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.
Research Topics
Landscape Response to Climate Change
Climatic changes associated with modern global warming have been documented widely, but physical landscape responses are poorly understood. Landscape signals of modern climate change relate to human health and safety, infrastructure, water security, and ecosystems. Our project investigates landscape responses to modern climate change, primarily in the western US, focusing on slope failures, watershed sediment yields, river morphology, and aeolian (wind-blown) sediment mobilization.
Post-Fire Sediment Mobilization
Watershed sediment yields increase after fire, but by how much and with what driving factors is not well understood for some regions. Our group studies several CA wildfires, monitoring sediment yield and related processes. We have studied landscape change after seven California fires spanning 2016 to 2022.
Effects of Large Dam Removal
Colleagues and I have studied river response to large dam removals on the Elwha River, WA, and Carmel River, CA, and study the Klamath River (CA and OR) preparing for dam removals there. I helped lead a USGS Powell Center working group on the state of dam-removal science.
Landscape Response to Hydroclimatic Extremes
Western US landscapes export large sediment fluxes, due to steep terrain, tectonic activity, and potential for extreme rain. I study landscape response to hydroclimatic disturbances—drought and extreme rain. We studied sediment export from the San Lorenzo River, CA, from record rainfall in 2017; and debris flows caused by intense rain in 2018 over the Tuolumne basin. Understanding such disturbances is critical to constraining effects of extreme events on landscapes and sediment budgets.
Landscape Evolution in the Colorado River Ecosystem
From 2003 to 2017 I studied connectivity among fluvial, aeolian, and hillslope processes in the Colorado River corridor, AZ. Since 1963, dam operations have altered flows and sediment supply in the Colorado River, Grand Canyon National Park. Loss of sandbars in the dammed river reduces windblown sand supply to aeolian dunes, affecting archaeological-site stability and ecosystem properties.
Aeolian Landscape Stability
Our work quantified sediment accumulation and landscape stability in areas of the California desert considered for solar-energy projects. I also studied aeolian landscapes on the Navajo Nation, where during drought wind-blown sand mobility has destabilized ground surfaces, endangering housing and transportation, jeopardizing grazing lands, and impacting air quality.
Science and Products
Klamath Dam Removal Studies
Sediment Transport in Coastal Environments
Landscape Response to Disturbance
Coastal watershed and estuary restoration in the Monterey Bay area
U.S. West Coast and Alaska Marine Geohazards
USGS science supporting the Elwha River Restoration Project
Dam removal: synthesis of ecological and physical responses
Science and Products
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Klamath Dam Removal Studies
In January of 2024, the removal of four dams along the mainstem Klamath River will allow for volitional fish passage above the dams and will create more dynamic flow and sediment transport conditions below the dams. The release of reservoir sediment to downstream river reaches during and following dam removal may result in novel water quality, sediment transport, and geomorphic conditions. The...Sediment Transport in Coastal Environments
Our research goals are to provide the scientific information, knowledge, and tools required to ensure that decisions about land and resource use, management practices, and future development in the coastal zone and adjacent watersheds can be evaluated with a complete understanding of the probable effects on coastal ecosystems and communities, and a full assessment of their vulnerability to natural...Landscape Response to Disturbance
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.Coastal watershed and estuary restoration in the Monterey Bay area
Objectives: Support further work by the USGS and collaborating federal, state, and local agencies and academic partners in analyzing the effectiveness of restoration work in coastal watersheds and estuaries in the Monterey Bay area. The USGS will play a supporting role in field efforts led by NOAA and California State University - Monterey Bay to measure physical and ecological changes in the...U.S. West Coast and Alaska Marine Geohazards
Marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.ByNatural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, 3-D CT Core Imaging Laboratory, Core Preparation and Analysis Laboratory and Sample Repositories, Big Sur Landslides, Deep Sea Exploration, Mapping and Characterization, Subduction Zone ScienceUSGS science supporting the Elwha River Restoration Project
The Elwha River Restoration Project has reconnected the water, salmon, and sediment of a pristine river and coast of the Olympic Peninsula of Washington.Dam removal: synthesis of ecological and physical responses
Dam decommissioning is rapidly emerging as an important river restoration strategy in the U.S., with several major removals recently completed or in progress. But few studies have evaluated the far-reaching consequences of these significant environmental perturbations, especially those resulting from removals of large (>10-15 m tall) structures during the last decade. In particular, interactions b - Data
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