Amy East

I study how landscapes change over time, focusing on response to hydroclimatic and anthropogenic disturbances. These studies inform resource management as well as fundamental understanding of earth-surface processes. I am also interested in how sediment moves from source to sink, and how the sedimentary record reflects changes in sediment supply and transport.

Biography

**Please note: Prior to 2014, my name was Amy Draut and my earlier publications used that name. **

Research Geologist, U.S. Geological Survey, Coastal and Marine Hazards and Resources Program (2006 - present), Santa Cruz, CA, Principal Investigator of USGS Landscape Response to Disturbance project

Editor-in-Chief, Journal of Geophysical Research, Earth Surface: January 2019 - present.

 

Postdoctoral Researcher, U.S. Geological Survey / University of California, Santa Cruz (2003 - 2006)

Ph.D., Geology and Geophysics, 2003

  • Massachusetts Institute of Technology / Woods Hole Oceanographic Institution Joint Program, Cambridge and Woods Hole, MA

B.S., Geological Sciences and Environmental Studies, 1997

  • Tufts University, Medford, MA

 

Research Topics

(Selected publications listed beneath each topic. For a complete publication list, contact me at aeast@usgs.gov)

Landscape Response to Modern Climate Change

Climatic changes associated with global warming over the past 50 years have been documented widely, but physical landscape responses are poorly understood. Detecting landscape signals of modern climate change is difficult for many reasons, but is important because these problems relate closely to human health and safety, infrastructure, water security, and ecosystems. My USGS colleague Joel Sankey and I recently published a synthesis study using a literature review to examine landscape responses to modern climate change in the western United States, focusing on slope failures, watershed sediment yields, river morphology, and aeolian (wind-blown) sediment mobilization. Our review indicated that some changes to slope stability and aeolian sediment are evident, whereas factors other than climate have been more important thus far in controlling sediment yields and fluvial channel morphology. We identify ways in which more information is needed from many more places, in the western U.S. and globally, to understand landscape response to ongoing climate change. We encourage expansion of synthesis efforts to integrate historical and contemporary data and scientific capabilities, and to do so in other regions globally (including reporting negative results).

East, A.E., and Sankey, J.B., 2020, Geomorphic and sedimentary effects of modern climate change: current and anticipated future conditions in the western United States: Reviews of Geophysics, 58, e2019RG000692. https://doi.org/10.1029/2019RG000692

 

Post-fire sediment mobilization

After wildfire, watershed sediment yields commonly increase substantially, but by how much, and with what driving factors, is not well understood for some regions. Our group has been studying landscape response to several northern California wildfires in recent years, monitoring sediment yield and processes exporting sediment. We have active research on the 2018 Carr Fire in Whiskeytown National Recreation Area, and in the Santa Cruz Mountains, where the CZU Lightning Complex Fire burned in summer 2020. Check back for updates and forthcoming publications soon.

 

Effects of Large Dam Removal on River Channel and Floodplain Morphology

I have studied river response to large dam removals on the Elwha River, Washington, and Carmel River, California, and participate in research on the Klamath River (Calif. and Oregon) anticipating future dam removals there. Dam-removal research allows us to understand better how landscapes respond to large sediment pulses, a long-standing problem in geomorphology that is rarely studied at field scales because of the unanticipated nature of most sediment pulses. Because dam removal is increasingly used as a means to restore watershed and coastal enviroments, it is critical to understand how physical and biological systems respond. I was one of five Principal Investigators on a USGS Powell Center working group that synthesized the state of knowledge in dam-removal science.

East, A. E., Logan, J. B., Mastin, M. C., Ritchie, A. C., Bountry, J. A., et al. (2018). Geomorphic evolution of a gravel-bed river under sediment-starved versus sediment-rich conditions: river response to the world’s largest dam removal. Journal of Geophysical Research, Earth Surface, 123, 3338–3369. Doi: 10.1029/2018JF004703

Harrison, L. R., East, A. E., Smith, D. P., Logan, J. B., Bond, R. M., et al. (2018). River response to large-dam removal in a Mediterranean hydroclimatic setting: Carmel River, California, USA. Earth Surface Processes and Landforms, 43, 3009–3021. https://doi.org/10.1002/esp.4464

Ritchie, A.C., Warrick, J.A., East, A.E., Magirl, C.S., Stevens, A.W., Bountry, J.A., Randle, T.J., Curran, C.A., Hilldale, R.C., Duda, J.J., Gelfenbaum, G.R., Miller, I.M., Pess, G.R., Foley, M.M., McCoy, R., and Ogston, A.S., 2018, Morphodynamic evolution following sediment release from the world’s largest dam removal: Nature Scientific Reports, v. 8, 13279, doi:10.1038/s41598-018-30817.

East, A.E., Pess, G.R., Bountry, J.A., Magirl, C.S., Ritchie, A.C., Logan, J.B., Randle, T.J., Mastin, M.C., Minear, J.T., Duda, J.J., Liermann, M.C., McHenry, M.L., Beechie, T.J., and Shafroth, P.B., 2015, Large-scale dam removal on the Elwha River, Washington, USA: River channel and floodplain geomorphic change. Geomorphology, v. 228, p. 765–786, doi:10.1016/j.geomorph.2014.08.028

Warrick, J.A., Bountry, J.A., East, A.E., Magirl, C.S., Randle, T.J., Gelfenbaum, G., Ritchie, A.C., Pess, G.R., Leung, V., and Duda, J.J., 2015, Large-scale dam removal on the Elwha River, Washington, USA: Source-to-sink sediment budget and synthesis. Geomorphology, v. 246, p. 729–750.

Draut, A.E., and Ritchie, A.C., 2015, Sedimentology of new fluvial deposits on the Elwha River, Washington, USA, formed during large-scale dam removal: River Research and Applications, v. 31, p. 42–61, doi:10.1002/rra.2724

Draut, A.E., Logan, J.B., and Mastin, M.C., 2011, Channel evolution on the dammed Elwha River, Washington, USA: Geomorphology, v. 127, p. 71-87.

Draut, A.E., Logan, J.B., McCoy, R.E., McHenry, M., and Warrick, J.A., 2008, Channel evolution on the lower Elwha river, Washington, 1939 to 2006: US Geological Survey Scientific Investigations Report 2008-5127, http://pubs.usgs.gov/sir/2008/5127/

See also our synthesis papers on dam removal:

Bellmore, J.R., Pess, G.R., Duda, J.J., O’Connor, J.E., East, A.E., Foley, M.M., Wilcox, A.C., Major, J., Shafroth, P.B., Magirl, C.S., Anderson, C.W., Evans, J.E., Torgersen, C.E., and Craig, L.S., 2019, Conceptualizing ecological responses to dam removal: if you remove it, what’s to come? BioScience, 69 (1), 26-29, https://doi.org/10.1093/biosci/biy152

Major, J.J., East, A.E., O’Connor, J.E., Grant, G.E., Wilcox, A.C., Magirl, C.S., Collins, M.J., and Tullos, D.D., 2017, Geomorphic responses to dam removals in the United States—a two-decade perspective, in Tsutsumi, D., and Laronne, J., eds., Gravel-Bed Rivers: Processes and Disasters, p. 355–384. Wiley-Blackwell, ISBN 978-1-118-97140-6.

Foley, M.M., Bellmore, J.R., O’Connor, J.E., Duda, J.J., East, A.E., Grant, G.E., Anderson, C.W., Bountry, J.A., Collins, M.J., Connolly, P.J., Craig, L.S., Evans, J.E., Greene, S.L., Magilligan, F.J., Magirl, C.S., Major, J.J., Pess, G.R., Randle, T.J., Shafroth, P.B., Torgersen, C.E., Tullos, D., and Wilcox, A.C., 2017, Dam removal—listening in: Water Resources Research, v. 53, 5229–5246, doi:10.1002/2017WR020457.

 

Landscape response to extreme hydroclimatic disturbances, California

Landscapes of the western U.S. coast commonly produce and export large sediment fluxes, given their steep terrain, tectonic activity, and potential to receive extreme rainfall. I study landscape response to severe hydroclimatic disturbances in several California watersheds, including drought and extreme rainfall (on seasonal and individual-event scales), and some post-fire runoff situations. We have been studying a regime shift in sediment export from the San Lorenzo River, central CA coast, as a result of record rainfall in the winter of 2017, which induced substantial fluvial sediment flux due to landslide debris becoming abundant in the watershed (East et al., 2018), and looked at coupling between the fluvial suspended-sediment regime and coastal geomorphic response. Colleagues and I have also published records from an extreme landslide and debris-flow situation caused by intense rainfall in 2018 over the Tuolumne basin, Sierra Nevada foothills. That two-hour rain event produced substantially more sediment than the river normally carries in a year, despite being generated from only one-twentieth of one percent of the basin area. Understanding the effects of such hydrologic disturbances is critical to constraining effects of extreme events on landscapes and sediment budgets, with applications for infrastructure and human safety, river and coastal ecosystems, and water-resource security. This is an especially critical research need as modern climate change is likely to generate more extreme rain events.

Collins, B. D., Oakley, N. S., Perkins, J. P., East, A. E., Corbett, S. C., & Hatchett, B. J. (2020). Linking mesoscale meteorology with extreme landscape response: effects of narrow cold frontal rainbands (NCFRs). Journal of Geophysical Research – Earth Surface, 125, e2020JF005675. https://doi.org/10.1029/2020JF005675

East, A.E., Stevens, A.W., Ritchie, A.C., Barnard, P.L., Campbell-Swarzenski, P.L., Collins, B.D., and Conaway, C.H., 2018, A regime shift in sediment export from a coastal watershed during a record wet winter, California—implications for landscape response to hydroclimatic extremes: Earth Surface Processes and Landforms, v. 43, p. 2562–2577.

 

Physical vs. Ecological Drivers of Channel Change

Identifying the relative contributions of physical and ecological processes to channel evolution remains a substantial challenge in fluvial geomorphology. We used 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 ecological factors—excessive elk impacts after wolves were extirpated a century ago—are the dominant controls on channel planform of these gravel-bed rivers. We found that channel width and braiding show strong relationships with recent flood history; all four rivers have widened significantly in recent decades, consistent with increased flood activity since the 1970s. Channel planform also reflects sediment-supply changes, e.g., response of the Elwha River to a landslide. We surmised that the Hoh River, which shows a unique multi-decadal trend toward greater braiding, is adjusting to increased sediment supply associated with rapid glacial retreat. However, we inferred no correspondence between channel evolution and elk abundance, suggesting that in this system effects of the wolf-driven trophic cascade are subsidiary to physical controls on channel morphology. Our examinations of stage–discharge history, historical maps, photographs, and descriptions, and empirical geomorphic thresholds do not support a previous conceptual model that these rivers underwent a fundamental geomorphic transition resulting from large elk populations in the early 20th century. These findings differ from previous interpretations of Olympic National Park river dynamics, and also contrast with previous findings in Yellowstone National Park.

East, A.E., Jenkins, K.J., Happe, P.J., Bountry, J.A., Beechie, T.J., Mastin, M.C., Sankey, J.B., and Randle, T.J., 2017, Channel-planform evolution in four rivers of Olympic National Park, Washington, U.S.A.: the roles of physical drivers and trophic cascades: Earth Surface Processes and Landforms, v. 42, p. 1011–1032.

East, A.E., Jenkins, K.J., Happe, P.J., Bountry, J.A., Beechie, T.J., Mastin, M.C., Sankey, J.B., and Randle, T.J., 2018, Reply to “Wolf-triggered trophic cascades and stream channel dynamics in Olympic National Park: a comment on East et al. (2017)”: Earth Surface Processes and Landforms, doi:10.1002/esp.4288.

 

Landscape Evolution in the Colorado River Ecosystem

From 2003 to 2017 I had active research on the connectivity among fluvial, aeolian, and hillslope processes in the Colorado River corridor, southwestern USA. Since 1963, Glen Canyon Dam operations have substantially altered river flow and fluvial sediment supply in the Colorado River corridor through Grand Canyon National Park. My work focuses on the role of aeolian sand in ecosystem development and archaeological-site preservation, and the influence of controlled floods on aeolian sand supply and transport in the river corridor. Because fluvial and aeolian sedimentary systems are strongly coupled there, the loss of fluvial sandbars in the dammed river reduces the supply of windblown sand to aeolian dunes above the high water line. Where aeolian sand supply has been lost in post-dam time, the ecosystem changes as biologic soil crust and vegetation replace formerly open sand. This study, which included making comparisons between Grand Canyon and a less regulated reach of the Colorado River upstream in Cataract Canyon, Utah, is the first study to show that river regulation by dams affects the evolution of aeolian landscapes up above the river's high water line, demonstrating a newly recognized human impact on arid environments.

East, A.E., Collins, B.D., Sankey, J.B., Corbett, S.C., Fairley, H.C., and Caster, J., 2016, Conditions and processes affecting sand resources at archeological sites in the Colorado River corridor below Glen Canyon Dam: U.S. Geological Survey Professional Paper 1825, 104 pp., http://dx.doi.org/10.3133/pp1825

Sankey, J.B., Kasprak, A., Caster, J., East, A.E, and Fairley, H.C., 2018, The response of source-bordering aeolian dunefields to sediment-supply changes, 1. Effects of wind variability and river-valley morphodynamics: Aeolian Research, v. 32, p. 228–245.

Sankey, J.B., Caster, J., Kasprak, A., and East, A.E., 2018, The response of source-bordering aeolian dune fields to sediment-supply changes, 2. Controlled floods of the Colorado River in Grand Canyon, Arizona, USA: Aeolian Research, Aeolian Research, v. 32, p. 154–169.

Sankey, J.B., and Draut, A.E., 2014, Gully annealing by aeolian sediment: field and remote-sensing investigation of aeolian-hillslope-fluvial interactions, Colorado River corridor, Arizona, USA: Geomorphology, v. 230, p. 68-80.

Draut, A.E., 2012, Effects of river regulation on aeolian landscapes, Colorado River, southwestern USA: Journal of Geophysical Research—Earth Surface, v. 117, F02022, doi:10.1029/2011JF002329

Draut, A.E., and Rubin, D.M., 2008, The role of aeolian sediment in the preservation of archaeological sites in the Colorado River corridor, Grand Canyon, Arizona: USGS Professional Paper 1756, http://pubs.usgs.gov/pp/1756/

Draut, A.E., et al., 2008, Application of sedimentary-structure interpretation to geoarchaeological studies in the Colorado River corridor, Grand Canyon, Arizona, USA: Geomorphology, v. 101, p. 497-509.

 

Aeolian Landscape Stability

Constraining the processes governing aeolian landscape stability and associated windblown sediment transport is both an interesting research problem and essential for planning human occupation of arid lands. I work with the Bureau of Land Management and USGS and University of Washington colleagues to quantify rates of sediment accumulation and characterize spatial variations in landscape stability in areas of the Mojave Desert, California, that are being considered for major expansions of solar-energy projects. This work began in 2019 and our findings are going through review currently. 

Previously, I worked on an interesting aeolian-process study on the Navajo Nation. Native Americans of the southwestern U.S. live on ecologically sensitive arid lands with limited resources. On the 65,000 km2 Navajo Nation, one third of the land surface is covered by aeolian sand dunes. Higher temperatures, reduced precipitation, and the spread of exotic plants are transforming the landscape, negatively impacting residents, many of whom live a traditional, subsistence lifestyle. During the past 14 years of drought, wind-blown sand mobility has increased appreciably and destabilized ground surfaces, endangering housing and transportation, jeopardizing grazing lands, and impacting air quality. I worked with the USGS Navajo Nation Land Use Project led by Margaret Hiza Redsteer to study processes that are rapidly altering these lands. We studied how aeolian sand transport, vegetation abundance and assemblage, and stabilizing biologic soil crust vary with seasonal and longer-term climatic changes and livestock use.

Draut, A.E., Redsteer, M.H., and Amoroso, L., 2012, Vegetation, substrate, and aeolian sand transport at Teesto Wash, Navajo Nation, 2009–12: U.S. Geological Survey Scientific Investigations Report 2012-5095, 78 p., http://pubs.usgs.gov/sir/2012/5095/.

Draut, A.E., Redsteer, M.H., and Amoroso, L., 2012, Recent seasonal variations in arid landscape cover and aeolian sand mobility, Navajo Nation, southwestern U.S., in Giosan, L., and others, eds., Climate, Landscapes and Civilizations: American Geophysical Union Monograph 198, p. 51–60.

 

Sedimentary, Tectonic, and Geochemical Processes of Active Margins

I have worked on both modern and ancient tectonic and sedimentary processes along active margins. Currently, my work in this area focuses on the Queen Charlotte Fault, the plate boundary between the Pacific and North American plates along southeastern Alaska. This work is ongoing thanks to great new data sets (multibeam bathymetric and shallow seismic-reflection data) collected in 2015 and 2016... stay tuned. Much of my work in the ancient record dealt with island-arc magmatism, which is thought to be a primary way to generate continental crust. Origin of continental crust is a contentious issue, as scientists must reconcile geochemical disparities between most arc volcanism and bulk continental crust. Studying evolution of modern and ancient accreted arc terranes contributes new understanding into arc-continent collision processes, with implications for understanding more about these important systems - both their role in forming continental crust, and, from a geohazards perspective, their ability to generate large tsunamigenic earthquakes. I have worked in accreted arc terranes of Ireland, Alaska, and Taiwan, studying geochemical and sedimentary processes that accompany arc-continent collision, and also worked around the Aleutian arc studying sedimentary and tectonic evolution of the forearc evident from sedimentary basin development. By better understanding the structural history and sedimentary environments of Alaska and the Aleutians, we aim to clarify the risk of great earthquakes and tsunami generation there.

Draut, A.E., and Clift, P.D., 2013, Differential preservation in the geologic record of island-arc sedimentary and tectonic processes: Earth-Science Reviews, v. 116, p. 57–84.

Ryan, H.F., Draut, A.E., Scholl, D.W., and Keranen, K., 2012, Influence of the Amlia fracture zone on the evolution of the Aleutian Terrace forearc basin, central Aleutian subduction zone: Geosphere, v. 8, no. 6, p. 1254–1273, doi:10.1130/GES00815.1.

Draut, A.E., Clift, P.D., Amato, J.M., Blusztajn, J., and Schouten, H., 2009, Arc-continent collision and the formation of continental crust - a new geochemical and isotopic record from the Ordovician Tyrone Igneous Complex, Ireland: Journal of the Geological Society, London, v. 166, p. 485 - 500.

Draut, A.E., Clift, P.D., and Scholl, D.W., eds., 2008, Formation and applications of the sedimentary record in arc collision zones. GSA Special Paper 436, collection of 18 papers.

Draut, A.E., and Clift, P.D., 2006, Sedimentary processes in modern and ancient oceanic arc settings - evidence from the Jurassic Talkeetna Formation of Alaska and the Mariana and Tonga arcs, western Pacific: Journal of Sedimentary Research, v. 76, p. 493 - 514.

Clift, P.D., Draut, A.E., Kelemen, P.B., Blusztajn, J., and Greene, A., 2005, Stratigraphic and geochemical evolution an oceanic arc upper crustal section—the Jurassic Talkeetna Volcanic Formation, south-central Alaska: Geological Society of America Bulletin, v. 117, p. 902–925, DOI: 10.1130/B25638. 

Draut, A.E., and Clift, P.D., 2001, Geochemical evolution of arc magmatism during arc-continent collision, South Mayo, Ireland: Geology, v. 29, p. 543-546.

 

Terrestrial Sediment Effects on Coral Reef Ecosystems

Terrestrial sediment input to the coastal ocean can threaten coral-reef ecosystems. In Hawaii, sedimentation on nearshore reefs is a concern because changing land-use patterns (urbanization, agricultural practices, and nonnative species expansion) can increase sediment entering coastal waters, inhibiting photosynthesis and smothering corals. Working with the USGS Coral Reefs Project in 2005 and 2006, I collected sediment cores in Hanalei Bay and used them to trace flood sediment delivery. We found that winter flood sediment stays in the bay for months after a large flood event if the wave energy is not great enough to flush sediment out of the bay, highlighting an important difference between hydroclimatic processes in tropical vs. temperate zones. Whereas in temperate regions (like the California coast) floods and wave energy usually coincide, which rapidly reworks flood sediment near shore, in tropical regions the deposition and reworking of flood sediment are often seasonally decoupled. When tropical flood sediment stays near shore for months during summer low wave energy, this can harm coral reefs, particularly if sediment influx increases (land use changes) and/or climate change brings more summer rain to Hawaii, as some models of future climate project.

Draut, A.E., Bothner, M.H., Field, M.E., Reynolds, R.L., Cochran, S.A., Logan, J.B., Storlazzi, C.D., and Berg, C.J., 2009, Supply and dispersal of seasonal flood sediment from a steep, tropical watershed - Hanalei Bay, Kauai, Hawaii, USA: Geological Society of America Bulletin, v. 121, p. 574 - 585.

Storlazzi, C.D., Field, M.E., Bothner, M.H., Presto, M.K., and Draut, A.E., 2009, Sedimentation processes in a coral reef embayment: Hanalei Bay, Kauai: Marine Geology, v. 264, p. 140-151.