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Resource Assessment Commission, November 1993
ISBN 0 64429457
2.0.1 The coastal zone has a special place in the lives of Australians. Most Australians want to live there and if they can't they want to take their holidays there. It contains diverse ecosystems and a high proportion of Australia's industrial activity occurs in the zone. It is a priceless national resource.
2.0.2 In the first section of this chapter the Inquiry defines the coastal zone and briefly describes it in terms of the definitions used. Section 2.2 describes the natural processes that occur there. The uses and development of the zone's resources, in particular building, tourism and mariculture, are discussed in Section 2.3. Section 2.4 discusses conservation reserves and areas of special significance in the zone. The effects of coastal zone resource uses are discussed in Section 2.5 and Australians' attitudes to the coastal zone and the uses of its resources are described in Section 2.6. Conclusions are reached in Section 2.7.
2.0.3 Further information about the range and extent of coastal resources, their principal uses, and the values associated with them can be found in two information papers prepared by the Inquiry, Resources and Uses of the Coastal Zone (RAC 1993m) and Values and Attitudes Concerning the Coastal Zone (RAC 1993q).
2.1.0 The Inquiry adopted the 1991 approach of the OECD Environment Directorate in defining the coastal zone according to the nature of the problem being examined, particularly the objectives of management. The marine boundary of the coastal zone is defined by the Inquiry to be 200 nautical miles seaward of the low-water mark. That boundary marks the extent of the Australian Fishing Zone, which is larger in area than the whole of the Australian land mass. Since there are strong links between resource uses in river catchments and marine areas the Inquiry used two definitions of 'coastal zone' for identifying and describing the landward extent of resources and human activities in Australia's coastal zone: existing local government administrative areas abutting the coast as a basis for examining the extent of human uses and activities; and natural drainage basins abutting the coast for describing the extent of physical and biological resources (see RAC 1993m).
2.1.1 Figure 2.1 shows the coastal zone as defined by administrative boundaries. Under this definition the zone occupies about 1.318 million square kilometres, approximately 17 per cent of the land area of Australia. Figure 2.2 shows the coastal zone as defined by drainage basins. Under this definition the zone occupies about 1.327 million square kilometres, again approximately 17 per cent of the area of Australia.
2.1.2 Including its external territories, Australia has one of the largest marine zones in the world (8.9 million square kilometres) and one of the longest coastlines (approximately 70 000 kilometres) (Zann 1993). The coastline of mainland Australia itself, including Tasmania, is approximately 36 700 kilometres (ABS 1990). The coastal zone contains a wide range of climatic, geological and oceanographic regions, which in turn house a very rich store of biological diversity. The zone supports a diverse and interacting mixture of terrestrial, estuarine and marine ecosystems, ranging from coral reefs to coastal forests, which directly or indirectly provide many of the resources needed for a broad range of commercial and non-commercial uses and activities. The zone also contains the largest areas of coral reefs of any nation and the third-largest area of mangroves, and it has globally significant populations of a number of endangered species.
2.1.3 Based on the local government definition, Australia's coastal zone supports about 86 per cent of total population, including nearly one-half of Australia's indigenous population. In the past 20 years the zone has witnessed significant increases in population and tourism growth and has been the location of many types of development. About half of Australia's total population growth has occurred in nonmetropolitan parts of the zone, particularly on the Sunshine Coast and the Gold Coast of Queensland, in the south-west of Western Australia, in far north Queensland, and on the central and north coasts of New South Wales.
2.1.4 The coastal zone is especially significant because it contains a high proportion of the resources used to produce goods and services; much of Australia's commercial and industrial activity is found in land- and sea-based enterprises located in the zone. In particular, it is where most of the fishing industry, tourism and other service industries, and significant parts of the agriculture, forestry, mining (including petroleum) and manufacturing industries are concentrated. Provision of land, sea and air transport facilities is a major activity in the zone, as is the provision of other infrastructure associated with the production and consumption of goods and services. It is also the area providing a high proportion of recreational opportunities in Australia.
2.2.0 Australia's coastal zone exhibits a broad range of physical features-coastal plains, hills and mountains, river catchments and drainage basins, beaches, cliffs, estuaries, wetlands and other enclosed water bodies, oceans, coral reefs, islands, mudflats and dunes. The biological features of the coastal zone are extremely varied, with a wide range of flora and fauna inhabiting the terrestrial and aquatic environments. Coastal ecosystems are characterised by complex interactions between the flora and fauna and the physical elements of both terrestrial and marine ecosystems. For example, mangrove ecosystems are dependent on specific levels of water salinity, the location of seagrass beds is determined largely by the amount of available sunlight, and coastal forest ecosystems are influenced by topography, soil moisture and nutrient gradients (see RAC 1993m).
2.2.1 The environment of the coastal zone is subject to continuing change brought about by natural processes. This is particularly the case in the shore zone, which is that area most directly influenced by marine processes such as the actions of waves, currents, tides and storm surges. These processes interact and continuously shape and modify the physical features of the shore zone, including beaches, spits, sand dunes and offshore sandbars. These physical features are part of a naturally dynamic system; their form and location change in response to changes in marine processes and in the availability of sand and other sediments.
2.2.2 Many of the sandy coastlines of Australia are a legacy of the last major sea-level rise. Since the sea reached its present level, around 6000-7000 years ago, the supply of sand to the shore zone in many parts of Australia has stabilised or declined. Erosion that occurs along some parts of the Adelaide beaches, for example, is largely a result of a natural lack of sand.
2.2.3 Superimposed on the more or less continuous changes that occur as a result of the natural dynamism of the shore zone are rapid changes that occur in response to short-term natural events such as cyclones, floods and storms. Such events, which have caused major environmental damage and economic loss, have occurred in much of Australia's coastal zone in recent years, including major flooding and beach erosion along the east coast in the 1950s, 1960s and 1970s (see Box 2.1). Despite the relative absence of major storm events over the past 15 or so years, many parts of the Australian coast are vulnerable to natural hazards. Serious concerns exist about the capacity of many local governments to assess the vulnerability of coastal areas to such natural hazards (Thom, Submission 577, p. 2).
2.2.4 Over at least the past 40 000 years, humans have become increasingly important agents of change in the coastal zone, the most dramatic changes having occurred since European colonisation in Australia, about 200 years ago. The resources of the zone have been, and continue to be, modified by a wide range of human activities. The scale of modification ranges from dredging operations that directly influence localised water flows to regional-scale changes in land use, such as clearing of vegetation for agriculture and residential development, that alter the dynamics of water catchments and offshore water quality.
Box 2.1 Examples of the effects of natural processes in the coastal zone
During 1949-52 the New South Wales and Queensland coasts were hit by a succession of storms. Although not particularly violent, the storms caused substantial erosion because there was not enough time between storms for the sand to build-up again.
At least 22 lives were lost when the Hunter and northern rivers of New South Wales flooded in 1955. More than 10 000 houses were flooded and 100 houses were swept away in Maitland, the most severely affected town.
Extensive erosion and property damage was sustained on the Gold Coast and in the Sydney-Newcastle region during storms in 1967. The Gold Coast was hardest hit during June and Sydney was affected by severe storms in late August and again in November.
In January 1970 Cyclone Ada ravaged islands in the Great Barrier Reef, resulting in the loss of 13 lives and millions of dollars of damage.
In January 1974 serious flooding occurred in many parts of Australia. Brisbane was particularly hard hit with 6000 homes flooded, 13 lives lost and damage of about $200 million. The New South Wales coast was also hit by a sequence of storms in May-June 1974, causing extensive beach erosion and damage to property, particularly in Sydney and environs.
On Christmas Day of 1974 Darwin was devastated by a powerful cyclone. The city was almost completely flattened and about 50 people were killed. Twenty-six thousand people were evacuated from Darwin by air.
Source: Aplin et al. (1987).
2.2.5 It is not easy to disentangle the impacts of natural variability in coastal zone processes from impacts that may arise from human activities-such as global warming resulting from increased levels of greenhouse gases in the atmosphere (see Box 2.2)-or from coastal zone management practices that can, for example, interfere with the movement of sediment along the coast. Beach erosion in southern Queensland has, for instance, been exacerbated by the effects of breakwaters built at the mouth of the Tweed River. Similarly, localised erosion near Busselton in Western Australia has been intensified by the construction of groynes intended to slow a natural regression of the shoreline that is due largely to diminishment of the sand supply since current sea levels were reached.
2.2.6 From a resource management perspective, the uncertainties related to the climatic and sea-level implications of an enhanced greenhouse effect are closely linked to the natural dynamics and variability of physical processes that operate in the coastal zone. Regardless of possible sea-level rise and accompanying changes in wind and wave strength and direction due to the greenhouse effect, variability in the frequency and severity of storm events presents a significant hazard along many parts of the Australian coast.
Box 2.2 Global warming and the coastal zone
Although scientists are generally in agreement that global warming is occurring, the process and effects are not fully understood and the rates of change and the magnitude of many impacts remain uncertain. Based on the most recent revision of the Intergovernmental Panel on Climate Change 'business as usual' scenario, the following impacts are predicted:
Any rapid changes in climate may change the composition of ecosystems. Some species will benefit; others will be unable to migrate or adapt rapidly enough and may become extinct.
Human settlements exposed to natural hazards such as coastal or river flooding, severe drought, landslides, severe storms and tropical cyclones will be most vulnerable to impacts of the enhanced greenhouse effect.
Source: IPCC (1991).