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- Title
Effects of Marsh Migration on Flooding, Saltwater Intrusion, and Crop Yield in Coastal Agricultural Land Subject to Storm Surge Inundation.
- Authors
Guimond, Julia A.; Michael, Holly A.
- Abstract
Low‐lying coastlines are vulnerable to sea‐level rise and storm surge salinization, threatening the sustainability of coastal farmland. Most crops are intolerant of salinity, and minimization of saltwater intrusion is critical to crop preservation. Coastal wetlands provide numerous ecosystem services, including attenuation of storm surges. However, most research studying coastal protection by marshes neglects consideration of subsurface salinization. Here, we use two‐dimensional, variable‐density, coupled surface‐subsurface hydrological models to explore how coastal wetlands affect surface and subsurface salinization due to storm surges. We evaluate how marsh width, surge height, and upland slope impact the magnitude of saltwater intrusion and the effect of marsh migration into farmland on crop yield. Results suggest that along topographically low coastlines subject to storm surges, marsh migration into agricultural fields prolongs the use of fields landward of the marsh while also protecting groundwater quality. Under a storm surge height of 3.0 m above mean sea level or higher and terrestrial slope of 0.1%, marsh migration of 200 and 400 m protects agricultural yield landward of the marsh‐farmland interface compared to scenarios without migration, despite the loss of arable land. Economic calculations show that the maintained yields with 200 m of marsh migration may benefit farmers financially. However, yields are not maintained with migration widths over 400 m or surge height under 3.0 m above mean sea level. Results highlight the environmental and economic benefits of marsh migration and the need for more robust compensation programs for landowners incorporating coastal wetland development as a management strategy. Plain Language Summary: Coastal wetlands are frequently the barrier between low‐lying agricultural land and the ocean and thus are the lifeline for salt‐intolerant crops, particularly during storm events when seas surge and rise several meters above normal conditions. However, sea level rise and erosion at the ocean's edge are causing marshes to shrink in size, particularly when marshes are not allowed to migrate landward—a critical mechanism through which marshes sustain land area in the face of global climate change. In this study, we use numerical models designed to represent a generalized marsh and agricultural field to explore how marsh migration into adjacent agricultural land impacts saltwater flooding and crop yield during storm events. Our work shows that along low‐lying coastlines that experience large storm events, marsh migration into agricultural land can protect crop yield compared to scenarios without marsh migration, while also limiting saltwater contamination of the groundwater. However, along steeper coastlines and with smaller storm events, marsh migration does not benefit the farmer through maintained crop yield. Results suggest that marsh migration is an effective management strategy along topographically low coastlines subject to frequent storm surges and may financially benefit farmers in the short term and long term. Key Points: Marshes reduce storm‐surge induced surface and subsurface saltwater intrusionReduced flood extent by marsh migration protects upland crop yieldMarsh migration may provide financial benefits to farmers
- Subjects
SALTWATER encroachment; STORM surges; CROP yields; FARMS; MARSHES; SEA level; COASTAL wetlands
- Publication
Water Resources Research, 2021, Vol 57, Issue 2, p1
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1029/2020WR028326