COAST AND MARINE
Australia's fragile environment combined with past management practices
means that the natural resources (soil, water and vegetation) of many
areas are degraded. Natural resource degradation affects our environment
and the quality and quantity of natural resources available to current
and future generations.
People form landcare groups to work together to improve the management
of natural resources and to care for their local environment.
Landcare groups throughout NSW are working on a wide range of coast
and marine issues. These include:
· Coastal degradation
· Estuarine and floodplain degradation
· Soil degradation (acid soils, soil erosion,
acid sulphate soils)
· Wetlands
Coastal Degradation
The issue
The coastline is under constant attack from the natural forces of wind
and waves. Because of this, the coastline is constantly changing: beaches
and sand dunes erode and are rebuilt in response to wind attack, and
sand dunes can migrate inland. Many sections of the coastline are moving
inland at a significant rate.
Human activities along the coastline can increase the speed of these
changes. Coastal degradation is caused by inappropriate development
and management along the coastline. Coastal developments for tourism,
residential, commercial (including mining of heavy metals and sand)
and recreational purposes places pressure on coastal areas, and may
cause degradation.
The weed, Bitou Bush has invaded a large amount of the NSW coastline,
taking the place of native vegetation. Sand dunes covered by Bitou Bush
do not have the same stable protection against wind erosion as those
covered by native vegetation.
Global climate changes associated with the greenhouse effect may also
increase the rate of coastal degradation.
What can be done?
Several measures can be taken to remediate coastal degradation, including:
· adequate planning to prevent unwise coastal development
· locating buildings, roads and powerlines away from the frontal
dune system
· managing existing healthy dunes to prevent degradation
· building fences and protected pathways to prevent erosion caused
by pedestrians and vehicles
· repairing damaged dunes - the four main steps involved in rehabilitation
are rebuilding, planting, fencing and maintenance
· excluding vehicles from beaches and frontal dunes unless special
circumstances apply.
For further information about coastal degradation please click
here.
(Information courtesy of the Department of Environment and Climate Change)
Estuarine and Floodplain Degradation
The issue
Floodplain degradation is the erosion of land forming the alluvial
river flats that are periodically covered by floodwater. These areas
are often the most productive lands in a catchment. Degradation includes
the loss of river flats by topsoil stripping or gullying, loss of property,
crops, livestock and wildlife habitats, including estuaries.
Floodplain degradation can be caused by inappropriate development of
the floodplain and the clearing of vegetation. Floodplain erosion often
occurs where there has been a change in land use from grazing to cropping.
Erosion is increased by artificial drainage works and other structures
which concentrate flood flows.
What can be done?
There are several options for good floodplain management including:
· ensuring artificial systems follow natural drainage patterns
· keeping enough pondage on floodplains to slow flood waves moving
downstream
· constructing wide floodways to avoid water traveling at high
speed
· maintaining native vegetation in broader natural floodplain
areas.
For further information about Estuaries please click here.
(Information courtesy of the Department of Environment and Climate
Change)
For further information about Floodplain Management please click
here.
(Information courtesy of the Department of Environment and Climate Change)
Soil Degradation
Acid soils
The issue
Some soils are naturally acid, and others become acid from many years
of intensive agriculture, especially the growing of annual shallow rooting
legume pastures, production of hay and use of ammonium fertilisers.
Soil acidity affects a pasture's ability to establish good ground cover
and deep roots. This lack of cover and plant vigour causes the land
to be susceptible to weed infestation and erosion.
Soil acidity also makes it difficult to manage other degradation problem.
It is hard to grow perennial pastures to slow dryland salinity and obtaining
sufficient groundcover to slow erosion is difficult on acid soils.
What can be done?
There are several measures which can be taken to prevent or repair
acid soils, including:
· using less acidifying farming systems
· applying lime to reduce and prevent soil acidity
· using deep-rooted perennial pastures.
Soil erosion
The issue
Sheet erosion is the removal of
soil on sloping land by rainfall and flowing water.
Rill erosion is the removal of soil
by rainfall and flowing water, forming channels up to 30cm deep.
Gully erosion is the removal of
soil by water flow forming channels deeper than 30cm, down which sediment
and suspended materials flow.
Wind erosion occurs when soil particles
are detached from the soil surface and are blown away by wind.
Sheet, rill and gully erosion cause soil, nutrients and plants to be
removed and washed into rivers or onto other land. Eroded land becomes
less productive because the soil and nutrients are lost. Chemicals can
spread from the eroded material and pollute waterways or affect marine
life.
Wind erosion removes fine soil particles leaving only larger particles.
This reduces the amount of nutrients left in the soil and the soil's
ability to hold moisture for plant growth. Wind erosion can also lead
to dust storms, causing air pollution.
Erosion occurs when the soil is bare and not covered by plants. This
often results from surface soil problems such as salinity, sodicity
and structural degradation. It frequently occurs as a result of excessive
cultivation, overclearing, overgrazing and drought. Wind erosion occurs
in areas that are exposed to wind, especially on sandy soils.
What can be done?
Methods for preventing and treating erosion include:
· ensuring soils are covered with vegetation
· contour farming and strip cropping
· conservation farming, including reduced tillage, stubble retention
and improved crop rotations
· reduced stocking rates and pasture improvement
· soil and water conservation earthworks.
Wind barriers and groundcovers on bare areas help to slow down wind
velocity and therefore reduce wind erosion.
Acid Sulphate Soils
The issue
Development in estuarine floodplains of coastal NSW for agriculture,
urban development and sand mining has exposed soils which are naturally
waterlogged and rich in iron sulphides. When these soils are exposed
to air, sulphuric acid is produced, hence the name acid sulphate soils.
This sulphuric acid moves through the soil, acidifying soil water,
groundwater and eventually surface waters, having a severe impact on
the environment.
Soil can become so acid and toxic that few plants will grow from it
and the surface can become bare and scalded. This affects agricultural
productivity and the natural environment. The acid also corrodes concrete,
iron and steel, damaging pipelines, bridges, floodgates and other structures.
Heavy rain in areas of acid sulphate soils can cause the acid water
to flow into estuarine environments, resulting in fish kills and degrading
of estuarine habitats. Acid sulphate soils also affect fish by lowering
growth rates and damaging their skin and gills.
What can be done?
Measures to prevent acid sulphate soils from occurring and to repair
affected areas include:
· research into the distribution of soils which contain iron
sulphides.
· avoiding disturbance or drainage of soils containing iron sulphides.
· applying lime to neutralise the sulphuric acid (costly for
large areas)
· covering land with water to prevent the soils from being exposed
to air
· use of wide, shallow drains to drain quickly from the surface
of low-lying land without exposing the iron sulphide layer beneath the
soil.
For further information on acid sulphate soils please click here.
(Information courtesy of the NSW Government)
For further information on all forms of soil degradation please
click here.
(Information courtesy of the NSW Government)
Wetlands
The issue
Wetlands are important ecosystems. They provide a valuable link between
surface water and groundwater, they filter out nutrients and pollutants
and hold large amounts of water, preventing flooding. Wetlands are also
home to numerous plants and animals, acting as nursery, feeding and
shelter areas for fish and other aquatic life.
Wetlands have been lost through drainage, dredging and filling in for
agriculture or residential land. They are affected by river works, irrigation
and water supply structures, inappropriate management, pollution from
industrial, agricultural and urban runoff, and salinity. In some wetlands,
native plants and animals are threatened by overgrazing and competition
with introduced species.
Drainage of some coastal wetlands has exposed acid sulfate soils that
impact on agricultural and fisheries activities.
What can be done?
Measures which can be taken to protect existing wetlands and improve
degraded wetlands include:
· promoting the importance of wetlands in maintaining property
and catchment productivity
· creating parks and reserves to protect wetlands
· preventing pollution from entering wetlands
· maintaining and improving native vegetation in and around wetlands
· fencing off wetlands from stock and keeping wetlands on farms
as wildlife refuges
· maintaining the natural cycle of flooding and drying out in
wetlands.
For further information on wetlands please click here.
(Information courtesy of the Department of Environment and Climate
Change)
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