Tuesday 29 December 2015

El-Nino in New Zealand: the South Island drought

Marlborough drought could break records
Marlborough will face record-breaking dry conditions if the region does not get a decent drop of rain in the next four days.

The Wither Hills, in Blenheim, look dry and barren, as Marlborough heads towards the lowest rainfall since 1969.
The Wither Hills, in Blenheim, look dry and barren, as Marlborough heads towards the lowest rainfall since 1969.
28 December, 2015

Marlborough District Council operations and maintenance engineer Stephen Rooney said there had been no rain in the district in the past week, with the exception of a small amount on the lower east coast.
Unless substantial rain was received soon, Marlborough would experience a season on par with the big droughts of 1973, 1998 and 2001, Rooney said.
"With only four days of the year remaining, Blenheim looks very likely to surpass its lowest ever rainfall of 398 millilitres recorded in 1969."
A continued dry stretch would see Marlborough record the driest year since records began in 1930.
There was still the chance of a brief period of rain late on Wednesday, but this was not expected to be significant, he said.
The Southern Valleys Irrigation Scheme, which fed water from the Wairau River to about 4500 hectares of mostly vineyard land south of Renwick, was predicted to be shut off before the weekend, Rooney said.
The shut off was predicted after the Wairau River average flow dropped to 10 cubic metres per second on Sunday.
"Without rainfall to increase river flows the scheme will be shut off in the next couple of days, probably before the weekend," he said.
Nautilus Estate winery manager and winemaker Clive Jones said the first shut off of the summer was not a surprise. 
"The first water shut off is not major. People shouldn't panic. If it stays off for a week then it becomes critical. If we don't get further rain it will be significant."
It was too early to be talking of vineyards trucking in water, he said.
Significant rain in the headwaters of the Wairau River in the West Coast would be enough to replenish water in Blenheim, he said.
Nautilus had one vineyard property on the irrigation scheme but it had back-up water storage.
"After last year everyone predicted it was going to be another dry season. The shut off is part and parcel of the business."
For those that had no back-up, the impact on vines was a case-by-case depending on the soil type, Jones said.
"The reality is vines need water.
"Grapes are currently sizing up. If water is restricted they may not get as big."
Astrolabe viticulturist Jeremy Hyland said they were lucky to have just 30 hectares of grapes using the Southern Valleys Irrigation scheme. 
They had a back-up storage dam providing a couple of weeks worth of water for irrigation if the scheme was shut off.
"For some they won't have back-up plans. It's bad timing. 
"It has been so dry everything is dying off anyway."
Grapes would hit their critical growth phase in a month when they would need the largest amount of water, Hyland said.
Grapes used water when ripening to transport nutrients and maintain the strength of the plant, he said.
"If vines come under stress prior to that it is going to be very hard."
River flows had dropped steadily over the past week. Waihopai class B takes were now unavailable, and it was likely that Awatere B, Wairau B, Waihopai A, and Rai restrictions would come into force in the next five to 10 days, Rooney said.
Disciplined Renwick water users in the urban network had staved off water restrictions in the township until the New Year.
Council water engineers cut back the output from the Renwick bore field on Christmas Eve, reducing it by 4 litres per second to ensure the water level remained above the pumps.  
This reduced overall output to 42 litres per second but because Renwick residents were holding their demand below 2500 cubic metres per day. This output was enough to meet demand.  
"If this, and their reduced water use in the early evening, continues restrictions can be delayed until early in the New Year."  
The Wairau aquifer level was still dropping but its rate of decline appeared to have slowed, Rooney said.
"A good rainfall is still needed to stave off the restrictions that are likely to be required in January."
Renwick residents were urged to irrigate gardens in the early morning and late evening to avoid high rates of evaporation and water lost in the wind.
 - The Marlborough Express

Marlborough drought 

threatens grape harvest

A winemaker in Marlborough says extremely dry weather is already taking its toll on vineyards in the region.

The sun rises over the vineyards of Waikakaho Valley in Marlborough The sun rises over the vineyards of Waikakaho Valley in Marlborough - Photo: RNZ / Tracy Neal

29 December, 2015

Water restrictions are likely for residents in Marlborough as the region prepares for what could be one of the driest summers in decades.

The Marlborough District Council said unless there was a substantial amount of rain soon, the region would experience a severe drought.

Yealands Family Wine founder Peter Yealands said the area was as dry as he could remember.

"There is no soil moisture whatsoever. If you're trying to drive a post into the ground, it's nearly impossible."

"We've never never anticipated such an extreme drought, or dry, so early in the season.

Mr Yealands said most wineries would have a backup water supply for dry conditions, but it would only last a month.

He said if he ran out of water he may have to sacrifice some of his crop to save the vines.

Marlborough mayor Alistair Sowman says wine is the dominant economy driver in the region.

"If we don't get any rain by the end of the week, the southern valleys irrigation scheme, that irrigates about 4500 ha - mainly grapes - is likely to be turned off, and that's a major."

Mr Sowman said if the irrigation scheme was turned off, water would have to be trucked to vineyards.

Listen to more on Summer Report ( 4 min 8 sec )

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