Hydro through a public float. Community groups rallied to stop the sale of Snowy Hydro and by June 2006 the Australian Prime Minister withdrew the Commonwealth's intention to sell Snowy Hydro.
The natural environment surrounding the Snowy River formed part of the subject matter and setting for the 'Banjo' Paterson poem The Man from Snowy River, first published in 1890. The Snowy River has also been immortalised in a 1920 The Man from Snowy River silent film, as well as in the better-known 1982 Fox film The Man from Snowy River and its 1988 Disney sequel film The Man from Snowy River II (U.S. title: " Return to Snowy River" – UK title: " The Untamed"), as well as in The Man from Snowy River (TV series) and , all of which were based on the Banjo Paterson's poem.
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