Irrigators fears rise as Murray storages dry up
DROUGHT in the Murray–Darling Basin is starting to bite as low rainfall and high temperatures conspire to reduce runoff and deplete water storages.
A SEVERE drought in the Murray–Darling Basin has raised concern among SA irrigators as water storage levels have dropped dramatically in the past 24 months.
The Bureau of Meteorology drought report reveals near lowest year-to-date rainfall in the Basin, second only to the Federation Drought of 1902, combined with the warmest January to September (+2.10C).
Climatologist Blair Trewin said warmer temperatures had increased evaporation rates and sapped soil moisture.
“Clearly 2018 has been a very severe drought here in the Murray-Darling Basin,” he said.
“We need to continue monitoring the situation closely.”
Basin water storages, full at the end of 2016, were down to 54.5 per cent, compared with 73.9 per cent this time last year.
“If we were to have another year as bad as the one we’ve just had, that would start putting us into the sort of territory where we were in the Millennium Drought, or alternatively if we had a few mediocre years,” Mr Trewin said.
“We’ve seen over the last 12 months a drop of around 20 per cent in storage levels in the Basin, so you can do the maths as to how long you can sustain that before getting into significant issues.”
Murray–Darling Basin Authority head of river management Andrew Reynolds says the Basin Plan ensures available water is shared across all users, including irrigators and the river environment.
“We have enough water in storage to meet the needs of South Australia this year, and South Australia is expected to receive its full annual entitlement flow of 1850 gigalitres,” he said.
“How much it rains in the Murray and the Darling catchments over the next 12 months will influence the water available next year, and we monitor conditions continually so we are well prepared.
“The MDBA plans for the full range of scenarios from extreme dry to wet.”
Water is “prioritised for critical human needs” across the Basin for drinking and household water before being allocated for any other use.
As the Authority explains on its website, “climate change is predicted to increase drought frequency and severity in the Basin”.
“Changes in rainfall patterns and warming temperatures, leading to higher rates of evaporation, are adding to the intensity and impacts of both floods and droughts.
“These changes will continue to increase the complexities and uncertainties faced by water managers.”
In SA irrigation allocations have been provided at 100 per cent and the Department for Environment and Water says that’s not about to change.