In Uncharted Territory

Tropical Cyclone Jasper in the Wet Tropics World Heritage Area

North Queensland and the Wet Tropics World Heritage Area (the Area), which lie next to the Great Barrier Reef, were hit by a Category 2 tropical cyclone in December 2023. In the scheme of tropical cyclones, a Category 2 is not the worst, and Jasper was extremely slow moving. 

Residents were put on alert in early December as a tropical low formed in the South Pacific near Fiji. By Dec. 4, that low entered the Australian region and it was officially given a name, Cyclone Jasper. It developed into a Category 3 severe tropical cyclone fueled by warm sea surface temperatures and low wind shear. Wind shear is wind that runs at right angles to the main wind’s direction and can weaken or turn strong winds.

By Dec. 9, conditions had eased, but on Dec. 11 the cyclone turned west and headed straight for the Queensland coast. Residents from Townsville to Cooktown held their breaths, some of them stocked up on supplies, and plenty more tuned in to their radios.

For two days nothing much happened as Jasper slowly approached the coast. 

The sting in the tail 

The cyclone’s lack of speed proved to be the sting in its tail. When it finally made landfall on Dec. 13 it had weakened but was still a Category 2. It was centred over the remote Aboriginal town of Wujal Wujal, 175 km north-west of Cairns, and hit at 8 p.m. Areas south of the cyclone’s centre suffered the strongest winds, with gusts estimated up to 130 km/h. Those winds weakened as Jasper moved inland, where it stalled and finally fell off the radar after Dec. 14.

Just as the winds were slow to come, the rains that followed took their own good time to leave. A surface trough developed across the tropical north and into the Coral Sea over the weekend of Dec. 16-17. The resulting intense rains hammered the coast and catchments – already drenched by earlier falls – for nearly a week.

The seven-day record totals on Dec. 19 were 2.252 meters at Bairds near the Daintree River with several other rain gauges throughout the region measuring more than two meters.

“I don’t know what the word is – amazing, miraculous, Biblical,” said a north Queensland resident describing what he saw in the floods of December 2023. 

The Human Impact

The effects on residents were serious, critical in places. The entire population of Wujal Wujal – more than 300 people – was evacuated by air after the town flooded. Residents were taken to outlying towns including Cairns and Cooktown while clean up and reconstruction took place, and it was not until April they started returning. Disconnection from country is difficult and painful for many Aboriginal people, and returning is an important part of the healing process.

One resident of Palm Cove, in Cairns’ northern beaches, described the cyclone as a “rolling nightmare,” as they were hit by winds on the Thursday and Friday and then by rain over the weekend, which reached nearly two meters within 24 hours. Gutters failed, piping gave way, ceilings collapsed, and severe floodwaters rose throughout the northern suburbs of Cairns as well as through towns further north. Cairns is a city of 153,000 people. Its international airport, built next to a mangrove swamp, was closed for days due to flooding.

At the Lion’s Den Hotel outside Rossville, 210 km north of Cairns, 18 people were plucked from the roof by helicopter. The previous highwater mark at the pub was halfway up the bar.

The Tully, Murray, Herbert, Daintree, Barron, Annan, and Mossman rivers, as well as plenty of creeks and streams in between, burst their banks. Bruce Jennison, principal conservation officer at the Wet Tropics Management Authority (the Authority), said every watercourse north of Clifton Beach, itself one of Cairns’ northern beaches, suffered scouring.

“We’re in unusual territory due to the level of impact,” he said, in a characteristic understatement. 

Cape Tribulation, a village of 120 people 110 km north of Cairns, was cut off in December, and some communities nearby were isolated for two weeks or more. Children could not get to school, and businesses, including tourism businesses, were without customers. The Cape Tribulation-Bloomfield Road was still closed in May after countless landslips came down a fortnight after the rains. 

The sheer weight of the water scoured vegetation along the banks of every watercourse, and some to an enormous extent. Pieces of mountainsides were swept downstream and sometimes, out to sea. It was as if a giant had scraped its fingernails across the land and dragged soil and trees and shrubs away, down to bare rock in places. 

The Wet Tropics 

The Area is an incredibly special place, heritage-listed by United Nations Educational, Scientific and Cultural Organisation (UNESCO) in 1988. The Area contains some of the world’s oldest continuously surviving tropical rainforests, estimated at 100 million years old. It is also home to more than 20 rainforest Aboriginal tribal groups – more than 20,000 First Nations people – with continuing traditional connections to their lands.   

The Area comprises about 45 percent of an almost 20,000-square km bioregion containing Australia’s highest biodiversity, with more than 700 endemic species of animals and plants and spectacular landscapes. Ancient plant lineages persist there, including half of the world’s lineages of primitive flowering plants, and the world’s songbirds originated there 50 million years ago.  

The Area is ranked the second most irreplaceable World Heritage Area on earth. The nearby Great Barrier Reef, another globally significant protected area, the only place in the world where two natural World Heritage sites lie side-by-side and are interdependent.  

The Authority has the responsibility of managing the Area for the enjoyment of present and future generations. In protecting the values, the Authority guides how much vegetation can be trimmed along roadsides, and where it should be disposed of. Arboreal animals such as tree kangaroos and possums require canopies to safely cross roads.

To ensure habitats are maintained and to support natural regeneration, pruned vegetation must generally be disposed of near the site where work takes place. Road spoil from within the Area should be disposed of as close as possible to where it came from, and not pushed over the edge of the road into the forest. 

After natural disasters guidelines say fallen trees and other debris should be removed as soon as possible. Standing trees need to be assessed and dangerous ones removed. Vegetation should be placed carefully back into the forest where possible, and road verges must not be cleared beyond their existing footprint. 

But the December floods put the Area into uncharted territory. The damage was particularly disconcerting and alarming to scientists who study and work there. At a meeting of the Authority’s Scientific Advisory Committee in March, one scientist said the deluge was “unprecedented” but not “unpredicted.”

“With climate change, it’s been predicted for 20 years,” Bruce Jennison said.

“This has been different from other cyclones. We are now dealing with an enormous amount of spoil in landslides and scouring in watercourses, so this is a unique response to a disaster. We’ve never had this amount of spoil to deal with.”

Authority conservation officers are now advising infrastructure service providers, such as the Cook and Douglas shire councils, how to deal with the huge amount of spoil and fallen vegetation. The region’s service providers include Queensland Rail, the Department of Transport and Main Roads (TMR), and the state-owned electricity generation agency CleanCo, which runs a weir at Kuranda and the Barron Gorge Hydroelectric Power Station. 

“We are dealing with thousands of tons of debris,” Jennison said.

“It can’t all be deposited within the World Heritage Area, but we are trying to keep spoil sites as local as possible. All that debris, the rocks, silt and sand and the vegetation, has been ripped out and deposited on the floodplain where the roads and bridges are. In many places the road bridges have acted as dams and large debris fields have formed upstream.” 

He said if it weren’t for the infrastructure, vital to the life of communities in the Area, the Authority would have left the debris where it was.

“Our principles are to try not to interfere with natural processes as much as possible,” he said.

“Usually, vegetation can be disposed of close to where it has fallen, but in this case, given the thousands of tonnes of vegetation and spoil, it has to be removed to an open space.”

That has come with agreements with local farmers and graziers who are accepting the spoil by the truckload onto their farms. At the Noah Range alone, inland from Cape Tribulation, at least 2,500 truckloads of spoil have been carted away, and by May the process was continuing as further slips occurred.

“The impact on Douglas Shire’s road network has been enormous, and council has asked for assistance from TMR to rebuild the Cape Tribulation-Bloomfield Road,” Jennison said.

“Under the emergency response plan TMR sought the Authority’s environmental advice on how to deal sensitively with the fallen vegetation, landslips and the debris that blocked watercourses in the World Heritage Area.”

Consulting Traditional Owners 

He said detailed discussions were held at each site regarding logistics around clearing landslips, re-establishing drainage under bridges and replacing damaged pipes. Decisions were made about what vegetation could be removed, where it should be removed to, and what spoil could be removed and to where. One of the gratifying things for the Authority, he said, had been ensuring relevant traditional owners (TOs) had been included in the process.

“I think some councils were initially overwhelmed by the scale of the damage to their road networks and jumped to their emergency response without consulting the appropriate TOs,” he said. 

“What’s been gratifying is that service providers have sought our advice in relation to cultural heritage matters regarding TOs.

“It’s vitally important that TOs are consulted about works that take place on their traditional Country. In this case it was Jabalbina, the Cultural Heritage Representative Body for the Eastern Kuku Yalanji People. 

“Traditional owners want to keep natural materials that have been disturbed by the flood on Country as much as possible, as the Authority does.

“The fallen vegetation and the spoil are part of their country. The Authority and the traditional owners are on the same page, providing the same advice about disposing of spoil as close as possible to the site from where it originated. 

“The Authority’s advice to service providers has made them aware of the potential for impacts on Aboriginal culture and traditions and how important it is to engage with agencies that represent traditional owners, such as Jabalbina.” 

He said in the event no cultural heritage sites were damaged during the emergency response phase, but consulting TOs was now recognized as a lesson to be front of mind for every agency working on disaster recovery in the Area.

“Because of the scale of destruction to the roads in the World Heritage Area, and because Douglas Shire Council and TMR have asked for our close support with environmental monitoring and advice on rebuilding the Cape Tribulation-Bloomfield Road, our conservation officers are spending more time than usual working in the field. 

“This is as well as our work supporting the emergency response of the other infrastructure service providers such as CleanCo, Queensland Rail, and the other councils that have been affected.” 

Six months on councils and TMR are still rebuilding the road network, stabilizing unconsolidated rocks and landslips by shotcreting landslips, installing pipes, re-establishing drainage, and soil-nailing road foundations.

Further scientific monitoring is continuing in the Area. The scouring, “mini scars” and “breakthroughs” on beaches are all obvious in aerial pictures, including around the northern beaches of Cairns. Breakthroughs are new stream outlets into the sea where none existed before.

Even the prolonged freshwater plume and sediment pouring out of the rainforest could affect corals, marine animals and seagrass. The Great Barrier Reef is already under stress from climate change and in early 2024 suffered one of the worst coral bleaching events ever. 

Eyes on Hazards 

Scientists are monitoring feral pests such as cane toads, expected to make “incursions” into exposed areas, tilapia, which can move from one river to another via freshwater flood plains, and pigs, which are vectors for weed seeds and pathogens and cause physical damage. Pigs already have established populations throughout the entire Area.

There is also a potential for an increased crocodile presence as scoured stream sides allow for more basking opportunities. Although it’s difficult to predict, early reports from the Annan River catchment indicate there are more crocodiles upstream, so there is concern for local communities along the river.

One of the threats with invasive weeds is that some, such as pond apple or aggressive pasture grasses, could trigger landscape change. Jennison hopes resources will be available to fund a program of weed management on steep slip faces. 

A Changing Climate 

Part of the beauty and unique character of the wet tropics is the endemism of many species. Some frogs, for example, have found niches in a few pools around waterfalls, and one landslide could be the “end of the game” as one scientist put it, for some. Captive breeding trials of the vulnerable Bloomfield River cod, which exists only in an 11-km stretch of river between two waterfalls, are being investigated.

Between 1600-1800 AD, the Cairns area was hit by possibly five Category 4 and Category 5 tropical cyclones, but since European settlement none that big has come ashore.

“Cyclones are a natural part of life in the tropics, and natural to the life of tropical rainforests,” said Scott Buchanan, executive director of the Authority. 

“They can open the canopy, clear dead wood and big trees and make way for other species to grow, which is natural ecological succession. Change is a normal part of any rainforest. To geomorphologists these are natural processes in action, but while it is a natural process we are now asking if an event this big is natural, or normal. 

“We know rain associated with tropical cyclones has become more prolonged and more intense, and it’s happening globally due to climate change. It’s something we are starting to see here, and it will continue. 

“Our work is to protect, rehabilitate and share the Wet Tropics World Heritage Area in perpetuity, and the questions for us now are how we manage the landscape and change our practices in this changing climate. 

“We are working to ensure the World Heritage Area is in as good a shape as possible before the next major cyclone hits.”

ABOUT THE AUTHOR

Andrew McKenna

Andrew McKenna has worked as a writer and journalist for more than 30 years in Australia and New Zealand. He has taught journalism at universities for 10 years and worked as a communications specialist in the public and private sectors including for publishing houses and environmental NGOs.