Dealing with salinity in Wheatbelt Valleys - Department of Water

MANAGEMENT OPTIONS FOR MERREDIN
Management systems need to be developed which suit the community in both the short and longer term.
Options which have a high cost need to be developed in tandem with ones which have a lower cost (eg
trees, agronomic options) or higher financial return.
Factors such as chance of success, infrastructure damage, flooding risk and community impact need to
be considered along with the impacts on agriculture.
Perennial plants in recharge and discharge areas
Tree planting in the area west of the township has resulted in the decline of water tables by about 2 m.
The amount of recharge into the shallow and deep aquifer system can be reduced by planting more
trees close to and within the town boundary.
However, maximum reduction in groundwater levels can be achieved by integrating both biological and
engineering management options.
Groundwater Pumping
The alluvial aquifers and lower saprolite (weathered and fractured basement materials) have a moderate
permeability. Therefore, if the present trend in rise of water tables continues, groundwater pumping will
be a technically feasible option.
Disposal of the resulting saline water to evaporation ponds and by desalination for drinking purposes is
being trialled.
Improving the management of natural drainage systems
During the wet season, some of the town areas are waterlogged due to poor drainage. For example,
Cohn’s creek and land adjacent to the Dryland Research Institute is waterlogged and is contributing to
groundwater recharge. In addition, some tributary creeks are not efficient in conveying surface runoff to
the main drainage system.
To overcome this situation it is recommended to facilitate the natural flow of water along creek lines, and
to revegetate the drainage lines to create a soil-water buffer.
Construction of a new town dam
A third town dam has been built to augment current storage capacity. Overflow of stormwater drainage
from the current dams will be collected by the proposed dam. The dam also collects water from the roof
of the Co-operative Bulk Handling storage.
This may decrease risk of flooding, groundwater recharge and water logging problems.
Formation of the Water Action Group and the Bushland Conservation Group
The formation of these two groups will maintain community interest in the vegetation and water use
issues related to the Merredin community.