There are two types of salinity—dryland salinity and irrigation
salinity. Dryland salinity occurs when native perennial vegetation
is replaced by shallow rooted crops and grazing activities. The
amount of rain taken up by plants is dramatically reduced, and
so the water table rises, bringing with it salt stored deep in
the soil. The same process occurs for irrigation salinity, induced
by heavy irrigation, not rainfall.
The salinity crisis currently facing South Australia has been
well publicised, with large areas of agricultural land lost to
high concentrations of surface and sub-surface salt. Salinity
is also a issue for Adelaide's drinking water supplies. Furthermore
high salt concentration in water causes the deterioration of pipes
and other infrastructure, increasing community costs.
The effect of salinity on the environment is widespread. Individual
plants may be replaced by salt-tolerant species, while animals
may be lost as their food source disappears; ultimately, entire
ecosystems can change. The surface movement of saline water across
the landscape increases sediment erosion through the breakdown
of the soil structure. Similarly, saline groundwater can seep
into rivers affecting water quality. In general, increasing salinity
leads to a reduction in biodiversity and an increase in the prevalence
of more salt tolerant species.
>> More
general information on salinity in inland waters
