New techniques for measuring cliff change from historical photographs

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U.S. Geological Survey scientists and their coauthors from the California Coastal Records Project have found a way to use historical aerial photographs to accurately measure coastal erosion. Applying a low-cost technique called “structure-from-motion” to five sets of oblique aerial photos spanning the years 2002 to 2010, the scientists measured the volume of material eroded from coastal cliffs at Fort Funston, on the westernmost edge of San Francisco. Their results were published October 21, 2016 in the Journal of Coastal Research. Quantifying coastal change is essential for calculating trends in erosion, evaluating processes that shape coastal landscapes, and predicting how the coast will respond to future storms and sea-level rise, all critical for communities along the California coast.

To learn more, read the Sound Waves newsletter article. Also, watch Jon's interview which aired on CBS SF Bay Area, October 28th.

 

A man sits at a desk in front of a computer monitor and keyboard, pointing to the image and talking.

USGS research geologist Jon Warrick explains the process of structure-from-motion data acquisition from photographs. Photo credit: Amy West, USGS Pacific Coastal and Marine Science Center

A man sits at a desk in front of a computer monitor and keyboard, pointing to the image and talking.

Warrick explains a “difference map” constructed from structure-from-motion data. Red areas indicate loss of material (erosion); blue areas show addition of material (deposition). Photo credit: Amy West, USGS Pacific Coastal and Marine Science Center

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Date published: December 30, 2016

New Maps from Old Photos: Measuring Coastal Erosion in California

USGS scientists and their coauthors from the California Coastal Records Project have found a way to use historical aerial photographs not just to see evidence of coastal erosion, but to accurately measure how much has occurred over time.