Hard yakka field work underpins decisions for Northern Australia
Some projects are so big in scale and ambition, it’s the detail that tells the real story.
The Federal Government released its White Paper on Developing Northern Australia: Our North, Our Future, in September 2015, outlining plans for economic development over the next two decades. Senator Matt Canavan, Minister for Resources and Northern Australia, delivered the first progress report to Federal Parliament in October.
Northern Australia’s “time has come”, is the call that has accompanied the Federal Government’s statements on the White Paper.
“By 2030 more than two-thirds of the world’s middle class will be in Asia, Senator Canavan told Parliament. “And, even more relevant for the north, the percentage of the world’s population living in the tropical region is expected to grow from 40 per cent today to 50 per cent by 2050.”
“This growth in our region promises to deliver dividends for all Australians. More than half of Australian exports leave from ports in northern Australia. We all own a stake in seeing the successful development of northern Australia.”
CSIRO is currently undertaking the $15 million Northern Australia Water Resource Assessment (NAWRA), to investigate opportunities for water and agricultural development in three priority regions in northern Australia: the Fitzroy River catchment in Western Australia, the catchments surrounding Darwin in the Northern Territory, and the Mitchell River catchment in Queensland. This follows the successful Flinders and Gilbert agricultural resource assessment completed in 2014.
The assessments cover land suitability, indigenous interests, agriculture, surface and groundwater, water storage, ecology as well as climate.
But here’s the story that provides tangible evidence of work being done that will underpin the project reports submitted in June 2018: The hard yakka of field work.
Colours of the soil tell the story of country
Field work? The land suitability assessments – looking at soil quality – took 10 teams in troop carriers on 12-day field trips totalling 120 days out in the field surveying more than 500 soil sites from mid May to mid October.
On the latest trips, to coincide with the dry season, the teams collected more than 3000 soil samples for analysis.
CSIRO land resources information officer Seonaid Philip said it was some of the most extensive field work done in the north for years – and she ran the logistics.
“It’s been a great experience, the people engaged in this profession are interested because they love it. There were seasoned campaigners, people like Peter R. Wilson who came out of retirement. All these people want to see development in the right way,” she says.
The most remote destination was 150km south east from Fitzroy Crossing, sometimes pitching tents in the car headlights, working under 35 degree sun – and sometimes in the rain – with hand-turned augers or working with the a core sample rig, to discover sometimes poor soils and on other occasions richer depths of promise.
“It’s eerily beautiful. From the delta of the Mitchell catchment in Queensland to the 350 million-year-old Devonian Reef in Western Australia; we’re an old landscape,” Philip says.
“Some of the soil samples you just want to eat – red basalt and some alluvial soils, they just look delicious.”
Key to the scale of the work was the use of digital soil mapping (DSM), cutting-edge technology that tells the field crews where to sample and map very large areas to take the bias, and some of the leg work, out of the soil surveys.
Core samples collected are now in the lab being tested under the full suite of wet chemical analyses to test for agriculturally-important qualities such as clay content, water retention and salinity. They’re also tested using mid infrared spectroscopy (MIR) – a technique that enables an even wider range of important soil properties to be discovered and mapped.
Tracing the water above and below ground
The groundwater field work conducted during the winter took in six two-week field trips across all three catchments, covering an area of around 70,000 square kilometres and visiting up to 200 water bores. The field work included groundwater sampling for chemistry and environmental tracers and to characterise groundwater flow processes, measuring water levels and installing groundwater level loggers to capture long-term changes in water levels.
Andrew Taylor, experimental scientist in CSIRO’s Water Resource Management Program and leader of the groundwater hydrology activity in NAWRA, says all three study regions are unique and groundwater resources in many aquifers are yet to be well characterised.
“These aquifers occur over very large areas where water isn’t currently being utilised for agriculture,” Taylor says. “Very little is currently understood about what opportunities and risks would come with their development.”
In parts of the Darwin catchments, intense wet season rainfall enters aquifers and supports ecosystems such as springs and rainforest patches. In the Mitchell catchment, the topography is like a giant ramp hundreds of kilometres long. Surface water runs off the elevated, high rainfall part of the catchment, across very old, hard rock geology and into the mid-section of the catchment, where some of it infiltrates into the aquifer systems of the Great Artesian Basin (GAB) and Karumba Basin, and the remainder flowing onto the plains and out to the Gulf of Carpentaria.
In the Fitzroy catchment, there are large consolidated regional sandstone and limestone aquifers of the Canning Basin and an unconsolidated alluvial aquifer surround the mighty Fitzroy River. These aquifers host groundwater systems replenished from wet season rainfall that in some locations throughout the catchment support dry season river flows and instream pools.
“There are some key parts of each study region we want to characterise, in particular the most prospective regional aquifers, to understand the nature of the groundwater systems they host,” Taylor says.
“This characterisation involves many facets including drilling, groundwater and surface water sampling and ground surface surveying. For example, aquifer outcrops where the water goes into the aquifer systems are often not well understood and are the subject of targeted drilling next year. We’ll be drilling the outcrops themselves to see what connection those aquifers have with the Fitzroy itself.”
Meanwhile, surface water assessments have included LiDAR surveys over areas that have never been studied. LiDAR stands for Light Detection and Ranging, a method of using pulsed laser from a plane to measure distances to the Earth to produce a digital representation of the landscape. The elevation data show the shape of the riverbed, where the water flows and how it floods.
Next step: High performance computers
From the variations of red of Northern Australian country, the work will next step into the blue glow of high performance computer rooms where all the data collected from field work will be modelled.
Ross Searle, senior experimental scientist and a project leader behind the Soil and Landscape Grid of Australia, says there are approximately 100 different types of environmental data used in the land suitability models – from climate to topographical indicators and geophysical features.
“The modelling establishes the relationship between the observed data and the range of environmental measures. We then produce a range of soil property maps which are combined to provide soil limitations and, at the end, a suitability framework to establish the potential land uses,” Searle says.
“This is the biggest land suitability assessment project using these digital techniques, probably in the world.
“It’s challenging in a range of ways. A lot of this technology and modelling has only been used on small-scale research, but we’re moving it into an unprecedented scale. Land suitability has traditionally been based on soil maps developed from observed data combined with expert knowledge. We are now being explicit about every step in the process, making the creation of the maps an easily repeatable task. Using digital soil mapping techniques (DSM) also allows us, for the first time, to quantify how certain we are about our land suitability predictions at each individual pixel.”
Providing tangible information for the big decisions
CSIRO’s Northern Territory Research Leader, Dr Chris Chilcott, says the field work would not have been possible without the involvement of state and Northern Territory agencies who provided equipment, labour, expertise and data. The team has been careful to ensure that all the data collected is fully compatible between states and territories.
The field work campaigns have been an exercise in constructive cooperation across jurisdictions.
Some of the work being done as part of the NAWRA field work is also at the frontier of science, from the digital soil mapping to exploring interesting new ways to store water, including managed aquifer recharge, he says.
“We can’t tell whether or not development will happen,” Chilcott said. “But our work will allow people to make up their own minds, to advocate for or against development. It will be an objective assessment of the land and water available and everyone will have access to the same information.”
Read more about NAWRA.