Drought ‘not broken’ in Marlborough despite rain

Despite most of Marlborough getting a good dump of rain earlier this month the region is not in the clear of its drought just yet.

The downpour even spurred a warning for about 500 people in one Marlborough town to evacuate, although this did not eventuate after the rainfall ended up being less than forecast.

Marlborough District Council surface water hydrologist Charlotte Tomlinson has been updating the council’s environment and planning committee each month on the dry conditions in the region.

Charlotte last week told the committee despite the downpour, the drought had not been “broken.”

That drought was declared on the same day of her last update to the committee.

Agriculture Minister Todd McClay on March 14 categorised the drought as a medium-scale adverse event, which opened up Government-funded support options.

“Parts of Marlborough, Tasman and Nelson districts are in the grip on an intense dry spell,” Todd said.

Charlotte said soil moisture had replenished “for now” as had river flows, and water restrictions in the region had been lifted.

“But crucially, the Wairau aquifer has not refilled from one single event like this and we need more small to moderate rain events over autumn and winter,” she said.

The aquifer was the main groundwater system under the Wairau Plain and a source of irrigation, drinking and stock water.

Water seeping from the Wairau River into the aquifer was the main way it recharged. Its levels had dropped since 1973.

In March, levels of the aquifer at Conders Bend, near Renwick, were at its lowest levels ever measured.

Charlotte said the damage had already been done in terms of crop failures and pasture growth.

“I think rain this late in the year means that there's not enough time for good pasture growth going into winter,” she said.

“So there definitely still will be ongoing issues there.

“And those who rely heavily on their dam for stored water throughout the irrigation season will also be looking for those small to moderate weather events to be able to top up their dam storage.”

Charlotte said Blenheim received 66mm of rain, which brought rainfall since July 2023 to a total of 260mm.

“Average rainfall is 615mm, so we're still looking pretty low as an annual total, but it was definitely good to get that little rain last week,” she said.

Other areas of Marlborough, such as Kenepuru Head in the Marlborough Sounds had 200mm.

“That sort of tail effect of El Niño is still definitely occurring.

In south Marlborough, the Awatere had 110mm and Flaxbourne at the Lower Waima had about 75mm.

“So, there was good widespread rain throughout the region which is really good news.”

She said the current outlook is for below average rainfall to continue through to late Autumn.

LDR is local body journalism co-funded by RNZ and NZ on Air.