The Virginia Institute of Marine Science (VIMS) in collaboration with its partners, the Land Trust Alliance, Sustainable Chesapeake, and The Nature Conservancy, explored and refined questions critical for advising and guiding landowners who farm within coastal areas that are vulnerable to sea level rise and saltwater intrusion, and ultimately, loss of arable cropland in the Chesapeake Bay watershed. While the questions posed are those that agricultural experts across the coastal zones are struggling with, this effort focused on identifying the current state of the science and informational gaps; building current, best professional guidance for landowner conservation program choices; and developing a research framework for improving our understanding and building capacity to maximize, incentivize, and secure ecosystem services beyond food provision at the farm-scape scale.
Critical to an understanding of the scope and scale of the challenge of sea level rise to agriculture is the need for a method to readily identify and assess those lands most at risk from both rising seas and salt water intrusion. On-the-ground stakeholders and partners including landowners and farmers have worked diligently to prioritize conservation delivery intended to offset these impacts including growing alternative agricultural crops that are better adapted to saltwater intrusion and implementing riparian buffers, ditch management, and to some extent, wetland restoration. The approach undertaken in this effort evaluated lands most vulnerable to sea level rise and saltwater intrusion at the county level, to provide information on the scale of potential impact as well as dominant soil types that will be affected.
The dynamics of sea level rise and saltwater intrusion create rapidly changing landscapes. In Somerset County, Maryland, 420 acres of marsh were lost and 1507 acres of uplands were converted to marsh from 2009 to 2017 (Gedan et al. 2020). In Accomack County, VA, between 1977 and 2016, 13,025 acres of marsh were lost due to erosion and sea level rise and 9,187 acres of new marsh were created through migration (CCRM 2019). Alongside these changes to land types, there can be significant implications for nutrient loads in rivers and streams adjacent to flooded farmlands. Researchers at the University of Maryland have been assessing the impacts of saltwater intrusion on nutrient runoff from agricultural fields, and this research indicates that saltwater intrusion is linked to increased nitrogen and phosphorus transport from farm fields to adjacent marshes (Weissman and Tully 2020).