| Abstract: |
Poplar Island is a national showcase for the incorporation of sea level rise into wetland restoration planning and design, as undertaken by the US Army Corps of Engineers (USACE). The Poplar Island Project serves as a test bed for collaborative development of appropriate methods, protocols, and services to support ecosystem restoration and monitoring in the face of sea level rise. It is a man-made island in the mid-Chesapeake Bay region which serves as the dredge disposal site for clean sediments from the Baltimore harbor approach channels. The site is managed by Maryland Environmental Services (MES), for the Maryland Port Administration (MPA) and the USACE-Baltimore District. Over 730 acres of wetlands are being built and further expansions to the island are planned. Permit agreements with the NOAA/National Marine Fisheries Service (NMFS) call for 80% of the wetlands to be classified as low marsh and 20% to be high marsh. Low marshes are inundated more regularly and for longer periods than high marshes and represent valuable fish habitats. Given the low tidal range of the Bay and the small elevation difference between low marshes and high marshes, this marsh construction project requires very accurate and precise elevation and water level data to ensure that it achieves the appropriate habitat ratios. To support this need for accurate water levels at the boundaries of the land/Bay interface during the restoration effort, a modeling study was conducted to quantify water lever variability over synoptic, seasonal, and decadal time scales and to evaluate changes in the circulation in the vicinity of the island as restoration efforts are being conducted. The computational tool of choice for this modeling effort was NOAA/National Ocean Service (NOS)’s new Chesapeake Bay Operational Forecast System (CBOFS2). In order to address the specific issues pertaining to Poplar Island, a finely resolved model that encompasses the environs of Poplar Island was seamlessly coupled to/nested within the larger CBOFS2 computational domain. A series of hindcast studies were conducted which included : (i) examination of the extent of inundation under a series of synoptic events, such as hurricanes and extra-tropical events, and high and low river discharge events employing the existing morphology of Poplar Island, (ii) a downscaling of the IPCC projections at the entrance to Chesapeake Bay to evaluate its impacts at Poplar Island and, (iii) quantifying of the impact of island accretion as the result of restoration activities on the circulation near the island. The results of these hindcasts will provide accurate water levels at the shoreline encompassing Poplar Island to support future inundation studies within its intertidal zone and marshes. |
