Tidal wetlands face serious threats from rapid environmental changes. They are challenged by accelerated rates of rising water levels and increased storm surge associated with climate change. In response, these habitats have adapted a survival mechanism called marsh migration.

Marsh migration is the act of tidal wetlands moving from their current locations, away from rising sea levels, towards higher and drier land to avoid drowning. The ground that wetlands migrated from is eventually flooded and becomes open water.

Marsh migration is a natural way for wetlands to ensure their own survival into the future.

Marsh Migration Suitability Analysis

DNREC completed a mapping study in 2023 to model and predict the most suitable areas for tidal wetlands to migrate into. This model is built from many different mapping layers including existing wetlands, soils, land use/land cover (LULC), slope, elevation and sea level rise estimates. Once all the information was combined, areas for marsh migration were scored ranging from 0 (unsuitable) to 12 (highly suitable).

The results focus on areas that scored from 10 to 12 that are highly suitable locations for marshes to move to. The model identified 21,449 acres of highly suitable lands along existing tidal wetlands under a 4-foot sea level rise scenario.

Overall, the model is meant to be a guidance tool for professionals and landowners. The highly suitable acres represent the best of all suitable habitat statewide, to narrow our focus to priority areas. Most of the highly suitable migration pathways are predicted in Kent and Sussex County.

Importance of Marsh Migration

Tidal wetlands provide a variety of ecosystem services to humans and the natural world alike. Their persistence means continued benefits such as erosion control, habitat preservation, carbon storage, storm protection and water quality improvement.

This landward movement can only happen where there are no natural or human-made physical barriers in the way, such as seawalls or roadways.

Knowing where these habitats could migrate to is critical for land management and property owners, as well as to ensure that wetlands have a future along our coasts.

Project Goals

DNREC is using this model to aid in better land management decisions and resiliency planning for many different stakeholders and groups. The overall project goals were to:

• Update and run a simplistic model in ArcGIS Pro combining many layers, SLR scenarios
• Identify areas with highest potential for future salt marsh migration
• Determine prime land use and ownership types involved
• Report results from a habitat conservation and an infrastructure resilience perspective
• Share results with targeted audiences to help inform land management decisions and develop actions for protection and preparation
• Educate landowners and connect them with helpful resources

Related Topics:  climate change, habitat, marsh migration, marshes, sea level rise, sustainability, tidal wetlands, watershed stewardship, wetlands