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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...
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Arizona Water Science Center
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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...
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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...
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Arizona Water Science Center
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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...
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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.
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Water Resources Mission Area
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Sediment Acoustics

The U.S. Geological Survey recognizes the need to provide sediment acoustic training and to develop standardized techniques and practices.
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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
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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
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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 A. Wright, Joel A. Unema
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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
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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

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
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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

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