Changes in landuse, seasonal variations in our weather and longer-term changes to climate can all affect surface water, groundwater, the flows between them, and the amounts of salt that they contain. The term "salinity" refers to the concentrations of salts in water or soils. Salinity can take three forms, classified by their causes: primary salinity (also called natural salinity); secondary salinity (also called dryland salinity), and tertiary salinity (also called irrigation salinity).