Overview of factors leading to dryland salinity and its potential hazard in New South Wales, Australia
A proposed new method for predicting the occurrence of dryland salinity is to 1) map current outbreaks of dryland salinity at a broad regional scale; 2) process the results of investigations at various scales of inquiry; and 3) develop predictive tools using Geographic Information Systems (GIS). In New South Wales, Australia, the clearing of native vegetation has led to increased groundwater recharge, with a subsequent rise of water tables, thereby resulting in dryland salinity. Areas where increased recharge was observed throughout the State correspond to broad areas of vegetation clearing. Relationships also exist between the occurrence of salinity and the interaction of particular land attributes and environmental features that result in groundwater levels approaching the land surface. The new tool for mapping dryland-salinity hazard is based on the relationship that exists between the occurrence of dryland salinity and particular combinations of land attributes. Dryland-salinity occurrence was mapped spatially and digitised into a GIS, and GIS analysis was conducted with a statistical technique called 'weights of evidence.' Using this tool, the relative degrees of salinity hazard of different areas were identified that would result if a disturbance to the water balance were to take place. The results are shown on salinity-hazard maps, which aid in prioritising areas for allocating resources and managing areas that display high hazard.