Threshold effects of hazard mitigation in coastal human–environmental systems

Abstract

Abstract. Despite improved scientific insight into physical and social dynamics related to natural disasters, the financial cost of extreme events continues to rise. This paradox is particularly evident along developed coastlines, where future hazards are projected to intensify with consequences of climate change, and where the presence of valuable infrastructure exacerbates risk. By design, coastal hazard mitigation buffers human activities against the variability of natural phenomena such as storms. But hazard mitigation also sets up feedbacks between human and natural dynamics. This paper explores developed coastlines as exemplary coupled human-environmental systems in which hazard mitigation is the key coupling mechanism. Results from a simplified numerical model of an agent-managed seawall illustrate the nonlinear effects that economic and physical thresholds can impart into coastal human-environmental system dynamics. The scale of mitigation action affects the time frame over which human activities and natural hazards interact. By accelerating environmental changes observable in some settings over human timescales of years to decades, climate change may temporarily strengthen the coupling between human and environmental dynamics. However, climate change could ultimately result in weaker coupling at those human timescales as mitigation actions increasingly engage global-scale systems.

The interactive relationship between coastal erosion and flood risk

“…Coastal zones have been described as displaying strong human-landscape interactions which give rise to instabilities in the response of the coastal zone to forcing, such as from sea level rise (Lazarus, 2014;Lazarus et al, 2016;McNamara and Werner, 2008). It is therefore possible to conceptualise erosion-flooding interactions as occurring in the broader context of human-landscape interactions in which risk receptors exert a degree of agency over the hazards to which they are exposed.…”

Anthropogenic controls on overwash deposition: Evidence and consequences

“…Previous studies address the impacts of anthropogenic structures and development on overwash delivery from a purely qualitative perspective, however, and these impacts have yet to be quantified. Not only is the presence of human development on islands increasingly common but there is a strong coupling between the socioeconomic value placed on barrier islands and the morphologic evolution of islands themselves [e.g., Werner and McNamara , ; McNamara and Werner , , ; McNamara and Keeler , ; Jin et al ., ; Lazarus , ]. Anthropogenic influence and associated feedbacks have long been recognized for their impact in other natural systems.…”

Characterizing storm response and recovery using the beach change envelope: Fire Island, New York

“…The resulting impacts from these events require a range of human and natural resource considerations, from threats to buildings and infrastructure to changes in habitat availability (Schlacher et al, 2007;Weinstein et al, 2007;FitzGerald et al, 2008;Gutierrez et al, 2009;Moser et al, 2014;Passeri et al, 2015). Often in the days and weeks following an event there is significant pressure to restore beaches and dunes through replenishment projects, wherein the potential for natural recovery is either overlooked (Lazarus, 2014), considered spatially and temporally insufficient, and/or poorly understood and as a consequence not factored into decision-making. Therefore measurements and characterizations of coastal change that can account for both storm impacts and recovery are essential for actionable and targeted coastal management.…”