What is a waterless barrier and how could it slow cane toads?

A dam near Gemtree, Northern Territory.
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Mike Letnic, UNSW

A federal parliamentary inquiry into stopping cane toads’ relentless march across Australia has proposed creating “waterless barriers” in the semi-arid land between Western Australia’s Kimberley and Pilbara regions.

Because cane toads need regular access to water to survive, the plan is to fence off man-made watering points like dams and tanks, creating the equivalent of a firebreak the toads cannot cross.

My colleagues and I have been working with the federal inquiry to create this proposal. Here are the facts.

What is a waterless barrier?

There are large areas of Australia that are naturally dry. Except after big rains, there’s very little above-ground water. When people began farming sheep and cattle out in the western ranges, they created artificial water points with the help of dams, tanks and bores.

These water points are refuges for cane toads during droughts and act as stepping-stones when it rains, because the toads can move safely from point to point. This is how they are colonising large areas of Australia.

But if the toads can’t reach open water they cannot live through a dry season. The proposal aims to restrict the toads’ access to the water, but still let the cattle drink.

The poisonous cane toads are considered non-native pests in Australia.
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What kind of fences are we talking about?

Many water sources are actually already inaccessible to cane toads. Steel or plastic tanks filled from pipelines or underground dams cannot be reached. Troughs give a very limited supply.

The main problem comes from turkeynest dams (these are classic dams: pools of water in the ground with a mounded earth edge). My colleagues and I did research years ago that found a simple 60cm fence is enough to keep cane toads out.

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This doesn’t mean fencing dams is easy: the stations where this would be most helpful are very remote and have plenty of water sources, so fencing (and maintaining) them all presents a logistical hurdle. However many stations are increasingly replacing dams with tanks, which serve the same purpose (and lose far less water to leakage and evaporation).

Cane toads need moisture to survive.
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Another promising development is the number of farmers installing “cut-off switches” for the pumps that fill dams. This is a move away from the older system of turning on a pump and leaving it on until the generator ran out of fuel – perhaps days later. This meant considerable overflow, and created ideal conditions for cane toads. Tanks with solar panels and a cut-off switch that senses when a trough is full can save farms water, power and money, as well as stranding cane toads.

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Read more:
Yes, you heard right: more cane toads really can help us fight cane toads

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Would it affect native animals?

It’s true some of these dams are now part of the landscape – they’ve been there for a long time. On the other hand, we’re talking about areas that did not originally have much above-ground water before people showed up, and most animals native to the area don’t really need the water (of course, they will drink it if it’s there).

The other part of the equation is the presence of cane toads seriously threatens native wildlife. Cane toads are poisonous and kill native predators, with devastating effects to the environment.

Herd cows drinking water from a Northern Territory dam.
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How big does the barrier need to be, and won’t the rains let the toads cross anyway?

The cattle stations in northern Australia are huge – often 5,000ha. On this scale, just a handful of stations could make a huge difference.

Research suggests a barrier of 50km across could stop toads in their tracks.

The distance a toad can travel in a day varies highly with the environment and weather. In a hot, humid environment a toad might be able to travel roughly 20-30km during a wet season; during cold or dry weather they’re stuck where they are.

Therefore even after heavy rains there won’t be enough water in standing puddles or river beds to let the toads cross the waterless barrier. The puddles would dry out, leaving the toads stranded and without access to dams they would quickly die.

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Read more:
The economics of ‘cash for cane toads’ – a textbook example of perverse incentives

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Why should we do it?

Cane toads haven’t been found in this part of Australia, but we believe they will be soon. By creating waterless barriers we can cut them off.

Excitingly, this strategy also has potential to be used in other parts of the country to push cane toads back, reclaiming invaded areas.

Most of the pests Australia has really gone to war against affect agriculture. Cane toads, on the other hand, are an environmental pest: they wreak havoc on native fauna, but have comparatively little impact on cash crops.

Eradication of environmental pests receives comparatively little resources. This proposal would be both a win against a devastating invader, and also a symbol of how much we care for our natural environment, and how important it is to protect it.

Mike Letnic, Professor, Centre for Ecosystem Science, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Satellite measurements of slow ground movements may provide a better tool for earthquake forecasting

The 2016 Kaikoura earthquake shattered the surface and twisted railway lines.
Simon Lamb, CC BY-ND

Simon Lamb, Victoria University of Wellington

It was a few minutes past midnight on 14 November 2016, and I was drifting into sleep in Wellington, New Zealand, when a sudden jolt began rocking the bed violently back and forth. I knew immediately this was a big one. In fact, I had just experienced the magnitude 7.8 Kaikoura earthquake.

Our research, published today, shows how the slow build-up to this earthquake, recorded by satellite GPS measurements, predicted what it would be like. This could potentially provide a better tool for earthquake forecasting.

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Shattering the landscape

The day after the quake, I heard there had been huge surface breaks in a region extending for more than 170 km along the eastern part of the northern South Island. In some places, the ground had shifted by 10 metres, resulting in a complex pattern of fault ruptures.

In effect, the region had been shattered, much like a fractured sheet of glass. The last time anything like this had happened was more than 150 years ago, in 1855.

Quite independently, I had been analysing another extraordinary feature of New Zealand. Over the past century or so, land surveyors had revealed that the landscape is moving all the time, slowly changing shape.

These movements are no more than a few centimetres each year – but they build with time, relentlessly driven by the same forces that move the Earth’s tectonic plates. Like any stiff material subjected to excessive stress, the landscape will eventually break, triggering an earthquake.

I was studying measurements made with state-of-the-art global positioning system (GPS) techniques – and they recorded in great detail the build-up to the 2016 Kaikoura earthquake over the previous two decades.

A mobile crust

GPS measurements for regions at the edges of the tectonic plates, such as New Zealand, have become widely available in the last 15 years or so. Here, the outer part of the Earth (the crust) is broken up by faults into numerous small blocks that are moving over geological time. But it is widely thought that even over periods as short as a few decades, the GPS measurements still record the motion of these blocks.

New Zealand straddles the boundary between the Australian and Pacific tectonic plates, with numerous active faults. Note the locked portion of the underlying megathrust.
Simon Lamb, CC BY

The idea is that at the surface, where the rocks are cold and strong, a fault only moves in sudden shifts during earthquakes, with long intervening periods of inactivity when it is effectively “locked”. During the locked phase, the rocks behave like a piece of elastic, slowly changing shape over a wide region without breaking.

But deeper down, where the rocks are much hotter, there is the possibility that the fault is slowly slipping all the time, gradually adding to the forces in the overlying rocks until the elastic part suddenly breaks. In this case, the GPS measurements could tell us something about how deep one has to go to reach this slipping region, and how fast it is moving.

From this, one could potentially estimate how frequently each fault is likely to rupture during an earthquake, and how big that rupture will be – in other words, the “when and what” of an earthquake. But to achieve this understanding, we would need to consider every major fault when analysing the GPS data.

Invisible faults

Current earthquake forecasting “reverse engineers” past distortions of the Earth’s surface by finding all the faults that could trigger an earthquake, working out their earthquake histories and projecting this pattern into the future in a computer model. But there are some big challenges.

The most obvious is that it is probably impossible to characterise every fault. They are too numerous and many are not visible at the surface. In fact, most historical earthquakes have occurred on faults that were not known before they ruptured.

Our analysis of the GPS measurements has revealed a more fundamental problem that at the same time opens new avenues for earthquake forecasting. Working with statistician Richard Arnold and geophysicist and modeller James Moore, we found the GPS measurements could be better explained if the numerous faults that might rupture in earthquakes were simply ignored. In other words, surface faults seemed to be invisible when looking at the slow movements recorded by GPS.

There was only one fault that mattered – the megathrust that runs under much of New Zealand. It separates the Australian and Pacific tectonic plates and only reaches the surface underwater, about 50 to 100km offshore. Prior to the Kaikoura earthquake, the megathrust was locked at depths shallower than about 30km. Here, the overlying Australian plate had been slowly changing shape like a single piece of elastic.

Slip at depth on the megathrust drives earthquakes in New Zealand, including the M7.8 Kaikoura Earthquake.
Simon Lamb, CC BY

The pacemaker for future quakes

In the conventional view, every big fault has its own inbuilt earthquake driver or pacemaker – the continuously slipping part of the fault deep in the crust. But our analysis suggests that these faults play no role in the driving mechanism of an earthquake, and the pacemaker is the underlying megathrust.

We think the 2016 Kaikoura earthquake provides the vital clue that we are right. The key observation is that numerous ruptures were involved, busting up the boundary between the two plates in a zone that ran more-or-less parallel to the line of locking on the underlying megathrust. This is exactly what we would anticipate if the slow build-up in stress was only driven by slip on the megathrust and not the deeper parts of individual crustal faults.

I remember once watching a documentary about the making of the Boeing 777 aircraft. The engineers were very confident about its design limits under flying conditions, but the Civil Aviation Authority wanted it tested to destruction. In one test, the vast wings were twisted so that their tips arced up to the sky at a weird angle. Suddenly, there was a bang and the wings snapped, greeted by loud cheering because this had occurred almost exactly when predicted. But the details of how this happened, such as where the cracks of metal fatigue twisted the metal, were something that only the experiment could show.

I think this is a good analogy for realistic goals with earthquake prediction. The Herculean task of identifying every fault and its past earthquake history may be of only limited use. In fact, it is becoming clear that earthquake ruptures on individual faults are far from regular. Big faults may never rupture in one go, but bit by bit together with many other faults.

But it might well be possible to forecast when there will be severe shaking in a region near you – surely something that is equally as valuable.

Simon Lamb, Associate Professor in Geophysics, Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Negative charge: why is Australia so slow at adopting electric cars?

Without a comprehensive network of recharging stations, like this one in Berlin, it’s little wonder that Australia is lagging behind other countries.
Author provided

Graciela Metternicht, UNSW and Danielle Drozdzewski, UNSW

In the race to adopt electric vehicles, Australia is sputtering along in the slow lane. Rather than growing, Australian sales of electric cars are actually in decline. In 2016 they represented just 0.02% of new car sales – even lower than in 2013.

Contrast that with Norway, the country with the highest levels of electric car adoption. Almost 30% of new cars sold there in 2016 were electric.

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Why are Australian motorists rejecting electric cars while those in other advanced economies are embracing them? High vehicle prices are an obvious barrier, as are motorists’ perceptions about the adequacy of the range of fully electric cars, as the National Roads and Motorists’ Association has noted. But that is only part of the answer.

Our current research, in which we used online questionnaires to survey Australian motorists’ attitudes to electric vehicles, suggests that a comprehensive network of recharging stations, particularly on popular intercity routes, is essential to encourage drivers to go electric. This seems to be even more important than subsidising the cost of the cars themselves.

Rechargers on highways, in country towns and at service centres need to be fast and convenient, so that motorists aren’t unduly delayed. Without the right charging infrastructure, there is no foundation to allow Australian motorists to go electric with confidence.

The average Australian motorist drives 36km per day for all passenger vehicles (see table 8 here). This is well within the range of modern fully electric vehicles – more than 150km for the models on sale in Australia – and actually less than Norwegians, who drive more than 40km a day on average.

Norwegian drivers also enjoy the highest proportion of rechargers in the world. But on another criterion the world leader is Estonia. It’s credited as the first nation to build a country-wide network, with a recharging station every 50km on major roads, and one in every town with a population of at least 5,000.

Bumps in the road

Every country that has successfully adopted electric cars has done so by providing an effective recharging network. But we can learn from what has gone wrong in some of these places too.

Our research suggests that governments need to ensure that recharging stations work for motorists, rather than just for the network providers. Recharge points should have standardised fittings, easy payment options such as credit and debit card facilities, and prompt maintenance – all features of existing fuel stations.

Imagine if you could only fill up with petrol by pre-registering with a network, such as Caltex or Shell, and making sure you had paid in advance before taking a long trip. It sounds ridiculous, but that is the situation electric motorists face in some places.

Britain has multiple subscriber-only recharging networks, which frequently have chargers that are out of order. Recently, sales of fully electric vehicles have stagnated and it has only been a surge in sales of plug-in hybrids that boosted sales to 1.45% in 2016, up from 1.09% in 2015.

California has solved that problem by introducing legislation to ensure that motorists don’t have to join a network and can pay for the electricity by credit card. As a result of this and other measures, such as privileged lane access and support for workplace recharging, electric cars now represent 4.8% of Californian car sales, far outstripping the US average of 0.9% in 2016.

Another Californian law ensures that the 40% of Californians who live in rental properties can recharge their cars at home. As Australians are increasingly living in high-rise developments, ensuring car parks have the capacity to recharge cars overnight will be critical. The technology exists to enable separate billing for each car, so making sure strata management allows installation will be essential for people in units and flats to adopt this low-polluting technology.

Introducing such legislation will be a necessary first step. China recently announced that it is working towards a timetable to end production and sales of internal combustion engine vehicles. It’s a good example, which Australia would be wise to follow.

This will be critical if we are to reduce transport-related emissions, toxic air pollution and noise, and improve our fuel security in the face of increasingly unstable geopolitical circumstances and our growing dependence on imported fuel.

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Read more: End of the road for traditional vehicles? Here are the facts

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Without an adequate recharging network, Australian motorists risk being left in the rear-view mirror as the rest of the world’s drivers go electric. With electric cars forecast to reach price equivalency with petrol cars by 2025, we need to help Australians overcome their anxieties about running out of charge before they reach their destination.

Governments can do this by mandating a comprehensive open-access recharging network to speed the uptake of electric vehicles. We won’t be able to fix the problem overnight but we have to get started. There is no shortage of other countries to look to for ideas.

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This article was coauthored by Gail Broadbent, a postgraduate researcher at UNSW’s School of Biological, Earth and Environmental Science.

Graciela Metternicht, Professor of Environmental Geography, School of Biological Earth and Environmental Sciences, UNSW and Danielle Drozdzewski, Senior Lecturer in Human Geography, UNSW

This article was originally published on The Conversation. Read the original article.

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Posts for the Time Being

I thought I’d post a quick update on what is currently happening with me and posts to my Blog. It is a short story really. I live in a town which is a massive tourist destination during the holiday season – especially at this time of year. What this means for me – being reliant on wireless access to the Internet – is real difficulty gaining Internet access. There are so many people in the area, using so many gadgets and the like, that the Internet is locked into a constant traffic jam. It is practically impossible to get Internet access most of the time. You do get the odd time where you can get access, but it is so slow that it is pointless to try and use it. For example – it takes minutes and minutes just for one page of the Blog to load.

I’ll keep trying to access the Net every so often, but it is likely I’ll be unable to post much for the next couple of weeks. There is good news – the number of tourists in the shopping centre here have diminished, which probably means we are heading back to some form of normality.