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US Watersheds: Underlying Geodynamic Processes And Human Impacts Considered

Date:
August 20, 2007
Source:
Geological Society of America
Summary:
Two papers in the August-September issue of Geosphere consider watersheds in the US. The Yellowstone watershed is unique because of its changing discharge values over the twentieth century, as well as its overall lower scaled discharges with drainage areas. Climatic trends that control the timing of winter snowpack melting, increased frequency and intensity of forest fires, and increased human consumptive water use in downstream areas may all contribute to the observed behavior in discharges for the Yellowstone watershed.
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Two papers in the August-September issue of Geosphere consider watersheds in the US.

The first paper investigates the relationship between discharge and drainage area for five rivers: the John Day, Salmon, Wabash, Greenbrier, and Yellowstone. The rivers were selected to minimize, but not eliminate, the impacts of dams and diversions such as for irrigation on river discharges.

A minimum of 60 years of continuous discharge records from the U.S. Geological Survey national surface water database were analyzed for changes in discharge characteristics between watersheds as well as over time.

The results show that the studied watersheds can be grouped into two broad categories. The John Day, Salmon, Wabash, and Greenbrier rivers have discharges that increase linearly as their drainage area increases.

The Yellowstone watershed is unique because of its changing discharge values over the twentieth century, as well as its overall lower scaled discharges with drainage areas. Climatic trends that control the timing of winter snowpack melting, increased frequency and intensity of forest fires, and increased human consumptive water use in downstream areas may all contribute to the observed behavior in discharges for the Yellowstone watershed.

The results from the study of this set of rivers have broad implications for studies ranging from the modeling of fluvial erosion to allocations of water resources for human and environmental purposes.

FIrst article: "Natural and anthropogenic influences on the scaling of discharge with drainage area for multiple watersheds," Joshua C. Galster, Lehigh University

Snake River watershed as indicator of geodynamic processes

The second paper explores the mobility of regional watershed divides as a key geomorphic metric that can distinguish between various tectonic and dynamic mantle flow processes driving crustal deformation in the greater Yellowstone region of the northwestern United States.

This new analysis quantifies the differences between the locations of the present-day Snake River drainage divide from divides synthetically generated from digital topography filtered at specific wavelengths.

Results suggest that the topography of the Yellowstone area is supported by both dynamic mantle flow and crustal flexural mechanisms, whereas further to the west along the Snake River Plain, the topography is supported only by flexural mechanisms.

Our analysis suggests that the eastward migration of the Snake River drainage divide lags behind the continued northeastward propagation of high standing topography associated with the Yellowstone hotspot by 1 to 2 million years.

Second article: "Position of the Snake River watershed divide as an indicator of geodynamic processes in the greater Yellowstone region, western North America," Karl W. Wegmann et al., corresponding author: Frank J. Pazzaglia: Lehigh University


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Geological Society of America. "US Watersheds: Underlying Geodynamic Processes And Human Impacts Considered." ScienceDaily. ScienceDaily, 20 August 2007. <www.sciencedaily.com/releases/2007/08/070816113223.htm>.
Geological Society of America. (2007, August 20). US Watersheds: Underlying Geodynamic Processes And Human Impacts Considered. ScienceDaily. Retrieved May 23, 2017 from www.sciencedaily.com/releases/2007/08/070816113223.htm
Geological Society of America. "US Watersheds: Underlying Geodynamic Processes And Human Impacts Considered." ScienceDaily. www.sciencedaily.com/releases/2007/08/070816113223.htm (accessed May 23, 2017).

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