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A key issue faced in dam removal is the rate and timing of remobilization and discharge of stored reservoir sediments following the removal. Different removal strategies can result in different trajectories of upstream sediment transport and knickpoint migration. We examine this issue of for the Marmot Dam removal in Sandy River, Oregon, USA using both physical experiments and field studies accompanying removal of the dam in October 2007. The physical experiment was designed to provide insights on how and if the position of a cofferdam notch will affect how reservoir sediments are remobilized, with the goal of minimizing the volume of sediment stranded in terraces. Data and observations indicate that at lower failure...
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Hydrodynamic models are often used to reduce uncertainty regarding the outcomes of dam removal, though the accuracy of these models is not regularly evaluated post-removal. With the goal of improving understanding on the accuracy and limitations of making predictions of sediment dynamics following dam removal, we compare predicted and observed sediment erosion and deposition in the reservoir and downstream for the Chiloquin Dam removal. Results from a 1D (HEC-RAS) hydraulic and sediment transport analysis (Yang equation) are compared to pre- and post-removal bathymetric and sediment surveys. Observed bathymetric changes indicate minimal response in both the reservoir and the downstream reaches to the removal, due...
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Rapids on the Colorado River in Grand Canyon attract over 20,000 white-water enthusiasts a year and are considered one of the premiere collections of rapids in North America. While this collection of rapids is an important recreational resource, relatively little is known of the specific hydraulics of individual rapids. Flow measurements are occasionally made in the low-velocity reaches between rapids, but the turbulent and dangerous nature of rapids makes in-situ data collection challenging. The present study measured hydraulics within a small rapid in Grand Canyon as well as an alluvial reach of the Colorado River in Glen Canyon using a Sontek Argonaut acoustic Doppler velocimeter (ADV)2. The ADV was mounted near...
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Abstract (from http://ascelibrary.org/doi/abs/10.1061/(ASCE)HE.1943-5584.0001282): A novel multisite cascading calibration (MSCC) approach using the shuffled complex evolution–University of Arizona (SCE-UA) optimization method, developed at the University of Arizona, was employed to calibrate the variable infiltration capacity (VIC) model in the Red River Basin. Model simulations were conducted at 35 nested gauging stations. Compared with simulated results using a priori parameters, single-site calibration can improve VIC model performance at specific calibration sites; however, improvement is still limited in upstream locations. The newly developed MSCC approach overcomes this limitation. Simulations using MSCC...
Categories: Publication;
Types: Citation;
Tags: Indigenous Peoples,
Rivers, Streams and Lakes,
South Central CASC,
Tribes and Tribal Organizations,
Water, Coasts and Ice, All tags...
hydrological modeling,
optimization,
water, Fewer tags
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The paper suggests the ‘middle out’ as an additional, and sometimes alternative approach to ’bottom-up’ and ’ top-down’ efforts to drive low carbon innovations and practices in society. Individuals are often seen by policy makers as the target agents for changing their own behaviour. To induce bottom-up change in energy demand patterns, governmental and non-governmental organizations have produced information tools such as carbon calculators, real-time feedback, and media based campaigns encourage individuals to reduce their carbon emissions voluntarily. At the same time, government employs top-down regulatory approaches to reduce emissions. These are being demonstrated in the introduction of market mechanisms (e.g....
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