Andy Ritchie
Science and Products
Exploring the USGS Science Data Life Cycle in the Cloud
Executive Summary Traditionally in the USGS, data is processed and analyzed on local researcher computers, then moved to centralized, remote computers for preservation and publishing (ScienceBase, Pubs Warehouse). This approach requires each researcher to have the necessary hardware and software for processing and analysis, and also to bring all external data required for the workflow over the...
Accurate bathymetric maps from underwater digital imagery without ground control
Structure-from-Motion (SfM) photogrammetry can be used with digital underwater photographs to generate high-resolution bathymetry and orthomosaics with millimeter-to-centimeter scale resolution at relatively low cost. Although these products are useful for assessing species diversity and health, they have additional utility for quantifying benthic...
Hatcher, Gerry; Warrick, Jonathan; Ritchie, Andrew C.; Dailey, Evan; Zawada, David G.; Kranenburg, Christine; Yates, Kimberly K. World’s largest dam removal reverses coastal erosion
Coastal erosion outpaces land generation along many of the world’s deltas and a significant percentage of shorelines, and human-caused alterations to coastal sediment budgets can be important drivers of this erosion. For sediment-starved and erosion-prone coasts, large-scale enhancement of sediment supply may be an important, but poorly understood...
Warrick, Jonathan; Stevens, Andrew W.; Miller, Ian M.; Harrison, Shawn R; Ritchie, Andrew C.; Gelfenbaum, Guy R. Characterizing the catastrophic 2017 Mud Creek Landslide, California, using repeat Structure-from-Motion (SfM) photogrammetry
Along the rugged coast of Big Sur, California, the Mud Creek landslide failed catastrophically on May 20, 2017 and destroyed over 400 m of scenic California State Highway 1. We collected structure-from-motion (SfM) photogrammetry data using airborne platforms that, when combined with existing airborne lidar data, revealed that the area exhibited...
Warrick, Jonathan; Ritchie, Andrew C.; Reid, Mark E.; Schmidt, Kevin; Logan, Joshua B. Morphodynamic evolution following sediment release from the world’s largest dam removal
Sediment pulses can cause widespread, complex changes to rivers and coastal regions. Quantifying landscape response to sediment-supply changes is a long-standing problem in geomorphology, but the unanticipated nature of most sediment pulses rarely allows for detailed measurement of associated landscape processes and evolution. The intentional...
Ritchie, Andrew C.; Warrick, Jonathan; East, Amy E.; Magirl, Christopher S.; Stevens, Andrew W.; Bountry, Jennifer A.; Randle, Timothy J.; Curran, Christopher A.; Hilldale, Robert C.; Duda, Jeffrey J.; Miller, Ian M.; Pess, George R.; Eidam, Emily; Foley, Melissa M.; McCoy, Randall; Ogston, Andrea S. Geomorphic evolution of a gravel‐bed river under sediment‐starved vs. sediment‐rich conditions: River response to the world's largest dam removal
Understanding river response to sediment pulses is a fundamental problem in geomorphic process studies, with myriad implications for river management. However, because large sediment pulses are rare and usually unanticipated, they are seldom studied at field scale. We examine fluvial response to a massive (~20 Mt) sediment pulse released by...
East, Amy E.; Logan, Joshua B.; Mastin, Mark C.; Ritchie, Andrew C.; Bountry, Jennifer A.; Magirl, Christopher S.; Sankey, Joel B. A regime shift in sediment export from a coastal watershed during a record wet winter, California: Implications for landscape response to hydroclimatic extremes
Small, steep watersheds are prolific sediment sources from which sediment flux is highly sensitive to climatic changes. Storm intensity and frequency are widely expected to increase during the 21st century, and so assessing the response of small, steep watersheds to extreme rainfall is essential to understanding landscape response to climate...
East, Amy E.; Stevens, Andrew W.; Ritchie, Andrew C.; Barnard, Patrick L.; Campbell‐Swarzenski, Pamela L.; Collins, Brian D.; Conaway, Christopher H. Ecological parameters in the Elwha River estuary before and during dam removal
The Elwha and Glines Canyon dams were removed from the Elwha River in Washington State from 2011 to 2014. We collected data for a variety of metrics in the estuary and on the river delta before (2006-2011) and during (2012-2014) dam removal to assess how increased sediment transport and deposition affected habitats, vegetation, invertebrates, and...
Foley, Melissa M.; Shafroth, Patrick B.; Beirne, Matthew M.; Paradis, Rebecca; Ritchie, Andrew C.
California State Waters Map Series—Offshore of Pigeon Point, California
Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly...
Cochrane, Guy R.; Cochran, Susan A.; Cochrane, Guy R.; Watt, Janet T.; Dartnell, Peter; Greene, H. Gary; Erdey, Mercedes D.; Dieter, Bryan E.; Golden, Nadine E.; Johnson, Samuel Y.; Endris, Charles A.; Hartwell, Stephen R.; Kvitek, Rikk G.; Davenport, Clifton W.; Krigsman, Lisa M.; Ritchie, Andrew C.; Sliter, Ray W.; Finlayson, David P.; Maier, Katherine L.
California State Waters map series—Offshore of Scott Creek, California
Introduction In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly...
Cochrane, Guy R.; Cochran, Susan A.; Cochrane, Guy R.; Dartnell, Peter; Johnson, Samuel Y.; Greene, H. Gary; Erdey, Mercedes D.; Dieter, Bryan E.; Golden, Nadine E.; Endris, Charles A.; Hartwell, Stephen R.; Kvitek, Rikk G.; Davenport, Clifton W.; Watt, Janet T.; Krigsman, Lisa M.; Ritchie, Andrew C.; Sliter, Ray W.; Finlayson, David P.; Maier, Katherine L.
Southern Salish Sea Habitat Map Series: Admiralty Inlet
In 2010 the Environmental Protection Agency, Region 10 initiated the Puget Sound Scientific Studies and Technical Investigations Assistance Program, designed to support research in support of implementing the Puget Sound Action Agenda. The Action Agenda was created in response to Puget Sound having been designated as one of 28 estuaries of...
Cochrane, Guy R.; Cochrane, Guy R.; Dethier, Megan N.; Hodson, Timothy O.; Kull, Kristine K.; Golden, Nadine E.; Ritchie, Andrew C.; Moegling, Crescent; Pacunski, Robert E. Large-scale dam removal on the Elwha River, Washington, USA: source-to-sink sediment budget and synthesis
Understanding landscape responses to sediment supply changes constitutes a fundamental part of many problems in geomorphology, but opportunities to study such processes at field scales are rare. The phased removal of two large dams on the Elwha River, Washington, exposed 21 ± 3 million m3, or ~ 30 million ...
Warrick, Jonathan A.; Bountry, Jennifer A.; East, Amy E.; Magirl, Christopher S.; Randle, Timothy J.; Gelfenbaum, Guy R.; Ritchie, Andrew C.; Pess, George R.; Leung, Vivian; Duda, Jeff J. Sedimentology of new fluvial deposits on the Elwha River, Washington, USA, formed during large-scale dam removal
Removal of two dams 32 m and 64 m high on the Elwha River, Washington, USA, provided the first opportunity to examine river response to a dam removal and controlled sediment influx on such a large scale. Although many recent river-restoration efforts have included dam removal, large dam removals have been rare enough that their physical and...
Draut, Amy; Ritchie, Andrew C.
Moving Mountains: Elwha River Still Changing Five Years After World’s Largest Dam-Removal Project: More than 20 million tons of sediment flushed to the sea
Starting in 2011, the National Park Service removed two obsolete dams from the Elwha River in Olympic National Park, Washington. It was the world’s largest dam-removal project. Over the next five years, water carrying newly freed rocks, sand, silt and old tree trunks reshaped more than 13 miles of river and built a larger delta into the Pacific Ocean.
Time-lapse view of California Highway 1 reconstruction after 2017 landslide
USGS scientists produced an animated GIF in coordination with the California Department of Transportation (Caltrans) re-opening of State Highway 1 through Big Sur on July 18, 2018.
USGS Monitors Huge Landslides on California's Big Sur Coast, Shares Information with California Department of Transportation
On May 20, 2017, more than 2 million cubic meters of rock and dirt—enough to fill a line of dump trucks nearly a thousand miles long—collapsed down the steep slopes at Mud Creek on California’s Big Sur coast, about 140 miles south of San Francisco. A pile of rubble almost a third of a mile wide buried California State Highway 1 over 65 feet deep and added about 13 acres of new land to the...