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the region's natural assets

The Corangamite Region is famous for its spectacular coastline and the Great Ocean Road from Geelong, stretching as far west as the "Twelve Apostles" near Port Campbell; for the historic gold mining region centred around Ballarat; and for the Victorian Basalt Plain which slopes west to east through the centre of the Region, flanked by the Otway Range to the south and the Central Highlands to the north. Volcanic hills emerge from the Basalt Plain in the west, which provide a backdrop to the large lakes that are set in an otherwise flat landscape. The lakes are of international ecological significance for migratory birds including brolgas, while the Region is home to many icons of Australian fauna including kangaroos, wallabies, koala, echidna and platypus.

The Region has been radically altered by European settlement, and further development places more pressure on the natural environment, through population growth, increasing affluence and production technologies. Some changes are irrevocable; some may be able to be reversed. The Region faces important choices in the balance between economic development, environmental health and social well-being.

5.1 geology

Geologically the Region is recent in comparison to other parts of Australia. Its oldest rocks are the sedimentary and low-grade metamorphic rocks of the Central Highlands (Ordovician, 400 to 500 million years), and the Otway Range (Cretaceous, 65 to 136 million years). The central Basalt Plain is Quaternary, and results from a volcanic region centred near Camperdown, which was active as recently as 7,000 years ago, and as recorded in aboriginal histories. Older superficial deposits of Cretaceous and Tertiary origin flank the eastern, northern and western slopes of the Otway Range and the Bellarine Peninsula. Geological diversity is one of the responsible factors for the varied landscapes of the Region. Make a Comment

5.2 climate

The climate is temperate Mediterranean. Winter rainfall predominates, while summers are warm and dry. Streams are generally perennial, though with much reduced flows in summer. Rainfall varies greatly across the Region - highest along the Otway Ridge and the northern uplands. The central valley, comprising the Basalt Plain, is in a rain shadow, and experiences much lower rainfall. Make a Comment

5.3 waterways

5.3.1 overview

The Region comprises four Australian Water Resources Council (AWRC) River Basins - Lake Corangamite, Barwon, Moorabool and the Otway Coast. Only the last of these Basins is completely hydrologically separate from the others. Within each of the basins there are several significant river systems including the Aire, Barwon, Gellibrand, Curdies, Leigh, Moorabool and Woady Yaloak Rivers. The condition os waterways in each of the four river basins is described in Table 3, Current condition of waterways in the corangamite region.

moorabool basin

There are no streams in the Moorabool Basin that are in excellent or good condition, with the majority of streams rated as being in poor condition. The condition of the waterways in this basin is most probably the result of extensive demand for water for both urban and rural uses, impacting significantly on stream flows. More than 60% of available surface water supplies are utilised.

One part of the Moorabool Basin, Hovells Creek, is a small waterway that rises in the Brisbane Ranges and flows into Limeburners Bay within Port Phillip Bay, north east of Geelong. barwon basin

The Barwon River system occupies most of the eastern volcanic plain, and drains the high-rainfall upper slopes of the Otway Range to the south (Barwon River) and the Central Highlands to the north (Leigh-Yarrowee River). In its lower reaches the Barwon is joined by the Leigh then the Moorabool Rivers, and passes through Geelong and Lake Connewarre before arriving at its estuary at Barwon Heads.

The majority of streams in the Barwon Basin are in marginal to poor condition. The few streams that are in excellent or good condition occur predominately in the water supply catchment areas in the south of the Basin. More than 85% of the landscape is cleared and there are many threats to the waterways in the catchment, including high urban water resource demand, urban development, sedimentation and algal blooms.

The Barwon system is separated from the Lake Corangamite Basin to its west by only a shallow north-south divide on the volcanic plain. This can overflow during high rainfall/ runoff events, or when water is transferred into the Barwon Basin by the operation of two drainage schemes.

lake corangamite basin

The Lake Corangamite Basin has no natural outlet to the sea, but drainage works have established two interconnections to the Barwon Basin. This landlocked basin is dominated by a series of saline lakes, into which all its watercourses run.

The young geology of the basin gives rise to a poorly defined system of drainage. Damming of lava flows and depressions in many craters have formed a large number of lakes and swamps. There are a total of 758 wetlands greater than one hectare within this basin.

All of the streams within the Basin flow into the lakes. In the north-west of the Basin Mundy Gully Creek and the Gnarkeet Chain of Ponds enter Lake Gnarpurt and Corangamite, respectively. The Woady Yaloak River rises in the north and flows south into Cundare Pool and to the Barwon via a channel, taking in the waters of the Narunghil, Kuruc-A-Ruc and Ferrers Creeks. Pirron Yallock Creek drains the south-west of the Basin below Lake Corangamite and Deans and Barongarook Creeks flow northwards toward Lake Colac in the south-east.

The streams in the Lake Corangamite Basin are either in marginal or very poor condition. Most of the catchment is cleared for agricultural pursuits and many wetlands are drained.

otway coast basin

The Otway Coast Basin is formed by a divide on its northwestern boundary with the Lake Corangamite Basin, and then follows the Otway ridge north eastwards, finally abutting the Barwon Basin near the coast, west of Torquay. The southern boundary is the coastline from near Peterborough and the Curdies River estuary to Breamlea, a distance of some 150km. The Basin contains many short south-flowing rivers.

Unlike other Basins in the Corangamite Region, about 60% of the Otway Coast Basin is covered by forest. Consequently, there are a significant proportion of streams that can be classed as being in good or excellent condition. Most of the streams of high quality are in the central section of the Basin, which contains many high ecological values. Streams that are in marginal, poor and very poor condition are generally located in the western and eastern sections of the Basin.

Many of the short ephemeral streams in the Coastal Otway Basin are listed as "ecologically healthy streams", due to no diversions from these waterways (see Table 4, Ecologically healthy waterways). The continued maintenance of the natural flow regimes in these systems is a high priority.

systems in excellent condition (heritage rivers)

Within the Victorian River Health Strategy there are 17 systems, "Victorian Heritage Rivers", identified with outstanding values that require protection for current and future generations. A 35 km reach (or corridor) of the Aire River from Hopetoun Falls Scenic Reserve to the ocean is the only one identified within the Corangamite Region.

The Aire River is also listed as a "Victorian Representative River" (Victorian River Health Strategy, 2002) for its entire length. Make a Comment

5.4 hydrogeology

There are local, intermediate and regional groundwater flow systems, the latter originating in the central basin area. The central part of the Corangamite Region faces very similar hydrogeological conditions to those found in the Victorian part of the Murray-Darling Basin, as it contains a substantial cross regional catchment groundwater flow system, the Basalt Plains. The hydrogeology of the Region is complex, as it matches the geology, with salinity evident from both primary and secondary sources. Groundwater from the Otway foothills is of particular significance for water supply to Geelong and for stock water supplies in the Lakes/Plains & Northern Foothills sub-Region.

There is shallow groundwater over much of the Basalt Plain. Victoria's Salinity Management Framework, 2000 gives estimates of areas with given depths to water table, shown in Table 5, Areas of shallow groundwater. Make a Comment

5.5 lakes and wetlands

The extensive systems of lakes and wetlands are a defining feature of the Region, and are of national and international significance. Thirteen wetlands, listed in Table 6, ramsar listed wetlands, have been classified under the Ramsar Convention. The Region includes all of the Western District Lakes Ramsar Site and parts of the Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site. These areas support 40 species listed under the China-Australia Migratory Bird Agreement (CAMBA), 36 species under the Japan-Australia Migratory Bird Agreement (JAMBA), and 49 species listed under the Bonn Convention.

Lake Corangamite, the largest permanent inland natural lake in Australia, is a haven for migratory and non-migratory birds, and its small islands are essential nesting grounds. Lake Connewarre contains the most extensive example of Wilsonia herblands and Distichlis grasslands in Australia. A number of other plants reach their southern limit here, and the White Mangrove its western limit.

There are over 1,400 other wetlands greater than one hectare, comprising 65,000 ha in total (See Table 7, Summary of wetland loss in the corangamite region). Of these, 340 are listed as significant. Most are located on or adjacent to private land, which can make management difficult (Harding, 2002). More than 150 wetlands (> 1 ha), totalling over 12,000 ha have been drained or grazed (DCNR, 1995). Some landholders have been restoring and enhancing wetlands on their properties. Make a Comment

5.6 terrestrial resources

5.6.1 land use

Table 8, Land use within each of the regionís four river basins shows the current land use in each of the four river Basins of the Region. Notable features are the dominance of livestock grazing, which occurs generally in the south of the Region, and of dryland agriculture, which occupies the central valley and northern slopes. There is little irrigation compared with northern Victorian regions. There is a minimal area of nature conservation in the Moorabool and Barwon River catchment areas and a high level of nature conservation and forest in the Otway Coast Basin.

European settlement has led to massive changes in land use, including the removal of grassland communities for crops and introduced pastures, woody vegetation removal for agriculture, the exploitation of woodlands and native hardwood forests for construction timber, firewood and gold mining requirements, and more recently the introduction of exotic plantation forests.

Unlike the Central Highlands, where vegetation was decimated in the gold mining boom of the mid 19th century, the forests of the Otways survived broad scale clearing due to the intractability of the terrain for agriculture, and the absence of economic mineral deposits. Much of the area cleared for farming was eventually abandoned and subsequently reclaimed by the Government and re-forested or naturally regenerated to native forest. The vast majority of the Otways forests were subject to timber harvesting and wildfires over the last 100 years. Sawmills were established throughout the Otway Range and were moved as nearby timber resources became exhausted. The larger trees were generally left, as they were less suitable for processing due to fire damage, rot and the number of hollows. Regeneration then occurred through seed-fall from these larger remaining trees, leading to many uneven aged stands (i.e. stands with a predominance of only a few, or even one, age group). Make a Comment

5.6.2 indigenous cultural heritage values

Aboriginal cultural and heritage sites include scarred trees, mounds, middens, artefact scatters, quarry sites, stone arrangements, structures and art sites. Some sites are sacred including burial sites. Places where Aboriginals have lived and worked, massacre sites and locations that are historically significant for the Aboriginal community are also a part of modern Aboriginal heritage. Land disturbance on sites of past Aboriginal occupation and resource use is an anathema to Aboriginal cultural and heritage values. Make a Comment

5.6.3 soil

The Corangamite Region has a diversity of geology and climate that has resulted in a variety of landforms and associated land uses. The Region's soils reflect this diversity. They range from recently deposited wind-blown sands to heavy clays derived from highly weathered volcanic parent material. Structure of the red volcanic soils is renowned for ease of management, whereas the soils of the Central Highlands, the basalt plains and the coastal plains are known for their potential to become waterlogged during the wetter months. Soil fertility is widely variable and local fertiliser use is high. Soils are naturally acidic throughout most of the Region. Make a Comment

Data for soils in the Region is currently being updated and completed through a land resource assessment. This assessment will provide an inventory of soils for the Region, their main physical and chemical properties, and maps of soil distribution in relation to landform and geology.

5.7 biodiversity

The Corangamite Region is renowned for its diversity of landscape and natural habitats that support an equally varied range of native flora, fauna and ecological communities. As a community we need to protect, enhance and restore our biodiversity, as it is essential for our well-being - physical, spiritual, social and economic.

Understanding our biodiversity assets is the first step in being able to achieve biodiversity conservation in the long term. Over many years scientific information has added to the considerable body of community knowledge to develop a good understanding of the Regions biodiversity assets, including native vegetation communities, threatened native flora and fauna species and significant habitats and ecological processes. A summary of these known assets is represented here, but is far from complete.

The Corangamite Region is home to many Australian and Victorian rare or threatened species (AROT or VROT) as demonstrated in Table 9, Status and numbers of Australian and Victorian rare and threatened fauna species in the Corangamite Region. Make a Comment

5.7.1 native vegetation

The natural vegetation is strongly influenced by the pattern of rainfall and soils across the Region. Eucalypts dominate on higher ground. The Otway Range supports dense temperate rainforest and wet sclerophyll forests, however there is a rain shadow effect. Grassland communities on the plains and ridges of the central valley developed after the creation of the volcanic plain. Rainfall increases at higher elevation to the north, and the natural vegetation is mainly open woodland.

Forest communities have the best vegetative representation in the Region. The original areas of scrub, grasslands, heaths and woodlands are much depleted in both quality and quantity. This is a major threat to habitat for native fauna.

Our native ecosystems are diverse and complex. Bio-geographic regions (bioregions) capture the patterns of ecological characteristics in the landscape, providing a natural framework for recognising and responding to biodiversity values. As bioregions reflect underlying environmental features, they can also be related to the patterns of use of land. Within Victoria there are 27 bioregions. Five of these bioregions cover the Corangamite Region: Central Victorian Uplands; Otway Plain; Otway Ranges; Victorian Volcanic Plain; and Warrnambool Plain.

Ecological Vegetation Classes (EVCs) are distinct vegetation types that are based on differences in broad landscape features, ecological processes, vegetation structure and floristics. EVCs are the basic mapping units used for vegetation planning and conservation assessment at landscape, regional and broader scales in Victoria. They provide a finer level of detail than bioregions on which to base planning and are used to identify assets, understand threats and refine priorities for actions. EVC mapping has been completed for the Corangamite Region as part of the West Victoria Regional Forest Agreement process.

From a total area of over 1.3 million ha less than 25 per cent remains with a cover of the original native vegetation, and much of this is found in the forests of the Otway Range and in the Ballarat area. Of this remaining native vegetation, one third of it is managed primarily for conservation purposes and about half is considered 'threatened' in terms of its conservation status. Most of this threatened native vegetation is on private land.

Figure 3, Degree of threat to native vegetation in the five bioregions of corangamite, shows that more than 80 per cent of the native vegetation is threatened in three of the five bioregions present in Corangamite Region (the Victorian Volcanic Plains, Warrnambool Plains and Central Victorian Uplands), and of these one region (the Victorian Volcanic Plains) has only 3.6 per cent of its total area under native vegetation. The Otway Plains has around 30 per cent of its area in native vegetation of which around half is threatened. By contrast, the Otway Range (bottom right of the graph) has over 80 per cent native vegetation cover, little of which is threatened.

Table 10, Priority ecological vegetation classes in the corangamite region, shows the Ecological Vegetation Classes that cover the Corangamite Region. Approximately half of the remaining native vegetation in the Region is on private land or along roadsides, streams or disused rail lines. Seventy per cent of this vegetation is rare, endangered or vulnerable.

Table 11, Regional benchmarks for native vegetation on private land, identifies the remnant native vegetation within each bioregion on private land and provides a benchmark in order to achieve a net gain in quality and extent of native vegetation over time. Make a Comment

5.7.2 native fauna

The Region is home to many well-known Australian animals including kangaroos, wallabies, koala, echidna and platypus. Icon species that require protection include the Eastern Barred Bandicoot, Striped Legless Lizard, Plains Wanderer, Rufous Bristlebird, Spot-tailed Quoll, Hooded Plover, Orange-bellied Parrot, Corangamite Water Skink and Platypus. Colonial nesting birds and cave-dwelling bats are nominated under the Flora and Fauna Guarantee Act, 1988. Make a Comment

5.7.3 natural habitats and ecological processes

The Corangamite Region has a wealth of significant natural habitats that are highly important in terms of the natural biodiversity they contain, including:

  • Internationally significant wetland habitats of the Western District Lakes and Geelong/ Lower Barwon;
  • Internationally significant habitats for migratory bird species under JAMBA and CAMBA;
  • Near pristine waterways and estuaries of the Otway Coast; and
  • National Parks and Reserves. Make a Comment

5.8 the coastal and marine environment

5.8.1 landscape

The Region's coastline contains areas of spectacular forest descending down steep slopes to many rocky headlands and crescent-shaped sandy bays. The protection of the internationally recognised landscape values along this stretch of the coastline is of paramount importance. Make a Comment

5.8.2 port phillip bay

The southwestern shores of Port Phillip Bay, including Corio Bay at Geelong, lie within the Corangamite Region. The Bay is the most ecologically important bay in Victoria, and one of the top ten sites in Australia. It contains examples of all eight of the Victorian wetland types, and five geomorphic sites of State significance, including mud islands, sand hummocks, Hovell's Creek, Limeburners Bay and Point Wilson. It is internationally important for 12 species of shorebird, and nationally important for two species of shorebird. It supports tens of thousands of swans, ducks, grebes, coots, crested terns, petrels, pelicans and ibis. The site is home to the critically endangered Orange-bellied Parrot.

The wetlands and seagrass meadows of the inshore marine waters of the Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site are important fish habitat and nursery areas that support a significant commercial and recreational fishery. Make a Comment

5.8.3 the estuaries

Corangamite's 20 estuaries along the southern shoreline are mainly wave-dominated. They are highly sought-after locations for recreation and residential development, and are ecologically fragile. Only the St George River is considered pristine. As can be seen in Table 12, Estuaries of the region and their condition, many estuaries have been modified. Make a Comment

5.8.4 marine waters

The health of coastal waters is vital to the tourist industry, fishing and aquaculture industries, as well as for its biodiversity.

The condition of Corangamite's coastal waters is generally good, with low levels of nutrients, turbidity and bio-contaminants, and generally good light conditions. Attention to nutrient and sediment fluxes in the catchments, and appropriate management of stormwater and wastewater in coastal towns is essential to preserve this good condition.

The Corangamite Region is unique in that it has the highest number of marine bioregions (three) within its Region. The marine and estuarine waters support a diversity of species in habitats such as seagrass meadows, mud flats, intertidal and sub-tidal rocky reefs, mangroves, kelp forests and pelagic systems. The quantity and quality of water draining from the catchment influence the health of these habitats, creating fluctuations in salinity and the amount of nutrients in the water. Temperature fluxes are also influenced by large-scale changes in oceanic currents. Make a Comment

5.8.5 marine protected areas

The marine biodiversity is unique in the Corangamite Region and its importance has been recognised through the establishment of various marine national parks and sanctuaries. In an internationally recognised initiative, Marine National Parks have been established at the Twelve Apostles, Point Addis, and Port Phillip Heads; and Marine Sanctuaries have been established at The Arches (Port Campbell), Marengo Reefs (Apollo Bay), Eagle Rock, Point Danger, and Barwon Bluff. Make a Comment

5.9 assets of special significance

Environmental, social and economic assets recognised at Regional, State, National or international level, and therefore of Regional significance, are:

  • the productive agricultural land base, which supports a very significant part of the dairy industry as well as beef, cereals, fine wool production, horticulture, viticulture and other intensive agricultural industries;
  • the proclaimed water supply catchments;
  • groundwater reserves;
  • the network of perennial rivers and streams;
  • Ramsar wetlands, and wetlands recognised under other international agreements;
  • the National Parks and conservation reserves;
  • rare and endangered native grasslands and the threatened fauna associated with native grasslands;
  • landscape and cultural heritage of the Basalt Plain, stony rises and wetlands;
  • the coastal landscape and estuaries;
  • the heritage-listed Aire River;
  • Marine National Parks; and
  • Marine sanctuaries. Make a Comment