Gourlay and Tunstall on dryland salinity
The Sunday program on salinity, as it related to irrigation and the Murray-Darling, was pretty old stuff; pointscoring about some silly past statements (such as the NFF/ACF proposal to spend $65 billion) combined with a Pollyanna view of the current situation, familiar in general tone to anyone who’s followed climate change denialism.
What was interesting and new to me was the claim, put forward by Rob Gourlay and Brian Tunstall that the standard model of dryland salinity, based on rising water tables, is wrong and that the real cause is poor soil quality. The show also featured a farmer who claimed to solve salinity problems by defying the advice of the experts. This reminded me of a much older challenger to standard hydrology, Harry Whittington and his interceptor banks, which I discussed briefly here
I haven’t worked on dryland salinity for a few years now, but I’ve followed the issue reasonably closely, particularly through the work of Dave Pannell at University of Western Australia, who’s one of Australia’s leading agricultural economists. Unlike me, Dave’s a bit of an enviro-sceptic* (he’s written favorably about Lomborg, for example), but no-one I know is better informed on dryland salinity. So I was interested to see his reaction to all this. Suffice it to say he’s unimpressed A quick summary
that the rising groundwater theory of salinity is wrong, and should be replaced by a theory based on soil health) is problematic, to say the least. Channel 9 interviewed almost all of the small band of scientists (the â€œsoil-health teamâ€?) who have for some years been pushing this line, but not a single person who would be qualified to present the counter view. Now Australia is a big place, and there may well be different mechanisms in operation in different places. But for the soil-health team to claim that the rising groundwater theory is universally wrong is quite outrageous. …
The proponents of the alternative theory need to subject their ideas to the standard method of quality assurance in science, by publishing their evidence in a peer-reviewed journal. They have not yet done that.
*Not perfectly phrased. Dave takes a properly sceptical attitude to the evidence on salinity and other environmental issues he’s worked on, as all good scientists should do. At times, though, I think he’s too kind to people like Lomborg, who claim to be sceptics but are promoting a viewpoint that’s just as credulous as that of the environmental alarmists like the Club of Rome, but in the opposite direction.
On the other issues, Pannell agrees with Jennifer Marohasy that scientists overstated the salinity problem in the late 1990s, though in comments here he agrees with me that “she is spraying bullets around a little indiscriminately”. I broadly agree with Pannell’s criticism of both of the National Land and Water Audit (as I mentioned here, and the NFF/ACF $65 billion proposal (I estimated about $2 billion here). But I don’t think these instances of exaggeration amount to a large-scale fraudulent conspiracy or anything like it.
Coming the core point of my disagreement with Marohasy, Pannell notes
The causes of the fall in salinity are well known: extensive pumping of saline groundwater, and a long period of below-average rainfall.
Despite this positive news, it is believed that, if rainfall returns to average levels, salinity from dryland areas will eventually overtake the effects of the groundwater interception schemes â€“ river salinity levels will rise again. Indeed, if there is even a brief period of above-average rainfall, salinity levels will probably be elevated for some time afterwards. (It is now appreciated that salinity in the river is driven to a large extent by episodic flooding.)
… we should not forget that the likely future area of salt-affected land is still very large (probably something of the order of 6 million ha) and that for salinityâ€™s impacts on water resources, infrastructure, and biodiversity, area is not the issue, anyway. The lesson is that salinity investments (like other environmental investments) need to deal with the issues soberly, based on the best available evidence.
I couldn’t agree more.
A final note on Gourlay and Tunstall. As Dave Pannell pointed out to me, their model is totally different from, and inconsistent with, Whittington’s. Yet if you look at this report presenting their views, they say
The clearest evidence of the lack of general applicability of the rising groundwater
model is presented by Paulin. The work and observations by Whittington in the Western Australian wheat belt reported by Paulin demonstrate …
So it looks as if it’s back to the interceptor banks!