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Full-Text Articles in Earth Sciences

Utility Of Bench Scale Sand Tank Experiments At Assessing Permeable Reactive Barrier Design, Brandon Meier Dec 2019

Utility Of Bench Scale Sand Tank Experiments At Assessing Permeable Reactive Barrier Design, Brandon Meier

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of this work was to evaluate the utility of bench scale sand tank experiments at assessing permeable reactive barrier (PRB) design. Our criteria for meeting this goal was that differences between PRB designs could be identified solely by measuring concentration in outflow from the sand tank models. For our PRB designs (funnel-and-gate, staggered wells, and parallel bars), numerical simulations clearly showed that PRB design had a quantifiable effect on outflow concentration, provided that the solute reacted with the PRB materials. Conversely, use of a conservative (non-reactive) solute did not allow us to discern between PRB design alternatives. Employing …


Assessment Of Impacts To Hydroclimatology And River Operations Due To Climate Change Over The Colorado River Basin, William Paul Miller May 2010

Assessment Of Impacts To Hydroclimatology And River Operations Due To Climate Change Over The Colorado River Basin, William Paul Miller

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation investigated the impacts of climate change to the hydroclimatology and river and reservoir management operations within the Colorado River Basin. Preliminary research indicated observed warming trends throughout the Colorado River Basin and corresponding seasonal trends to the magnitude and timing of runoff in the Colorado River Basin. Subsequent research investigated the changing character of precipitation and corresponding impacts to streamflow over the Colorado River Basin. Analysis of snowpack telemetry (SNOTEL) stations over the American West and Colorado River Basin indicated decreasing trends in annual snowpack, often at least at the 95% confidence interval. A shorter snowpack season was …


Role Of Forward Model In Surface-Wave Studies To Delineate A Buried High-Velocity Layer, Xiaohui Jin, Barbara Luke, Carlos Calderon-Macias Mar 2009

Role Of Forward Model In Surface-Wave Studies To Delineate A Buried High-Velocity Layer, Xiaohui Jin, Barbara Luke, Carlos Calderon-Macias

Civil and Environmental Engineering and Construction Faculty Research

Procedures are tested and compared for processing Rayleigh surface wave data to obtain one-dimensional shear wave velocity profiles for a hypothetical site that contains a buried high-velocity layer (HVL). The main purpose of such an investigation would be to discriminate and characterize the HVL. When target dispersion curves are derived from synthetic time histories, for the most part, the HVL is better identified when profiles are inverted using only the fundamental mode of Rayleigh wave propagation, rather than a more compatible but more complex forward model. The outcomes imply that in practice, a simple forward model might be more successful …


Interpreting Surface-Wave Data For A Site With Shallow Bedrock, Daniel W. Casto, Barbara Luke, Carlos Calderon-Macias, Ronald Kaufmann Jan 2009

Interpreting Surface-Wave Data For A Site With Shallow Bedrock, Daniel W. Casto, Barbara Luke, Carlos Calderon-Macias, Ronald Kaufmann

Civil and Environmental Engineering and Construction Faculty Research

The inversion of dispersive Rayleigh-wave data has been shown to be successful in providing reliable estimated shear-wave velocities within unconsolidated materials in the near surface. However, in a case where the multi-channel analysis of surface waves method was applied to a site consisting of clay residuum overlying basalt bedrock, inversion for the fundamental-mode Rayleigh wave resulted in shear-wave velocities within the rock that are less than half of expected values. Forward modeling reveals that the fundamental-mode dispersion curve is hardly sensitive to bedrock velocity perturbations over a practical range of wavelengths, leading to poorly constrained solutions. Standard surface-wave methods can …


Alternative Principal Components Regression Procedures For Dendrohydrologic Reconstructions, Hugo G. Hidalgo, Thomas C. Piechota, John A. Dracup Nov 2000

Alternative Principal Components Regression Procedures For Dendrohydrologic Reconstructions, Hugo G. Hidalgo, Thomas C. Piechota, John A. Dracup

Civil and Environmental Engineering and Construction Faculty Research

Streamflow reconstruction using tree ring information (dendrohydrology) has traditionally used principal components analysis (PCA) and stepwise regression to form a transfer function. However, PCA has several procedural choices that may result in very different reconstructions. This study assesses the different procedures in PCA-based regression and suggests alternative procedures for selection of variables and principal components. Cross-validation statistics are presented as an alternative for independently testing and identifying the optimal model. The objective is to use these statistics as a measure of the model's performance to find a conceptually acceptable model with a low prediction error and the fewest number of …


The 1963-64 Lake Mead Survey, J. M. Lara, J. I. Sanders, Bureau Of Reclamation Aug 1970

The 1963-64 Lake Mead Survey, J. M. Lara, J. I. Sanders, Bureau Of Reclamation

Publications (WR)

The 1963-64 Lake Mead survey was run to compute the reservoir capacity. Results of the geodetic and hydrographic surveys and sediment sampling equipment are described. The geodetic survey showed Hoover Dam subsided an average of 118 mm since 1935. Sonic sounding, photogrammetry, and crosssectional profiling methods were used to run the hydrographic survey. Reservoir area and capacity tables were generated using an electronic computer. The present lake capacity is 29,755,000 acre-ft and the reservoir surface area is 162,700 acres at elevation 1229 ft. 2,720,000 acre-ft of sediments accumulated in the lake since 1935. A unit weight of 60 Ib/cu ft …


Comprehensive Survey Of Sedimentation In Lake Mead, 1948-49, W. O. Smith, C. P. Vetter, G. B. Cummings, U.S. Bureau Of Reclamation Jan 1960

Comprehensive Survey Of Sedimentation In Lake Mead, 1948-49, W. O. Smith, C. P. Vetter, G. B. Cummings, U.S. Bureau Of Reclamation

Publications (WR)

Reservoirs are becoming an increasingly prominent feature of the American landscape. Built for flood mitigation and to change a fluctuating river into a dependable source of water for irrigation, power, and other purposes, they are predestined, like natural lakes, to be destroyed sometime following their creation. Sedimentation sooner or later robs most lakes and reservoirs of their capacity to store water. The significance of sedimentation in the life of Lake Mead, the largest artificial reservoir in the world, was realized when the plan for the reservoir was conceived, and an aerial survey of the floor was made in 1935 before …