Growing up in Bangladesh, Ataur Rahman knew well the devastation caused by flooding. Nearly a fifth of the country is flooded during an average year and three-quarters sits less than 10 metres above sea level, so he lived with the ever-present threat of inundation. “Bangladesh has a lot of flood problems,” says the Western Sydney University water engineer, “so I had an interest in doing research in this area from a young age.”
Several decades later, that interest led Rahman to a detailed study of flood risk across Australia and a research program that has changed the practice of flood estimation nationally. It has been translated into a web-based tool that offers governments, businesses and farmers a picture of what is likely to happen if a flood hits their region. The program’s ultimate goal is to minimise future flood damage.
Floods account for nearly 30 per cent of Australia’s natural disasters, and take a devastating toll. The damage caused by flooding in Queensland and New South Wales in February 2022 exceeded $4.8 billion.
Prior to this research, the existing method of flood calculation was limited by risk being estimated within state borders. Rahman and his colleague Khaled Haddad discounted arbitrary provincial boundaries, instead dividing the country into 14 regions based on hydrological patterns.
The design of what is now known as the Regional Flood Frequency Estimation tool was assisted by Professor George Kuczera of the University of Newcastle, and flood hydrology and water resource allocation expert, Erwin Weinmann. In all, the project involved collaborations from 14 organisations and the National Committee on Water Engineering at Engineers Australia.
“For any point in Australia, if you put in the latitude and longitude, you can assess the risk of flood. It looks at what could happen, and helps minimise the impact,” Rahman says.
“It’s very fast and easy to apply using a web interface. It has been used to design bridges and embankments, and to better protect the community.”
It has been particularly valuable in rural areas, he notes, where it provides vital additional details for the safe and effective design of farm infrastructure.
If floods are already a major problem for Australia, climate change means that minimizing their damage will only become a bigger challenge in future. “The severity of rainfall is increasing and flooding is intensifying,” Rahman says (see ‘Debbie’s Deluge’).
The tool is already being used by local governments, state water agencies, road authorities and consultants. Rahman says it was recently used to estimate flood risk in 560 locations at once, delivering results within 30 minutes. It has been used as part of the Australian Rainfall and Runoff national guidelines, a public collection of data and software designed to help with risk mitigation and community resilience.
As the flood threat grows, Rahman intends to continue to develop the model. “Ultimately, we want to include more data to continually improve accuracy.”
Need to know
- WSU research has developed a better flood-mapping tool
- Other WSU research has developed a tool to assist water treatment plant operators
- Both have been adopted by industry
Rahman is not the only Western researcher to be bringing his formative experiences to bear on new solutions. A childhood in Sri Lanka and the enthusiasm of an early mentor led Western’s Professor Sathaa Sathasivan to find a solution for treating drinking water.
“In Sri Lanka, people have trouble getting good quality water,” Sathasivan says. “That was an area of concern to me.”
Sathasivan had studied civil engineering before deciding to change direction and embark on doctoral studies in environmental engineering, where his PhD supervisor had a passion for drinking-water microbiology. The supervisor’s enthusiasm was passed on, and Sathasivan has worked in the field ever since.
Sathasivan’s work focuses on disinfectant technology. Amongst other things, he has been investigating a chemical called chloramine (see box), a safer and cheaper alternative to the more standard water treatment approach.
The traditional method combines filtration to remove larger contaminants and chlorine to neutralise smaller contaminants such as bacteria and viruses. While chlorine is effective, it is also expensive and a potential health hazard, producing by-products when the chlorine reacts with other compounds that might occur in ‘raw’ water. Some of these by-products are thought to be carcinogenic, although the evidence is far from certain.
Chloramine, which is formed when ammonia is added to chlorine, does not produce these unwanted by-products, is considerably cheaper, and more resistant to break down than chlorine — lasting about ten times longer. All of this makes it a far more desirable chemical for water treatment.
However, chloramine has one major weakness: under certain conditions, bacteria may feed on free ammonia in the chloramine-treated water, producing a chemical called nitrite. The runaway chemical and biological processes sometimes consume all the chloramine in a water supply without any warning, leaving insufficient levels for effective treatment.
Sathasivan and colleagues addressed this problem, through a project funded by industry and Western by developing a tool to predict when runaway nitrification might occur.
The tool emerged from the team’s research into factors that influence the likelihood of a nitrification event, such as the concentration of chlorine and ammonia in the water reservoir, the temperature and pH of the water, and other variables such as fluid dynamics within the reservoir.
The benefits of the research were so important that the Australian Research Council funded a Linkage grant of $1.1 million with industry funding from five water utilities in Sydney and Queensland.
The tool developed by Sathasivan and his colleagues does more than simply predict when nitrification events are likely to occur. It also helps water treatment plant operators decide what to do about a possible nitrification problem, and when to act; what dose of chlorine to use to bring the bacteria back down to safe levels; what impact this will have on the consumer; how long to treat; and also the possible impacts of outside events such as extreme rainfall, extreme heat or bushfires. It can also help identify infrastructure problems that might be contributing to a higher risk of nitrification, which can help with longer-term investment decisions.
Sathasivan’s work is now being used by South East Queensland Water in its investigation of disinfection improvements. SEQ Water currently uses chlorine to disinfect at the treatment plant, but uses chloramine for secondary disinfection, when the water leaves the plant to its pouring out of the consumer’s tap.
Brett Myatt, project lead for the South East Queensland disinfection optimisation project, says he’s interested to see if disinfection improvements could be made.
SEQ Water regularly sends 1,000 litre-samples of their treated water to Sathasivan, who continues to run experiments modelling the effect of environmental conditions on nitrification.
This work has revealed that water’s pH has a particularly significant impact on the risk of such events.
The findings are helping SEQ Water to prioritise their actions. “We’re talking infrastructure investment of millions of dollars,” says Myatt. “So it’s making us confident it will have a significant effect.”
In 2017, Tropical Cyclone Debbie and its remnants devastated Queensland, northern New South Wales and northern New Zealand. In Lismore, it pushed the Wilsons River to a peak of 11.59 metres, breaching a levee built in 2005 for the first time. The peak was not as high as previous floods in 1954 and 1974, but the speed of the river’s rise was noteworthy. Earlier events have typically followed extended periods of rain. Debbie dumped most of its rain in 24 hours, and it happened in a year without the La Niña conditions that have typically contributed to earlier devastating floods on the east coast.
Ammonia is a simple compound made of one nitrogen atom, with three hydrogen atoms arranged around it. In chloramine, the structure is the same, but one hydrogen atom is replaced with a chlorine atom. The chlorine used for water disinfection has no nitrogen involved. Instead, it is two chlorine atoms bonded directly to each other.
Meet the Academic | Professor Ataur Rahman
Dr Ataur Rahman is a Professor in Water Engineering in the School of Engineering, Design and Built Environment at Western Sydney University. He obtained his BEng (Civil) from Khulna University of Engineering and Technology (KUET) in 1982, Masters in Hydrology from National University of Ireland in 1990 and PhD from Monash University, Australia in 1997. He worked at Dhaka University of Engineering and Technology (DUET), Bangladesh Water Development Board, Sinclair Knight Merz, CRC for Catchment Hydrology and Queensland University of Technology before joining Western Sydney University in 2002.
He has served as a Visiting Academic at Cornell University (USA), Vienna University of Technology (Austria), The University of Newcastle (Australia), Masdar Institute of Science and Technology (UAE), Institute of National Scientific Research (Canada) and UNSW Sydney and has supervised over 22 PhD and 9 Masters by Research students to successful completion. Currently, he is supervising 9 PhD students and two Masters by Research students.
Dr Rahman has authored 521 publications including 155 ISI listed journal articles. He co-developed the ARR RFFE Model 2019, which is widely used for design flood estimation in Australia as a part of the new Australian Rainfall and Runoff (the national guide). He led the ARR Project 5 for 10 years to its successful completion and received the G N Alexander Medal from The Institution of Engineers, Australia in 2002 for an outstanding research paper on loss modelling for design flood estimation. He won the Vice-Chancellor’s Excellence Award for Higher Degree Research, Training and Supervision in 2015 and 2017 and has completed over 15 funded research projects.
Dr Rahman is on the editorial board of three international journals and is the founder Chair of GCSTMR (Global Circle for Scientific, Technological and Management Research), which has organised numerous conferences around the globe. He is the frequent reviewer of over 10 top level international journals in water and environmental engineering. He is Co-Chair of the Water Education and Research Committee of the Australian Water Association, and a Fellow of Engineers Australia. He was selected as one of the top 2% scientists globally based on 2020 research data. His publications have received over 7200 citations in Google Scholar (with h-index of 42).
Meet the Academic | Professor Sathaa Sathasivan
Professor (Sathaa) Arumugam Sathasivan joined Western Sydney University (WSU) in January 2012. Prior to joining WSU, he was an Associate Professor/Senior lecturer at Curtin University for 6 years and managed projects totaling about $1.2 million, including an ARC linkage grant project. In total, he has attracted research funding of about $4 million including ARC Linkage projects worth $1.4million.
Sathaa supervised 25 postgraduate students inclusive of 12 PhD students to successful completion. Sathaa brings a nice mixture of industrial and academic experience in environmental engineering from around the world. He finished his PhD in The University of Tokyo in Water Quality Engineering and then worked as a research fellow in the same university for two years. Following this, Sathaa was an Assistant Professor in Asian Institute of Technology, Bangkok for two years.
Prior to joining Curtin, he worked with Sydney Water Corporation as a Water Quality Scientist for six years on several operational and research and development projects which included Cooperative Research Centre for Water Quality and Treatment.
His main research interest is in drinking/recycled water distribution systems and water treatment processes to deliver safe water at a minimal cost. He uses biotechnology/chemistry/modelling as appropriate in water/wastewater research. He loves the challenges the sustainable development present and the opportunities life cycle assessment tool and other technologies offer.
Higher Degree Research at Western
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Future-Makers is published for Western Sydney University by Nature Research Custom Media, part of Springer Nature.