In my recent research, I have developed the River Avulsion and Floodplain Evolution Model (RAFEM) and coupled it to the Coastline Evolution Model (CEM), using the Community Surface Dynamics Modeling System Basic Model Interface. With this new morphodynamic river delta model, I am exploring how both upstream (e.g., changing river properties) and downstream (e.g., sea-level rise, changing wave climate) controls affect large-scale delta morphology and river avulsions. I am also investigating how human influences on rivers (e.g., damming and levees) and coastlines affect the dynamics and feedbacks within the system.
In previous work with Dr. Marco Marani and fellow Duke PhD student Anna Braswell, I have investigated how climate change impacts coastal marsh resilience. Coastal marshes provide numerous ecosystem services, are an important carbon sink, and are exposed to drowning as sea-level rise accelerates. Using a meta-analysis of the available observa- tional data, we model the coupled marsh vegetation and morphological dynamics. We found that the fertilization effect of elevated atmospheric CO2 significantly increases marsh resilience to drowning and decreases the spatial extent of marsh retreat under high rates of sea-level rise. While this direct CO2 fertilization effect has so far been neglected in marsh modeling, we find it is central in determining marsh survival under the foreseeable range of climatic changes. Read more here.
Pocket (embayed) beaches are positioned between rocky headlands and adorn about half the world’s coastlines. Previous work suggested seasonality or oscillations in climate indices control erosion and accretion along these shorelines; however, using the Coastline Evolution Model (CEM) developed by my adviser and former students, I found that patterns of shoreline change can be found without systematic shifts in wave forcings. Using Principal Component Analysis, I identified two main modes of sediment transport dynamics: a shoreline rotation mode, which had been previously studied, and a shoreline “breathing” mode, which I newly discovered. Using wavelet analysis, I determined the characteristic timescales of these modes, which emerge from internal system dynamics (rather than changes in the wave forcing; e.g., seasonality). To confirm the breathing mode’s existence, I retroactively identified this mode in observations of pocket beach shoreline change from different parts of the world. Characterization of these modes, as well as their timescales, better informs risk assessment and coastal management decisions along thinning shorelines, especially as climate change affects storminess and wave energy variations across the world. Read more here.
As an undergraduate researcher, I collected and analyzed sediment samples from Explorers Cove at the mouth of Taylor Valley, Antarctica, to determine the sediment transport pathways and depositional processes beneath multi-year sea ice. Read more here.