Northern Rivers gauges the long-lasting effects from its unusually bone-dry summer – Curious North Coast NSW


April 18, 2019 05:43:15

If you sweltered through summer and wondered if it would ever rain again, you weren’t the only one.

People across the Northern Rivers region of New South Wales are gauging any long-lasting effects from its unusually bone-dry summer.

In January, an average of just six millimetres of rain fell across the normally wet, subtropical corner of the state.

Many places had zero rainfall, making it their driest January on record, all the while heat records were tumbling.

The odd 35-degree-plus spike is not unusual in January or February, but Grafton, Casino and Lismore were breaking temperature records as late as March.

“We saw some fairly extreme climate conditions,” Bureau of Meteorology (BOM) climatologist Felicity Gamble said.

“A string of particularly strong heatwaves hit the region in January and [there was] a real lack of rainfall.”

Water use restricted

Water trucks were seen rumbling along rural roads, topping up empty water tanks for the many people who ran out after an extended dry period that began in October.

Being on the tablelands, Tenterfield was the worst-affected area in our patch.

Earlier this month, the council voted on level 4.5 water restrictions, meaning that watering of public gardens and fields is banned, as is the use of potable water for mixing concrete, while domestic gardens can only be watered between 5:30pm and 6:00pm.

The council estimates there are fewer than 170 days’ worth of drinking water remaining in its main storage without substantial rain.

Horticulturalists hard hit

It was a tough summer for farmers.

There is little-to-no subsoil moisture — that’s bad for pastures, crops and particularly bad for tree horticulture.

Scott Clark said he invested his life savings planting a 5,000-tree pecan orchard at Lagoon Grass near Lismore.

“I’ve lived here all my life, 47 years — I don’t think it’s been as dry as what it is at the moment,” he told ABC North Coast’s Kim Honan in February.

“The small crop we had is gone, we won’t get anything. The stress the trees are under, we’re hand-watering just to keep them alive.

“There’ll be tiny little nuts there but they’ll be unsaleable. Some of the younger trees are starting to have losses, they’re starting to die.”

And the effects will be felt down the track, with next year’s crop likely to be poor and cracks opening up on the orchard floor.

“There’s one crack that’s five or six metres long and I can’t touch the bottom of it, so that’s causing root damage, and as it’s opening up it’s breaking roots; smaller feeder roots that help keep the trees alive are being broken,” Mr Clark said.

It’s a similar story for some in the macadamia industry, with stressed trees shedding immature nut in January and February just before the six-month harvesting season was due to start.

‘Never known a season like it’

Australian Macadamia Society boss Jolyon Burnett said he’d heard born-and-bred growers say that they had never known a summer like it.

“The tree tends to shut down a little bit, doesn’t photosynthesise as much, and doesn’t get to fill up with that beautiful buttery kernel that we all know and love.”

As with the pecan growers, macadamia growers have seen losses of up to 10 per cent of their crop due to the shedding of immature nut, and the nut that is saleable can be 10 per cent smaller in kernel size.

It’s uncharted territory in the Northern Rivers, but Mr Burnett said the industry could take a lead from South Africa which had a two-year drought from 2014.

“They had tree death, and the trees that survived have taken really until now to fully recover, so we do expect it will take a couple of years [here] to get back to full health,” he said.

What about the baby storks?

The region’s many wetlands, including the Everlasting Swamp near Lawrence, didn’t receive the inundation that triggers breeding from the smallest creature up to the black-necked stork, often wrongly named the jabiru.

Ecologist and researcher Dr Greg Clancy has spent years cataloguing the movements of the Clarence Valley’s 20 pairs of black-necked storks.

“You need enough expansive waterbodies with good populations of these fish for the storks to breed; because the wetlands have been dry, we’ve had very little breeding in the past couple of years,” he said.

“If the rains aren’t that heavy and the wetlands don’t fill, there’ll be another year when we don’t get baby storks.”

It can be harder to track the impact on the region’s wildlife, which will move to find water, than on trees.

Dr Clancy said he suspected there was some loss of rainforest trees and possibly even eucalypts because of the unusual dry.

“A lot of Australian wildlife is adapted to not taking in a lot of drinking water, so a lot of species can hang out for a while,” he said.

“But the plants are under a lot of pressure, and particularly rainforest species can die, even gum trees can die, but it’s hard to know with wildlife because they’ll move around.”

Algal blooms and fish kills

There were reports of fish kills in the upper Richmond River, with around 70 dead fish visible — nothing compared to Menindee’s estimated one million dead fish, although there may have been many more under the water.

Blue-green algal blooms flourished in Lake Ainsworth at Lennox Head, Jabour Weir at Casino and Bray Park Weir near Murwillumbah.

That’s not uncommon here in summer when still or slow-moving water warms up to around 28 or 29 degrees.

Ironically, if temperatures continue to rise in future summers, water bodies like Lake Ainsworth could become too warm for blue-green algae, according to Ballina Shire Council environmental health officer Rachel Jenner.

What’s behind this unusual summer?

So what drove this dry, baking, unusual summer?

Quite a few things apparently.

Ms Gamble said one factor was an absence of cold fronts in the south, which could have brought rain or at least cooled the air masses bringing heat from the interior.

“We also had a very dry lead up, quite a dry spring, which was a result of a climate driver that we call the Indian Ocean dipole, and that went into a positive phase,” she said.

“It’s a little bit like El Nino, but it happens in the Indian Ocean.”

Further north, the monsoon season in the tropics had one of the latest onsets on record.

“It didn’t really kick in in Darwin until January 23, which is about three weeks later than the average onset, and that also meant the heat in the interior of the country was able to build up considerably,” Ms Gamble said.

The third major influence was a lack of east coast lows, which can’t be predicted much more than week in advance.

Worrying signs for the future

So will we return to that typical late spring-summer pattern of afternoon rainstorms clearing in time for a beautiful sunset, followed by plenty of rain in late summer and autumn?

Ms Gamble said yes, but that there were also some worrying indicators for more intense floods and fires.

“I think that’s still likely to be a typical pattern for the Northern Rivers area,” she said.

“There’s high confidence that there’ll be increased intensity of extreme rainfall events over future decades, so although there’s no clear trend in summer rainfall, there does seem to be evidence that rainfall will be more intense rather than more rain days, and quite high confidence of harsher fire conditions for that part of NSW as well.”

Who asked the question?

Lennox Head resident Alice Moffett asked Curious North Coast: “What has been the impact of the dry weather during summer, which has always been our wet season?”

Ms Moffett said she felt like the summer of 2018-19 was unusually dry.

“I noticed this was the hottest summer I’ve experienced in the Northern Rivers, particularly the driest,” she said.

“I noticed plants starting to brown off and die, and normally it’s our wet season, and I just began to wonder what impact that was having on the plants and the rest of the biodiversity.

“Normally smaller plants and palms would be fine over summer, but some of the rainforest species like bromeliads that normally flourish, were just not getting the water.”

Ms Moffett said she was concerned about how the community would manage into the future if long stints between substantial rain continued.

While you’re here … are you feeling curious?









Source link

About the Author

Australia News
More Than 20 Years in News and jobs

Be the first to comment on "Northern Rivers gauges the long-lasting effects from its unusually bone-dry summer – Curious North Coast NSW"

Leave a comment

Your email address will not be published.


%d bloggers like this: