Date of Award

1-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School

College of Science and Mathematics

Department/Program

Earth and Environmental Studies

Thesis Sponsor/Dissertation Chair/Project Chair

Jorge Lorenzo-Trueba

Committee Member

Pankaj Lal

Committee Member

Eric Forgoston

Committee Member

Thomas Herrington

Abstract

In response to coastal erosion driven by storms, sea-level rise, and local gradients in sediment supply, communities defend their homes and maintain beach recreation by widening beaches via soft engineering (i.e., beach nourishment) or hard engineering (i.e., groins). Past research has found that, at regional scales, the net effect of these interventions has in many cases not only counteracted historically observed beach erosion, but has reversed erosional trends, on average shifting shorelines seaward. While groins trap sediments locally at and upcoast of the structure relative to the direction of alongshore transport, however, they often have adverse downcoast impacts, resulting in heightened erosion and forcing communities to respond with new engineering measures or by abandoning their beachfront properties. This research aims to understand the key drivers of community-scale coastal management decisions. Toward this, I developed a model that couples natural coastal dynamics (i.e., geomorphology) with the economics of beach management, which is used to compare different protection schemes to determine their economic consequences. In the first chapter, I explore the effect of inter-community beach nourishment coordination, and find that coordination is most important economically for both communities when they have different property values because the less wealthy town tends to nourish more than necessary if they preserve their beach alone. In chapter two, I perform regression analyses with field data on community-scale nourishment, socioeconomics, and geomorphic conditions in New Jersey, and find that both a community’s beachfront wealth and its proportion of commercial property value (i.e., a proxy for its level of tourism) help explain its beach nourishment decisions. In chapter three, I employ the geomorphic-economic model in communities downdrift of a groin subject to heightened beach erosion, and find that the community’s beachfront property value and its size (a proxy for its tax base) help explain how (i.e., nourishment, groin, both, or neither) and when it will respond. In a scenario in which climate change causes shorelines to retreat more rapidly and the overexploitation of sand/rock resources dramatically increases its cost, less wealthy communities may be unable to keep pace with the changing conditions and instead abandon their properties altogether, leaving only the wealthiest homeowners along the coast. Furthermore, tourism-centric communities facing these threats may respond with different nourishment approaches to meet recreational demand compared to their residential-dominated counterparts. Finally, for communities subject to groin-induced erosion, it is possible that the historical transition away from groins to beach nourishment as the main management response over the last half century could be reversed in the future, and groins could again become the more commonplace approach as communities adapt to sea-level rise. Such divergent outcomes based upon wealth disparity, extent of a local tourism economy, and spatial proximity to groin-induced erosion should be considered in future policy development at the state and federal levels.

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