Late in Collapse, Jared Diamond makes an interesting point about water in Australia. Apparently, many agricultural areas have salt deposits below the depth of soil reached by plant roots. As long as there is plant cover and irrigation is not excessive, the salt stays down there. When people employ ‘broadcast’ irrigation – which sprays large volumes of water everywhere – soil gets moistened down to the salt layer, causing productivity losses in that land and other land downhill.
As such, the problem is actually not water scarcity, but a level of water abundance that permits broadcast approaches in place of more efficient (and non-salinizing) drip irrigation methods.
This is a nice demonstration of a point also made by Michael Pollan and others: often, when a commodity is ‘cheap’ to a consumer, it is because the expensive externalities associated with it largely fall on other people. The Australian case also illustrates how natural abundances and scarcities are not necessarily what establish incentives and encourage or discourage different behaviours, but rather the whole collection of both natural and artificial incentives that exist at a particular time and place.
Related post: Drought subsidies