Exploring unintended feedbacks between coastal hazard, exposure, and vulnerability

Abstract

Coastal zones are more densely populated than any other landscape on Earth. These regions are also dynamic places that naturally change shape and position, especially in response to sea-level rise, leaving the infrastructure that sustains high coastal populations exposed to natural coastal hazards. Therefore, to make exposed infrastructure less vulnerable to damage, shorelines are deliberately altered with hazard protections. Some developed coasts have been altered on such spatial scales that they no longer act like natural coastlines. Instead, they function as coupled human-landscape systems, where shoreline dynamics reflect interactions and feedbacks between human alterations and natural coastal processes. The Atlantic Coast of the USA has over 2500 km of developed coastline, and is arguably the largest coastal coupled human-landscape system in the world, and is dominated by beach nourishment: a type of coastal hazard protection that involves widening an eroding beach with imported sand. Beach nourishment buffers exposed infrastructure from coastal hazards, and also serves as a stock of natural capital for tourism economies. However, despite ubiquitous nourishment along the US Atlantic since the 1960s, coastal risk continues to increase. This dynamic is an expression of the “safe development paradox”, in which exposure to hazard continues to rise, despite increased efforts to protect against hazard impacts. This thesis explores unintended feedbacks between coastal hazard, exposure, and vulnerability evident along the US Atlantic Coast. My work examines why beach nourishment might have the counter-productive consequence of increasing risk. This thesis also presents a conceptual framework that may enable future models of coastal risk to incorporate “big data” approaches to illuminate and explore the “safe development paradox”, and to test whether prospective management strategies might mediate coastal risk or exacerbate it.

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ORCID for Eli Lazarus: orcid.org/0000-0003-2404-9661

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