| 02 Apr 2026
Valuing Salt Marshes as Nature-based Infrastructure for Coastal Flood Mitigation: A Case Study of Chatham County, GA
Abstract. Flooding poses significant economic challenges to coastal counties, affecting nearly 40 % of the U.S. population. Nature-based solutions, also known as green infrastructure, are increasingly recognized as effective alternatives or complements to traditional gray infrastructure for flood risk mitigation. This study examines the flood damage reduction benefits of salt marshes, a key type of green infrastructure. We use physics-based spatially explicit hydrodynamic models to simulate storm scenarios and the resulting inundation depths with and without salt marshes. We then translate hydrological data into economic benefits by applying two distinct approaches, one based on the traditional US Army Corps of Engineers depth-damage function and another with an estimated depth-damage function derived from the National Flood Insurance Program (NFIP) claims data. Applying our integrated approach to the case study area, Chatham County in Georgia, we find that salt marshes contribute to significant damage reductions, ranging from $ 30 million to $ 40 million for a storm representative of the 1 % annual exceedance probability event. This study offers policymakers valuable insights into implementing flood mitigation strategies through marshland conservation. Our integrated modeling framework is readily adaptable to coastal regions worldwide where salt marshes or similar coastal ecosystems provide flood-mitigation services.
The manuscript under consideration for publication addresses the capacity of salt marsh vegetation to reduce coastal flood damages to buildings at Chatham County, Georgia, USA. The study used an existing hydrodynamic model in combination with depth damage functions to estimate flood damages and corresponding reductions provided by current salt marsh cover. Finally, spatial distribution of these benefits are studied using a GIS overlay with socioeconomic data.
The novelty is in the expansion of the damage function based on National Flood Insurance Program (NFIP) starting from the work by Wing et al. (2020). Specifically, fitting a non-linear function and including residential homes up to three stories with and without basement. I found the research gap poorly described and making a too large claim, as combining hydrodynamic modelling with depth-damage function is to-date a standard procedure and is even applied at the global scale (e.g. Tiggeloven et al. (2022), and local scale (e.g. Philippines by Menendez et al. (2018)). In addition, the hydrodynamic model which is presented as state-of-the-art is omitting critical physical processes to accurately predict coastal inundation especially in vicinity of coastal wetlands. Finally, the level of validation of the integrated framework is lacking and is in my opinion a critical component in the analysis. In this review I highlight a number of attention points that could be implemented as part of a major revision, but would require substantial alternation of the approach and/or structure of the manuscript. A detailed review is provided in the attachment.