Environmental Engineering Reference
In-Depth Information
Priority will be given to replanting deep-rooted perennial plants to
reduce the amount of water leaking to watertables and the salinisation of
rivers, wetlands and valley bottoms. To achieve the best results for rural
communities and the environment, we need to integrate planning to
enhance biodiversity and to control recharge.
A sustainable land use might consist of:
30 per cent of the area permanently covered in native vegetation,
including trees, shrubs and grasses
20 per cent covered in deep-rooted trees, shrubs and grasses, planted
primarily to control recharge and produce income from grazing and
farm forestry
30 per cent used intensively for annual crops, and
20 per cent used less intensively for mixed grazing and cropping.
The correct balance between different types of land use will vary for dif-
ferent catchments.
The amount of remaining native vegetation determines the extent to
which biodiversity and ecosystem functions are intact. A number of studies
have analysed the changes in the rate of loss of connections between patches,
the rate of loss of species, and lag times associated with random and non-
random clearing, and identified thresholds of connectivity.
Landscape diagnosis, targets, and management priorities all depend on
the landscape context. The scale of revegetation and its strategic location
also need to match the particular groundwater system that is controlling the
expression of the salinisation process. We are starting to understand how
groundwater flow systems can be applied to catchments and used to inform:
the extent to which we need to change land use and reduce recharge
in order to halt, and maybe reverse, the spread of salinity, and
the lag times between initiating actions to reduce recharge or
intercept saline groundwater and any evidence of responses in
groundwater levels or salt delivery.
Both the extent of the changes we must make to land use and the time lag
before the changes affect salt discharge to land and water resources are far
greater than is widely recognised. It is estimated that after measures to
reduce recharge have been implemented, there will be no evidence of
groundwater and therefore salt responses at the discharge end of the system
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