Coupled economic‐coastline modeling with suckers and free riders

Abstract

[1] Shoreline erosion is a natural trend along most sandy coastlines. Humans often respond to shoreline erosion with beach nourishment to maintain coastal property values. Locally extending the shoreline through nourishment alters alongshore sediment transport and changes shoreline dynamics in adjacent coastal regions. If left unmanaged, sandy coastlines can have spatially complex or simple patterns of erosion due to the relationship of large-scale morphology and the local wave climate. Using a numerical model that simulates spatially decentralized and locally optimal nourishment decisions characteristic of much of U.S. East Coast beach management, we find that human erosion intervention does not simply reflect the alongshore erosion pattern. Spatial interactions generate feedbacks in economic and physical variables that lead to widespread emergence of "free riders" and "suckers" with subsequent inequality in the alongshore distribution of property value. Along cuspate coastlines, such as those found along the U.S. Southeast Coast, these long-term property value differences span an order of magnitude. Results imply that spatially decentralized management of nourishment can lead to property values that are divorced from spatial erosion signals; this management approach is unlikely to be optimal.

Masked Shoreline Erosion at Large Spatial Scales as a Collective Effect of Beach Nourishment

“…This suggests that, in addition to getting redistributed across the shoreface, if some nourishment sand is redistributed laterally by wave-driven gradients in alongshore sediment transport, neighboring coastal communities may benefit from each other's nourishment investments (Lazarus, McNamara, et al, 2011). A community that does not invest in beach nourishment may still benefit from the beach nourishment projects of its neighbors-in resource economics, a dynamic related to the 10.1029/2018EF001070 prisoner's dilemma known as "free-riders" and "suckers" (Gopalakrishnan, McNamara, et al, 2016;Williams et al, 2013).…”

Economics of Coastal Erosion and Adaptation to Sea Level Rise

“…A logical next step is to embed multiple adaptation strategies into this capital-theoretic framework and continue to build in more realism grounded in the physical science. The second track starts with sophisticated models of geomorphology and climate dynamics and embeds stylized economic decision rules into them , with recent attempts to include some capital-theoretic underpinnings (Lazaurs et al 2011;Williams et al 2013). These numerical frameworks deal more seamlessly with spatial-dynamics and multiple adaptation strategies at the extensive margin but are not constructed to be optimized.…”

“…Though highly stylized, this result points to the recklessness of spatially decentralized coastal planning as an adaptation strategy for climate change. Placing the single-community decision rule into a more complex (and more realistic) coastline model leads to an alternating pattern of suckers and free riders, where the sucker communities overprovide public goods relative to the free riders (Williams et al 2013). In essence, these models base the decision rule on equation (1) but take account for more realistic spatialdynamics of coastal geomorphology.…”

Threshold effects of hazard mitigation in coastal human–environmental systems

“…A body of recent numerical modeling research examines the coupled economic-beach dynamics of developed shorelines, with particular attention to beach nourishment (Slott et al, 2008(Slott et al, , 2010Smith et al, 2009;Slott et al, Lazarus et al, 2011;Murray et al, 2013;Ells and Murray, 2012;Jin et al, 2013;McNamara and Keeler, 2013;Williams et al, 2013). The work frames beach nourishment as a cumulative cost-benefit optimization problem (Smith et al, 2009), adopting an environmental economics approach typically applied to a renewable resource like timber (e.g., Hartman, 1976).…”