Living shorelines enhanced the resilience of saltmarshes to Hurricane Matthew (2016)

Abstract

Nature-based solutions, such as living shorelines, have the potential to restore critical ecosystems, enhance coastal sustainability, and increase resilience to natural disasters; however, their efficacy during storm events compared to traditional hardened shorelines is largely untested. This is a major impediment to their implementation and promotion to policy-makers and homeowners. To address this knowledge gap, we evaluated rock sill living shorelines as compared to natural marshes and hardened shorelines (i.e., bulkheads) in North Carolina, USA for changes in surface elevation, Spartina alterniflora stem density, and structural damage from 2015 to 2017, including before and after Hurricane Matthew (2016). Our results show that living shorelines exhibited better resistance to landward erosion during Hurricane Matthew than bulkheads and natural marshes. Additionally, living shorelines were more resilient than hardened shorelines, as they maintained landward elevation over the two-year study period without requiring any repair. Finally, rock sill living shorelines were able to enhance S. alterniflora stem densities over time when compared to natural marshes. Our results suggest that living shorelines have the potential to improve coastal resilience while supporting important coastal ecosystems.

Oceanography and Marine Biology

“…biodiversity enhancement) if this technique is to replace or complement artificial structures. Although hard ecoengineering is less challenging to implement from a coastal defence perspective, there is growing evidence that created or restored habitats using soft engineering can also provide protection that is equivalent to or better than traditional engineered hard structures (Gittman et al 2014, Smith et al 2017a, Smith et al 2018. As mentioned previously, soft engineering approaches and hard structures may even operate synergistically to enhance coastal protection (Smallegan et al 2016, Vuik et al 2016)-as successful hybrid schemes in some cases.…”

“…Often, there is stronger support for hard engineering approaches (Gray et al 2017) that have been more thoroughly tested over time (Sutton-Grier et al 2015), even when they are unnecessary or less cost effective than soft or hybrid alternatives (Scyphers et al 2014, Gittman & Scyphers 2017. In contrast, where the asset is less crucial for social and economic health or primarily of local significance, there may be a higher chance for adopting more experimental (and potentially riskier) ecoengineered shoreline approaches that provide protection under most (but not the most severe) storm events, or for which the evidence of efficacy in terms of shoreline protection is limited (but see Gittman et al 2014, Smith et al 2018. Which ecoengineered shoreline approaches can and should be adopted will largely be influenced by the degree to which the environment has already been modified by anthropogenic activities (Bouma et al 2014).…”

An Integrative Approach to Assessing Property Owner Perceptions and Modeled Risk to Coastal Hazards

“…Some limited work has been conducted in North Carolina that integrates homeowner perceptions with field measures. This was targeted to assess the relationship between perceptions of waterfront homeowners regarding shoreline protection methods to actual measures of their efficacy when impacted by hurricanes [20].…”

Salt marshes for flood risk reduction: Quantifying long-term effectiveness and life-cycle costs

“…Such hybrid combinations of natural and engineered shorelines are sometimes referred to as 'living shorelines' (Davis et al, 2015) or 'green infrastructure' (Silva et al, 2017). Presence of structures can lead to higher marsh elevations (Gittman et al, 2014), enhanced erosion resistance during storms, and higher stem densities (Smith et al, 2018), compared to natural marshes. During storms, both the detached structure and the salt marsh can help in reducing wave loads on the flood defense behind the living shoreline.…”