I am a PhD candidate in the MIT-WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering working with Dr. Jeff Donnelly in the Coastal Systems Group. I study how hurricanes and other large storms have impacted coastal New England over the last 2,000 years.
As coastal population continues to grow in both size and wealth, hurricanes pose a growing threat to infrastructure, life, and environment. Sea-level rise has continued to threaten coastal communities at alarming rates, and evidence suggests that sea-level rise will exacerbate the effects of storm surge, increasing the potential for land loss. In New England, where both population and economic resources are concentrated largely on the coast, research into the impact of increased storm intensity and sea level rise is imperative to resilience of these coastal communities.
Inverse modeling of hurricane intensity
Quantitative tropical cyclone records for the entire Atlantic basin date back to the 1850s, making it the most comprehensive tropical cyclone dataset. Historical records for the Atlantic extend as far back as 1492 C.E., but they are largely anecdotal and sporadic, pieced together from ship logs and personal accounts. Since our instrumental and historical records are too short (and, at times, fragmented) to understand interactions between tropical cyclones and climate on a longer (multidecadal to centennial to millennial) scale, proxy records are imperative for reconstructing millennia of tropical cyclone impacts and understanding the climate forcing responsible for driving the changes in these impacts.
Though the frequency of intense-hurricane landfalls in southeastern New England is well constrained through analysis of overwash deposits, the intensity of these storms, particularly prehistoric events, is not. Recent research has focused on using the maximum grain size of sediment within a storm deposit, combined with information such as offshore wave climate and distance of the deposit from the barrier overwashed, as a more accurate indicator for the wave heights of a storm event. Using these inverse modeling techniques, it is possible to estimate the intensity of storms for which no historical record exists.
Influence of storms on the resilience of coastal bays and marshes
Coastal bay systems play an integral role in protecting coastal communities from flooding and other destruction associated with hurricanes and nor'easters. As sea level continues to rise and tropical cyclones and other storms increase in intensity, these coastal bays and marsh systems are increasingly at risk for destruction. Salt marshes in particular have long been lauded as buffers to storm surges, wind-generated waves, and elevated water levels.
Following Redfield's bi-directional model of salt marsh evolution, salt marshes along the eastern coast of the United States keep pace with moderate sea-level rise. Recent geological evidence, however, suggests that some extreme storm events may cause significant marsh erosion. Other studies suggest that extreme storm events cause net influx of sediment to the system, improving the resilience of marshes to extreme weather. This spectrum of impacts has major implications for coastal inundation risk to lives and property, as well as the resilience of these coastal wetlands to a changing climate.
As a former environmental educator, I love opportunities to share science in fun and accessible ways. I am always happy to share demonstrations or lessons on various topics including climate, hurricanes, salt marshes, storm surge, coastal protection, sediment coring, paleotempestology, and Cape Cod natural history.
Castagno, K. A.(2018). Salt Marsh Restoration and the Shellfishing Industry: Co-evaluation of Success Components. Coastal Management, 46 (4), 297-315. https://doi.org/10.1080/08920753.2018.1474069
A product of my master's thesis, where I researched the ecologic and social linkages between salt marsh restoration and the shellfishing industry on outer Cape Cod, MA. Restoration projects are valued for far more than their direct provisioning ecosystem services, with many shellfishermen emphasizing the cultural value of the salt marsh above all else.
Castagno, K. A., Jiménez‐Robles, A. M., Donnelly, J. P., Wiberg, P. L., Fenster, M. S., & Fagherazzi, S. (2018). Intense Storms Increase the Stability of Tidal Bays. Geophysical Research Letters, 45, 5491-5500. https://doi.org/10.1029/2018GL078208
In order to counteract rising sea levels, a coastal bay needs to increase its bottom elevation by trapping enough sediment in salt marshes and tidal flats. Here, we show that intense storms provide sediments to the bay and marsh systems of the Virginia Coast Reserve, thereby increasing their long‐term stability.
Pruss, S. B., Castagno, K. A., Fike, D. A., & Hurtgen, M. T. (2016). Carbon isotope (δ13Ccarb) heterogeneity in deep-water Cambro-Ordovician carbonates, western Newfoundland. Palaeogeography, Palaeoclimatology, Palaeoecology, 458, 52-62. https://doi.org/10.1016/j.palaeo.2015.10.004
An extension of my undergraduate honors thesis, we explore the difference in δ13Ccarb values between clast and matrix from the conglomerate-rich sequences of the Cambro-Ordovician Cow Head Group in western Newfoundland, Canada.