Mangatangi Dam in the Hunua Ranges, pictured in July. While dam levels have increased much since last summer's big dry, they're still sitting nearly 20 per cent below normal. Photo / Alex Robertson
Mangatangi Dam in the Hunua Ranges, pictured in July. While dam levels have increased much since last summer's big dry, they're still sitting nearly 20 per cent below normal. Photo / Alex Robertson
Even after months of Auckland downpours, pockets of drought in the region linger on from the biggest dry to hit the region in a quarter of a century.
But those parched spots are expected to be soon swept away by what's forecast to be a warm but wet summer under La Nina - and Watercare's boss says the agency is already in a "strong position" to meet coming demand.
Niwa's latest monitoring showed "hotspots" of excessively dry soils were now few and far between around most of the North Island, after the western and central areas received rainfall totalling more 50mm or more last week.
Although northern spots also received some rain, small to moderate drops in soil moisture were still recorded across Northland, Auckland, the Coromandel and the East Cape - with the driest ground currently found in the Far North.
In the South Island, soils were driest compared to normal for this time of year in lower Westland - and wettest around Nelson.
All the while, patches of orange and yellow on drought maps - denoting drier than normal conditions - were still to be found around the Auckland region.
Source / Niwa
Niwa meteorologist Ben Noll said pockets of hydrological drought were still holding on from last summer.
"Hydrological drought is basically how the moisture in the ground is doing, both near the top of the soil, and all the way down to lower depths as well," he said.
"Sometimes that can be out of synch with meteorological drought, which we relate more to rainfall patterns.
"So it may be the case that, given how incredibly dry it was in Auckland earlier this year, that ground is still not fully replenished."
While big rainfall events were helpful for bringing up dam levels, too much rain falling at once on parched soils often ran off before it could be properly absorbed into the soil.
Noll said isolated drought pockets remained most visible from the North Shore, southward to the Hunua Ranges.
"I think in many ways we have alleviated [the drought], but there are still lingering reminders of what once was, earlier this year."
He expected that, if a La Nina climate system now influencing our weather kept delivering its much-needed moisture to the region, those remnants would be gone by mid-summer.
"The further we get into summer, it may even be we're looking at the other side of the coin, with respect to flooding events. As we saw in Napier, those high-intensity rainfall events can be a hallmark of La Nina, but where they land is anyone's guess."
As at this morning, Auckland's dam storage levels were sitting at 72 per cent of capacity - still well below the 91 per cent that was normal for this time of year.
Extra water reserves were expected to come from several upgrades to bores and reservoirs.
A completed Pukekohe East reservoir, due to be officially opened today, would allow the Waikato water treatment plant to draw an extra 25 million litres each day.
Further boosts would come from two Pukekohe bores coming back into operation with a new modular treatment plant, an upgraded Onehunga aquifer, the new Papakura water treatment plant, and the returned service of the Hays Creek dam.
Watercare also credited efforts by Aucklanders to slash their water use this year.
"Aucklanders have saved more than 7 billion litres of water since restrictions were put in place in May, which is a fantastic effort," chief executive Marlon Bridge said.
"These savings, together with new sources we have brought online, have allowed us to minimise abstraction from our Hunua dams while they recover from drought."
You're keeping it green, AKL. Your 7-day rolling avg water usage is sitting bang on 400 million litres - well below the target of 433. And, our total water storage is looking OK at 72.47%. It should be 91.11%, but it's better than it was a few months ago.#save20aklpic.twitter.com/GcifDHzteC
"I am confident we are in a strong position heading into summer, which is why we recommended residential water restrictions be adjusted to allow people to use hand-held hoses with trigger nozzles.
"But we are not out of the woods yet and the need to save water hasn't gone away – we are still asking people to use water wisely because it is a precious resource."
Bridge also pointed out that summer forecasts were now more favourable than the dry position predicted back in May.
"They are indicating we could be in for a warm and wet summer, with active tropics bringing bursts of heavy rain followed by a dry period of a week or so. There is also a reasonable chance of a four-week dry period.
"Even if the weather turns out to be drier than what's predicted and dam levels drop, if Aucklanders keep up their good water-saving habits and use their hoses responsibly we should avoid the need to impose more stringent restrictions."
