Landscape Response to Disturbance
Science Center Objects
This project characterizes and measures sediment-related effects of landscape disturbances (such as major storms, drought, or wildfire) and river management. We focus primarily on the U.S. west coast, and our work relates to natural hazards and resource management.
USGS scientists examining landslides in the Tuolumne watershed, California, caused by an extreme rain event in 2018. Photo credit: Ian Buckley
Climate models project that in the future the western U.S. will experience more extreme rain events, greater wildfire activity, and more pronounced swings between extreme drought and extreme wet conditions. These changes could result in landscapes shedding more sediment from hillslopes and transporting it along rivers to the coast. At the same time, removal of aging dams is becoming common in the U.S.; dam removal (and some other human activities) releases sediment downstream, changing the river and coastal environments. Our research is guided by the questions: How does the scale of landscape response (such as the amount of sediment generated) correspond to the scale of disturbance (the amount of storm rainfall)? What controls lag times in landscape response signals—how long after a disturbance do its effects appear downstream, and how long do they last? How do superimposed disturbances, such as fire and subsequent storms, or a dam removal followed by extreme rain, combine to drive landscape evolution? How will variations in landscape sediment output affect the amount of sediment reaching the coast, and how might that affect the shape and evolution of beaches?
In the aftermath of the 2018 Carr Fire, northern California, sediment has eroded from burned hillslopes and accumulated in some areas of Whiskeytown Lake. A recent sediment deposit is shown here in the Whiskey Creek section of the lake. USGS scientists study landscape evolution after fires and storm rainfall to determine how intensively these disturbances impact affected areas and for how long. Photo credit: Amy East, USGS
Currently active tasks:
- Dam removal. Our team studies river and coastal response to sediment released by large dam removals, in collaboration with other federal, state, tribal, and academic researchers. Research efforts include long-term studies of the Elwha River, Washington (largest dam removal worldwide), the Carmel River (largest dam removal in California), and Klamath estuary (four pending dam removals in California and Oregon).
- Landscape response to extreme rainfall. Extreme rain can cause major landslides and flooding, greatly increasing the amount of sediment moving along rivers to the coast. We study effects of extreme rain in, for example, the San Lorenzo and Tuolumne Rivers (California), collaborating with the Coastal Change Hazards program, USGS Geology, Minerals, Energy, and Geophysics Science Center, and others.
- Post-fire sediment mobilization. Hillslopes commonly shed large quantities of sediment in the aftermath of a wildfire, with potential hazards for downstream communities, infrastructure and water supply. The size and duration of these effects vary widely among landscapes, and have not been measured in detail for many regions. We are collaborating with the National Park Service and other partners to investigate post-fire landscape evolution after the 2018 Carr Fire, northern California, a federally declared disaster. Our efforts focus on Whiskeytown National Recreation Area, evaluating sediment movement that affects Whiskeytown Lake and surrounding watersheds.
Evolution of the shoreline around the Elwha River mouth, Washington, before, during and after dam removal, 2011–2017. Two large dams were removed from the Elwha River between 2011 and 2014 in the largest dam removal worldwide thus far, releasing more than 20 million tons of sediment downstream. These images show the effects of new sediment depositing around the river mouth and being reworked by waves and currents. The Elwha River and other recent dam-removal sites are generating new understanding of ways in which river and coastal systems respond to human activity. Image from Warrick and others, 2019, Scientific Reports.
USGS scientists surveying the Elwha River channel, Washington, to study its response to two large dam removals. Photo credit: J.T. Minear
Geomorphic and sedimentary effects of modern climate change: Current and anticipated future conditions in the western United States
Hydroclimatic changes associated with global warming over the past 50 years have been documented widely, but physical landscape responses are poorly understood thus far. Detecting sedimentary and geomorphic signals of modern climate change presents challenges owing to short record lengths, difficulty resolving signals in stochastic natural systems...
East, Amy E.; Sankey, Joel B. 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. Conceptualizing ecological responses to dam removal: If you remove it, what's to come?
One of the desired outcomes of dam decommissioning and removal is the recovery of aquatic and riparian ecosystems. To investigate this common objective, we synthesized information from empirical studies and ecological theory into conceptual models that depict key physical and biological links driving ecological responses to removing dams. We...
Bellmore, J. Ryan; Pess, George R.; Duda, Jeffrey J.; O'Connor, Jim E.; East, Amy E.; Foley, Melissa M.; Wilcox, Andrew C.; Major, Jon J.; Shafroth, Patrick B.; Morley, Sarah A.; Magirl, Christopher S.; Anderson, Chauncey W.; Evans, James E.; Torgersen, Christian E.; Craig, Laura S. 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. River response to large‐dam removal in a Mediterranean hydroclimatic setting: Carmel River, California, USA
Dam removal provides a valuable opportunity to measure the fluvial response to changes in both sediment supply and the processes that shape channel morphology. We present the first study of river response to the removal of a large (32‐m‐high) dam in a Mediterranean hydroclimatic setting, on the Carmel River, coastal California, USA. This before‐...
Harrison, Lee R.; East, Amy E.; Smith, Douglas P.; Logan, Joshua B.; Bond, Rosealea; Nicol, Colin; Williams, Thomas H.; Boughton, David A.; Chow, Kaitlyn; Luna, Lauren Geomorphic responses to dam removal in the United States – a two-decade perspective
Recent decades have seen a marked increase in the number of dams removed in the United States. Investigations following a number of removals are beginning to inform how, and how fast, rivers and their ecosystems respond to released sediment. Though only a few tens of studies detail physical responses to removals, common findings have begun to...
Tsutsumi, Daizo; Laronne, Jonathan B.; Major, Jon J.; East, Amy E.; O'Connor, Jim E.; Grant, Gordon E.; Wilcox, Andrew C.; Magirl, Christopher S.; Collins, Matthias J.; Tullos, Desiree D. Dam removal: Listening in
Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals—particularly large dams—and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals...
Foley, Melissa M.; Bellmore, James; O'Connor, James E.; Duda, Jeffrey J.; East, Amy E.; Grant, Gordon G.; Anderson, Chauncey W.; Bountry, Jennifer A.; Collins, Mathias J.; Connolly, Patrick J.; Craig, Laura S.; Evans, James E.; Greene, Samantha; Magilligan, Francis J.; Magirl, Christopher S.; Major, Jon J.; Pess, George R.; Randle, Timothy J.; Shafroth, Patrick B.; Torgersen, Christian E.; Tullos, Desiree D.; Wilcox, Andrew C. Channel-planform evolution in four rivers of Olympic National Park, Washington, U.S.A.: The roles of physical drivers and trophic cascades
Identifying the relative contributions of physical and ecological processes to channel evolution remains a substantial challenge in fluvial geomorphology. We use a 74-year aerial photographic record of the Hoh, Queets, Quinault, and Elwha Rivers, Olympic National Park, Washington, U.S.A., to investigate whether physical or trophic-cascade-driven...
East, Amy E.; Jenkins, Kurt J.; Happe, Patricia J.; Bountry, Jennifer A.; Beechie, Timothy J.; Mastin, Mark C.; Sankey, Joel B.; Randle, Timothy J. Large-scale dam removal on the Elwha River, Washington, USA: river channel and floodplain geomorphic change
A substantial increase in fluvial sediment supply relative to transport capacity causes complex, large-magnitude changes in river and floodplain morphology downstream. Although sedimentary and geomorphic responses to sediment pulses are a fundamental part of landscape evolution, few opportunities exist to quantify those processes over field scales...
East, Amy E.; Pess, George R.; Bountry, Jennifer A.; Magirl, Christopher S.; Ritchie, Andrew C.; Logan, Joshua B.; Randle, Timothy J.; Mastin, Mark C.; Minear, Justin T.; Duda, Jeffrey J.; Liermann, Martin C.; McHenry, Michael L.; Beechie, Timothy J.; Shafroth, Patrick B. 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.-
Date published: May 27, 2020Bathymetry, topography and orthomosaic imagery for Whiskeytown Lake, northern California
Approximately 93% of the area within Whiskeytown National Recreation Area was burned extensively during the Carr Fire, including all of the landscape surrounding and draining into Whiskeytown Lake. The lake, a federally managed reservoir, therefore acted as a sediment trap for material eroded from hillslopes and streambeds in the aftermath of the Carr Fire. USGS measured ...
-
Date published: June 4, 2018River-channel topography and sediment grain size on the Elwha River, Washington, 2006 to 2017
This data release presents topographic and sediment grain size data collected by the USGS in the Elwha River channel between 2006 and 2017. These data have been used to inform interpretations of geomorphic and sediment evolution in the Elwha River before, during, and after dam removal, including the response to several flood events. We measured topography and bed-sediment grain size in five...
-
Date published: December 12, 2017River-channel topography, grain size, and turbidity records from the Carmel River, California, before, during, and after removal of San Clemente Dam
The San Clemente Dam, built in the 1920s on the Carmel River in Monterey County, California, was removed during 2014 and 2015. The dam-removal project was the largest in California to date, and one of the largest in the U.S. The USGS collected data before, during, and after the removal of the dam to study how the river channel's topographic profiles and sediment distributions changed...
-
Date published: June 8, 2018Amy East elected GSA Fellow for insights into landscape response to changes in sediment supply
The Geological Society of America (GSA) elected USGS research geologist Amy East to be a GSA Fellow, “an honor bestowed on the best of our profession,” at the spring GSA Council meeting.