10 November 2016

Climate real culprit behind aquifer decline

Blaming irrigating farmers for the decline in Mid Canterbury’s aquifer levels is an overly simplistic response to a larger climatically-induced problem, says IrrigationNZ CEO Andrew Curtis.

Aquifers right across Canterbury are running low primarily due to three winters of little rainfall and low snow levels, says Mr Curtis. While late spring saw increases in rainfall, the months preceding this were very dry and the cumulative impact of three winters of low recharge is now showing underground.

“People look at the recent rain and think the aquifers should be bouncing back, but it doesn’t work like that. Aquifer recharge is a relatively slow moving process. For the Mayfield area it’s very much driven by winter rainfall. With three dry winters behind us, we were always going to have to be careful about water use coming into this season. In fact, local groundwater irrigators are also facing exactly the same issues. Most of the irrigation around Mayfield actually comes from irrigation schemes that supply alpine water from the Rangitata or Rakaia Rivers – the irrigators are not using groundwater. The bigger picture is that we have been close to drought for three years and many water resources are under pressure.”

Mr Curtis says with increasing uptake of SMART Irrigation practice and technology, some irrigators are actually reducing the water they apply – lessening their impact on the resource, while at the same time saving them time and money.

“We advise irrigators only to apply water when necessary and employ SMART Irrigation practices and technology to ensure they manage their water allocation sensibly. We certainly don’t want to see anyone wasting water and want to reassure the public that with careful and prudent use, irrigation within current allocation levels can be sustainable.”

It was inaccurate to say “irrigation was currently going “full tit” as recent data showed a slow start to the season, with many irrigation schemes reporting lower demand from farmers for water, due to the persistent cold and wet conditions.

Ashburton District Council’s response to the Mayfield crisis using technology to treat a stockwater supply for drinking water was innovative and met with Public Health approval.

“We can understand that people are upset about the decline in their local aquifer but the bigger picture is we need to plan for climate change and the likely impacts on aquifer recharge. We need to be looking at how we use science to provide us with solutions. The Hinds Managed Aquifer Recharge (MAR) project is already showing positive results and it’s quite feasible that local drinking water supplies could also be supported by similar MAR projects to make them more sustainable. Alternatively a direct alpine supply could also be a solution.”

ends

© Scoop Media