Australian Natural Resources Atlas

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Map of local flow systems associated with sand dunes

Fact Sheet 10. Local flow systems associated with sand dunes

Regions

Local flow systems associated with sand dunes are found on the sand dunes of the eastern wheat belt sandplains in Western Australia and in the mallee in Victoria.

Critical attributes that determine groundwater behaviour in response to land management

Discussion

This groundwater flow system type develops in highly permeable sand dunes. It is characterised by ephemeral perched groundwater flow occurring in response to seasonal `filling up' that discontinues once the system has drained of the seasonal pulse. This means that management timeframes for the system are relatively brief, and that positive benefits from recharge management can be expected within years of their application. However, the highly permeable nature of the surface material, and the episodic nature of recharge, means that salinity management options must be particularly effective in intercepting considerable and highly variable volumes of water, and at other times existing through long periods with little moisture. This considerably limits the options that are likely to be appropriate to this groundwater flow system.

Potential options and their suitability for salinity management

Recharge management

Pasture agronomy Existing pasture options may be able to reduce recharge sufficiently to prevent these systems filling up seasonally and also to respond to the longer-term variability of rainfall patterns.

Cropland agronomy Existing cropping options are unlikely to be able to reduce recharge sufficiently to prevent these systems filling up seasonally and certainly not able to prevent episodic recharge in years of excessive rainfall.

Woody perennial vegetation Woody perennial vegetation offers considerable potential for reducing recharge to levels necessary for controlling salinity, particularly where species mixes can opportunistically use episodic rainfall when it occurs.

Plantation forestry Plantation forestry would be technically effective in reducing recharge to levels necessary for controlling salinity. The low rainfall of these regions means that most tree species are unlikely to be successfully established. There is some potential to use mallee species that are adapted to low rainfall regimes and using episodic rainfall when it occurs.

Engineering watertable management

Surface drainage The high permeability and diffuse, episodic recharge characteristics of these landscapes mean that surface drainage generally has limited application. It is likely to be appropriate in conjunction with land use options that can efficiently use the drained water before it infiltrates back to the groundwater system.

Sub-surface drainage The permeability of these landscapes and diffuse, episodic recharge characteristics mean that sub-surface drainage generally has limited effectiveness. It is likely to be appropriate in conjunction with land use options that can efficiently use the drained water before it infiltrates back to the groundwater system.

Groundwater pumping The transmissive nature of these aquifers means that groundwater pumping is technically feasible, although its appropriateness is likely to be limited by high groundwater salinity and whether there are productive uses for it.

Managing saline resources

Halophytic vegetation The high salinity and semi-arid area of dune seepages are well suited to the establishment of halophytic vegetation.

Salt-tolerant grasses/clovers Salt-tolerant grasses have potential for establishing a vegetative cover and some production from seepages in regions with othrewise excessive soil salinity and aridity.

Saline horticulture & silviculture Some opportunities exist for specialist horticultural and tree products useful in gaining production from saline seepages associated with dunes in semi-arid areas.

Salt harvesting The relatively low salinities and low groundwater volumes associated with dune systems mean that salt harvesting is unlikely to be a viable option.

Saline aquaculture Saline aquaculture may be technically viable, but gaining sufficient groundwater from the low volume aquifers is likely to be an issue.

Combining options

The use of two or more of the above options (appropriate to the prevailing climate, soil type and landscape position) typically may have a beneficial salinity management effect.


Table of Contents for the Australian Dryland Salinity Assessment 2000

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