Wheatbelt groundwater rising

The West Australian

Groundwater levels in some parts of WA's South West are rising despite the effects of a drying climate.

This is one of the findings from an analysis of about 1500 monitoring bores on more than 400 farming properties and public land in a comprehensive report published by the Department of Agriculture and Food.

Department principal research scientist Richard George said results from monitoring conducted from 2007 to 2012 showed the State's salinity problem had not dried up and gone away.

"Dryland salinity affects agricultural crop and pasture production and is strongly linked to groundwater levels," Dr George said.

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"When groundwater rises, there is a high risk that salt is also brought to the land surface.

"Rainfall over the past decade has been lower than the long-term average for most of the region.

"However, this study found that water tables rose in 40 per cent of bores monitored, was stable in another 40 per cent, while the remainder fell.

"Groundwater has continued to rise in and around salt- prone areas over much of the region.

"While rising water levels have been moderated in some areas by reduced winter rainfall, in others areas the effect of factors such as summer storms, time since clearing and land use have driven the rise in water tables."

The South West agricultural region covers 25 million hectares, of which about two thirds of land is cleared for agriculture.

Dr George said salinity had severely affected more than one million hectares and reduced productivity on a similar area of the most productive farmland.

"This data has been combined with salinity hazard mapping and estimates of salt-affected land on a map depicting the risk of salinity expanding beyond its current extent and affecting production on more agricultural land," he said.

"This information is expected to be particularly valuable to natural resource management groups as they review their salinity-related investment plans."

The highest salinity risk levels were found in East Binnu Sandplain, Dandaragan Plateau, South-Western Zone of Ancient Drainage (south-central Wheatbelt), Esperance Sandplain.

Find the full groundwater survey results and analysis - published as Resource Management Technical Report 388 - on the department website at agric.wa.gov.au.

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