Coastal Vulnerability Amidst Climate Change: The Dual Effects of Altered Biogeomorphology and Variable Seas on Pacific Coast Dunes

EPA Grant Number: F13B20274
Title: Coastal Vulnerability Amidst Climate Change: The Dual Effects of Altered Biogeomorphology and Variable Seas on Pacific Coast Dunes
Investigators: Biel, Reuben Gabriel
Institution: Oregon State University
EPA Project Officer: Lee, Sonja
Project Period: September 16, 2014 through September 16, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Ecology

Objective:

To better approach this overarching question, this project will (1) determine the relationship between climate, sand characteristics, vegetation and dune shape (i.e., height, width) in Pacific Northwest coastal sand dunes; (2) model how future climate conditions in the Pacific Northwest may modify coastal dune shape; and (3) project how altered dune shape, sea level rise and possible variations in storminess will affect coastal vulnerability to flooding and erosion.

Approach:

To explore the relationship between climate, sand, vegetation and dune shape, sand dune vegetation density and topography were measured at 124 locations throughout Oregon and southern Washington in 2012 and in 2014. To better determine the influence of temperature on beachgrass abundance and morphology, this project comprises a year-long warming experiment at Hatfield Marine Science Center (Newport, Oregon) to measure growth and competition between the two dominant, invasive beachgrasses, Ammophila arenaria and Ammophila breviligulata. These data will be used to model how dune shape and dune grass distributions and abundances may be altered under changing temperatures in the Pacific Northwest. XBEACH and other coastal hazard models will be used to assess how projected foredune shape, sea level rise and variations in storminess may affect future coastal vulnerability to flooding and erosion.

Expected Results:

Dune shape varies along the coast. In southern Washington, dunes are typically shorter and wider and are dominated by A. breviligulata, while Oregon dunes are often taller and narrower and dominated by A. arenaria. It is likely that the differences in both beachgrass distributions and differences in regional sand supply predominantly control dune shape, but the underlying cause for the differences in beachgrass distribution remain unknown. Nevertheless, A. arenaria dunes, due to their taller stature, may provide greater protection against dune scarping and shoreline recession during major storms. Even so, rising temperatures, stronger storms and sea level rise may present a significant threat to coastal areas, either indirectly by altering beachgrass distribution or abundance or directly by causing increased erosion and flooding.

Potential to Further Environmental/Human Health Protection

Dune shape varies along the coast. In southern Washington, dunes are typically shorter and wider and are dominated by A. breviligulata, while Oregon dunes are often taller and narrower and dominated by A. arenaria. It is likely that the differences in both beachgrass distributions and differences in regional sand supply predominantly control dune shape, but the underlying cause for the differences in beachgrass distribution remain unknown. Nevertheless, A. arenaria dunes, due to their taller stature, may provide greater protection against dune scarping and shoreline recession during major storms. Even so, rising temperatures, stronger storms and sea level rise may present a significant threat to coastal areas, either indirectly by altering beachgrass distribution or abundance or directly by causing increased erosion and flooding.

Supplemental Keywords:

climate change, coastal protection, sand dunes

Progress and Final Reports:

  • 2015
  • Final