Aquifers full for summer

22:30, Dec 04 2012

Aquifers in Marlborough are full going into the summer irrigation season, the Marlborough District Council says.

Council environmental science and monitoring manger Alan Johnson said higher-than-average rainfall had reduced demand for water and recharged key aquifers.

This meant there should be plenty of water available for irrigation this summer.

However, forecasts suggested pressure on aquifers and surface water could increase.

"The sun has been shining brightly for the last two weeks and forecasts from Niwa and MetService are for above-average temperatures and below-average rainfall," he told the council environment committee meeting on Friday.

Despite its large size, the Wairau aquifer was quickly affected by fluctuations in the Wairau River, he said.


It appeared to have only several months of storage, and levels could fall quickly.

The Wairau River lost seven cubic metres of water a second at low flows and research was under way to see whether this increased during flood flows, Mr Johnson said.

If this was the case, the council might be able to allocate more water for irrigation.

In the water-short, southern valleys, aquifer levels were rebounding strongly, Mr Johnson said.

Since 2008, more water had flowed down the Omaka River, keeping shallow to medium-depth wells in Woodbourne and below the southern Wairau Plain higher than usual.

Metered groundwater use in these catchments had declined after the introduction of the Southern Valleys Irrigation Scheme in 2004 and wetter weather since 2008, Mr Johnson said.

The Marlborough Express