‘Black box’ of rules hampers management of Murray-Darling Basin flows

The Gwydir River - part of the Murray Darling Basin

A new UNSW study demands better transparency around the idiosyncratic water management rules governing water allocation in the Murray-Darling Basin.

by Caroline Tang

The often-overlooked “human factor” in water management rules can have serious consequences for water supply for both irrigated agriculture and the environment, new UNSW Sydney research has found.

The study, published in the international publication Journal of Hydrology last month, investigated the elaborate myriad of decisions that river managers make about how to allocate and account for the water available.

Alarmingly, when researchers swapped the rules governing the Gwydir and Macquarie rivers of the Murray-Darling Basin in NSW, their analysis revealed stark differences in the water volume available long-term for the rivers and irrigation diversion: between −6% and +0.1% in the Gwydir River and between −4% and +22% in the Macquarie River.

Lead author Dr Celine Steinfeld, Adjunct Research Fellow at UNSW’s Centre for Ecosystem Science, said the researchers’ findings had significant implications for licensed water users and the governments which own, audit and manage water in rivers under the Murray-Darling Basin Plan.

“Water sharing plans and the Basin Plan itself are supposed to allow for clear tracking of what happens to the water in the rivers, but these documents are complex and opaque, and it is virtually impossible for the general public to understand how water is allocated to a licence,” Dr Steinfeld said.

“What is clear, is that there are major differences in how a set of inconsistent and largely unknown rules influence the volume of water available to irrigators and the environment in the rivers of the Murray-Darling Basin.

“So, the amount of water allocated to billions of dollars’ worth of water licences is not simply a matter of how much water is available in a catchment.”

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Or its coverage in the Sydney Morning Herald here

Find the full research paper in the Journal of Hydrology

https://doi.org/10.1016/j.jhydrol.2020.125009