Impacts of Sea-Level Rise, Accretion, and Subsidence on Recent Changes in Elevation of the Sprague Marsh in Phippsburg, Maine.

This project uses sediment elevation tables (SET) and feldspar horizons to assess the recent changes in the elevation at Sprague Marsh. Previous SET data was compiled from the results recorded by different researchers at Bates College. Basic surveying methods were used to observe the elevations of each SET relative to the entire marsh. The elevation (deposition), accretion (burial), and subsidence rates, which reflect the change from 2014-2020. Sediment elevation tables allow us to calculate these rates and observe the changes in elevation on a smaller scale. The deposition rates at SETs 1, 2, 3, and 4 are 0, 1.61, 3.27, and 3.22 mm/yr, respectively. The burial rates of SETs 1-4 are 1.94, 2.17, 2.61, and 4.72, and the resulting subsidence rates are 1.94, 0.55, -0.66, and 1.50 mm/yr, respectively. Current sea-level rates in Maine, combined with the human impacts on Sprague Marsh, can be used to determine the marsh’s overall vulnerability. The loss of salt marshes in Maine would be devastating due to the marsh’s significance to the coastal ecosystem in the way they provide habits and food for organisms and sequester carbon. Therefore, solutions that protect and conserve marshes are vital before sea-level impacts are irreversible