Annual to decadal morphodynamics of the foredune system at Greenwich Dunes, Prince Edward Island, Canada Jeff Ollerhead, 1 * Robin Davidson-Arnott, 2 Ian J. Walker 3 and Sojan Mathew 4 1 Department of Geography and Environment, Mount Allison University, Sackville, NB, Canada, E4L 1E4 2 Department of Geography, University of Guelph, Guelph, ON, Canada, N1G 2 W1 3 Department of Geography, University of Victoria, Victoria, BC, Canada, V8W 3P5 4 Bureau of Economic Geology, The University of Texas at Austin, Austin, TX, USA, 78712 Received 17 November 2011; Revised 8 August 2012; Accepted 30 August 2012 *Correspondence to: Jeff Ollerhead, Department of Geography and Environment, Mount Allison University, Sackville, NB, Canada, E4L 1E4. E-mail: jollerhead@mta.ca ABSTRACT: The purpose of this study was to quantify relationships between season, sediment availability, sediment transport pathways, and beach/foredune morphology at Greenwich Dunes, PEI. This was done for periods ranging from a few days to multiple decades using erosion pins, bedframe measurements, annual surveys, and digital photogrammetry using historical aerial photographs. The relative significance of seasonal/annual processes versus response of the foredune system to broader geomorphic controls (e.g. relative sea level rise, storms, etc.) was also assessed. The data show that there are clear seasonal differences in the patterns of sand supply from the beach to the foredune at Greenwich and that there are differences in sediment supply to the foredune between the east and west reaches of the study area, resulting in ongoing differences in foredune morphology. They also demonstrate that models that incorporate wind climate alone, or even models that include other factors like beach moisture, would not be able to predict the amount of sediment movement from the beach to the foredune in this environment unless there were some way to parameterize system morphology, especially the presence or absence of a dune ramp. Finally, the data suggest that the foredune can migrate landward while maintaining its form via transfers of sediment from the stoss slope, over the crest, and onto the lee slope. Although the rate of foredune development or recovery after disturbance changes over time due to morphological feedback, the overall decadal evolution of the foredune system at Greenwich is consistent with, and supports, the Davidson-Arnott (2005) conceptual model of dune transgression under rising sea level. Copyright © 2012 John Wiley & Sons, Ltd. KEYWORDS: dune evolution; morphodynamic; dune ramp; foredune erosion Introduction Foredune systems constitute a significant coastal landform both geomorphically and ecologically. They are also valued for their recreational amenities and, increasingly over the past few decades, for the role they can play in protecting human infrastructure near the coast from the impact of large waves, storm surge, and salt water intrusion (Bochev-van der Burgh et al., 2011). Foredune dynamics can be studied within the framework of beach/dune interaction (Psuty, 1988; Sherman and Bauer, 1993; Hesp, 2002; Houser and Ellis, 2012). This framework incorporates recognition of the cycle of sediment exchange between the foredune system and the beach and nearshore systems, as well as the role played by the beach and the littoral sediment budget in influencing both the rate of sand supply to the foredune system and in moderating the effects of erosion by large waves and storm surge (Saye et al., 2005). Processes controlling beach/dune interaction and dune evolution can be examined at a range of spatial and temporal scales (Sherman and Bauer, 1993; Roy et al., 1994; Houser and Ellis, 2012). In the short-term (temporal scale of seconds to a few days and spatial scale of tens of metres) considerable progress has been made in both measuring (Svasek and Terwindt, 1974; Leatherman, 1976; Hesp, 1983; Sarre, 1989; Wal and Mcmanus, 1993; Arens, 1994; Davidson-Arnott et al., 2005; Anthony et al., 2006; Houser et al., 2008; Bauer et al., 2009) and modelling (Kriebel and Dean, 1985; Arens et al., 1995; Bauer and Davidson-Arnott, 2003; Roelvink et al., 2009; Jackson et al., 2011) the factors that control erosion and accretion of dunes. There have also been a number of investigations (Orford et al., 2000; Arbogast et al., 2002; Aagaard et al., 2007; Martinho et al., 2008; Clemmensen et al., 2009; Anthony et al., 2010; Reimann et al., 2011) of the evolution of coastal dunes and dune fields on a long time-scale (temporal scale of centuries to millennia, spatial scale of kilometres to tens of kilometres). The focus of this paper is on measurement of beach/dune interaction on a medium scale (time-scale of months to multi- decadal and spatial scale of hundreds of metres to kilometres) at Greenwich Dunes, Prince Edward Island, Canada. At this scale there have been a number of studies that have mapped foredune EARTH SURFACE PROCESSES AND LANDFORMS Earth Surf. Process. Landforms 38, 284–298 (2013) Copyright © 2012 John Wiley & Sons, Ltd. Published online 16 October 2012 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/esp.3327