Person

Jon J Major

Scientist In Charge, CVO

Volcano Science Center

Email: jjmajor@usgs.gov
Office Phone: 360-993-8927
Fax: 360-993-8980
ORCID: 0000-0003-2449-4466

Supervisor: Christina Neal

5 items:

Landscape context and the biophysical response of rivers to dam removal in the United States Abstract Dams have been a fundamental part of the U.S. national agenda over the past two hundred years. Recently, however, dam removal has emerged as a strategy for addressing aging, obsolete infrastructure and more than 1,100 dams have been removed since the 1970s. However, only 130 of these removals had any ecological or geomorphic assessments, and fewer than half of those included before- and after-removal (BAR) studies. In addition, this growing, but limited collection of dam-removal studies is limited to distinct landscape settings. We conducted a meta-analysis to compare the landscape context of existing and removed dams and assessed the biophysical responses to dam removal for 63 BAR studies. The highest... Categories: Publication; Types: Citation
Dam removal: Listening in Abstract Dam removal is widely used as an approach for river restoration in the United States. The increase in dam removals--particularly large dams--and associated dam-removal studies over the last few decades motivated a working group at the USGS John Wesley Powell Center for Analysis and Synthesis to review and synthesize available studies of dam removals and their findings. Based on dam removals thus far, some general conclusions have emerged: (1) physical responses are typically fast, with the rate of sediment erosion largely dependent on sediment characteristics and dam-removal strategy; (2) ecological responses to dam removal differ among the affected upstream, downstream, and reservoir reaches; (3) dam removal... Categories: Publication; Types: Citation
Geomorphic Responses to Dam Removal in the United States – a Two-Decade Perspective Recent decades have seen a marked increase in the number of dams removed in the United States. Investigations following a number of removals are beginning to inform how, and how fast, rivers and their ecosystems respond to released sediment. Though only a few tens of studies detail physical responses to removals, common findings have begun to emerge. They include: (1) Rivers are resilient and respond quickly to dam removals, especially when removals are sudden rather than prolonged. Rivers can swiftly evacuate large fractions of reservoir sediment (≥50% within one year), especially when sediment is coarse grained (sand and gravel). The channel downstream typically takes months to years--not decades--to achieve a... Categories: Publication; Types: Citation
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 between physical and ecological aspects of dam removal are poorly known. From recent work, however, observations are now available from several diverse settings nationwide to allow synthesis of key physical and ecological processes associated with dam removals, including fish and benthic community response, reservoir erosion,... Categories: Project; Tags: Active, All Working Groups, Dam removal, Dams, Ecosystems, All tags...
Digital elevation model of South Fork Toutle River, Mount St. Helens, based on June–July 1980 airborne photogrammetry The lateral blast, debris avalanche, and lahars of the May 18th, 1980, eruption of Mount St. Helens, Washington, dramatically altered the surrounding landscape. The eruption produced mudflows in the South Fork Toutle River basin, which drains the western slopes of the volcano. Orthophotography was acquired shortly after the eruption (June 19 and July 1). Survey extent includes South Fork Toutle River, from its headwaters at Talas and Toutle Glaciers to its mouth at the confluence with North Fork Toutle River near Toutle, Washington. In 2004, Photo Sciences, Inc., under contract to the U.S. Geological Survey (USGS), used softcopy photogrammetry techniques to produce a contour map, breaklines, and masspoints. A USGS... Tags: Cascade Range, Cowlitz County, DEM, Ecology, Forestry, All tags...

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