Valuing natural habitats for enhancing coastal resilience: Wetlands reduce property damage from storm surge and sea level rise

Abstract

Storm surge and sea level rise (SLR) are affecting coastal communities, properties, and ecosystems. While coastal ecosystems, such as wetlands and marshes, have the capacity to reduce the impacts of storm surge and coastal flooding, the increasing rate of SLR can induce the transformation and migration of these natural habitats. In this study, we combined coastal storm surge modeling and economic analysis to evaluate the role of natural habitats in coastal flood protection. We focused on a selected cross-section of three coastal counties in New Jersey adjacent to the Jacques Cousteau National Estuarine Research Reserve (JCNERR) that is protected by wetlands and marshes. The coupled coastal hydrodynamic and wave models, ADCIRC+SWAN, were applied to simulate flooding from historical and synthetic storms in the Mid-Atlantic US for current and future SLR scenarios. The Sea Level Affecting Marshes Model (SLAMM) was used to project the potential migration and habitat transformation in coastal marshes due to SLR in the year 2050. Furthermore, a counterfactual land cover approach, in which marshes are converted to open water in the model, was implemented for each storm scenario in the present and the future to estimate the amount of flooding that is avoided due to the presence of natural habitats and the subsequent reduction in residential property damage. The results indicate that this salt marshes can reduce up to 14% of both the flood depth and property damage during relatively low intensity storm events, demonstrating the efficacy of natural flood protection for recurrent storm events. Monetarily, this translates to the avoidance of up to $13.1 and $32.1 million in residential property damage in the selected coastal counties during the '50-year storm' simulation and hurricane Sandy under current sea level conditions, and in the year '2050 SLR scenario', respectively. This research suggests that protecting and preserving natural habitats can contribute to enhance coastal resilience.

Coastal wetlands mitigate storm flooding and associated costs in estuaries

“…Marsh mitigation of storm ooding has accompanying economic bene ts, reducing ood damage costs by an average of 37% for large storms across the estuaries within our study. Savings from ungrazed and grazed marsh vegetation scaled exponentially with storm intensity, with the relative marsh-driven cost savings considerably higher than the 1-16% savings previously predicted for similar signi cant tropical storms along open coastlines dominated by extensive fringing or back-barrier marshes 41,57,72 . The estimated absolute ood damage savings within estuaries are similar to those previously estimated for hurricane-exposed US coastlines 73,74 , and considerably greater than the value of other saltmarsh services such as carbon storage 75,76 or livestock grazing 77,78 .…”

“…Despite evidence of both localised and upstream, estuary-scale, dampening of waves and surge in isolation, there remains a lack of knowledge on how these multi-scale processes interact to holistically reduce ood risk and impacts throughout estuaries ( Supplementary Table S1) ( Figure 1). Accordingly, the contributions of saltmarshes to storm ood mitigation may be grossly underestimated and economically undervalued 56,57 .…”

The Case for a Critical Zone Science Approach to Research on Estuarine and Coastal Wetlands in the Anthropocene

“…For example, Ouyang et al (2018) describe the pivotal role that coastal wetlands play in mitigating the impacts of cyclones and hurricanes, more especially in the context of climate change, and estimate that the economic value of this approaches US$200 billion in China alone. Rezale et al (2020) demonstrate, for coastal wetlands in New Jersey, USA, that the appropriate management and maintenance of salt marsh vegetation can reduce flooding depths in storm events and significantly reduce property damage in the future, a conclusion also reached by, among others, Highfield et al (2018), Vásquez-González et al (2019) and Montgomery et al (2019). Yang et al (2018b) document the substantial trade-offs that must be accounted for when these systems are allowed to deteriorate and that coastal land reclamation-a process that has been rampant in Asia in general and in China in particular (Sengupta et al 2020)-is particularly deleterious.…”

Estuarine and Coastal Ecosystems as Defense Against Flood Damages: An Economic Perspective

“…More recently, some valuation studies of the protective value of estuarine and coastal ecosystems (ECEs) have developed the expected damage function approach as an alternative to the replacement cost method (Barbier, 2007;Barbier and Enchelmeyer, 2014;World Bank, 2016;Beck et al, 2018;Highfield et al, 2018;Menéndez et al, 2020;Rezaie et al, 2020). This method assumes that an ECE provides a nonmarketed service, such as "protection" of economic activity, property and even human lives, which benefits individuals through limiting damages.…”