Research Associate



Office: LSP232B


B.S. Florida Institute of Technology, Physical Oceanography.
Ph.D. Scripps Institution of Oceanography, Applied Ocean Science.
Post-Doc. Naval Postgraduate School, Nearshore Morphodynamics


Research Interests

I am a Nearshore Physical Oceanographer, which means that I study the physics of the nearshore environment. The nearshore includes the dry beach and the adjacent dunes as well as the surf zone, where waves are breaking, currents are strong and sand is transported by those waves and currents (this generally includes the seafloor out to about 8 meters water depth). I recently obtained funding to continue two research projects (summer, 2010).

The first project, funded by the National Science Foundation, is to examine the variability of sand grain size both in space and in time on beaches. I have developed a hand held digital camera, which I use to estimate sand grain from macro images of sand. Using this camera system, detailed maps of grain size on a beach can be obtained (Gallagher et al. submitted 2011).  These detailed maps of grain size will be used to initialize and test state-of-the-art computer models (in collaboration with Ad Reniers at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science) to determine the importance of varying grain size on our ability to predict erosion, deposition and other dynamic changes on beaches.

The second project, funded by the Office of Naval Research, will examine the dynamics of megaripples, bedforms with heights of about 20cm and lengths of a few meters that are common in the nearshore environment. These features act as roughness elements (bumps on the seafloor), thus affecting wave and current energy dissipation and sediment transport (they cause suspension and they migrate). I have developed a computer model that simulates megaripples based on simple rules and self-organization principles. This model will be extended to bedforms that exist in tidal inlets, where flows from waves and quasi-stationary tidal currents are both important.

Both of my projects involve field work (going to beaches, making measurements, working with colleagues, etc.) as well as computer time (data analysis, model adaptation and implementation, writing code, etc.). Any student interested in geomorphology, morphodynamics, nearshore processes, data analysis, self-organization, computer simulations of natural phenomena, etc. should come and talk to me about interesting and fun multidisciplinary research projects.


Recent Publications

Gallagher, Edith L. (2011) Computer Simulations of Self-Organized Megaripples in the NearshoreJournal of Geophysical Research, Earth Surface, 116, F01004, doi:10.1029/2009JF001473.

Gallagher, Edith L., Jamie MacMahan, Ad Reniers. Spatial and temporal variations in grain size on beaches, estimated from digital images. Submitted to Marine Geology, Oct 2010.

MacMahan, James, J. A. Brown, J. W. Brown, E. B. Thornton, A. J. H. M. Reniers, T. P. Stanton, M. Henriquez, E. L. Gallagher, J. Morrison, Martin Austin, Tim Scott, Nadia Senechal (2010) Mean lagrangian flow behavior on open coast rip-channel beaches: a new perspective, Marine Geology, 268, 1-10.