Sasha Zigic: On the evolution of ocean modelling

The business of forecasting how oceans move

When RPS’ General Manager Ocean Science and Technology Dr. Sasha Zigic stepped inside a Gold Coast start-up 26 years ago, little did he know he would be embarking on his dream career: modelling the movements of oceans – and remaining in the same consultancy all this time. 

As an undergraduate civil engineering student at the time, his lecturer had suggested doing work experience, and the rest as they say is history.

“As civil engineering was all about bridges and roads and structures, there was nothing related to what I really wanted to do in the marine environment space so, I absolutely hated it.” 

“It was sheer luck that my lecturer put me onto this start-up. They needed someone that was willing to do water quality sampling on weekends, and they showed me this thing on a screen called ocean modelling.”

Ocean modelling involves building forecast models by using the latest wind and ocean currents information provided by various government agencies to help predict the movement of marine pollution  across our seas.  

Back in the early 90s, engineering was limited to the disciplines of electrical, mechanical, and civil. It would take another decade before Sasha gained a qualification in environmental engineering by completing his PhD, and now he boasts a deep understanding of the complexities of dispersion modelling.   

From the western suburbs of Melbourne to Gold Coast’s beaches

Growing up in Melbourne’s St Albans, a suburb largely made up of former migrants who arrived in Australia in the 70s, Serbian descent Sasha never imagined he’d be leaving his north-western soccer-loving suburb and relocating to the hub of the sun, surf, and sand on the Gold Coast. 

“I was at the furthest point from marine ocean modelling, there was no such thing on my horizon,” he recalls. 

In fact, back then Sasha was toying with other ideas. This included soaring in the skies as a pilot, treating patients as a physio, and hitting the road as an intrepid traveller and volunteer in Africa. 

“I had been talking to my parents about becoming a pilot since I was ten years old, but in the early 90s there was a recession and there weren’t many pilot jobs unless you were spraying crops, so I disappointed my parents by giving up on that career.” 

“Then I became fascinated by physio after injuring myself while playing soccer (I was a keen player at the time) – and I became intrigued by how our bodies work. But that didn’t last long before I started to make plans to join Australian Volunteers Abroad to travel to Africa.” 
 
Yet, none of the scenarios Sasha had played out in his mind came into effect once he discovered ocean modelling. 

“I just knew this is where I wanted to be,” he reminisces, as he fondly thinks back to that first introduction to modelling. 

Nowadays, Sasha is a leading expert in his field, who specialises in investigating water circulation and the fate of pollutants within offshore, coastal, and port environments. He’s participated in hundreds of hydrodynamic and dispersion modelling studies within Asia Pacific waters for oil and chemical spills, sediment dispersion from dredging, and routine discharges such as wastewater, cooling, and produced water.

Sasha also provides training and guidance for national oil spill and search and rescue drift modelling software used by response agencies globally. He leads RPS’ 24-7 emergency modelling response team supporting many response agencies including the Australian Maritime Safety Authority, Australian Marine Oil Spill Centre, Civil Aviation Authorities and Maritime response agencies of Singapore, Indonesia and Malaysia, Maritime New Zealand, and the International Tanker owner’s pollution fund.

Understanding ocean modelling

For many years Sasha struggled to articulate exactly what his day-to-day work entailed, as ocean modelling was an unfamiliar concept to many, until recently. 

“Trying to describe what we do has been very, very challenging for many, many years because it's so diverse, and modelling for many years hasn't been a topic of discussion.” 

These days, the seasoned coastal and ocean modeller has worked out an elevator pitch to talk about his life’s passion. 

“If I’m at a BBQ where I've met someone for the first time, I'd say we do computer modelling and it involves modelling the movement of an oil spill or chemical spill and where that spill might track to, based on the conditions of the currents and the winds.”

“I’d add that our predictions are used by response teams to understand where it's heading and what it's going to hit, and they can better manage the incident and protect the environment better.” 

Aside from responding to marine pollution emergencies, another core part of Sasha’s role is predicting and preventing disasters in the first instance. 

“If you've got a new gas pipeline by a major operator that’s hundreds of kilometres in length, for instance, they may need to dredge the seabed to lay that pipeline. So, my team looks at where the dredge sediments will travel, to assess the potential environmental impacts because generally the pipelines will be laid in a sensitive environment.”

“You might have mangroves, corals, or seagrass, and if the dredged sediments disburse onto these habitats, it could cause harm. So, we work out where the sediments will travel to and look at ways of minimising that impact.” 
 
Sasha has also worked in drift modelling predictions to help with locating missing persons, vessels, and aircrafts lost at sea. 

“We do search and rescue or search and recovery – it could be that we’re looking for a catamaran with a few people on board or we’re looking for a ship that's just lost its containers. If a fisherman's lost at sea, for instance, the water police use our software to work out the search area. However, there are situations where it's beyond their ability, so they call us to assist with tracking where that person/s or object/s is lost at sea.” 

“I've been the duty officer when a ship has lost its shipping containers overboard during huge storm events and they need to be retrieved promptly as those containers could be causing environmental harm and safety issues.” 

Ocean dynamics and data: a new era for industry

Now, more than ever, scientists have been gathering data about our oceans in an effort to understand changing coastal conditions, and to produce a detailed picture of the impact of climate change. According to NASA, for instance, 90 percent of global warming is occurring in the ocean. By looking at the salty depths of our oceans, scientists can mark seasonal trends and flag regional differences – and warn us about extreme variations.    

This level of data collection and access to real-time information has had the biggest influence on Sasha’s modelling work. He says, “there's been significant technological advancement in terms of predicting how oceans move.”

“The biggest change has been in our understanding of our environment. We’ve been able to leverage off that information and use that detailed data as part of our assessments at RPS.”  

“So, if there is an oil spill, for instance, we can predict how far it will track and determine the risk of exposure to a particular area – and pinpoint it accurately.”
 
“Before our clients can drill for oil or undertake any sort of operations, they need to put together an environmental plan to work out what their potential impacts are, and that's where our environmental planning team would come in,” he adds.  

Industry adopts ocean modelling

Another notable shift in Sasha’s role has been the growing acceptance of modelling by operators and government agencies. 

“Modelling is now embedded in regulations and processes, and operators understand the need for modelling.” 

“In the last decade or so, operators have looked to modelling to consider whether or not their operation is likely to have a major impact or not on the environment – and whether they need to reassess or refine their operations – and that’s a very big change.”   
 
“The biggest trend that I've noticed over the last five years is that government agencies and operators want more information. Organisations want to understand ‘what does it mean for me’ and they also want to understand the science too now,” he adds.  

With this shift in thinking, Sasha has also seen a push for greater stakeholder engagement. 

“Industry are not only looking at how will something like an oil spill impact their operations, but there’s been a big emphasis on the impact on stakeholders – and that can be anyone.” 

Yet, while industry is pulling in unison in the same direction, the solutions to the problems they encounter remain unique. Sasha says that’s because a lot of the time the sorts of challenges they encounter have never been tackled before. 

“For example, we once received a call in the middle of the night telling us that the blades from an offshore wind farm had come off during really strong wind events, and it had shattered into a thousand pieces.” 

“That’s a unique event and in that situation, you can't pull a solution off-the-shelf and say, ‘how do we go from A-Z?’ So, we develop our own sound methodologies that meet client needs.” 

In a situation like that, Sasha says time is a critical factor. 

“That debris, which is made up of resin and variety of different other components has broken into thousands of pieces and drifted into the ocean and is now travelling to a beach somewhere.” 

“Our clients need to know where to track that debris as quickly as possible because not only can it cause pollution to the environment, it's also a safety issue, as someone on that beach can cut themselves on that fibreglass.” 

According to Sasha, when it comes to marine emergencies response times needs to be swift. 

“If there is an incident, we need to generally respond within two hours, whether it’s day or night, Christmas, or New Year’s Day. So, we’re on duty 24/7, 365 days a year.” 

An enduring interest in ocean modelling

As a General Manager, Sasha is responsible for developing and executing strategic plans, overseeing project work, managing client relationships, overseeing financial budgets, and training and managing staff. Despite his leadership role, he still gets to work a lot of the time doing modelling. 

“I spend close to 70% of my time on the modelling work because one of the things that I've found over the years is that clients want to understand the nuances that you went through to come to a solution.” 

Sasha says he loves being hands-on and working in the ‘trenches’, so-to-speak. 

“I continue to enjoy what I do because it's very technical. And it continues to challenge me, even years later. I love the fact that I get to work with such talented and knowledgeable people too. I've got an incredible team that I’ve been working with for decades.” 

“I also love that we get to do so many different things from dredging operations to tracking debris and we get to work on massive projects and have an influence over how our clients manage their operations.” 

Sasha’s most recent modelling work has included a detailed sediment dispersion modelling study for Tokelau Air Services, to get their first airfield underway. Located in the remote group of atolls in the South Pacific Ocean, halfway between Hawaii and New Zealand, the services plan to develop an 800-metre-long runway. Sasha’s team have been commissioned to assess the potential influence or impact on water quality and benthic habitats, given the project would involve dredging and land reclamation on the Nukunonu atoll, which is the main atoll of Tokelau.    

Breaking through cultural barriers

With Sasha’s modelling work spanning the Asia-Pacific, he’s experienced stark differences between some countries when it comes to regulatory operating environments. Without a doubt, some regions have posed greater challenges, yet Sasha says, “RPS has been able to influence, assist, and provide guidance with our knowledge of working internationally.” 

“There are cultural barriers with some countries, but we've developed a strong relationship with both regulators and oil and gas operators across APAC, and we're perceived as the go to company.” 

“When we consider that we're an Australian based business, and not local, we've been incredibly successful. We get to work for the largest oil and gas companies in the world.” 

On a personal-level, Sasha feels completely comfortable traversing different cultural norms. His bi-lingual upbringing has given him a strong sense of how different countries communicate and make decisions differently. 

In the global business world, Sasha’s name has also turned out to be a great icebreaker at overseas meetings.  

“It's been quite funny at times because Sasha can also be a girl's name. And in some countries, particularly in Malaysia, when I show up to meetings the clients will lower their guard and say, ‘we thought you were a lady’.” 

Modelling one’s of the greatest mysteries

In 2014, international passenger flight Malaysia Airlines’ MH370 disappeared from radar while heading to China and a short time after departing from Kuala Lumpur International Airport. Carrying 230 passengers and a crew on board, the plane vanished, without a sign. Aside from a few small pieces of fuselage found, to this day, this event remains one of aviation’s greatest mysteries. 

During the extensive search for MH370, Sasha and the RPS team provided day-to-day drift modelling predictions to the Australian government. It remains one of Sasha’s most memorable moments in modelling. 

“The Australian government asked us to provide ongoing day-to-day modelling for their search and recovery efforts. So, we were in Canberra for 40-plus days providing daily updates which was used by all the response agencies to work out daily plans.”

“I recall that moment being quite worrying because you've got military vessels and planes, civilian vessels and planes, and you've got the whole world watching. And basically, our modelling was guiding them where to go.” 

“We can locate people and objects lost at sea at an accuracy rate of above 95%. With that in mind, we thought we were going to have a positive effect, but of course, the plane and the black box were never found. It’s one of the great mysteries of our lifetime.” 

Navigating unchartered territory

Using the latest modelling technologies, Sasha and his team will now be also looking for ways to help meet Australia’s 2050 net zero emissions goals. As part of this new remit, the team will look for ways to minimise the environmental impact of alternative energy systems or future fuels, like carbon capture storage (CCS), hydrogen, and ammonia. 

“For instance, in the event there is a pipeline leak of carbon dioxide (CO2) during CCS operations, it will be emitted into the water column. Most of the CO2 will escape into the atmosphere, but some of it will remain in the water column, which might change the physical properties of the water, and that could have an impact on nearby sensitive areas like a coral reef or seagrass,” explains Sasha.  

“Our work will be able to work out that if there was a release of CO2 and the environmental risks and potential impact on nearby habitats such as coral.”   

When it comes to ammonia, Sasha’s team are set to provide advice on how to transport it safely across the seas. 

“Knowing what will happen during an incident, that's where we come into it. So, we must think, will the ammonia immediately flash off? Does it cause safety concerns? If so, how far?” 

Hydrogen is another renewable energy superpower that Sasha and his team will view through the lens of modelling. With hydrogen plants being proposed all along the Australian coastline, particularly in WA, Sasha says they’ll be keeping a close eye on the extraction process.   

“Water sourced from ocean for the desalination plant will be discharged via a diffuser and then the question becomes what does that do to the environment? So, that's where our team will step in and will be modelling the potential impact of the treated wastewater.”