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Water Matters Dealing with another dry season SOPHIE PREECE
MARLBOROUGH HAD its longest recorded dry spell this summer, suffering more than two months without substantial rain. But vineyards came through February in better shape than the same time last year, when many growers lost irrigation rights from early February. While “it is certainly getting pretty dry”, vines overall are looking significantly better than this time in 2019, said Fruition’s Jim Mercer in late February. “We’re in a better situation, but if we don’t get significant rain in the next three weeks, some people could start to struggle.” Plant & Food Research scientist Rob Agnew says the Blenheim station recorded just 1mm of rain between December 21 and February 21, then a 5.2mm addition on February 22, making it just 6.2mm of rainfall in the 66 days from 21 December to 24 February. “This is the lowest rainfall total for that length of time on record.” But while rainfall was lower than the same period in 2019, the Wairau River was better off, hovering between 8 and 12 cumecs throughout most of
February, but not dropping below the 8 cumec cutoff for irrigators taking Class A water from the Wairau. That is likely due to rainfall further up the catchment, as well as Trust Power operations, says Rob. “Up until the last week of February we have dodged a bullet compared to last year.” In 2019, the continued dry and limited irrigation opportunity saw leaves fall off stressed vines, while some growers caught short trucked in tanks of water. Jim says the industry has learned from that, and this year have been at pains to improve soil moisture levels before water shutdowns, while not watering so much that the canopy becomes too lush. Meanwhile, more dams are going in, with 16 resource consent applications for new dams in Marlborough last year, according to records from the Marlborough District
Feeling parched?
“With irrigation on for half an hour it will not infiltrate any depth and won’t be efficient.” Council. Eleven of those have been consented and five are still being processed. Jim says companies are also investing more in the maintenance of their irrigation systems. That can be a “constant battle” because of pumps clogging or wearing out, solenoid malfunctions and hares and rabbits damaging driplines, by chewing through to find remnant water, says Jim. “They create a lot of small leaks…
Last summer highlighted how important Marlborough’s surface water resources are for irrigators. Hydrologist Val Wadsworth has years of experience and knowledge. Get in touch, especially if you want more water storage for your vineyard. Val can provide river flow and rainfall records and explain the science behind them. River and rainfall information can also be found at www.hydro.marlborough.govt.nz Val Wadsworth Hydrologist
DDI: 03 520 7441 | M: 021 667 746 val.wadsworth@marlborough.govt.nz www.marlborough.govt.nz
18 / Winepress March 2020
