Peter Griffiths
Peter Griffiths serves as the Regional Director and the Deputy Regional Director for Operations for the USGS Rocky Mountain Region.
Professional Experience
U.S. Geological Survey, Denver, CO, 2015 to present. Deputy Regional Director for Operations, Rocky Mountain Region.
U.S. Geological Survey, Denver, CO, 2009 to 2015. Assistant Chief, Central Branch of the National Research Program, Water Mission Area.
U.S. Geological Survey, Tucson, AZ, 2005 to 2009. Research Hydrologist, National Research Program.
Education and Certifications
M.S., 1995, University of Arizona, Geosciences (Minor in Hydrology)
B.A., 1987, Yale University, Archeological Studies
Science and Products
Filter Total Items: 34
Debris flows and rapids in Grand Canyon; implications for erosion rates and evacuation of sediment from tributary canyons
No abstract available.
Authors
Robert Webb, Peter G. Griffiths, Theodore S. Melis
Sediment delivery by ungaged tributaries of the Colorado River in Grand Canyon, Arizona
Sediment input to the Colorado River in Grand Canyon, Arizona, is a valuable resource required to sustain both terrestrial and aquatic ecosystems. A total of 768 ungaged tributaries deliver sediment to the river between Glen Canyon Dan and the Grand Wash Cliffs (river miles - 15 to 276). The 32 tributaries between the dam and Lee's Ferry produce only streamflow floods, whereas 736 tributaries in
Authors
Robert H. Webb, Peter G. Griffiths, Theodre S. Melis, Daniel R. Hartley
Entrainment and transport of cobbles and boulders from debris fans
No abstract available.
Authors
James E. Pizzuto, Robert Webb, Peter G. Griffiths, John G. Elliott, Theodore S. Melis
Reworking of aggraded debris fans
No abstract available.
Authors
Robert Webb, Theodore S. Melis, Peter G. Griffiths, John G. Elliott
Lava Falls Rapid in Grand Canyon: Effects of Late Holocene debris flows on the Colorado River
Lava Falls Rapid is the most formidable reach of whitewater on the Colorado River in Grand Canyon and is one of the most famous rapids in the world. Debris flows in 1939, 1954, 1955, 1966, and 1995, as well as prehistoric events, completely changed flow through the rapid. Floods cleared out much of the increased constrictions, but releases from Glen Canyon Dam, including the 1996 controlled flood,
Authors
Robert H. Webb, Theodore S. Melis, Peter G. Griffiths, John G. Elliott, Thure E. Cerling, Robert J. Poreda, Thomas W. Wise, James E. Pizzuto
Initiation of debris flows in tributaries of the Colorado River in Grand Canyon, Arizona
Debris flows are initiated in tributaries of the Colorado River in Grand Canyon when intense rainfall causes failures in colluvium and (or) bedrock. Most debris flows occur in the summer during localized convective thunderstorms with rainfall intensities as high as 40 mm/hr. Rarer and larger debris flows occur during unusually warm frontal storms in winter. Hourly precipitation data suggest that s
Authors
Peter G. Griffiths, Robert Webb, Theodore S. Melis
Debris flows in Grand Canyon National Park: Peak discharges, flow transformations, and hydrographs
Direct measurements of debris-flow hydrograph and flow behavior in remote drainage areas are rare. We infer hydrographs and flow behavior for recent debris flow in bedrock tributaries of the Colorado River from preserved stratigraphic relations, sedimentology and surface morphology of debris fans and evidence of flow-surface elevations. We propose that 3 types of debris-flow hydrographs occur in G
Authors
Theodore S. Melis, Robert Webb, Peter G. Griffiths
Reworking of aggraded debris fans by the 1996 controlled flood on the Colorado River in Grand Canyon National Park, Arizona
Debris flows from 600 tributaries in Grand Canyon periodically deposit poorly sorted sediment on debris fans along the Colorado River between Lakes Powell and Mead. Before regulation, stable fans and rapids along the river resulted from the interaction of tributary debris flows and large, mainstem floods. Floods in the Colorado River maintained fans and rapids as highly-reworked deposits of boulde
Authors
Robert H. Webb, T.S. Melis, Peter G. Griffiths, J. G. Elliott
Initiation and frequency of debris flows in Grand Canyon, Arizona
Debris flows occur in 600 tributaries of the Colorado River in Grand Canyon, Arizona when intense precipitation causes slope failures in bedrock or colluvium. These slurries transport poorly sorted sediment, including very large boulders that form rapids at the mouths of tributaries and control the longitudinal profile of the Colorado River. Although the amount of rainfall on the days of historic
Authors
Peter G. Griffiths, Robert H. Webb, Theodore S. Melis
Magnitude and frequency data for historic debris flows in Grand Canyon National Park and vicinity, Arizona
Debris flows occur in 529 tributaries of the Colorado River in Grand Canyon between Lees Ferry and Diamond Creek, Arizona (river miles 0 to 225). An episodic type of flash flood, debris flows transport poorly-sorted sediment ranging in size from clay to boulders into the Colorado River. Debris flows create and maintain debris fans and the hundreds of associated riffles and rapids that control the
Authors
T.S. Melis, R. H. Webb, Peter G. Griffiths, T.J. Wise
Science and Products
Filter Total Items: 34
Debris flows and rapids in Grand Canyon; implications for erosion rates and evacuation of sediment from tributary canyons
No abstract available.
Authors
Robert Webb, Peter G. Griffiths, Theodore S. Melis
Sediment delivery by ungaged tributaries of the Colorado River in Grand Canyon, Arizona
Sediment input to the Colorado River in Grand Canyon, Arizona, is a valuable resource required to sustain both terrestrial and aquatic ecosystems. A total of 768 ungaged tributaries deliver sediment to the river between Glen Canyon Dan and the Grand Wash Cliffs (river miles - 15 to 276). The 32 tributaries between the dam and Lee's Ferry produce only streamflow floods, whereas 736 tributaries in
Authors
Robert H. Webb, Peter G. Griffiths, Theodre S. Melis, Daniel R. Hartley
Entrainment and transport of cobbles and boulders from debris fans
No abstract available.
Authors
James E. Pizzuto, Robert Webb, Peter G. Griffiths, John G. Elliott, Theodore S. Melis
Reworking of aggraded debris fans
No abstract available.
Authors
Robert Webb, Theodore S. Melis, Peter G. Griffiths, John G. Elliott
Lava Falls Rapid in Grand Canyon: Effects of Late Holocene debris flows on the Colorado River
Lava Falls Rapid is the most formidable reach of whitewater on the Colorado River in Grand Canyon and is one of the most famous rapids in the world. Debris flows in 1939, 1954, 1955, 1966, and 1995, as well as prehistoric events, completely changed flow through the rapid. Floods cleared out much of the increased constrictions, but releases from Glen Canyon Dam, including the 1996 controlled flood,
Authors
Robert H. Webb, Theodore S. Melis, Peter G. Griffiths, John G. Elliott, Thure E. Cerling, Robert J. Poreda, Thomas W. Wise, James E. Pizzuto
Initiation of debris flows in tributaries of the Colorado River in Grand Canyon, Arizona
Debris flows are initiated in tributaries of the Colorado River in Grand Canyon when intense rainfall causes failures in colluvium and (or) bedrock. Most debris flows occur in the summer during localized convective thunderstorms with rainfall intensities as high as 40 mm/hr. Rarer and larger debris flows occur during unusually warm frontal storms in winter. Hourly precipitation data suggest that s
Authors
Peter G. Griffiths, Robert Webb, Theodore S. Melis
Debris flows in Grand Canyon National Park: Peak discharges, flow transformations, and hydrographs
Direct measurements of debris-flow hydrograph and flow behavior in remote drainage areas are rare. We infer hydrographs and flow behavior for recent debris flow in bedrock tributaries of the Colorado River from preserved stratigraphic relations, sedimentology and surface morphology of debris fans and evidence of flow-surface elevations. We propose that 3 types of debris-flow hydrographs occur in G
Authors
Theodore S. Melis, Robert Webb, Peter G. Griffiths
Reworking of aggraded debris fans by the 1996 controlled flood on the Colorado River in Grand Canyon National Park, Arizona
Debris flows from 600 tributaries in Grand Canyon periodically deposit poorly sorted sediment on debris fans along the Colorado River between Lakes Powell and Mead. Before regulation, stable fans and rapids along the river resulted from the interaction of tributary debris flows and large, mainstem floods. Floods in the Colorado River maintained fans and rapids as highly-reworked deposits of boulde
Authors
Robert H. Webb, T.S. Melis, Peter G. Griffiths, J. G. Elliott
Initiation and frequency of debris flows in Grand Canyon, Arizona
Debris flows occur in 600 tributaries of the Colorado River in Grand Canyon, Arizona when intense precipitation causes slope failures in bedrock or colluvium. These slurries transport poorly sorted sediment, including very large boulders that form rapids at the mouths of tributaries and control the longitudinal profile of the Colorado River. Although the amount of rainfall on the days of historic
Authors
Peter G. Griffiths, Robert H. Webb, Theodore S. Melis
Magnitude and frequency data for historic debris flows in Grand Canyon National Park and vicinity, Arizona
Debris flows occur in 529 tributaries of the Colorado River in Grand Canyon between Lees Ferry and Diamond Creek, Arizona (river miles 0 to 225). An episodic type of flash flood, debris flows transport poorly-sorted sediment ranging in size from clay to boulders into the Colorado River. Debris flows create and maintain debris fans and the hundreds of associated riffles and rapids that control the
Authors
T.S. Melis, R. H. Webb, Peter G. Griffiths, T.J. Wise