DROWNED FORESTS AND BURIED SALT MARSHES: RECONSTRUCTING LOCAL-RELATIVE SEA LEVEL CHANGE ALONG THE DELAWARE RIVER ESTUARY

As global temperatures rise, coastal communities and wetlands are at risk of inundation. Researchers have shown a global rate of sea level rise of 1.8mm/yr for the 20^th. This long-term rate subsumes the more recent, and far more rapid, rate of sea level rise measured from 1993 to 2008 at 3.11 +/- 0.6mm/yr. Additionally, the 100-year estimate reflects eustatic change only. However, because of changes in base level and sediment supply, the effects of sea level rise do not manifest evenly along coastlines. Therefore, it is important to assess changes on a site-by-site basis. In this study, we determine the local-relative rate of sea level change for the Delaware Estuary coastline between the bay mouth and the C&D Canal. Because low-gradient estuarine shorelines are sensitive to small changes in sea level, this region is particularly vulnerable to erosion and coastal retreat. Since historic tide gauge records do not exist for the study area, we use the dendrochronologic record from a downed cedar forest and C¹⁴ dates of basal Spartina alterniflora peat to establish two independent proxies for local-relative sea level rise. Understanding the historic response of a coastline to sea level rise permits policy makers and natural resource managers to better anticipate the effects of climate change on the estuary’s fragile wetland biomes and coastal developments.