From sky to server

From sky to server

Source: NIWA – National Institute of Water and Atmospheric Research

Ominously large and bloated with moisture, angry clouds sweep across the Fiordland coast.

Winds drive the storm system higher and torrential rain begins thudding into the earth below. It doesn’t take long before heavy drops start falling plumb into the mouth of the Takahe Valley rain gauge, in the Murchison Mountains just west of Lake Te Anau.

The raindrops are about to make their mark at a national scale.

In a matter of seconds, they will trigger a response from the automated gauge and be registered in an ever-growing climate database that plays a key role in decision making across the country.

The raindrops falling at NIWA’s Takahe Valley weather station collect in a small, seesaw-like receptacle called a tipping bucket. Bit by bit, the water level inches upward. The bucket over balances, dumps its load and resets for another take.

A datalogger records the tip and pings the information to a server at NIWA’s Christchurch office. From there it travels along a high-speed network to NIWA’s Wellington office, where it is automatically entered into long-term storage in New Zealand’s national Climate Database – more commonly known as CliDB.

For a meteorologist, CliDB is the motherlode. It stores weather data from all over New Zealand, Antarctica and the Pacific Islands. The earliest recordings are from the mid-1800s, with the latest information flowing in from a network of hundreds of stations like that in Takahe Valley.

The database is growing fast. If it is raining hard in the Murchison Mountains, the automated rain gauge generates a measurement every six seconds. Ten minute and hourly readings are also taken – rain, hail or shine. Weather stations, of course, measure far more than just rainfall. Sensors put together by NIWA’s Instrument Systems division simultaneously record temperature, wind speed, air pressure and humidity. Some specialist stations measure solar radiation, and every instrument is busy feeding its own stream of data into the network.

With stations dotting the country and weather fronts hitting all points of the compass, the numbers quickly add up. In January alone, more than 1.5 million new rainfall data points flooded into CliDB.

In total, CliDB is connected to more than 600 weather stations – a network that stretches out across New Zealand, north into the Pacific and as far south as Antarctica. Many of the facilities are maintained by other agencies, such as MetService, the Department of Conservation and regional councils.

The database also incorporates a host of additional weather information provided by sources ranging from drifting ocean buoys and shipping vessels to historic observations gathered from lighthouses or aircraft.

Readings from seven key sites – Auckland, Masterton, Wellington, Nelson, Hokitika, Lincoln and Dunedin – are particularly important. Stations at these locations have been benchmarking New Zealand’s average annual temperature since 1909. NIWA’s seven station temperature series has confirmed NZ’s average annual temperature has increased by about 1°C over the past 100 years.

NIWA is the custodian and the curator of all the information flooding into CliDB. The data is rigorously quality controlled and audited to international standards, with machine learning playing an increasingly significant role as computers are programmed to hunt for gaps and flag anomalies in the dataset.

Keeping tabs on muddy waters

Keeping tabs on muddy waters

Source: NIWA – National Institute of Water and Atmospheric Research

He says invertebrates like worms, crabs and shellfish can provide many of the answers to changes in estuaries.

“We’ve developed indices of estuarine health that are based on the composition of these invertebrate communities. For example, if all the species that are sensitive to mud are disappearing, we might have a strong indication that too much fine sediment is being added to the estuary.

“In a single core of sediment you can get 30 to 40 species and up to 300 individuals.”

“It requires a lot of understanding of these species, but when you know a little about their sensitivities and how they respond to these different types of stressors, you can get good information on what’s happening in the environment and what’s driving it.”

He says the invertebrates that live in estuarine sediments are perfect for this research: they’re long-lived and they don’t move around too much.

As well as studying the invertebrates, researchers also analyse the samples to assess what kinds of sediments and contaminants are entering the estuary.

Lohrer says, together, these methods give researchers a clear understanding of what is changing.

NIWA has worked closely alongside the Auckland Council for more than three decades to monitor estuaries in the region.

Lohrer says that the collaborative nature of the partnership has been key to research success and, ultimately, better estuary management.

“If they trust in the science and can incorporate it into policy that protects the marine environment, for a variety of users and uses, that’s the most beneficial thing.”

“That, to me, is real success.”

After a productive morning on the Mahurangi Estuary, the researchers take a quick look at some of their samples before heading out to the remaining sites.

If carrying the backpacks through the mud was resistance training for the legs, the sieving is a full-on workout for the arms.

After a minute of vigorous shaking, the sediment clears through the mesh, leaving an array of crabs, worms and shellfish.

The researchers funnel the invertebrates into labelled containers filled with an alcohol solution that preserves the samples for laboratory analysis.

Hailes and Carter work like clockwork. It’s almost intuitive for them.

Norse goddess reveals seabed secrets

Norse goddess reveals seabed secrets

Source: NIWA – National Institute of Water and Atmospheric Research

A large, orange Scandinavian robot gives NIWA’s marine geologists an in-depth look at changes to the seafloor off Kaikōura.

The 2016 earthquake left an all-too-visible trail of destruction across Kaikōura’s landscape. Buildings were shattered, road and rail links severed, and massive scars cut across hillsides and coastal terraces alike.

What wasn’t so immediately obvious was the impact the 7.8 magnitude quake had on the deep underwater canyon just hundreds of metres off the coast.

The Kaikōura Canyon starts less than a kilometre out from land, as the seabed plunges to depths of more than 600m, and eventually to 2000m, creating a formation of channels and ravines which fan 60km out into the Pacific Ocean.

Cold currents rising from the deep bring nutrient-rich waters into the canyon system, helping to create a uniquely productive habitat nourishing organisms ranging from small seafloor invertebrates through to the region’s iconic dolphins and whales.

Marine geoscientist Dr Joshu Mountjoy describes the canyon as the bridge between the land and the ocean, connecting sedimentary systems, capturing carbon and supporting rich ecosystems.

Multibeam seabed surveys carried out by NIWA’s research vessels Tangaroa and Ikatere after the 2016 quake revealed dramatic changes. Huge amounts of mud and sediment, estimated at 850 million tonnes, were shaken from the canyon rim, flowing down the underwater channels and out into the Pacific.

This massive submarine sediment flow, tracked at least 700km to the north, instantly turned the canyon floor from a biodiversity hotspot full of marine life into a barren, almost uninhabited seascape.

Late last year Mountjoy led another team of researchers back to the waters off the Kaikōura coast aboard Tangaroa.

“We were interested in understanding the physical process that had removed such a huge amount of sediment and rock from the canyon. It was also a chance to establish how the ecosystems were recovering after such a major event, and measure the amount of sediment re-entering the canyon,” Mountjoy says.

“Although we had done surveys before, we now needed a way to capture the extent of the post-earthquake changes at a much higher resolution.”

To get such a detailed picture of conditions almost two kilometres under the surface, Mountjoy recruited the help of the European marine research alliance, Eurofleets+. NIWA is the only southern hemisphere member of this 27-country alliance.

In October, Rán, a 6.5m autonomous underwater vehicle named after the Norse goddess of the sea, arrived in Wellington on loan from Sweden’s Gothenburg University.

Fully equipped with its own suite of sensors for remotely scanning the seafloor and monitoring oceanographic conditions, Rán was also accompanied by two European technicians who both had to undergo full quarantine procedures prior to joining the voyage.

Pre-programmed and deployed from the stern of Tangaroa, Rán descended to the depths of the canyon floor, operating for up to 29 hours before needing to return to the research vessel.

It is the first time this type of technology has been used in New Zealand waters, and sweeping as low as 20m above the seabed, the AUV was able to map the entire canyon floor at resolutions 25 times higher than earlier surveys.

During Tangaroa’s research voyage, Rán completed a total of 14 dives, surveyed over 2,000km of seafloor at an average speed of 7km/h, and acquired a staggering 1.6 billion datapoints.

“The data has given us unprecedented insight into how submarine canyons are created,” says Mountjoy.

“The mid-lower canyon is dominated by giant gravel waves that are carving out the bedrock.

“We already knew that dunes 20m high and 200m across had shifted 500m down the canyon. But the data collected by the AUV now shows that these dunes are made of boulders up to 7m across.”

“It is hard to imagine how much power is required to move rocks of that size, but that’s exactly what has happened in that area.”

The research team are currently working their way through the detailed data files recovered during Rán’s successful mission – a high-resolution treasure trove which Mountjoy believes will lead to a clearer international understanding of post-earthquake continental shelf processes.

This story forms part of Water and Atmosphere – February 2021, read more stories from the series.

A job for the buoys

A job for the buoys

Source: NIWA – National Institute of Water and Atmospheric Research

“You put everything together and then put the units through some rigorous testing, so that when they’re deployed, we have complete faith in the system.”

Each buoy comprises two main components – a Bottom Pressure Recorder (BPR) that sits on the sea floor, and a large, yellow float on the surface above.

Deploying both components requires a sophisticated mix of precision positioning on the high seas, sophisticated marine mapping below and a deep understanding of ocean currents. NIWA’s flagship research vessel Tangaroa and Brewer’s deployment team onboard are fully equipped to deliver.

A bathymetric survey of the seafloor using multibeam echosounders checks to ensure the gradient is less than 5 degrees, with no obstructions to interfere with signals travelling through the ocean.

Current and wave conditions are also assessed. Once the site has been cleared, the two components are lifted off the ship, and their separate moorings are carefully positioned hundreds of metres below.

The BPR and the float communicate with each other through the water column. Every 15 seconds the BPR records the height of the ocean above and sends that information to the surface buoy once an hour. From there the data goes via satellite to the server based at GNS Science’s National Geohazards Monitoring Centre back in Wellington.

“Tsunami are very long period waves, with some having wave lengths of up to an hour,” says Brewer.

“Wind and swell waves are short period waves, so by measuring every 15 seconds we are cutting out those short waves and concentrating on the big differences.”

The future shape of water

The future shape of water

Source: NIWA – National Institute of Water and Atmospheric Research

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Hanging high above the water, technician Hamish Sutton (right) and his ecohydraulics colleague Dr Hamish Biggs carefully position themselves to measure the flow of the Hurunui River below. [Photo: Lana Young, NIWA]

Twenty-five metres above the Hurunui River, Hamish Sutton is leaning over the side of a metal cage hanging from a cable. Far below, bobbing on the swiftly flowing waterway is a small boat struggling to stay afloat.

This scene in the north Canterbury hills may look a little precarious, but precise science is under way. Sutton is measuring the flow of the Hurunui River. In the corner of the metal cage a laptop is recording data gathered by an instrument on the boat below that shoots hundreds of acoustic pulses into the water to measure depth and velocity.

Sutton, a NIWA environmental monitoring technician, prides himself on the numbers coming into his laptop. “If you’re not collecting quality data, it’s pretty pointless – it’s easy to forget that out here.”

Sutton’s quality data will be used to build a “rating” of the level and related flow of the Hurunui that will be added to records that began at this spot in the mid-1950s.

These measurements – and others like it all over the region – span monumental change in land use in rural Canterbury. They began before large-scale conversion to dairy farming required vast irrigation schemes. The Amuri scheme, which takes water from the Hurunui, is one of the earlier projects and feeds the now grassy paddocks of the plains.

Knowing the volume of water in a river and how fast it travels to the coast, is a vital step in deciding how that water can be used to provide hydroelectricity or grow crops or grass – or support a plethora of other industries crucial to our economy. Irrigated agriculture alone contributes about $4.8 billion annually to GDP, and accounts for about two-thirds of all water used in New Zealand. However, the demand and supply balance is changing for agriculture, as it is for other industries. Notwithstanding that taking water out of a river also alters its natural flow regime and can have unforeseen consequences elsewhere.

Or, as NIWA’s Chief Scientist for freshwater Dr Scott Larned puts it, solutions can sometimes create problems.

“The conventional wisdom is that you harvest flood water in the winter and store it until it’s needed in the summer. However, floods are required to carry gravels to the coastal zone and if there’s not enough gravel, the waves get hungry and start eroding the land. Sure, it’s a solution, but it’s also creating a problem.”

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Hydrologists gauge river flows using soundwaves fired into the water from the acoustic Doppler current profiler mounted on this small orange trimaran. [Photo: Lana Young, NIWA]

Larned and his team are preoccupied with one question: How much water should we leave in our rivers to maintain their ecological functions versus how much can be taken out for other uses?

It is a fundamental dilemma which has become more pressing as irrigation schemes and plans to dam or alter rivers have multiplied, at the same time as cultural, social and environmental issues demand more consideration.

Swirling around in the mix is climate change, and what that may mean for the future of the primary sector – and all of us.

To understand New Zealand’s water issues, it is important to note that, comparatively speaking, our rivers are short and steep and have little capacity to store or manipulate flows.

Demand for water continues to grow, yet it is increasingly recognised that appropriate river flow regimes are fundamental to maintaining healthy river systems.

Larned says changes to the way freshwater is allocated to farmers, industry, groups and individuals are inevitable. New national policies for freshwater were announced by the Minister for the Environment in September and focus heavily on river health and water quality issues. The policies also signal major improvements in water allocation, but with minimal guidance about how this will happen.

“Carrying out the science needed to put the policies into action is one of NIWA’s biggest responsibilities,” he says.

Larned says the research community will need to play its part to help deliver meaningful change.

While freshwater reform will be fraught, he is also certain it will happen.

“Water shortages will drive change. I expect there will be substantial progress over the next decade.”

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Farmer Bruce Baggott (right) talks with NIWA environmental monitoring scientist Graham Elley about the best use of water on his Canterbury dairy property. [Photo: Stuart Mackay]

One of the major issues is water consenting. New Zealand has an historical consenting system in which users are permitted to take certain amounts of water for long periods – up to 35 years in some cases. The system has little room for flexibility, and, as Larned points out, has become highly inequitable in places like Canterbury, where most of the available water is consented and there is little left for new applicants.

Treaty of Waitangi settlements have also granted some iwi rights to water and, notably, special status to the Whanganui River which recognises the river as having all the rights of a person. But, up until recently, water allocation rules have fundamentally been all about the economy, not kaitiakitanga. Reconciling the two is virtually unchartered territory.

Larned says NIWA possesses the bulk of hydrological science expertise in New Zealand and will need to provide the science that underpins water allocation reform. However, policy makers will be relying on community, iwi and other partners to identify their priorities and values.

“In one catchment the highest priority may be economic growth, for another it may be restoration of natural land. It is up to people to decide – we can then work out an allocation system to achieve that.”

Hydro-ecological modeller Dr Doug Booker leads a NIWA programme focused on understanding the effects of human water use on surface and groundwater systems. The aim is to inform more sustainable water allocation decisions.

Booker’s work includes carrying out the science behind options such as trading rights to access water, or permitting water to be used on a seasonal timeframe, rather than over decades.

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Catchment hydrologist MS Srinivasan says scientists need to get out on the farm if they are to help develop irrigation solutions. [Photo: Dave Allen]

Trading water is theoretically possible under the Resource Management Act, but it would be a radical change for New Zealand, and the infrastructure for it to be implemented doesn’t currently exist.

Booker says that water trading is seen in some quarters as an effective management mechanism because it can deliver economic benefits within environmental limits. It can also recognise the environment as a water user, and transfer water rights to the environment to support ecological, cultural, aesthetic or recreational values.

How we ultimately change to a more dynamic consenting process will be up to central and local government.

Back at NIWA’s Christchurch office, catchment hydrologist Dr MS Srinivasan adds another perspective to the views of his colleagues.

As we leave the city on a grey October day to meet North Canterbury farmer Bruce Baggott at Mandeville, Srinivasan is concerned about the potential lack of summer rain.

“We didn’t get the winter rainfall we needed; irrigation has started earlier this year, so water supply will be an issue.”

Srinivasan is the conduit between water efficiency science and its users. He has spent most of his scientific career working directly with farmers – he knows when scientists talk about climate variability, farmers talk about rain.

“Science cannot always be done behind closed doors – we have to come out and work with people and listen to them.”

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We find Baggott enjoying a beer at the Platform Bar after a local meeting about a controversial regional council proposal on nitrogen limits. He and his partner, Claire Mackay, moved to Canterbury from Northland in 2000 – when dairy farming was beginning to take off in the region.

They farm 235 hectares at Cust and run 850 cows. The couple is part of the Waimakariri Irrigation Scheme and work with NIWA on a Ministry of Business, Innovation and Employment-funded programme called Irrigation Insight.

Irrigation Insight is a five-year project involving a range of organisations across the sector looking to make better use of available water. The aim is to achieve a balanced irrigation approach that is economically sound and environmentally responsible.

For Baggott, that means starting each day on his tablet checking the high-resolution NIWA weather and soil moisture forecast tailored for his property, along with readings from his network of paddock soil moisture probes.

He has been working with NIWA for three years now, trialling the first tool of its kind developed to manage irrigation in a changing climate. Baggott is in awe of the technology available at his fingertips, but perhaps more appreciative of the partnership he has developed with Srinivasan and his colleague, environmental monitoring scientist Graham Elley.

“Farms are multi-million-dollar businesses and we are capable of making our own decisions, but we want the best information to help make those decisions,” says Baggott.

Elley says Irrigation Insight works because it is based on communication and co-innovation.

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Farmer Bruce Baggott starts each day on his tablet checking the high-resolution NIWA weather and soil moisture forecast tailored for his property, along with readings from his network of paddock soil moisture probes. [Photo: Stuart Mackay, NIWA]

“Every situation is unique – with its own set of controls, barriers, opportunities, people with different capacities, capabilities and aspirations, which can be in tension with each other. With all these things we are looking for an operating sweet spot, and that sweet spot is not the same for every farm.”

Future-proofing irrigation practices is best summed up by the desire to achieve a change in mindset from irrigating “just in case” to irrigating “just in time”, with science providing help around nutrient management, water supply and projected climate-change scenarios.

“We need to be looking beyond the biophysical solutions and work with people and listen to them,” says Srinivasan. “Science will give an answer, but everyone holds knowledge, and if we don’t listen, our solutions will not be complete and comprehensive.”

Farmers, says Baggott, are very willing to change and want to be part of shaping the future. “We are trying to improve the land – if we stuff it up, it comes back to bite you.”

This year MPI awarded $400,000 to a NIWA-led project that is examining future-proofing irrigation for climate change. It will develop an adaptation strategy tool to assess the irrigation supply and demand balance under a changing climate.

Further research is proposed that will look at transforming New Zealand’s approach to building water resilience.

If the future looks like a mix of science and farming done differently, then people like ecohydraulics scientist Dr Hamish Biggs will be crucial to the transition.

Biggs was with Sutton high above the Hurunui River for the recent river flow measurements. Minutes earlier he had been flying a drone over the same section of river, programming it to take similar flow measurements to those from Sutton’s small boat, so they can compare the drone for accuracy.

There is no internet coverage at the Hurunui site, but Sutton says it won’t be long before there will be fixed cameras here and at every site water is measured, transmitting huge swathes of data in real time.

“You’ll be able to get any kind of measurement any time you want and from anywhere you want. It will be a game changer for science and for the people who need that science.”

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Climate change and irrigation

Ask NIWA hydrologist Dr Christian Zammit how our future climate will impact irrigation and his first response is always: “It depends where you are.”

Zammit is the co-author of a recent report prepared for the Ministry for Primary Industries that analysed the effects of climate change on irrigation supply and demand.

The report gently suggests water users should be exploring a transition to a drought-resilient future “before it becomes necessary”. That’s because the outlook, although uncertain, spells major changes in wind and rainfall patterns.

“There will be more climate extremes across all New Zealand,” says Zammit.

The issue, he says, is that while New Zealand will still get plenty of water, it won’t always get it in the right places.

In essence the North Island will get drier, Marlborough, Tasman and North Canterbury will also get drier, but South Canterbury and below will get wetter.

Zammit’s report also found:

  • Demand for irrigated water is projected to increase across most of New Zealand, with effects emerging by 2050 in the North Island and later in the South Island
  • Irrigation restrictions will occur earlier in the year, mostly for the North Island
  • The reliability of river water supply tends to decline during the century
  • The decline in supply reliability and increase in irrigation demand point towards increasingly challenging conditions for irrigators.

Zammit says high-resolution modelling will help New Zealand adapt, but there will need to be some hard decisions made.

“We know temperatures are getting warmer and our precipitation is changing, but that gives us an opportunity to do things differently. It’s really about being prepared and making it a successful story for us.”

Opinion

What next for freshwater science?

Dr Scott Larned – Chief Scientist – Freshwater and estuaries

For most of the time humans have inhabited Aotearoa New Zealand, their impact on aquatic environments has been negligible.

Over the last century, things have changed. A five-fold increase in the human population, large-scale deforestation, intensive agriculture and urban development have all led to widespread water pollution and habitat loss. Many native aquatic species are now threatened with extinction.

There is still a realistic chance to reverse freshwater degradation in New Zealand, but only if we “go hard and go early”.

Going hard entails some stringent regulation, and that’s where the National Policy Statement for Freshwater Management (NPS-FM) comes in.

The NPS-FM came into effect in September 2020. Among other things, it requires councils to set objectives for rivers, lakes and estuaries, and specifies minimum allowable conditions for 18 different aspects of water quality and ecosystem health.

The NPS-FM also directs councils to use the Māori principles of Te Mana o te Wai as the policy framework – this is a profound change from previous legislation.

Full implementation of this wide-reaching policy statement could transform land and water management in New Zealand, and the environmental science community has a major role to play.

Much of the science carried out over the last decade to support the development of the NPS-FM concerned the ecological and human-health indicators that will be used to assess achievement of freshwater objectives.

The next big challenge for the science community is limit setting. This is the complex process of determining the amount of contaminant input (such as sediment and faecal bacteria) from land that is permitted before freshwater values deteriorate.

Limit setting requires scientific knowledge of the relationships between catchment land use and contaminant loss from land, and the impact of those contaminants on aquatic ecosystems and human health. This sounds deceptively simple. In practice, predicting contaminant losses and impacts in response to land use is difficult because of the complexities of catchments and aquatic ecosystems.

Direct observations alone are inadequate for predicting the effects of current land use, or forecasting effects in the future. The solution lies in combining observations with computer models that can link up the entire chain from land use to contaminant losses, to ecological and human health impacts, and finally to freshwater values.

Rapid progress is critical. New models will need to be built, and existing models will need renovation, but this is the most effective way to put the new freshwater policies into action.

Hotspot Watch 5 February 2021

Hotspot Watch 5 February 2021

Source: NIWA – National Institute of Water and Atmospheric Research

A weekly update describing soil moisture patterns across the country to show where dry to extremely dry conditions are occurring or imminent. Regions experiencing significant soil moisture deficits are deemed “hotspots”. Persistent hotspot regions have the potential to develop into drought.

Facts: Soil Moisture

Meagre rainfall was again observed across nearly all of the North Island during the past week, with most locations receiving 5 mm or less. In fact, much of the central North Island received no rainfall at all during the past week. The one exception was northern Hawke’s Bay and coastal Gisborne, where a small area received 15-30 mm. This led to substantial soil moisture decreases throughout the North Island. The driest soils across the North Island, when compared to normal for this time of the year, are found in the Far North and a portion of Ōpōtiki. Meanwhile, the wettest soils for this time of year for the North Island are located in western Taranaki. 

Hotspot conditions are now widespread across the North Island, including nearly all of Northland, Auckland, northern Waikato, and the east coast. Hotspots also cover much of Bay of Plenty, the Central Plateau, central Manawatū-Whanganui, and near Wellington City. The New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District as well as a small portion of East Cape. Widespread dry-to-extremely dry soils are in place in the remainder of Northland, Auckland, northern Waikato, western Bay of Plenty, East Cape, and much of the eastern North Island. 

In the South Island, it was a very dry week with most locations seeing 5 mm or less, and some areas receiving no rainfall at all. This led to moderate soil moisture decreases across nearly the entire South Island. The driest soils in the South Island compared to normal for this time of year are located in Nelson, northern Tasman, and eastern Southland, while the wettest soils for this time of the year for the South Island are found from northern Otago to central Southland. 

Hotspots are currently in place in Nelson, nearby parts of Tasman, coastal Hurunui District, and coastal Selwyn District. The New Zealand Drought Index (NZDI) map below shows that dry to very dry soils are found in the northeastern South Island. 

Outlook and Soil Moisture

Other than a few showers along the east coast through Saturday (6 February), high pressure will continue to bring dry weather to the North Island over the next several days. By the middle of next week (around 10 February), a front is likely to move across the North Island with a period of rain and perhaps thunderstorms. This could produce up to 15 mm for much of the North Island before high pressure returns late next week.  

With weekly rainfall totals up to 15 mm across the North Island during the next week, at least minor soil moisture decreases will again be possible for most locations. This will likely result in most current hotspots strengthening and expanding at least slightly.

High pressure will continue to bring dry weather to the South Island through this weekend. However, rain is likely to reach the West Coast by late Monday or Tuesday (8-9 February), and this rain may be heavy at times. By about Wednesday, low pressure forming nearby could spread moderate to heavy rainfall across much of the South Island. By late next week, high pressure returns with mostly dry weather. Weekly rainfall totals will depend on the exact location of low pressure next week, but substantial amounts are possible for some areas. Much of the West Coast could receive 150 mm or more, with perhaps 50 mm or more in the lower South Island. Amounts may be smaller in northern Canterbury and Marlborough, with 25 mm or less possible. 

Due to the expected rainfall in the next week, soil moisture increases will be likely in the West Coast and lower South Island. However, it’s possible that only small changes will occur in northern Canterbury and Marlborough. The current hotspots in the upper South Island may improve somewhat during the next week, while those in Canterbury may not change significantly. 

Background: 

Hotspot Watch: a weekly advisory service for New Zealand media. It provides soil moisture and precipitation measurements around the country to help assess whether extremely dry conditions are imminent.  

Soil moisture deficit:  the amount of water needed to bring the soil moisture content back to field capacity, which is the maximum amount of water the soil can hold. 

Soil moisture anomaly:  the difference between the historical normal soil moisture deficit (or surplus) for a given time of year and actual soil moisture deficits.

Definitions: “Extremely” and “severely” dry soils are based on a combination of the current soil moisture status and the difference from normal soil moisture (see soil moisture maps at https://www.niwa.co.nz/climate/nz-drought-monitor/droughtindicatormaps)

Hotspot: A hotspot is declared if soils are “severely drier than normal” which occurs when Soil Moisture Deficit (SMD) is less than -110 mm AND the Soil Moisture Anomaly is less than -20 mm. 

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Pictured above: Soil Moisture Anomaly Maps, relative to this time of year. The maps show soil moisture anomaly for the past two weeks. 

New Zealand Drought Index

As of 2 February, the New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District as well as a small portion of East Cape. Widespread dry-to-extremely dry soils are in place in the remainder of Northland, Auckland, northern Waikato, western Bay of Plenty, East Cape, much of the eastern North Island, and northeastern South Island. Please note: some hotspots in the text above may not correspond with the NZDI map. This difference exists because the NZDI uses additional dryness indices, including one which integrates the rainfall deficit over the past 60 days. Changes are therefore slower to appear in the NZDI compared to soil moisture anomaly maps that are instantaneously updated.

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Oceanic shark numbers decline amid research gaps

Oceanic shark numbers decline amid research gaps

Source: NIWA – National Institute of Water and Atmospheric Research

A lack of information about New Zealand oceanic shark populations is making it difficult to assess how well they are doing, says a NIWA researcher.

New research published in premier science journal Nature last week, with input from NIWA, showed the global population of oceanic sharks and rays has declined by more than 70 per cent in the past 50 years, with ongoing decline likely to lead to the extinction of some species.

NIWA fisheries scientist Dr Brit Finucci says New Zealand waters are home to about 113 shark species of which 20 are considered oceanic, meaning they spend most of their time in the open ocean.

While most of these species are not considered threatened in New Zealand, Dr Finucci says there is a rapidly growing body of research linking shark movements to environmental changes.

“We don’t have that information for New Zealand, and this is something we should start investigating. It is very hard to assess the status of many sharks in our waters because we don’t have shark-specific monitoring programmes.”

Some data is opportunistically collected either by other research surveys or reported by commercial fishers and fisheries observers.

“For some oceanic species we have noted possible declines in recent years, but we are unsure if these trends are a real decline in abundance, a change in the fishery, or a change in animal behaviour.”

The Nature paper noted that in the Pacific Ocean, abundances decreased steeply before 1990, and then declined at a slower rate recording an overall decline of 67 per cent

The global decline of oceanic shark numbers is mostly attributed to a huge increase in fishing since 1970, with half the world’s 31 oceanic shark species and their relatives now listed as endangered or critically endangered by the International Union for Conservation of Nature (IUCN).

Recently retired NIWA scientist Dr Malcolm Francis was a member of the IUCN Shark Specialist Group for more than 20 years and was a co-author of the Nature paper, contributing analysis of the blue, mako and porbeagle sharks.

These species are managed under New Zealand’s Quota Management System while another nine oceanic species are protected or managed under the Wildlife Act and Fisheries Act. The eight remaining New Zealand oceanic species have no specific species management.

“New Zealand not only has globally threatened oceanic species, but also some globally highly threatened deep-water species as well. We know these species are very susceptible to population declines because of their biology,” Dr Finucci says.

“NIWA has taken on a wide variety of shark research projects in the past including indicator analyses and stock assessments – these are important for monitoring shark populations. However, in order to do this modelling work, and do it well, we still need a lot of fundamental research of species’ biology and ecology. “

Dr Finucci says research that needed to be done included mapping critical habitats for populations, particularly nursery areas and pupping grounds, and determining movement patterns of sharks within New Zealand and beyond to inform the best timing of potential closed areas or seasons.

“Sharks have been part of our oceans for millions of years and if they disappear it is likely to be noticed in ways we haven’t yet measured.”

The Nature paper said that action was needed immediately to prevent shark population collapses and “myriad negative consequences for associated economic and ecological systems”.

“There is an urgent need for governments to adopt science-based catch limits for oceanic sharks that are capable of supporting sustainable fisheries, along with bycatch mitigation.”

Oceanic sharks found in New Zealand waters:

  • Oceanic whitetip, Carcharhinus longimanus

            Globally Critically Endangered. New Zealand protected species

  • Basking shark, Cetorhinus maximus

            Globally Endangered. New Zealand protected species

  • Shortfin mako, Isurus oxyrinchus

            Globally Endangered. Managed under the QMS

  • Common thresher shark, Alopias vulpinus

            Globally Vulnerable. No species-specific management in New Zealand

  • Smooth hammerhead, Sphyrna zygaena

           Globally Vulnerable. Managed under Schedule 4C of the Fisheries Act 1996

Shark numbers decline amid research gaps

Oceanic shark numbers decline amid research gaps

Source: NIWA – National Institute of Water and Atmospheric Research

A lack of information about New Zealand oceanic shark populations is making it difficult to assess how well they are doing, says a NIWA researcher.

New research published in premier science journal Nature last week, with input from NIWA, showed the global population of oceanic sharks and rays has declined by more than 70 per cent in the past 50 years, with ongoing decline likely to lead to the extinction of some species.

NIWA fisheries scientist Dr Brit Finucci says New Zealand waters are home to about 113 shark species of which 20 are considered oceanic, meaning they spend most of their time in the open ocean.

While most of these species are not considered threatened in New Zealand, Dr Finucci says there is a rapidly growing body of research linking shark movements to environmental changes.

“We don’t have that information for New Zealand, and this is something we should start investigating. It is very hard to assess the status of many sharks in our waters because we don’t have shark-specific monitoring programmes.”

Some data is opportunistically collected either by other research surveys or reported by commercial fishers and fisheries observers.

“For some species we have noted possible declines in recent years, but we are unsure if these trends are a real decline in abundance, a change in the fishery, or a change in animal behaviour.”

The Nature paper noted that in the Pacific Ocean, abundances decreased steeply before 1990, and then declined at a slower rate recording an overall decline of 67 per cent.

The global decline of oceanic shark numbers is mostly attributed to a huge increase in fishing since 1970, with half the world’s 31 oceanic shark species now listed as endangered or critically endangered by the International Union for Conservation of Nature (IUCN).

Recently retired NIWA scientist Dr Malcolm Francis was a member of the IUCN Shark Specialist Group for more than 20 years and was a co-author of the Nature paper, contributing analysis of the blue, mako and porbeagle sharks.

These species are managed under New Zealand’s Quota Management System while another nine oceanic species are protected or managed under the Wildlife Act and Fisheries Act. The eight remaining New Zealand oceanic species have no specific species management.

“New Zealand not only has globally threatened oceanic species, but also some globally highly threatened deep-water species as well. We know these species are very susceptible to population declines because of their biology,” Dr Finucci says.

“NIWA has taken on a wide variety of shark research projects in the past including indicator analyses and stock assessments – these are important for monitoring shark populations. However, in order to do this modelling work, and do it well, we still need a lot of fundamental research of species’ biology and ecology. “

Dr Finucci says research that needed to be done included mapping critical habitats for populations, particularly nursery areas and pupping grounds, and determining movement patterns of sharks within New Zealand and beyond to inform the best timing of potential closed areas or seasons.

“Sharks have been part of our oceans for millions of years and if they disappear it is likely to be noticed in ways we haven’t yet measured.”

The Nature paper said that action was needed immediately to prevent shark population collapses and “myriad negative consequences for associated economic and ecological systems”.

“There is an urgent need for governments to adopt science-based catch limits for oceanic sharks that are capable of supporting sustainable fisheries, along with bycatch mitigation.”

Oceanic sharks found in New Zealand waters:

  • Oceanic whitetip, Carcharhinus longimanus

            Globally Critically Endangered. New Zealand protected species

  • Basking shark, Cetorhinus maximus

            Globally Endangered. New Zealand protected species

  • Shortfin mako, Isurus oxyrinchus

            Globally Endangered. Managed under the QMS

  • Common thresher shark, Alopias vulpinus

            Globally Vulnerable. No species-specific management in New Zealand

  • Smooth hammerhead, Sphyrna zygaena

           Globally Vulnerable. Managed under Schedule 4C of the Fisheries Act 1996

ESR wastewater testing of COVID-19 showing no community spread

Source: ESR

ESR testing of wastewater for COVID-19 has so far showed no signs of community spread, but the crown research institute is urging people to stay vigilant.

Wastewater testing around the area of the latest cases has not picked up the SARS CoV-2 virus. Samples from Whangarei collected on the 26th January, and samples from the North Shore, Western Auckland, Central Auckland, Hamilton, Rotorua and Christchurch collected on the 25th January, have all come back negative.

ESR science leader Dr Brent Gilpin says while these results are pleasing and appear to back-up other surveillance tools, it should not dissuade people from going for testing.

“Highly infectious individuals can shed billions of viruses which means it is possible to detect in wastewater the presence of just a few infected individuals, but testing can’t exclude the possibility of one or two infectious individuals. It’s an extra layer of protection to add to the existing methods New Zealand already has in place. Anyone who is symptomatic or thinks they may have been exposed to an infected person must get tested regardless of the sewage testing results.”

ESR is continuing to collect and analyse sewage samples from other locations throughout the country, including the Upper North Island and will report to the Ministry of Health any unexpected positive detections.

Testing from earlier in January detected SARS-CoV-2 in Christchurch wastewater at the same time as there were a number of cases in managed isolation facilities, and sewage from the Jet Park Hotel is consistently positive.

Dr Gilpin says that ESR is showing its commitment to protect communities through smart science. 

“This is another example of new science approaches that ESR is implementing including our genome sequencing, public health intelligence and saliva testing which are really adding depth and insight to New Zealand COVID-19 response.”

The COVID-19 wastewater surveillance research project is funded by Ministry of Business, Innovation and Employment.

Hotspot Watch 28 January 2021

Hotspot Watch 28 January 2021

Source: NIWA – National Institute of Water and Atmospheric Research

A weekly update describing soil moisture patterns across the country to show where dry to extremely dry conditions are occurring or imminent. Regions experiencing significant soil moisture deficits are deemed “hotspots”. Persistent hotspot regions have the potential to develop into drought.

Facts: Soil Moisture

Minimal rainfall was observed across nearly all of the North Island during the past week, with most locations receiving 5 mm or less, and parts of the east coast receiving no rainfall at all. Meanwhile, parts of western Waikato, interior Taranaki, and northern Manawatu-Whanganui received 10-25 mm. This resulted in small-to-moderate soil moisture decreases across nearly all of the North Island during the past week. The driest soils across the North Island, when compared to normal for this time of the year, are found in much of Northland, northern and western Waikato, and parts of the east coast. Meanwhile, the wettest soils for this time of year for the North Island are located in southern Manawatu-Whanganui.

Hotspots are currently in place in most of Northland, parts of Auckland, northern Waikato, western Bay of Plenty, and most of the east coast from East Cape to Wairarapa. The New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District. Widespread dry-to-extremely dry soils are in place in the remainder of Northland, Auckland, northern Waikato, western Bay of Plenty, and East Cape.

Substantial rainfall occurred in the past week across the West Coast and Fiordland with widespread amounts of 75 mm or more. Much of Southland received 15-30 mm, but the remainder of the South Island received only minimal rainfall. In addition, very hot temperatures this week in the eastern South Island resulted in increased evaporation rates. This led to small-to-moderate soil moisture decreases across the entire South Island. The driest soils in the South Island compared to normal for this time of year are located in coastal Hurunui District, while the wettest soils for this time of the year for the South Island are found from southern Canterbury to central Southland.

A small hotspot remains in place in coastal Hurunui District, while new hotspots have formed in Banks Peninsula, Nelson, and nearby parts of Tasman.

Outlook and Soil Moisture

A front moving up the North Island today and tonight (28-29 January) will bring 5 mm or less to southern and eastern areas, with little if any rainfall elsewhere. A southeasterly wind flow will continue to produce light to moderate showers on Friday and Saturday along the east coast, with the remainder of the North Island remaining dry. High pressure will be located overhead during much of next week, resulting in widespread dry weather. Weekly rainfall totals may exceed 20 mm in parts of Hawke’s Bay and Gisborne, with 10 mm or less for the remainder of the eastern and lower North Island. However, the upper North Island may receive little if any rainfall during the next week.

With the exception of parts of Hawke’s Bay and Gisborne, where soil moisture changes may be minimal, moderate to even large soil moisture decreases are likely during the next week across a majority of the North Island. This will likely result in most current hotspots strengthening and expanding, particularly those in the upper North Island.

Showers and isolated thunderstorms will occur in the eastern South Island today and tonight (28-29 January), with localised amounts that could reach 15 mm. However, on Friday, high pressure will arrive, bringing dry weather to the South Island for about the next week or so. Weekly rainfall totals of 10-15 mm will be observed in the eastern and southern South Island, but only minimal rainfall is expected elsewhere.

Due to the expected rainfall in the next week, at least moderate soil moisture decreases are likely across a majority of the South Island. This will likely strengthen and expand the current South Island hotspots, while new hotspots may emerge in Marlborough and central Canterbury.

Background:

Hotspot Watch: a weekly advisory service for New Zealand media. It provides soil moisture and precipitation measurements around the country to help assess whether extremely dry conditions are imminent. 

Soil moisture deficit:  the amount of water needed to bring the soil moisture content back to field capacity, which is the maximum amount of water the soil can hold.

Soil moisture anomaly:  the difference between the historical normal soil moisture deficit (or surplus) for a given time of year and actual soil moisture deficits.

Definitions: “Extremely” and “severely” dry soils are based on a combination of the current soil moisture status and the difference from normal soil moisture (see soil moisture maps)

Hotspot: A hotspot is declared if soils are “severely drier than normal” which occurs when Soil Moisture Deficit (SMD) is less than -110 mm AND the Soil Moisture Anomaly is less than -20 mm.

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Pictured above: Soil Moisture Anomaly Maps, relative to this time of year. The maps show soil moisture anomaly for the past two weeks.

New Zealand Drought Index (NZDI)

As of 25 January, the New Zealand Drought Index (NZDI) map below shows that meteorological drought and severe meteorological drought are in place in the northern half of the Far North District. Widespread dry-to-extremely dry soils are in place in the remainder of Northland, Auckland, northern Waikato, western Bay of Plenty, and East Cape. Please note: some hotspots in the text above may not correspond with the NZDI map. This difference exists because the NZDI uses additional dryness indices, including one which integrates the rainfall deficit over the past 60 days. Changes are therefore slower to appear in the NZDI compared to soil moisture anomaly maps that are instantaneously updated.

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