Ian J Walker
I am a geomorphologist with expertise in sediment transport and erosion processes. I specialize in aeolian (windblown) and coastal systems, beaches and sand dunes, flow dynamics over complex terrain, coastal erosion, assessing climatic or land use change impacts in the coastal zone, and restoration of coastal dunes. I also study relative sea level changes and Holocene landscape evolution. My research involves a combination of field experiments to quantify sediment transport and erosion, high-resolution land surveying with terrestrial laser scanning (TLS) and unmanned aerial systems (UAS), and spatial stats for geomorphic change detection. I am currently a Professor at Arizona State University in the Schools of Geographic Sciences & Urban Planning and Earth & Space Exploration.
Address: School of Geographical Sciences & Urban Planning and
School of Earth & Space Exploration
5th floor, Coor Hall, Arizona State University
P.O. Box 875302, Tempe, AZ 85287-5302
Address: School of Geographical Sciences & Urban Planning and
School of Earth & Space Exploration
5th floor, Coor Hall, Arizona State University
P.O. Box 875302, Tempe, AZ 85287-5302
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During the 2015-16 El Niño season, elevated water levels and storm waves eroded the foredune and lowered the beach surface by ~ 1m. Erosion was greatest in the middle of the beach with dune scarping of over 2m where wave energy was focused. Minor accretion occurred during the summer of 2016 on the upper beach, and ramp rebuilding was observed mostly from slumping and avalanching of existing dune sands. The following winter 2017 storm season led to minor erosion on the beach and extensive incipient dune development and sand ramp recovery fronting the foredune to an extent close to pre-El Niño elevations.
Comparison of change surfaces between methods revealed limitations in the SfM method, namely due to vegetation effects on DTM generation, which limit its ability to detect change in the coastal environment. The costs, time, logistics, and accuracy for both SfM and TLS survey methodologies for coastal geomorphic change detection analysis is also evaluated. Combined, the UAS and SfM workflow provides a competitive solution to more expensive and time-consuming survey methods, such as TLS and aerial LiDAR, but its utility and accuracy is highly dependent on research objectives and post-processing techniques.