Cliff Metric Development and Analysis
Seacliff erosion is a serious hazard with implications for coastal management, infrastructure, and residential dwellings; seacliff erosion is often estimated using successive hand digitized cliff tops or bases to assess cliff retreat. Traditionally the recession of the cliff top or cliff base is obtained from aerial photographs, topographic maps, or in situ surveys. The availability of high-resolution light detection and ranging (lidar) data and high-resolution digital elevation models (DEMs) has led to advancements in quantifying seacliff erosion, such as measuring the cliff face bulk retreat defined as volumetric change. Irrespective of how or what is measured to categorize cliff erosion, the position of the cliff top and cliff base is important. Traditionally, the cliff top and base is often digitized by hand, which is time consuming and depends on analyst interpretation.
The cliff metric development and analysis project aims to establish an automatic procedure to delineate the cliff top and base from high-resolution lidar bare-earth DEMs. Cliff analysis in the Del Mar, California, area focuses on automatically measuring the change in cliff face geometry (erosion, accretion, convexity, and concavity), change in volume (total volume, erosion, and accretion volume across profiles) and horizontal change in cliff top and toe locations.
A detailed, systematic assessment of past cliff geomorphic change can lead to more accurate predictions of future changes such as erosion and collapse, and aid the development of cliff retreat models designed to project the physical impacts of climate change along the coast. The ability to automate the monitoring of coastal change through cliff metric analysis has important benefits for resource planning and hazard mitigation.
Additional information regarding cliff metric development and analysis is available at https://agu.confex.com/agu/fm14/meetingapp.cgi#Paper/9279
Pacific Ocean cliffs were surveyed to collect precise cliff elevation information metrics. U.S. Geological Survey photographs by Monica Palaseanu-Lovejoy and Cindy Thatcher.
U.S. Geological Survey (USGS) scientists Jeff Danielson and Amy Foxgrover acquire precise cliff elevation metrics near the Pacific Ocean. USGS photographs by Monica Palaseanu-Lovejoy and Cindy Thatcher.
U.S. Geological Survey (USGS) scientists Jeffrey Danielson and Monica Palaseanu-Lovejoy prepare for GPS surveys of California cliffs along the Pacific Ocean. USGS photograph by Cindy Thatcher
Comparison of automated and digitized cliff top and base (toe) metrics in Del Mar, California, overlain on high-resolution lidar-derived digital elevation model. U.S. Geological Survey image by Monica Palaseanu-Lovejoy.