Coastal Management Model plays a long game with rising tides

To prevent sea level rise in a world of warming, coastal cities usually follow standard playbooks with a variety of protective infrastructure options. For example, Seawalls can be designed based on modern climate forecasts, and city officials then proceed to calculate and build its cost-benefit ratios.

problem? Future climatic conditions could differ significantly from the forecasts of used climatic conditions, according to Ashmita Bhattacharya, a doctoral student in civil engineering in Pennsylvania and the first author of a study published in Nature Communications by an interdisciplinary team of researchers from the state of Pennsylvania and the University of Pittsburgh.

Communities risk overbuilding expensive infrastructure. Construction and maintenance contributes excessive carbon dioxide to the atmosphere, further exacerbating the speed of climate change and designing inadequate protections. This could lead to excessive flood-related damages and even more expensive repairs.

“The question regarding the current state of practice in climate adaptation is a major uncertainty related to how climate demand will evolve in the future,” says Chris Forrest, a professor in the Department of Climate Sciences at Pennsylvania’s Department of Meteorological Sciences and a research co-researcher. Global temperatures were recorded faster than expected in 2023 and faster than expected in 2024.

To avoid making potentially expensive investments that provide misinformation and potentially expensive because of the lack of the ability to reallocate resources used when future conditions are not expected, the team has created a model that provides decision support over time to make more information available, while still being available while still being able to maintain as low a cost as possible, according to a professor at the Department of Civil and Environmental Engineering, Pennsylvania and co-authors.

“Our approach suggests dynamic behavior in time, taking into account future scenarios in the optimal sense, while responding to actual, evolving climates,” Warn said.

According to Bhattacharya, the long-term strategic approach of the model could lead to significant savings for municipalities by proposing resources rather than committing resources for a comprehensive protection system, rather than committing resources for a comprehensive protection system. Researchers tested a scenario model inspired by Manhattan and Staten Island in New York and found that, based on real-time conditions and long-term goal observations, the model’s long-term adaptation recommendations are based on lower overall costs compared to traditional decision-making frameworks based on static cost-benefit analysis.

This model is supported by advanced mathematical and computational techniques. One known as the “(partially observable) Markov decision process” mathematically expresses the unpredictability of nature through “belief,” quantifying the uncertainty of future states, and assigning probability to each. This model constantly updates understanding of these beliefs regarding future sea level rise scenarios as new data are collected, as chess players carefully study the board after each move and carefully study the board to understand the potential for the opponent’s next operation.

Chess players forget to instantly capture the piece to maintain another move in the back pocket at a later point. Similarly, the model may recommend small seawalls first or not to take action unless certain conditions are met in the future. The proposed sequence of actions in the model is generated through a technique known as “dynamic programming.” This best evaluates decision trees like formations based on new data and latest decisions.

“The key to this is indirect or direct observations of physical processes: for example, a surge in sea level rise and storm surges that can be measurable via tidal age distance gauges,” Bhattacharya said. “This dynamic adaptation leads to reduced implementation, maintenance, damage and environmental impact compared to static cost-benefit actions.”

The model also explains the environmental impact of potential build or maintenance actions, Bhattacharya added. She explained that researchers linked actions such as concrete embankments. This generates carbon emissions from cement manufacturing, mining, transportation, equipment use and future repairs. This is the Environmental Protection Agency’s estimate of the social costs of carbon, an estimate of the damage caused by each tonne of carbon emissions caused by the massive amounts of carbon dioxide emissions.

In addition to traditional concrete-based infrastructure options, the researchers also evaluated nature-based solutions that can be independently or parallel to traditional “gray” infrastructure, such as concrete walls. For example, recommended actions may include adding smaller walls and oyster leafs. This could reduce the impact of incoming waves at much lower carbon emissions.

In simulation tests of the New York City coastline, researchers found that inclusion of the social costs of carbon promoted previous adaptation behaviors and took adaptation measures more frequently.

“This is because the goal of the adaptation problem is to minimize the overall cost of adaptation, including damage and the resulting carbon emissions,” Warn said. “The result is that by ignoring carbon emissions, we underestimate the overall cost of flood-related damage.”

The team’s future efforts are focused on expanding the model and testing it against increasingly detailed scenarios and various coastal contexts. According to the United Nations of the Ocean, eight of the world’s 10 largest cities are located along the coastline.

“The framework remains the same, but the data used (geography of local regions, asset values, etc.) should reflect the local area,” said Costas Papaconstantine, an associate professor of civil and environmental engineering in Pennsylvania.

He says the model can ultimately be used by governments or insurers to encourage adaptation measures, likening it to a time when the advent of anti-lock braking systems reduced car insurance rates.

“Similarly, the costs of the National Flood Insurance Program could reduce fees if protection measures are taken justly in time,” Papakonstantinou said. “Assurance coverage after a flood event can also be considered directly within our framework, especially when paid by an entity that is a decision-maker, such as the federal government.”

Pennsylvania collaborators also included Lauren McPhillips, an assistant professor of civil and environmental engineering, and Deigant Chhabuda, a doctoral student in civil engineering. From the University of Pittsburgh, collaborators included Melissa Bireck, Professor George M. Bivia Bevier, and the co-director of sustainable innovation at the Mascaro Center. Rahav Hasan is a doctoral student in civil engineering.