2.7 Dryland salinity Key messages Condition and trend More than one million hectares of agricultural land in the south-west of WA is • severely salt-affected. Dryland salinity has expanded throughout most of the south-west of WA since 1998, • especially following episodic rainfall events, such as occurred in 1999, 2000, 2005, 2006 and 2007. In cleared and developed for agriculture after 1960, most watertables continue to • rise, despite a decline in annual rainfall. As these areas approach a hydrological equilibrium, climate impacts will • ‘new’ become the dominant controller of groundwater level trends and the extent of dryland salinity. Hydrological equilibrium and the potential extent of dryland salinity may take many • decades to develop, especially in drier areas. Management implications The implications of dryland salinity to the agricultural industry are widespread and • include reductions in crop yield, area of arable land and land capability. The opportunity cost of lost agricultural production is at least $344 million per year. • Salinity also physically and financially impacts rural infrastructure, public and private water resources and biodiversity, with costs exceeding those to agriculture. Dryland salinity is a major cause of land degradation and remains a potential threat • to 2.8–4.5 million hectares of highly productive, low-lying or valley soils, across the south-west of WA. Management to contain or adapt to salinity is technically feasible using plant-based • and engineering options, though recovery is economically viable in only a few areas. Resource risk summary for risk of expansion of dryland salinity within hydrozones. 2.7.1
2.7 Dryland salinity Key messages Condition and trend • More than one million hectares of agricultural land in the south-west of WA is severely salt-affected. • Dryland salinity has expanded throughout most of the south-west of WA since 1998, especially following episodic rainfall events, such as occurred in 1999, 2000, 2005, 2006 and 2007. • In cleared and developed for agriculture after 1960, most watertables continue to rise, despite a decline in annual rainfall. • As these areas approach a ‘new’ hydrological equilibrium, climate impacts will become the dominant controller of groundwater level trends and the extent of dryland salinity. • Hydrological equilibrium and the potential extent of dryland salinity may take many decades to develop, especially in drier areas. Management implications • The implications of dryland salinity to the agricultural industry are widespread and include reductions in crop yield, area of arable land and land capability. • The opportunity cost of lost agricultural production is at least $344 million per year. Salinity also physically and financially impacts rural infrastructure, public and private water resources and biodiversity, with costs exceeding those to agriculture. • Dryland salinity is a major cause of land degradation and remains a potential threat to 2.8–4.5 million hectares of highly productive, low-lying or valley soils, across the south-west of WA. • Management to contain or adapt to salinity is technically feasible using plant-based and engineering options, though recovery is economically viable in only a few areas. 2.7.1 Resource risk summary for risk of expansion of dryland salinity within hydrozones.
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