The looming threat of aquifer salinisation

Abstract

The dramatic changes in the landscape since European settlement have radically altered regional water balances in semi-arid areas, which have not only resulted in land salinisation, but have and will cause salinisation of aquifers over the next 100 or so years in semi-arid areas of the Murray Basin. This process is triggered by two main processes ? land clearing and extractions for irrigation. The small amount of salt in rainfall has been concentrated by native mallee vegetation over thousands of years and is stored in the root zone, with salinities approaching that of sea water. Clearance of this native vegetation for dryland cropping has not only increased recharge, but has initiated the flushing of this salt down to underlying aquifers which often contain good quality groundwater. Irrigation extractions from shallow permeable aquifers have led to the recirculation and concentration of salt. These salinisation processes require a new interpretation of what sustainability means for groundwater development.