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Joel Unema

Joel Unema is a Hydrologist in the Arizona Water Science Center, Flagstaff Office

Science and Products

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Photo of USGS hydrologist collecting quarterly suspended-sediment samples from a kayak at Colorado River below Imperial Dam

Sediment Transport in the Colorado River and All-American Canal system at Imperial Dam

Like many other dams, Imperial Dam impounds much of the suspended sediment moving in the Colorado River but some of that suspended sediment makes its way to the All-American Canal, a major diversion for irrigation and municipal water. Water entering the All-American Canal is settled in several desilting basins to remove most of the remaining suspended sediment. The collected sediment from the...
By
Arizona Water Science Center
link

Sediment Transport in the Colorado River and All-American Canal system at Imperial Dam

Like many other dams, Imperial Dam impounds much of the suspended sediment moving in the Colorado River but some of that suspended sediment makes its way to the All-American Canal, a major diversion for irrigation and municipal water. Water entering the All-American Canal is settled in several desilting basins to remove most of the remaining suspended sediment. The collected sediment from the...
Learn More
link
Photograph show the initial energy wave of a flash flood on the Paria River in Arizona.

Grand Canyon Streamflow and Sediment Project

The AZWSC Grand Canyon Streamflow and Sediment project supports the work of Grand Canyon Monitoring and Research Center’s (GCMRC) Discharge, Sediment and Water Quality Project. This support is accomplished by collecting sediment, temperature, and streamflow data from tributaries of the Colorado River in Grand Canyon and by collecting temperature and streamflow data on the main stem of the Colorado...
By
Arizona Water Science Center
link

Grand Canyon Streamflow and Sediment Project

The AZWSC Grand Canyon Streamflow and Sediment project supports the work of Grand Canyon Monitoring and Research Center’s (GCMRC) Discharge, Sediment and Water Quality Project. This support is accomplished by collecting sediment, temperature, and streamflow data from tributaries of the Colorado River in Grand Canyon and by collecting temperature and streamflow data on the main stem of the Colorado...
Learn More
link
Sediment sampling and surrogates

Sediment Acoustics

The U.S. Geological Survey recognizes the need to provide sediment acoustic training and to develop standardized techniques and practices.
By
Water Resources Mission Area
link

Sediment Acoustics

The U.S. Geological Survey recognizes the need to provide sediment acoustic training and to develop standardized techniques and practices.
Learn More

Model Archive for indirect discharge computation for a 300-meter reach of Sand Creek, Wyoming, USA, 2023

This product includes a model archive using the iRIC-SAC Solver for indirect discharge computation of the spring snowmelt peak flow surveyed on May 27, 2023, and estimated to have occurred in early April 2023. The best-fit discharge for this flood is 3,500 ft3/s. Other data include topographic cross-section data, control points, and high-water marks collected by RTK GPS, and selected photographs o
By
Arizona Water Science Center

Surveyed coordinates and elevations in a 2020 resurvey of previously established cross sections on the Green River between Jensen and Ouray, Utah

These data were compiled for/to National Park Service and Upper Colorado River Endangered Fish Recovery Program. Objective(s) of our study were to resurvey previously established cross sections on the Green River, Utah, in, and upstream, from Ouray National Wildlife Refuge to document changes in channel width, depth, and cross-sectional area. These data represent the 2020 resurvey coordinates and
By
Southwest Biological Science Center

Surveyed coordinates and elevations in a 2017 resurvey of previously established cross sections on the Little Snake and Yampa rivers in Lily and Deerlodge parks, Colorado

These data were compiled for the National Park Service and Upper Colorado River Endangered Fish Recovery Program. Objective(s) of our study were to resurvey previously established cross sections on the Yampa and Little Snake rivers in the Deerlodge Park area to document changes in channel width, depth, and cross-sectional area. A secondary purpose of this study was to document the location of the
By
Southwest Biological Science Center

Streamflow measurement and channel cross section data from a synoptic base-flow survey of the Verde River, Arizona, USA January 2021

These data include a summary of a base flow survey of the Verde River within Verde Valley, a ~65km reach from ~7 km above Clarkdale, AZ to ~5km below the mouth of West Clear Creek. Data include discharge, water temperature, and specific conductance values from 22 sites on the Verde River and its tributaries, including Oak Creek, Beaver Creek, West Clear Creek, and irrigation ditches. These data al
By
Arizona Water Science Center

Topographic data, historical peak-stage data, and 2D flow models for the lowermost Little Colorado River, Arizona, USA, 2017

These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include example models in FaSTMECH and SToRM solvers in the iRIC framework, topographic data collected by LiDAR and total station in June 2017, and high water marks from nine historic floods. Other data also include location and other information for control points and g
By
Arizona Water Science Center

Geomorphic Change-Sediment Transport Data for the Little Colorado River, Arizona, USA

These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include topographic data collected by LIDAR and total station in June 2017, high water marks from nine historic floods, and control points and gage structures. Topographic data include ground topography collected by LIDAR and channel bathymetry collected by total station
By
Southwest Biological Science Center

Geomorphic Change-Sediment Transport Data for Kanab Creek, Arizona USA

These data were compiled to accompany flow modeling work on Kanab Creek near the mouth (USGS gage 09403850). The data include topographic data collected by a remote sensing detection light detection and ranging (LIDAR) system and surveying total station in June 2017, high water marks from six floods from 2011 to 2013, and control points and gage structures. Topographic data include ground topograp
By
Southwest Biological Science Center

Changes in sand storage in the Colorado River in Grand Canyon National Park from July 2017 through June 2020

Changes in the quantity of sand stored within river segments can affect aquatic and riparian habitat, archeological resources, and recreation. Since summer to fall of 2002, gaging stations on the Colorado River in Grand Canyon National Park and on its major tributaries and selected lesser tributaries have measured the mass of sand transported past each station, which allows for changes in the mass
Authors
Ronald E. Griffiths, David J. Topping, Joel A. Unema
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, Southwest Biological Science Center

Resurvey of cross sections on the Yampa and Little Snake Rivers in Lily and Deerlodge Parks, Colorado

Resurveys of seven geomorphologic cross sections located in the Lily Park and Deerlodge Park, Colorado, reaches of the Yampa and Little Snake Rivers were conducted in October 2017. These cross sections extend from Lily Park, at the confluence of the two rivers, to Deerlodge Park within Dinosaur National Monument. Four cross sections were first surveyed in 1983 and then resurveyed in 1997. The rema
Authors
Ronald E. Griffiths, David J. Topping, Christina Leonard, Joel A. Unema
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, Southwest Biological Science Center

Historical floods and geomorphic change in the lower Little Colorado River during the late 19th to early 21st centuries

The Little Colorado River is a major tributary to the Colorado River with a confluence at the boundary between Marble and Grand Canyons within Grand Canyon National Park, Arizona. The bedrock gorge of the lower Little Colorado River is home to the largest known population of Gila cypha (humpback chub), an endangered fish endemic to the Colorado River Basin. Channel conditions might affect the spaw
Authors
Joel A. Unema, David J. Topping, Keith Kohl, Michael J. Pillow, Joshua J. Caster
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, Southwest Biological Science Center

An assessment of uranium in groundwater in the Grand Canyon region

The Grand Canyon region in northern Arizona is a home or sacred place of origin for many Native Americans and is visited by over 6 million tourists each year. Most communities in the area depend upon groundwater for all water uses. Some of the highest-grade uranium ore in the United States also is found in the Grand Canyon region. A withdrawal of over 1 million acres of Federal land in the Gran
Authors
Fred D. Tillman, Kimberly R. Beisner, Jessica R. Anderson, Joel A. Unema
By
Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Arizona Water Science Center, New Mexico Water Science Center

Self-limitation of sand storage in a bedrock-canyon river arising from the interaction of flow and grain size

Bedrock-canyon rivers tend to be supply limited because they are efficient transporters of sediment and not because the upstream supply of sediment is small. A byproduct of this supply limitation is that the finer alluvium stored in these rivers has shorter residence times and smaller volumes than in alluvial rivers. To improve our understanding of disequilibrium sediment transport and its effect
Authors
David Topping, Paul Grams, Ronald E. Griffiths, David Dean, Scott Wright, Joel A. Unema
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, California Water Science Center, Southwest Biological Science Center

Assessing uranium and select trace elements associated with breccia pipe uranium deposits in the Colorado River and main tributaries in Grand Canyon, USA

Assessing chemical loading from streams in remote, difficult-to-access watersheds is challenging. The Grand Canyon area in northern Arizona, an international tourist destination and sacred place for many Native Americans, is characterized by broad plateaus divided by canyons as much as two-thousand meters deep and hosts some of the highest-grade uranium deposits in the U.S. From 2015–2018 major su
Authors
Fred D. Tillman, Jessica R. Anderson, Joel A. Unema, Thomas Chapin
By
Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Arizona Water Science Center, Geology, Geophysics, and Geochemistry Science Center

Water-magma interaction and plume processes in the 2008 Okmok eruption, Alaska

Eruptions of similar explosivity can have divergent effects on the surroundings due to differences in the behavior of the tephra in the eruption column and atmosphere. Okmok volcano, located on Umnak Island in the eastern Aleutian Islands, erupted explosively between 12 July and 19 August 2008. The basaltic andesitic eruption ejected ∼0.24 km3dense rock equivalent (DRE) of tephra, primarily direct
Authors
Joel A. Unema, Michael H. Ort, Jessica D Larsen, Christina A. Neal, Janet R. Schaefer
By
Volcano Hazards Program, Volcano Science Center

Science and Products

link
Photo of USGS hydrologist collecting quarterly suspended-sediment samples from a kayak at Colorado River below Imperial Dam

Sediment Transport in the Colorado River and All-American Canal system at Imperial Dam

Like many other dams, Imperial Dam impounds much of the suspended sediment moving in the Colorado River but some of that suspended sediment makes its way to the All-American Canal, a major diversion for irrigation and municipal water. Water entering the All-American Canal is settled in several desilting basins to remove most of the remaining suspended sediment. The collected sediment from the...
By
Arizona Water Science Center
link

Sediment Transport in the Colorado River and All-American Canal system at Imperial Dam

Like many other dams, Imperial Dam impounds much of the suspended sediment moving in the Colorado River but some of that suspended sediment makes its way to the All-American Canal, a major diversion for irrigation and municipal water. Water entering the All-American Canal is settled in several desilting basins to remove most of the remaining suspended sediment. The collected sediment from the...
Learn More
link
Photograph show the initial energy wave of a flash flood on the Paria River in Arizona.

Grand Canyon Streamflow and Sediment Project

The AZWSC Grand Canyon Streamflow and Sediment project supports the work of Grand Canyon Monitoring and Research Center’s (GCMRC) Discharge, Sediment and Water Quality Project. This support is accomplished by collecting sediment, temperature, and streamflow data from tributaries of the Colorado River in Grand Canyon and by collecting temperature and streamflow data on the main stem of the Colorado...
By
Arizona Water Science Center
link

Grand Canyon Streamflow and Sediment Project

The AZWSC Grand Canyon Streamflow and Sediment project supports the work of Grand Canyon Monitoring and Research Center’s (GCMRC) Discharge, Sediment and Water Quality Project. This support is accomplished by collecting sediment, temperature, and streamflow data from tributaries of the Colorado River in Grand Canyon and by collecting temperature and streamflow data on the main stem of the Colorado...
Learn More
link
Sediment sampling and surrogates

Sediment Acoustics

The U.S. Geological Survey recognizes the need to provide sediment acoustic training and to develop standardized techniques and practices.
By
Water Resources Mission Area
link

Sediment Acoustics

The U.S. Geological Survey recognizes the need to provide sediment acoustic training and to develop standardized techniques and practices.
Learn More

Model Archive for indirect discharge computation for a 300-meter reach of Sand Creek, Wyoming, USA, 2023

This product includes a model archive using the iRIC-SAC Solver for indirect discharge computation of the spring snowmelt peak flow surveyed on May 27, 2023, and estimated to have occurred in early April 2023. The best-fit discharge for this flood is 3,500 ft3/s. Other data include topographic cross-section data, control points, and high-water marks collected by RTK GPS, and selected photographs o
By
Arizona Water Science Center

Surveyed coordinates and elevations in a 2020 resurvey of previously established cross sections on the Green River between Jensen and Ouray, Utah

These data were compiled for/to National Park Service and Upper Colorado River Endangered Fish Recovery Program. Objective(s) of our study were to resurvey previously established cross sections on the Green River, Utah, in, and upstream, from Ouray National Wildlife Refuge to document changes in channel width, depth, and cross-sectional area. These data represent the 2020 resurvey coordinates and
By
Southwest Biological Science Center

Surveyed coordinates and elevations in a 2017 resurvey of previously established cross sections on the Little Snake and Yampa rivers in Lily and Deerlodge parks, Colorado

These data were compiled for the National Park Service and Upper Colorado River Endangered Fish Recovery Program. Objective(s) of our study were to resurvey previously established cross sections on the Yampa and Little Snake rivers in the Deerlodge Park area to document changes in channel width, depth, and cross-sectional area. A secondary purpose of this study was to document the location of the
By
Southwest Biological Science Center

Streamflow measurement and channel cross section data from a synoptic base-flow survey of the Verde River, Arizona, USA January 2021

These data include a summary of a base flow survey of the Verde River within Verde Valley, a ~65km reach from ~7 km above Clarkdale, AZ to ~5km below the mouth of West Clear Creek. Data include discharge, water temperature, and specific conductance values from 22 sites on the Verde River and its tributaries, including Oak Creek, Beaver Creek, West Clear Creek, and irrigation ditches. These data al
By
Arizona Water Science Center

Topographic data, historical peak-stage data, and 2D flow models for the lowermost Little Colorado River, Arizona, USA, 2017

These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include example models in FaSTMECH and SToRM solvers in the iRIC framework, topographic data collected by LiDAR and total station in June 2017, and high water marks from nine historic floods. Other data also include location and other information for control points and g
By
Arizona Water Science Center

Geomorphic Change-Sediment Transport Data for the Little Colorado River, Arizona, USA

These data were compiled to accompany flow modeling work on Little Colorado river above the mouth (USGS gage 09402300). The data include topographic data collected by LIDAR and total station in June 2017, high water marks from nine historic floods, and control points and gage structures. Topographic data include ground topography collected by LIDAR and channel bathymetry collected by total station
By
Southwest Biological Science Center

Geomorphic Change-Sediment Transport Data for Kanab Creek, Arizona USA

These data were compiled to accompany flow modeling work on Kanab Creek near the mouth (USGS gage 09403850). The data include topographic data collected by a remote sensing detection light detection and ranging (LIDAR) system and surveying total station in June 2017, high water marks from six floods from 2011 to 2013, and control points and gage structures. Topographic data include ground topograp
By
Southwest Biological Science Center

Changes in sand storage in the Colorado River in Grand Canyon National Park from July 2017 through June 2020

Changes in the quantity of sand stored within river segments can affect aquatic and riparian habitat, archeological resources, and recreation. Since summer to fall of 2002, gaging stations on the Colorado River in Grand Canyon National Park and on its major tributaries and selected lesser tributaries have measured the mass of sand transported past each station, which allows for changes in the mass
Authors
Ronald E. Griffiths, David J. Topping, Joel A. Unema
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, Southwest Biological Science Center

Resurvey of cross sections on the Yampa and Little Snake Rivers in Lily and Deerlodge Parks, Colorado

Resurveys of seven geomorphologic cross sections located in the Lily Park and Deerlodge Park, Colorado, reaches of the Yampa and Little Snake Rivers were conducted in October 2017. These cross sections extend from Lily Park, at the confluence of the two rivers, to Deerlodge Park within Dinosaur National Monument. Four cross sections were first surveyed in 1983 and then resurveyed in 1997. The rema
Authors
Ronald E. Griffiths, David J. Topping, Christina Leonard, Joel A. Unema
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, Southwest Biological Science Center

Historical floods and geomorphic change in the lower Little Colorado River during the late 19th to early 21st centuries

The Little Colorado River is a major tributary to the Colorado River with a confluence at the boundary between Marble and Grand Canyons within Grand Canyon National Park, Arizona. The bedrock gorge of the lower Little Colorado River is home to the largest known population of Gila cypha (humpback chub), an endangered fish endemic to the Colorado River Basin. Channel conditions might affect the spaw
Authors
Joel A. Unema, David J. Topping, Keith Kohl, Michael J. Pillow, Joshua J. Caster
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, Southwest Biological Science Center

An assessment of uranium in groundwater in the Grand Canyon region

The Grand Canyon region in northern Arizona is a home or sacred place of origin for many Native Americans and is visited by over 6 million tourists each year. Most communities in the area depend upon groundwater for all water uses. Some of the highest-grade uranium ore in the United States also is found in the Grand Canyon region. A withdrawal of over 1 million acres of Federal land in the Gran
Authors
Fred D. Tillman, Kimberly R. Beisner, Jessica R. Anderson, Joel A. Unema
By
Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Arizona Water Science Center, New Mexico Water Science Center

Self-limitation of sand storage in a bedrock-canyon river arising from the interaction of flow and grain size

Bedrock-canyon rivers tend to be supply limited because they are efficient transporters of sediment and not because the upstream supply of sediment is small. A byproduct of this supply limitation is that the finer alluvium stored in these rivers has shorter residence times and smaller volumes than in alluvial rivers. To improve our understanding of disequilibrium sediment transport and its effect
Authors
David Topping, Paul Grams, Ronald E. Griffiths, David Dean, Scott Wright, Joel A. Unema
By
Water Resources Mission Area, Ecosystems Mission Area, Arizona Water Science Center, California Water Science Center, Southwest Biological Science Center

Assessing uranium and select trace elements associated with breccia pipe uranium deposits in the Colorado River and main tributaries in Grand Canyon, USA

Assessing chemical loading from streams in remote, difficult-to-access watersheds is challenging. The Grand Canyon area in northern Arizona, an international tourist destination and sacred place for many Native Americans, is characterized by broad plateaus divided by canyons as much as two-thousand meters deep and hosts some of the highest-grade uranium deposits in the U.S. From 2015–2018 major su
Authors
Fred D. Tillman, Jessica R. Anderson, Joel A. Unema, Thomas Chapin
By
Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Arizona Water Science Center, Geology, Geophysics, and Geochemistry Science Center

Water-magma interaction and plume processes in the 2008 Okmok eruption, Alaska

Eruptions of similar explosivity can have divergent effects on the surroundings due to differences in the behavior of the tephra in the eruption column and atmosphere. Okmok volcano, located on Umnak Island in the eastern Aleutian Islands, erupted explosively between 12 July and 19 August 2008. The basaltic andesitic eruption ejected ∼0.24 km3dense rock equivalent (DRE) of tephra, primarily direct
Authors
Joel A. Unema, Michael H. Ort, Jessica D Larsen, Christina A. Neal, Janet R. Schaefer
By
Volcano Hazards Program, Volcano Science Center
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