Newswise — Powerful cyclones can push seawater miles inland, threatening densely populated communities and critical infrastructure built along coastal areas. A combination of exposure and complexity makes the Bay of Bengal in Southeast Asia a powerful test case for scientists seeking to better understand how tides, storm surge, river flows and sea level rise interact to drive extreme coastal flooding.
To better anticipate the region’s rare but potentially devastating floods, researchers at the U.S. Department of Energy’s Argonne National Laboratory are using advanced computer simulations to create thousands of tropical cyclone scenarios.
The research helps reveal how extreme storm tides could affect key coastal sites, including nuclear power plants, providing information that could guide safer infrastructure planning in one of the world’s most vulnerable coastal regions. Their findings, published in npj Natural Hazards, could inform operations and guide future plant siting.
Simulating cyclones to predict flood risks
The research team used Argonne’s Laboratory Computing Resource Center to simulate thousands of years of tropical cyclones under a range of atmospheric conditions. The researchers focused on storm-tide risks, which they define as the highest simulated water levels during a storm.
Assessing risks to nuclear infrastructure requires estimating low frequency events (extreme storm tides), which occur less often but pose significant threats. Natural hazard risks are often expressed in terms of event frequency. For example, a 50-year flood — one that is estimated to occur only once in a 50-year period — may be an acceptable risk for thermal power plants, but nuclear facilities require estimates for rarer events, such as 1,000-year floods. This makes it challenging to estimate risks from natural hazards since worldwide records of storm paths and intensity extending beyond 50 to 100 years aren’t available.
Nuclear infrastructure safety depends on using rebuilt data from related datasets or creating realistic predictions of storm events. The researchers used the second approach to generate a long historical record of storm surges along the coast of the Bay of Bengal.
Their simulations showed how changes in cyclone paths and strength could reshape flood risks. Historical cyclones, such as Cyclone Sidr (2007) and Cyclone Hudhud (2014), were used to test the accuracy of the models. The models used physics-based methods that do not rely on the small number of recorded tropical cyclones that have made landfall. Depending solely on historical records can either underestimate or overestimate flood risks.
“We wanted to understand how to evaluate the risk of building critical infrastructure in a hydrologically complex coastal area,” said Rao Kotamarthi, an Argonne senior scientist and one of the study’s authors. “We wanted to estimate the changes in low frequency events as would be necessary for siting nuclear reactors.”
Risk changes across the region
The researchers analyzed how different factors interact to influence the risk of flooding at sites of critical infrastructure. Their study found that adding up the effects of individual factors, such as tides and storm surges, can lead to inaccurate water level estimates. These estimates can be off by as much as 25 to 30 percent compared to estimates that account for how these factors interact with each other over long periods.
Simulations revealed that flood risks varied significantly across the Bay of Bengal’s coastline, with notable differences even within the same region.
- Decreased risk in Bangladesh: The Ganges-Brahmaputra-Meghna delta shows a lower risk from low frequency events as compared to some other locations along the coast. However, extreme flooding events are still possible, with water levels reaching several meters.
- Increased risk in India: India’s eastern coast, including areas near the Kovvada Atomic Power Project, show elevated risk from low frequency events. The study predicts up to a 78% increase in low frequency event risks compared to higher frequency events.
Additionally, complex factors, such as storm surges, tides, river discharge and sea-level rise, amplify flood risks. Wave setup (water accumulation caused by wave action) and tide-surge interactions are especially significant along India’s eastern coast.
Implications for infrastructure
As populations grow and more infrastructure is built in coastal areas, understanding these risks is essential. Policymakers and engineers are responsible for designing resilient systems to withstand extreme weather events. Critical facilities, such as nuclear power plants and hospitals, can incorporate these projections to prevent catastrophic damage.
Kotamarthi has been working with the International Atomic Energy Agency on hydrological and meteorological hazard impacts to nuclear sites.
“Since we are building more power plants in different locations, we need to do a more thorough analysis,” Kotamarthi said. “There’s more to consider than just elevation. Even existing plants likely will need to update safety rules to account for the estimated risks from these types of hazards.”
The researchers recommend proactive measures to reduce flood risks. These include improving safety protocols for existing infrastructure and conducting detailed flood risk assessments for new facilities.
Expanding the research
While Argonne’s method was applied specifically to sites of existing or proposed nuclear power plants in the Bay of Bengal, it can be used for any coastal region where storm-tide risk assessments are needed. The study highlights opportunities to expand this research to other vulnerable coastal regions worldwide.
Future research will expand storm datasets, refine projections for land sinking and river discharge, and leverage machine learning to enhance model efficiency and accuracy. These improvements will make predictions more reliable.
This research emphasizes the importance of localized flood risk assessments to protect infrastructure. It provides valuable insights for policymakers, engineers and disaster preparedness teams. Investing in high-resolution modeling and localized studies equips communities to mitigate the growing risks of extreme weather events.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology by conducting leading-edge basic and applied research in virtually every scientific discipline. Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
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