Environmental Engineering Reference
In-Depth Information
healthy river, according to Cullen. The economic development of the Murray-
Darling Basin is limited by the availability of water, though there is room for
greater efficiencies and a move from low to high value crops.
Any further population growth in the Basin will mean some water must
be transferred to domestic users from irrigators, who are still fighting the
withdrawal of water for environmental purposes. Nevertheless, most people
now recognise that water is a finite resource that must somehow be divided
fairly between the river itself, agriculture, industry and domestic use. It is
dawning on the planners and legislators of Canberra, the national capital
sited within the Basin, that if the city's population is to grow to a half million
from its current 320 000 then permanent water restrictions will be necessary.
Further dams to ensure water security for Canberra's citizens, while techni-
cally and economically possible, will probably be deemed ecologically unac-
ceptable because they will restrict environmental flows downstream.
Meanwhile coastal cities, also afflicted by water restrictions, continue to
grow unabated. As Cullen notes, Melbourne has insufficient water in the
existing catchment for the anticipated extra million people. On top of
improved efficiency, other measures such as the recycling of water will have
to be employed to ensure adequate supply. Infrastructure for wastewater
treatment or a third pipeline for recycled water all cost money, however, and
the 'balancing of the economic, environmental and social costs of such deci-
sions is not readily achieved' as Cullen notes. At some point, further popula-
tion growth must be deemed unaffordable and indeed, unsustainable.
Some believe that, despite water being a finite resource, improvements in
efficiency will allow Australia's population to grow for the foreseeable future.
Certainly, there have been considerable innovations in agriculture such as
drip irrigation for horticultural crops that have not only saved water but
impeded salinisation by reducing leakage beyond the root zone. As far as
domestic use is concerned, however, it is generally agreed among water util-
ities that a saving of only 25 per cent can be expected (Perkins 2002). Given
the uncertainties of climate change and the extent of overextraction, caution
is warranted in terms of further population growth.
Health
Tony McMichael (Chapter 2) reminds us that 'humankind, via its expansions
in numbers and economic intensity, is now overloading the biosphere' and
that the resurgence of infectious diseases has 're-emphasised population-level
