Masters Thesis Defense: John Malito

The Masters Thesis Defense of John Malito is presented by the University of North Carolina at Chapel Hill’s Department of Earth, Marine and Environmental Sciences. This event will be held on Tuesday, November 9th at 11:00 am. This event will be held in person and will also be streamed online. The physical location of the event is on UNC-CH campus in room 2204, the 2nd floor conference room of Venable/Murray Hall. To watch online join via Zoom Meeting ID 757 103 0185.

Title: Evolution of Arctic continental shelves: modelling morphodynamic feedbacks toclimate-driven increases in sea states

Abstract: Arctic marine environments, including the Alaskan Beaufort Shelf (ABS), are experiencing declines in sea ice coverage and duration. As a result, increasingly energetic sea states have been observed to drive accelerating coastal retreat. Continental shelves are the intermediary between deep-water and coastal processes, modifying waves as they pass over the shelf. Waves propagating toward the coast are attenuated by bottom friction while also inducing sediment transport, creating a morphodynamic feedback through erosion and deposition of the seabed. A Delft3D sediment transport model was used to test how present-day and increased projected waves impact shelf evolution over 1000 years, and how shelf geometry modifies propagation of waves toward the coast. Results showed that wave-induced sediment transport and morphologic adjustment was enhanced on a steeper shelf transect (Flaxman Island, AK) under increased projected waves. Redistribution of sediments from the inner shelf to the middle shelf led to attenuation of projected waves as the shelf evolved, creating a regulatory feedback loop. In contrast, effective wave attenuation across a flat shelf transect (Harrison Bay, AK) limited cross-shelf transport and morphologic change. Thus, morphodynamic feedbacks to the growing Arctic wave climate depend on shelf geometry and can impact future coastal erosion.