Geoscience Reference
In-Depth Information
Understanding the complexity of Australia's physical geog-
raphy is essential to appreciating the impact humans are having
there. The environment is extremely sensitive, and the potential
environmental issues in the future are thus critical. Consider
first the population of the country. As of 2012, the population
of Australia was a little over 22 million, with most people living
on the relatively humid margins of the country, especially the
continent's eastern side (Figure 20.20a). To put that number in
perspective, consider that the population of the United States,
which is fundamentally the same physical size as Australia, is
now about 314 million. Certainly, some of Australia's relatively
low population is related to its isolation and a very different
immigrant history compared to the United States. Another more
important factor is that the comparatively sterile physical en-
vironment of the country simply cannot support more people
on a sustainable basis. In fact, some believe that the country is
already
overpopulated and that the sustainable population may
be as low as 8 million people.
Given potential population issues in the country, it is es-
sential that Australian farmers maximize food production. Un-
fortunately, a key variable limiting this goal is the simple fact
that the vast majority of the country is unsuitable for agricul-
ture, as you can see in the land-use map in Figure 20.20b. As
a result of these opposing realities, many farmers have focused
on marginal drylands on the fringe of the outback to produce
food, particularly wheat. The primary wheat areas in Australia
are the Murray-Darling River basin in the southeastern part of
the country and the wheat belt region in the extreme southwest
(Figure 20.20c). The wheat belt region, for example, produces
about 20 to 25 million tons of wheat per year.
As you have seen in ancient Sumeria and the San Joaquin
Valley, dryland farming can increase soil salinity. Such soil sa-
linization is a serious problem in the wheat areas of Australia.
These regions are particularly susceptible to salt buildup because
Australia is naturally a very salty place. This natural salinization
of the continent has occurred due to the interaction of several
factors related to physical geography. First, much of the conti-
nent is essentially a closed basin where very little water flows to
the sea. As a result, when rain does fall, it tends to settle in spe-
cific places rather than flow away. Another factor is that any rain
which does fall contains microscopic salt particles derived from
the saline marine waters that surround the continent. Over mil-
lions of years these salts have gradually built up in Australian
N
Based on Statistical Local Area
Boundaries. 1 dot = 1000 people
0
250
500 km
0
200
400 mi
(a)
N
Approximate Outback boundary
(c)
Tropical fruits
Figure 20.20 Australian population and land use.
(a) Pop-
ulation geography of Australia. Note the relationship of dense
population clusters and the precipitation map in Figure 20.19.
(b) Map of land use in Australia. Again, note the geographical
relationship of land-use patterns and precipitation shown in
Figure 20.19. (c) Photograph of the wheat belt region in south-
western Australia.
Forestry
Natural vegetation
Wheat
Extensive grazing
Barren land
0
250
500 km
0
200
400 mi
(b)
