Last Thursday in Clark Hall, the Geosciences Department hosted a lecture by Dr. Alex Apotsos from the American Association for the Advancement of Science titled “Coastal Dynamics: Setting Up the Surfzone.” In his lecture, Apotsos explained the importance of coastal dynamics and the surf zone to daily life.
Apotsos completed his doctoral degree in applied ocean science and engineering from the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution’s Joint Program (MIT/WHOI) in oceanography. Additionally, Apotsos took policy courses throughout graduate school.
After completion of his degree in civil and environmental engineering, Apotsos became a member of the Peace Corps. During his two years in this program, he lived in Mali as a water and sanitation engineer.
Utilizing the knowledge he gained from his policy classes in graduate school, Apotsos returned from the Peace Corps to work under Senator Jon Tester (a Democrat from Montana). Under Tester, Apotsos concentrated on environmental, energy and water resources in issues such as how to deal with sites like old mines that pose flooding problems to surrounding communities.
After these initial introductions, the presentation addressed the importance of studying coastal dynamics. “Depending on how you define it, up to 60 percent of the population lives along the coast,” Apotsos said. This concentration of population around coastal areas, according to Apotsos, requires attention to coastal dynamics in order to create secure and efficient infrastructures in cities and communities.
Additionally, coastal dynamics factor strongly into several economic factors. “Ninety percent of international trade goes by ship,” Apotsos said. “It’s important to know how coastal dynamics are going to affect our ports because of this.”
Apotsos defined the coastal zone as the surf zone portion even though it is “a smaller area than how most oceanographers would define a coastal zone.” In this defined region, Apotsos depicted a series of factors with the potential of affecting a surfzone. These factors include waves, storms, run-up created by shoreline oscillation, tides, turbulence, setup and pressure.
Apotsos explained in detail the significance of setup, or “an increase in the mean sea level near the shoreline owing to breaking waves,” in studying coastal regions, especially the surfzone. Firstly, setup causes coastal flooding. It also drives flows that carry pollution and sediment, also known as beach erosion. “As we build more and more infrastructure along the coast, we need to be aware of water levels,” Apotsos said.
To do this, Apotsos explicated how to model setup. The individual eye cannot see setup. Instead, more intricate tools are necessary to create adequate observations and models. “It took people in the ’90s setting up pressure centers to prove that setup even exists,” Apotsos said.
According to Apotsos, waves carry momentum flux and because of this, larger waves have more energy and thus more momentum flux. When waves break, some of this momentum is released into the water to the shoreline where it begins to pile up. This pile up of water is the setup. “Setup is depth dependent,” Apotsos said. “There will be a larger setup in shallow water than in deep water.”
Understanding setup is very important to creating effective coastal infrastructure. “If I am going to build a house at the beach, I want to know how high the water will come,” Apotsos said. “You can use historical observations to estimate how high the high water level will be, but you need to use a predictive model to estimate the setup.”
An existing model called the Latin Hypercube Sampling (LHS) model under predicts the setup by approximately 50 percent, which, if this model were to be used, would cause someone to settle in geologically unsafe locations. “We need a better predictive model than this,” Apotsos said. The model neglects the effects that wave rollers and bottom stress can have on setup.
Apotsos discussed how alongshore dynamics, in addition to setup, are important to creating effective, safe coastal communities. He left the audience with the message that this field needs to be developed for the good of coastal populations as well as the economic value of the coast.