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At least 127 records · Page 7Linked to original sources
USGS2011

Adaptive finite volume methods with well-balanced Riemann solvers for modeling floods in rugged terrain: Application to the Malpasset dam-break flood (France, 1959)

The simulation of advancing flood waves over rugged topography, by solving the shallow-water equations with well-balanced high-resolution finite volume methods and block-structured dynamic adaptive mesh refinement (AMR), is described and validated in this paper. The efficiency of block-structured AMR makes large-scale problems tractable, and allows the use of accurate and stable methods developed for solving general hyperbolic problems on quadrilateral grids. Features indicative of flooding in rugged terrain, such as advancing wet-dry fronts and non-stationary steady states due to balanced source terms from variable topography, present unique challenges and require modifications such as special Riemann solvers. A well-balanced Riemann solver for inundation and general (non-stationary) flow over topography is tested in this context. The difficulties of modeling floods in rugged terrain, and the rationale for and efficacy of using AMR and well-balanced methods, are presented. The algorithms are validated by simulating the Malpasset dam-break flood (France, 1959), which has served as a benchmark problem previously. Historical field data, laboratory model data and other numerical simulation results (computed on static fitted meshes) are shown for comparison. The methods are implemented in GEOCLAW, a subset of the open-source CLAWPACK software. All the software is freely available at. Published in 2010 by John Wiley & Sons, Ltd.

International Journal for Numerical Methods in Flu↗
USGS2020

SPEAR: The next generation GFDL modeling system for seasonal to multidecadal prediction and projection

We document the development and simulation characteristics of the next generation modeling system for seasonal to decadal prediction and projection at the Geophysical Fluid Dynamics Laboratory (GFDL). SPEAR ( S eamless System for P rediction and EA rth System R esearch) is built from component models recently developed at GFDL—the AM4 atmosphere model, MOM6 ocean code, LM4 land model, and SIS2 sea ice model. The SPEAR models are specifically designed with attributes needed for a prediction model for seasonal to decadal time scales, including the ability to run large ensembles of simulations with available computational resources. For computational speed SPEAR uses a coarse ocean resolution of approximately 1.0° (with tropical refinement). SPEAR can use differing atmospheric horizontal resolutions ranging from 1° to 0.25°. The higher atmospheric resolution facilitates improved simulation of regional climate and extremes. SPEAR is built from the same components as the GFDL CM4 and ESM4 models but with design choices geared toward seasonal to multidecadal physical climate prediction and projection. We document simulation characteristics for the time mean climate, aspects of internal variability, and the response to both idealized and realistic radiative forcing change. We describe in greater detail one focus of the model development process that was motivated by the importance of the Southern Ocean to the global climate system. We present sensitivity tests that document the influence of the Antarctic surface heat budget on Southern Ocean ventilation and deep global ocean circulation. These findings were also useful in the development processes for the GFDL CM4 and ESM4 models.

Journal of Advances in Modeling Earth Systems↗
USGS2021

Heat flux from a vapor-dominated hydrothermal field beneath Yellowstone Lake

We report results from 149 heat flux measurements made over n ∼2-year interval at sites in and around a vapor-dominated geothermal field located at water depths of ∼100–120 m in Yellowstone Lake, Wyoming. Measurements of both in situ temperature and thermal conductivity as a function of depth were made with a 1 m probe via a remotely operated vehicle, and are combined to compute the vertical conductive heat flux. Inside the ∼55.5 × 10 3 m 2 bathymetric depression demarcating the vapor-dominated field, the median conductive flux is 13 W m −2 , with a conductive output of 0.72 MW. Outside the thermal field, the median conductive flux is 3.5 W m −2 . We observed 49 active vents inside the thermal field, with an estimated mass discharge rate of 56 kg s −1 , a median exit-fluid temperature of 132°C, and a total heat output of 29 MW. We find evidence for relatively weak secondary convection with a total output of 0.09 MW in thermal area lake floor sediments. Our data indicate that vapor beneath the thermal field is trapped by a low-permeability cap at a temperature of ∼189°C and a depth of ∼15 m below the lake floor. The thermal output of the Deep Hole is among the highest of any vapor-dominated field in Yellowstone, due in part to the high boiling temperatures associated with the elevated lake floor pressures.

Wyoming↗
USGS1997

Multiphase groundwater flow near cooling plutons

We investigate groundwater flow near cooling plutons with a computer program that can model multiphase flow, temperatures up to 1200°C, thermal pressurization, and temperature‐dependent rock properties. A series of experiments examines the effects of host‐rock permeability, size and depth of pluton emplacement, single versus multiple intrusions, the influence of a caprock, and the impact of topographically driven groundwater flow. We also reproduce and evaluate some of the pioneering numerical experiments on flow around plutons. Host‐rock permeability is the principal factor influencing fluid circulation and heat transfer in hydrothermal systems. The hottest and most steam‐rich systems develop where permeability is of the order of 10 −15 m 2 . Temperatures and life spans of systems decrease with increasing permeability. Conduction‐dominated systems, in which permeabilities are ≤10 −16 m 2 , persist longer but exhibit relatively modest increases in near‐surface temperatures relative to ambient conditions. Pluton size, emplacement depth, and initial thermal conditions have less influence on hydrothermal circulation patterns but affect the extent of boiling and duration of hydrothermal systems. Topographically driven groundwater flow can significantly alter hydrothermal circulation; however, a low‐permeability caprock effectively decouples the topographically and density‐driven systems and stabilizes the mixing interface between them thereby defining a likely ore‐forming environment.

Journal of Geophysical Research B: Solid Earth↗
USGS2008

Measuring gravity currents in the Chicago River, Chicago, Illinois

Recent studies of the Chicago River have determined that gravity currents are responsible for persistent bidirectional flows that have been observed in the river. A gravity current is the flow of one fluid within another caused by a density difference between the fluids. These studies demonstrated how acoustic Doppler current profilers (ADCP) can be used to detect and characterize gravity currents in the field. In order to better understand the formation and evolution of these gravity currents, the U.S. Geological Survey (USGS) has installed ADCPs and other instruments to continuously measure gravity currents in the Chicago River and the North Branch Chicago River. These instruments include stage sensors, thermistor strings, and both upward-looking and horizontal ADCPs. Data loggers and computers installed at gaging stations along the river are used to collect data from these instruments and transmit them to USGS offices. ?? 2008 IEEE.

Illinois↗
USGS1992

Geochemical effects of deep-well injection of the Paradox Valley brine into Paleozoic carbonate rocks, Colorado, U.S.A.

Brine seepage into the Dolores River from ground water in Paradox Valley, Colorado constitutes a major source of salt to the Colorado River. Plants are enderway to remove this source of salt by drawing down the Paradox Valley brine (PVB) and forcibly injecting it into a deep disposal well (4.8 km). Experiments were conducted to determine the effects of deep-well injection of PVB. The results show that PVB is near saturation with anhydrite at 25°C, and that heating results in anhydrite precipitation. The amount and the rate at which anhydrite forms is temperature, pressure, and substrate dependent. Paradox Valley brine heated in the presence of Precambrian rocks from the drill core produces the same amount of anhydrite as PVB heated alone, but at a greatly accelerated rate. A 30% dilution of PVB with Dolores River water completely eliminates anhydrite precipitation when the fluid is heated with the Precambrian rocks. Interaction of PVB and Leadville Limestone is characterized by dolomitization of calcite by brine Mg which releases Ca to solution. This added Ca reacts with SO 4 to form increased amounts of anhydrite. A 20% dilution of PVB by Dolores River water has no effect on dolomitization and reduces the amount of anhydrite only slightly. A 65% dilution of PVB by Dolores River water still does not prevent dolomitization but does suppress anhydrite formation. Computer modeling of PVB by programs utilizing the Pitzer ion-interaction parameters is in general agreement with the experimental results. Ion-activity products calculated by both SOLMINEQ and PHRQPITZ are close to equilibrium with both anhydrite and dolomite whenever these phases are present experimentally, although the calculations over-estimate by a factor of 2 the degree of saturation. Some discrepancies in the calculated results between the two programs are due largely to differences in mineral solubility data.

Colorado↗
USGS2020

A stress-similarity triggering model for aftershocks of the MW6.4 and MW7.1 Ridgecrest earthquakes

The July 2019 M w "> M w 6.4 and 7.1 Ridgecrest earthquakes triggered numerous aftershocks, including clusters of off‐fault aftershocks in an extensional stepover of the Garlock fault, near the town of Olancha, and near Panamint Valley. The locations of the off‐fault aftershocks are consistent with the stress‐similarity model of triggering, which hypothesizes that aftershocks preferentially occur in areas where the mainshock static stress change tensor is similar in orientation to the background stress tensor. The background stress field is determined from the inversion of earthquake focal mechanisms, with the spatial resolution adapted to the local density of earthquakes. The mainshock static stress change is computed using finite‐source models for the M w "> M w 6.4 foreshock and M w "> M w 7.1 mainshock. I quantify the similarity between these two stress fields using the tensor dot product of the normalized deviatoric stress tensors. The off‐fault aftershocks in the Garlock stepover and the Olancha area fall within lobes of positive stress similarity, whereas the aftershocks near Panamint Valley are partially within a lobe. The cluster in the Garlock fault stepover and the smaller of two clusters near Olancha occur in regions of locally anomalous background stress that results in higher stress similarity. I compute the spatial density of M ≥ 2.0 "> M≥2.0 aftershocks and find that the aftershock density increases as a function of stress similarity, with a factor of ∼ 15 "> ∼15 difference between high stress‐similarity and low stress‐similarity areas. This result is robust with respect to the choice of mainshock model and the uncertainty of the background stress field. The aftershock density varies substantially inside the high stress‐similarity lobes, however, indicating that other variable background conditions, such as material properties, temperature, and fluid pressure, may also be playing a role. Specifically, temperature and fluid pressure conditions might help explain the low rate of aftershocks in the Coso geothermal field.

California↗
USGS1997

Resistance formulas in hydraulics-based models for routing debris flows

The one-dimensional, cross-section-averaged flow equations formulated for routing debris flows down a narrow valley are identical to those for clear-water flow, except for the differences in the values of the flow parameters, such as the momentum (or energy) correction factor, resistance coefficient, and friction slope. Though these flow parameters for debris flow in channels with cross-sections of arbitrary geometric shape can only be determined empirically, the theoretical values of such parameters for debris flow in wide channels exist. This paper aims to derive the theoretical resistance coefficient and friction slope for debris flow in wide channels using a rheological model for highly-concentrated, rapidly-sheared granular flows, such as the generalized viscoplastic fluid (GVF) model. Formulating such resistance coefficient or friction slope is equivalent to developing a generally applicable resistance formula for routing debris flows. Inclusion of a nonuniform term in the expression of the resistance formula proves useful in removing the customary assumption that the spatially varied resistance at any section is equal to what would take place with the same rate of flow passing the same section under conditions of uniformity. This in effect implies an improvement in the accuracy of unsteady debris-flow computation.

Conference Paper↗
USGS2003

Surge dynamics coupled to pore-pressure evolution in debris flows

Temporally and spatially varying pore-fluid pressures exert strong controls on debris-flow motion by mediating internal and basal friction at grain contacts. We analyze these effects by deriving a one-dimensional model of pore-pressure diffusion explicitly coupled to changes in debris-flow thickness. The new pore-pressure equation is combined with Iverson's (1997) extension of the depth-averaged Savage-Hutter (1989, 1991) granular avalanche equations to predict motion of unsteady debris-flow surges with evolving pore-pressure distributions. Computational results illustrate the profound effects of pore-pressure diffusivities on debris-flow surge depths and velocities. ?? 2003 Millpress,.

Conference Paper↗
USGS2018

Harnessing big data to rethink land heterogeneity in Earth system models

The continual growth in the availability, detail, and wealth of environmental data provides an invaluable asset to improve the characterization of land heterogeneity in Earth system models – a persistent challenge in macroscale models. However, due to the nature of these data (volume and complexity) and computational constraints, these data are underused for global applications. As a proof of concept, this study explores how to effectively and efficiently harness these data in Earth system models over a 1/4° ( ∼ 25 km) grid cell in the western foothills of the Sierra Nevada in central California. First, a novel hierarchical multivariate clustering approach (HMC) is introduced that summarizes the high-dimensional environmental data space into hydrologically interconnected representative clusters (i.e., tiles). These tiles and their associated properties are then used to parameterize the sub-grid heterogeneity of the Geophysical Fluid Dynamics Laboratory (GFDL) LM4-HB land model. To assess how this clustering approach impacts the simulated water, energy, and carbon cycles, model experiments are run using a series of different tile configurations assembled using HMC. The results over the test domain show that (1) the observed similarity over the landscape makes it possible to converge on the macroscale response of the fully distributed model with around 300 sub-grid land model tiles; (2) assembling the sub-grid tile configuration from available environmental data can have a large impact on the macroscale states and fluxes of the water, energy, and carbon cycles; for example, the defined subsurface connections between the tiles lead to a dampening of macroscale extremes; (3) connecting the fine-scale grid to the model tiles via HMC enables circumvention of the classic scale discrepancies between the macroscale and field-scale estimates; this has potentially significant implications for the evaluation and application of Earth system models.

Hydrology and Earth System Sciences↗
USGS2016

Simulating groundwater flow in karst aquifers with distributed parameter models—Comparison of porous-equivalent media and hybrid flow approaches

Understanding karst aquifers, for purposes of their management and protection, poses unique challenges. Karst aquifers are characterized by groundwater flow through conduits (tertiary porosity), and (or) layers with interconnected pores (secondary porosity) and through intergranular porosity (primary or matrix porosity). Since the late 1960s, advances have been made in the development of numerical computer codes and the use of mathematical model applications towards the understanding of dual (primary [matrix] and secondary [fractures and conduits]) porosity groundwater flow processes, as well as characterization and management of karst aquifers. The Floridan aquifer system (FAS) in Florida and parts of Alabama, Georgia, and South Carolina is composed of a thick sequence of predominantly carbonate rocks. Karst features are present over much of its area, especially in Florida where more than 30 first-magnitude springs occur, numerous sinkholes and submerged conduits have been mapped, and numerous circular lakes within sinkhole depressions are present. Different types of mathematical models have been applied for simulation of the FAS. Most of these models are distributed parameter models based on the assumption that, like a sponge, water flows through connected pores within the aquifer system and can be simulated with the same mathematical methods applied to flow through sand and gravel aquifers; these models are usually referred to as porous-equivalent media models. The partial differential equation solved for groundwater flow is the potential flow equation of fluid mechanics, which is used when flow is dominated by potential energy and has been applied for many fluid problems in which kinetic energy terms are dropped from the differential equation solved. In many groundwater model codes (basic MODFLOW), it is assumed that the water has a constant temperature and density and that flow is laminar, such that kinetic energy has minimal impact on flow. Some models have been developed that incorporate the submerged conduits as a one-dimensional pipe network within the aquifer rather than as discrete, extremely transmissive features in a porous-equivalent medium; these submerged conduit models are usually referred to as hybrid models and may include the capability to simulate both laminar and turbulent flow in the one-dimensional pipe network. Comparisons of the application of a porous-equivalent media model with and without turbulence (MODFLOW-Conduit Flow Process mode 2 and basic MODFLOW, respectively) and a hybrid (MODFLOW-Conduit Flow Process mode 1) model to the Woodville Karst Plain near Tallahassee, Florida, indicated that for annual, monthly, or seasonal average hydrologic conditions, all methods met calibration criteria (matched observed groundwater levels and average flows). Thus, the increased effort required, such as the collection of data on conduit location, to develop a hybrid model and its increased computational burden, is not necessary for simulation of average hydrologic conditions (non-laminar flow effects on simulated head and spring discharge were minimal). However, simulation of a large storm event in the Woodville Karst Plain with daily stress periods indicated that turbulence is important for matching daily springflow hydrographs. Thus, if matching streamflow hydrographs over a storm event is required, the simulation of non-laminar flow and the location of conduits are required. The main challenge in application of the methods and approaches for developing hybrid models relates to the difficulty of mapping conduit networks or having high-quality datasets to calibrate these models. Additionally, hybrid models have long simulation times, which can preclude the use of parameter estimation for calibration. Simulation of contaminant transport that does not account for preferential flow through conduits or extremely permeable zones in any approach is ill-advised. Simulation results in other karst aquifers or other parts of the FAS may differ from the comparison demonstrated herein.

Florida↗
USGS1981

A transient laboratory method for determining the hydraulic properties of 'tight' rocks-I. Theory

Transient pulse testing has been employed increasingly in the laboratory to measure the hydraulic properties of rock samples with low permeability. Several investigators have proposed a mathematical model in terms of an initial-boundary value problem to describe fluid flow in a transient pulse test. However, the solution of this problem has not been available. In analyzing data from the transient pulse test, previous investigators have either employed analytical solutions that are derived with the use of additional, restrictive assumptions, or have resorted to numerical methods. In Part I of this paper, a general, analytical solution for the transient pulse test is presented. This solution is graphically illustrated by plots of dimensionless variables for several cases of interest. The solution is shown to contain, as limiting cases, the more restrictive analytical solutions that the previous investigators have derived. A method of computing both the permeability and specific storage of the test sample from experimental data will be presented in Part II.

International Journal of Rock Mechanics and Mining↗
USGS2025

Apportionment of oxygen demand contributions from aircraft and pavement deicer freezing point depressants in airport runoff, Milwaukee, Wisconsin, 2005–2022

Aircraft anti-icers and pavement deicers improve the safety of airport operations during winter precipitation events. Runoff containing these products can contribute elevated biochemical oxygen demand (BOD) to receiving streams. We monitored runoff from Milwaukee Mitchell International Airport at one upstream site, three outfall sites, and one downstream site from 2005 to 2022 for BOD, chemical oxygen demand (COD), and freezing point depressants used in deicing and anti-icing fluids to determine the primary sources of BOD and COD in the receiving stream. The greatest concentrations of BOD, COD, and freezing point depressants occurred at the primary outfall, which drains the main terminal area, and the secondary outfall, which drains cargo operations. The greatest loadings occurred at the primary outfall; loadings were an order of magnitude less at the secondary outfall due to a small drainage area with relatively low flow volumes. At the three outfalls, median concentrations of five-day BOD (BOD 5 ) and COD were 100–1,300 mg L −1 and 200–2,100 mg L −1 respectively. Apportionment computations indicated that propylene glycol from aircraft deicers and anti-icers was responsible for at least half of the BOD 5 and COD concentrations and loadings. Acetate from pavement deicers contributed another 7%–15% at each site. These findings suggest that management actions in the primary outfall drainage area that target propylene glycol–containing deicers have the greatest potential to decrease BOD 5 in airport runoff. This work demonstrates the usefulness of BOD and COD apportionment for identifying the deicing products and locations within an airport to prioritize for reduction or recovery and treatment.

Wisconsin↗
USGS2012

Modeling variably saturated subsurface solute transport with MODFLOW-UZF and MT3DMS

The MT3DMS groundwater solute transport model was modified to simulate solute transport in the unsaturated zone by incorporating the unsaturated-zone flow (UZF1) package developed for MODFLOW. The modified MT3DMS code uses a volume-averaged approach in which Lagrangian-based UZF1 fluid fluxes and storage changes are mapped onto a fixed grid. Referred to as UZF-MT3DMS, the linked model was tested against published benchmarks solved analytically as well as against other published codes, most frequently the U.S. Geological Survey's Variably-Saturated Two-Dimensional Flow and Transport Model. Results from a suite of test cases demonstrate that the modified code accurately simulates solute advection, dispersion, and reaction in the unsaturated zone. Two- and three-dimensional simulations also were investigated to ensure unsaturated-saturated zone interaction was simulated correctly. Because the UZF1 solution is analytical, large-scale flow and transport investigations can be performed free from the computational and data burdens required by numerical solutions to Richards' equation. Results demonstrate that significant simulation runtime savings can be achieved with UZF-MT3DMS, an important development when hundreds or thousands of model runs are required during parameter estimation and uncertainty analysis. Three-dimensional variably saturated flow and transport simulations revealed UZF-MT3DMS to have runtimes that are less than one tenth of the time required by models that rely on Richards' equation. Given its accuracy and efficiency, and the wide-spread use of both MODFLOW and MT3DMS, the added capability of unsaturated-zone transport in this familiar modeling framework stands to benefit a broad user-ship.

Ground Water↗
USGS1992

Morphology of the island of Hawaii

Digital elevation data for the island of Hawaii from the U.S. Geographical Survey gridded at 30 m spacing was used to generate a slope map, a shaded relief map, and plots that compare slope and elevation for each of the five volcanoes that compose the island.These computer- generated products are useful in analyzing the morphology of the sland. The volcanoes become steeper with increasing age. The five volcanoes, in order of increasing age, are Kilauea, Mauna Lao, Hualalai, Mauna Kea and Kohala; their average slopes are 3.3, 5.4, 6.6, 7.0, and 11.3, respectively. This relation apparently results from growth of the late, steeper alkali cap on the older volcanoes that include more viscous, thicker flows, flows that are smaller hence tend to pile up more near the summit vents, and volatile- rich lavas that commonly produce steep sided cinder cones at summit vents. The cause of the gentler slopes of younger volcanoes include the high proportion of exposed fluid lava flows from the shield building stage, the ponding of lava against earlier volcanoes, and the grading of lava to sea level; subsidence of the older volcanoes have cause these gently dipping near-seas-level lava flows to subside below the sea. Finally, steep erosional canyons have developed in large areas of the older volcanoes (notably Kohala). Virtually all of the major fault systems on the sland appear to be related to the upper parts of giant landslides, most of which are hidden below sea level on the submarine flanks of the volcanoes. These are generally normal faults in the tensional regime at the heads and upper parts of the landslides Subtle changes in slope hint at buried landslide related faults scarps that have been covered by subsequent lava flows. Major erosional canyons are present in only two places, each presumed to be in the amphitheaters of the major landslides. The probably formed in this setting because steam erosion is favored by the steep sloped generated at the heads of landslides. The slope map clearly displays two bands of steep slope on Mauna Kea that mark the terminal moraines at the edges of the last two advances of the Pleistocene ice cap.

Hawaii↗
USGS2013

Real-time piscicide tracking using Rhodamine WT dye for support of application, transport, and deactivation strategies in riverine environments

Piscicide applications in riverine environments are complicated by the advection and dispersion of the piscicide by the flowing water. Proper deactivation of the fish toxin is required outside of the treatment reach to ensure that there is minimal collateral damage to fisheries downstream or in connecting and adjacent water bodies. In urban settings and highly managed waterways, further complications arise from the influence of industrial intakes and outfalls, stormwater outfalls, lock and dam operations, and general unsteady flow conditions. These complications affect the local hydrodynamics and ultimately the transport and fate of the piscicide. This report presents two techniques using Rhodamine WT dye for real-time tracking of a piscicide plume—or any passive contaminant—in rivers and waterways in natural and urban settings. Passive contaminants are those that are present in such low concentration that there is no effect (such as buoyancy) on the fluid dynamics of the receiving water body. These methods, when combined with data logging and archiving, allow for visualization and documentation of the application and deactivation process. Real-time tracking and documentation of rotenone applications in rivers and urban waterways was accomplished by encasing the rotenone plume in a plume of Rhodamine WT dye and using vessel-mounted submersible fluorometers together with acoustic Doppler current profilers (ADCP) and global positioning system (GPS) receivers to track the dye and map the water currents responsible for advection and dispersion. In this study, two methods were used to track rotenone plumes: (1) simultaneous injection of dye with rotenone and (2) delineation of the upstream and downstream boundaries of the treatment zone with dye. All data were logged and displayed on a shipboard laptop computer, so that survey personnel provided real-time feedback about the extent of the rotenone plume to rotenone application and deactivation personnel. Further, these strategies facilitate adjustment of rotenone application and deactivation strategies in real time if necessary based on the observed advection and dispersion of the rotenone plume. Two large-scale and complex applications of rotenone in the Chicago Area Waterway System (CAWS) in 2009 and 2010 to combat invasive Asian carp are documented in this report. The application in Chicago Sanitary and Ship Canal (CSSC) in December 2009 involved more than 1,800 gallons of rotenone injected at multiple stations through a 6.2-mile reach of the canal near Lockport, Illinois. The rotenone plume was encased in Rhodamine WT dye so that two survey boats provided real-time feedback to shore personnel regarding the plume extent as it advected downstream. Real-time tracking of the rotenone was essential in this large-scale application because of the multistage injection strategy and the numerous deactivation points required to minimize collateral damage to fisheries in surrounding and receiving water bodies. All timing of application and deactivation operations relied on dye tracking. A second application of rotenone in May 2010 to the Little Calumet River near O’Brien Lock and Dam (Illinois) provided another opportunity for dye-tracking support operations; however, application and deactivation strategies were designed considering zero-flow conditions within the reach of interest. Therefore, dye was injected at the upstream and downstream boundaries of the rotenone application reach and was used to track movement of water in and out of a treatment reach, allowing proper deactivation to occur and avoiding unnecessary damage to fisheries downstream. The data collected during the real-time tracking operations for both applications allowed full documentation of the rotenone treatment for archival purposes and provided information for future applications. The methods presented in this report for real-time tracking and documentation of piscicide applications in riverine environments worked exceptionally well and allowed the multiagency Asian Carp Rapid Response Workgroup to carry out large-scale rotenone applications in urban waterways in an environmentally responsible manner with minimal collateral damage to fisheries outside the treatment reach. Traveltime information extracted from the boat-mounted and fixed-position fluorometers agrees well with empirical predictions from a preliminary dye study (mock rotenone injection) on this system completed in November 2009 on the CSSC and with previously published methods for estimating traveltimes of the peak, leading edge, and trailing edge of the plume. Although the rotenone application strategy called for zero-flow conditions on the Little Calumet River in 2010, downstream advection of treated water did occur, and dye tracing combined with velocity mapping allowed this advection to be documented and exposed the unique hydrodynamics and mixing within this reach. The large volumes of data collected during the operations allow documentation and visualization of the rotenone applications, thus providing feedback to planners and archival of the treatments for future reference. The methods developed in this report are directly transferrable to piscicide applications in water bodies in other locations, including rivers, ponds, or lakes, and can be used for real-time tracking of any passive contaminant that may enter a water body.

Illinois↗
USGS2004

Granular avalanches across irregular three-dimensional terrain: 2. Experimental tests

Scaling considerations indicate that miniature experiments can be used to test models of granular avalanches in which the effects of intergranular fluid and cohesion are negligible. To test predictions of a granular avalanche model described in a companion paper, we performed bench top experiments involving avalanches of dry sand across irregular basal topography that mimicked the complexity of natural terrain. The experiments employed a novel method of laser-assisted cartography to map the three-dimensional morphology of rapidly moving avalanches, thereby providing high-resolution data for comparison with model output. Model input consisted of two material properties (angles of internal and basal Coulomb friction of the sand), which were measured in independent tests, and of initial and boundary conditions that characterized the geometry of the experimental apparatus. Experimental results demonstrate that the model accurately predicts not only the gross behavior but also many details of avalanche motion, from initiation to deposition. We attribute this accuracy to a mathematical and computational formulation that conserves mass and momentum in three-dimensional physical space and satisfies the Coulomb equation in three-dimensional stress space. Our results support the hypothesis that a Coulomb proportionality between shear and normal stresses applies in moderately rapid granular flows and that complicated constitutive postulates are unnecessary if momentum conservation is strictly enforced in continuum avalanche models. Furthermore, predictions of our Coulomb continuum model contrast with those of a Coulomb point mass model, illustrating the importance of multidimensional modeling and model testing.

Journal of Geophysical Research Earth Surface↗
USGS1982

Applications of Landsat imagery to problems of petroleum exploration in Qaidam Basin, China

Tertiary and Quaternary nonmarine, petroleum-bearing sedimentary rocks in the Qaidam basin of remote western China have been extensively deformed by compressive forces. These forces created many folds which are current targets of Chinese exploration programs. Manual techniques of image analysis and interpretation were applied to computer-enhanced Landsat images of the western part of the Qaidam basin in an effort to evaluate the contributions of Landsat imagery in defining the geologic conditions of the basin and to determine its usefulness as an exploration tool in the region. Most success was realized in defining the structural geologic setting of the region. Image-derived interpretations of folds, strike-slip faults, thrust faults, normal or reverse faults, and fractures compared very favorably, in terms of locations and numbers mapped, with Chinese data compiled from years of extensive field mapping. The image studies resulted in the identification of at least one subsurface fold that had not been detected by field mapping. The results of this study have direct exploration significance. Many potential hydrocarbon trapping structures were precisely located and information was obtained that may have significant implications with respect to fluid migration or attempts to locate offset reservoirs and buried folds. In addition, the orientations of major structural trends defined from Landsat imagery correlate well with those predicted for the area based on global tectonic theory. These correlations suggest that similar orientations exist in the eastern half of the basin where folded rocks are mostly obscured by unconsolidated surface sediments and where limited exploration has occurred.

Qaidam Basin↗