For further information, see Chapter 5: Land.
Urban settlements and our population are concentrated along the eastern, south-eastern and south-western coastal fringes of Australia. This area overlaps, and sometimes conflicts, with the areas most suitable for intensive agriculture (i.e. higher rainfall zones within 200 kilometres of the coast and where the floodplains of major rivers provide the most fertile soil). Land managed for nature conservation is located primarily in central and northern Australia, and in the forested ranges of the east and south-west of both mainland Australia and Tasmania.
Some major trends in land use that are relevant to coastal Australia include:
- continuing urban expansion in both capital cities and major regional coastal cities (see also Chapter 10: Built environment)
- continuing expansion of the conservation and Indigenous estates (see also Chapter 6: Marine environment, and Chapter 8: Biodiversity)
- continuing decline in the area of native forest managed for wood production and a corresponding increase in the extent of native forest managed for conservation, much of which is found in coastal ranges (see Chapter 5: Land)
- changes in flows from rivers into estuaries and coastal environments, due to increased extraction of water for agricultural and urban use, and to drought over the past decade in many areas (see Chapter 4: Inland water)
- growth of mining developments in the north-west of Australia (see Chapter 6: Marine environment), which is increasing the number of people accessing coastal environments for recreation, warranting monitoring of its impacts
- improvements in land management practices in many (but not all) areas, which have reduced the flows of sediments and chemicals to the coast that were characteristic of major rainfall events in the past (see Chapter 4: Inland water).
Growing Australian and global populations will demand more food and fibre, and expanding settlements and infrastructure will continue to impact on the environment. Economic growth places more demands on natural resources, as well as generating financial resources and new technologies for environmental management. The changed climate regimes and sea level rise associated with global warming are expected to place new pressures on both the natural environment and primary production systems. All of these factors will affect coastal ecosystems, but particular pressure will come from the interaction between sea level rise and human settlements.
Acid sulfate soils occur naturally in both coastal (tidal) and inland or upland (freshwater) settings. When disturbed, sulfides within the soil react with oxygen in the air, forming sulfuric acid.2 Coastal development for tourism, towns and agriculture has disturbed large areas of acid sulfate soils, with significant environmental, economic and social costs to coastal communities. Adverse impacts of acid sulfate soils in coastal lowlands include:
- poor water quality (e.g. dissolved metal contaminants, low pH, reduced oxygen levels)
- direct killing of fish, or fish becoming more vulnerable to pathogens
- loss of critical habitat areas, aquaculture production, fish stocks, wetland biodiversity and amenity
- acid erosion of infrastructure
- the need for rehabilitation of disturbed areas.3
The public health implications of disturbing acid sulfate soils are not well understood. However, acidified coastal wetlands may provide predator-free habitat for species of mosquito that transmit arboviruses (e.g. Ross River virus). Acid dust mobilised during ploughing and construction activities may cause dermatitis and eye irritation.3
Risk mapping in various locations around Australia has lacked consistency and contained many large gaps. In collaboration with the National Committee for Acid Sulfate Soils, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) developed the Atlas of Australian Acid Sulfate Soils, which has now been incorporated into the Australian Soil Resource Information System.a
Local and state governments around Australia have produced policies, plans and guidelines for managing the risks of acid sulfate soils. At a national scale, the National Water Quality Management Strategy4 provides guidelines on water management, including management of acid sulfate soils; the National Strategy for the Management of Coastal Acid Sulfate Soils5 assists in coordinated management; and the handbook Managing acid and metalliferous drainage6 provides guidance on best-practice management for an Australian context.
Chapter 5: Land, and Chapter 8: Biodiversity discuss data on declines in native vegetation around Australia and its significance for biodiversity conservation. The greatest reductions in native vegetation extent have been in eastern, south-eastern and south-western Australia (Figure 11.2). Impacts on the coastal strip are highly variable around Australia’s coastline, ranging from very heavily cleared, with less than 10% remaining, in parts of Victoria and South Australia, through 31–50% remaining in large parts of the south-western and north-eastern coastal areas, to 71–100% remaining for most of northern Australia.