PALEO-LANDSCAPE RECONSTRUCTION AND FUTURE PREDICTIONS OF IMPACT OF SLR AND STORM SURGES IN DELAWARE BAY, USA

Delaware Bay is one of the largest estuaries along the eastern coast of North America. The coastal geomorphology is controlled by modern processes and the ancestral landscape. The estuary has been evolving since the early Holocene and continues to present due to relative sea level rise (SLR). The Delaware Bay region has been occupied by humans since thePaleoindian period (~ 12,000-8,000 BP). It is characterized as one of the most culturally diverse in colonial America and now is the location of several vibrant coastal communities. Accelerated sea-level rise and frequent storms are threatening the Delaware Bay coastal ecosystems, cultural resources, and living communities.

We used salt-marsh sediments as proxies for sea-level reconstructions and stratigraphic relationships to reconstruct paleo-landscapes. Paleo-environmental reconstructions document the coastal system response to natural changes and are critical to discover, document, and conserve buried archaeological sites as well as above ground historical resources.

We applied probabilistic SLR projections to identify coastal landscapes at high risk for inundation by the years 2030, 2050, 2080, and 2100, and the SLOSH model to predict the impacts of storm surges. Storms-surge simulations using parameters from 20 hurricanes that impacted the Delaware Bay region from 1992-2021 predicted a gradual increase in modeled storm surges over time for each SLR scenario. We have also identified coastal landscapes vulnerable to erosion and coastal flooding, including upstream locations along coastal tributaries.

Coastal sites without a protective dune system, should be considered at immediate risk from coastal flooding. A shoreline protected by dunes are most likely to be over washed during storms. Shoreline erosion, and more frequent storms combined with SLR will increase vulnerability of many coastal areas in the future. Since all endangered locations cannot be protected, our results should be of particular interest to stake holders, natural and historic preservation planners, and cultural resources managers to develop the most effective protective policies and preservation strategies.