Remote sensing of the impact of accelerated local sea level rise on wetlands

Abstract

The substantial relative sea level rise and more frequent storms predicted for the next 50 years, will impact coastal wetlands, beach erosion control strategies, salinity of estuaries and aquifers, coastal drainage systems, and coastal economic development. Coastal wetlands, including tidal salt marshes, tidal freshwater marshes and mangrove swamps, are generally within fractions of a meter of sea level, and could be lost, especially if the impact of relative sea level rise is amplified by coastal storms. To plan for wetland protection and sensible coastal development, scientists and managers need to monitor the changes in coastal wetlands as the sea level continues to rise. The primary objective of our study is to analyze changes at a unique Delaware Bay tidal wetland site, which faces an accelerated sea level rise due to a canal breach and to show how remote sensors and related techniques can be used for studying the impact of relative sea level rise (RSLR) and human activities on coastal wetlands. A secondary objective is to evaluate several RSLR models by trying to predict future changes at this test site. Preliminary results indicate that rapid changes of vegetation, hydrology, sediment accretion and erosion are taking place at the Milford Neck Conservation Area test site and that satellite and aircraft remote sensors, supported by a reasonable number of site visits, are highly suitable for mapping and studying these changes. The improved understanding of the processes occurring at this site will help wetland managers decide whether to intervene in the hydraulic regime by channel modification in order to accelerate or delay marsh development in a particular direction.