Doublethink is when we hold two contradictory beliefs in our minds simultaneously and accept both of them. Doublethink has been described as a form of trained, willful blindness to contradictions.
I reckon it afflicts a good percent of academics, activists, politicians and bureaucrats who comment on the management of water, particularly, groundwater in the Murray Darling Basin.
They are on the one hand concerned that there is not enough water and will be even less as a consequence of global warming, but at the same time they worry about rising groundwater now and into the future.
Consider a recent report titled ‘Risks to the shared water resources of the Murray-Darling Basin’ written by the CSIRO and published by the Murray Darling Basin Commission, in particular the section titled ‘Groundwater Extraction’.
It begins by stating that “groundwater stores are declining at alarming rates and this may jeopardise its future use locally”. It goes on to explain different ways that groundwater extraction can lead to reduced stream flows including:
1. When the area of pumping is close enough to a river that the hydraulic gradient between the area of pumping and the stream can be increased or even reversed, such that water flows from the stream to the aquifer, and
2. Extraction of groundwater that would otherwise flow into the river at a downstream point.
Read on and there is reference to high levels of groundwater extraction in the Shepparton-Katunga region contributing to salinity mitigation. This is code for salt interception schemes are a form of groundwater extraction.
There have been quite a few salt interceptions schemes built along the Murray River since 1982 to reduce river salinity levels and they appear to have been very successful at reducing river salinity levels. For example, levels at the key site of Morgan — which is just upstream from the offshoots for Adelaide’s water supply– have halved over the last 20 years.
The recent special federal government budget allocation of $500 million is for more salt interception schemes.
But hang-on, how much lower do we want to push Murray River salt levels and what is the tradeoff in terms of lost groundwater?
The section of the CSIRO report on ‘Groundwater Extraction’ then concludes with the comment that, “Clearing of native vegetation and irrigation has lead to raised water levels in many parts of the Basin, forcing saline groundwater out into the streams”.
No.
Where this was an issue we have constructed salt interception schemes and, across most of the Basin the problem is now falling, not rising groundwater levels.
Indeed groundwater levels in the Murray, Murrumbidgee and Coleambally irrigation areas — the regions considered most at risk of rising groundwater in eastern Australia — have generally fallen in the past decade.
They were rising in the 1970s but started falling by the late 1990s.
In 2004, the CSIRO provided me with the following reasons for the general fall in groundwater levels: improved land and water management practices; relatively dry climate over the past ten years and increased deeper groundwater pumping and higher induced leakage from shallow to deeper aquifers.
At what point will there be a realization that river salinity and rising groundwater are no longer key issues, the real issue is disappearing groundwater and it is likely to be exacerbated by the next salt interception scheme?
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.