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Urban floods: Nguyen Huynh earns PhD for research on assessing flood water exposure health risks

Taking floodwater samples on flooded streets in Ninh Kieu district (17 October 2016)

Nguyen Huynh from Vietnam successfully defended her PhD thesis and was awarded with a doctoral degree on 25 October 2023. Her promotor is Professor Chris Zevenbergen and her co-promotor Dr. Gerald Corzo Perez. Dr. Huynh shared a few insights as she embarks on a new chapter of her life.

My thesis in a nutshell

My research is about calculating the health risks pedestrians, cyclists and motorcyclists and public transport passengers are exposed to when they travel through urban floodwater that contains microbial pathogens - bacteria, viruses or other microorganisms that can cause disease. I did a case study in the Ninh Kieu District, Can Tho City, Vietnam, which is located on a Mekong tributary. This urban area experiences annual flooding due to heavy rain, high sea levels and flows from upstream regions. Floodwater that hits the area is polluted, particularly with microbial pathogens such as E. coli and rotavirus – these can cause vomiting and diarrhoea. I looked at how flood water exposure affects microbial health, something that had not yet been fully considered.

As part of my study, I developed an approach to use observed and simulated data to estimate the health risks of people being exposed to enteric pathogen concentrations – that is, pathogens that affect their intestine health. This approach can be used to improve the assessment of health risks in floods, not only in Vietnam but also worldwide. The study emphasizes that the microbial concentrations in floodwaters and the number of exposed people are key to the health impact of floods. Mitigation measures, therefore, should focus not only on reducing urban floods, but also on raising awareness of the local people of the risks of microbial concentrations in floodwater.

Flooded street in Ninh Kieu district (17 October 2016)
Flooded street in Ninh Kieu district (17 October 2016)Copyright: Huynh Thi Thao Nguyen

Memorable moments

The fieldwork in the Ninh Kieu district was memorable. Sampling a real flood event is challenging since it requires special equipment, proper facilities, safety considerations and trained workers. 

To catch the actual flood event, I stayed in the Ninh Kieu district for several days over a period of three months, from August to October 2016, a time that had a high potential of flooding due to heavy rain and high tide. Preparing and sampling flood waters gave me a better understanding of the pollution situation. The data from the samples were helpful for the health risk assessment and setting up the flood model. 
    
Local residents were curious about my research: I was the only one who looked happy on flooded streets as I put dirty floodwater in sterilized bottles - others were in a hurry to get home. In conversation with residents, I learned about their exposure to floods, their perception of health risks related to floodwater, and their needs. Through these discussions, I realized that my research may help improve the awareness of residents about potential health risks during floods. 

Seting up the water level sensor in manhole in Ninh Kieu district (17 October 2016)
Seting up the water level sensor in manhole in Ninh Kieu district (17 October 2016) Copyright: Huynh Thi Thao Nguyen

Challenges during my PhD studies

The challenging part of my PhD studies was not only gathering interdisciplinary knowledge on water quality, urban flood modelling and health risks, but also practicing soft skills such as time management, project management and research skills. Moreover, having a child in the middle of my PhD work and the COVID-19 pandemic made it quite difficult to focus on my research. My PhD research is my first big academic project, so I have learned many lessons.

The influence of my PhD research

In an ideal world, my PhD work would lead to a concept that enhances flood risk management (FRM) by calculating the annual expected "health effect" using the Disability-Adjusted Life Year (DALY) metric – this represents the disease burden. In FRM, the Expected Annual Damage (EAD) is commonly used to predict asset damages in monetary terms. Adding the concept from my PhD would mean also considering on the health consequences of flooding on exposed populations. This proposed method provides a more holistic approach to FRM that considers both asset damages and health consequences.

In addition, I hope that local residents can be made aware of the health risks of flood water, so that they can protect themselves by avoiding highly flooded streets, delaying traveling during floods, or use public transport on flooding days. Also, by improving the urban floodwater quality, especially in terms of microbial pollution, the urban floodwater can be utilized more efficiently.

PhD defence Nguyen Huynh
PhD defence Nguyen Huynh Copyright: Kyaw Zin Htoon

Future plans

I am a researcher at the Air Pollution and Climate Change Center (APAC) of the Institute of Environment and Resource (IER) of Vietnam National University Ho Chi Minh City (VNU), Vietnam. I would like to do more research on the health impacts/risks of residents caused by water/air pollution. I hope the results may support decision makers so that they can prioritize protecting vulnerable communities.

An important lesson

If I could give some advice myself on the first day of my PhD studies, I would say that the PhD work is a part of my life: let's enjoy it and other parts of my life too, such as spending quality time with family and friends. I would tell myself to focus on the PhD journey, but not to stress too much, or other beautiful moments of research may be missed.

Thesis title and summary

Including microbial health risk in flood risk assessment. A case study: Ninh Kieu district, Can Tho City in the Vietnamese Mekong Delta

Assessing microbial health risks related to floodwater is a complex undertaking, hindered by factors like the intricate nature of the microorganisms involved and the susceptibility of those exposed to them. This research contributes a framework and application that combines health risk assessment, disease burden calculation, and hydrodynamic modeling to estimate adverse health consequences of microbial pathogens in floodwater through traffic activities which is a common factor of exposure during floods. The case study is Ninh Kieu District (Can Tho City, Vietnam) located on the western side of Hau River, a Mekong tributary. The study focuses on the health risk and disease burden due to rotavirus A in floodwater in Ninh Kieu through traffic activities, especially for motorcyclists. This research is one of the first to consider the input parameter concentrations and the number of exposed people to reduce the health impact of flood risk. It reveals that mitigation measures should not only focus on reducing urban floods but also on raising awareness of the local people of microbial health risks in floodwater. The disease burden is considered the prime variable of the health indicator to represent the social dimension in the assessment of flood vulnerability.