Impacts of Future Sea Level Rise on the Coastal Floodplain

Introduction

The State of Maine is planning for a 2-ft rise in sea level over the next 100-years for projects within the coastal sand dune system (Chapter 355, Coastal Sand Dune Rules, pdf format-73Kb). This is in response to documented and predicted rises in sea level for the global oceans and the Gulf of Maine, including data collected at the City of Portland tide gauge between 1912 and 2002, which documents an approximate 0.2 m (0.6 ft) rise in sea level, in addition to Intergovernmental Panel on Climate Change (IPCC, 2001) projections of 0.5 m of global average sea level rise by 2100. An estimated 2-ft rise in sea level will have dramatic impacts along Maine's coastlines in terms of sensitive geographic areas including beaches and dunes, wetlands, and nearshore habitats.

Figure 1

The purpose of this demonstration project was to model a static 2-foot rise in sea level for an area of the Rachel Carson National Wildlife Refuge that is covered by Light Detection and Ranging (LIDAR) data flown in 2004 for the NOAA Coastal Services Center (NOAA, 2004). The study area utilized for this demonstration project is shown in Figure 1. This area was selected for multiple reasons. It is a nationally designated refuge, yet the surrounding area supports a multitude of development intensities (including the highly developed Drakes Island), reserves (Wells National Estuarine Research Reserve at Laudholm Farm), Coastal Barrier Resource Areas, species habitats (salt marshes, state-designated piping plover and least tern nesting habitat), various FEMA Flood Zone Designations, and landform types (beach and dune, salt marsh, scrub-shrub lowland, forested upland).

The Maine Geological Survey (MGS) also simulated a static 1-ft and 3-ft rise in sea level for the study area, and evaluated potential impacts on marsh habitat and flooding.

Contents Introduction Methodology Results Discussion Findings and Recommendations Conclusions References

Last updated on April 21, 2006