Fluid Sediment Research Articles

Formation of hydrothermal fluorite-hematite veins by mixing of continental basement brine and redbed-derived fluid: Schwarzwald mining district, SW-Germany

Hydrothermal fluorite-hematite veins represent a relatively rare vein type, which is sometimes associated with more common, fluorite-barite-quartz‑carbonate veins containing base metal mineralization. The origin and significance of the fluorite-hematite veins, and how they relate to the more common expression of mineralization, is essentially unknown. Here, we present new data illuminating the formation conditions of these “sulfide-barren” fluorite-hematite veins in a mining district known for hydrothermal Pb + Zn + Ag ores for which formation conditions are well understood: the Schwarzwald district in SW Germany. The exemplary Ödsbach-Hesselbach vein was chosen to study the fluids involved in fluorite-hematite precipitation through the first, direct investigation of fluid inclusions hosted in hydrothermal hematite using combined infra-red light microscopy, microthermometry and LA-ICPMS. The results indicate that the hematite-precipitating fluids are nearly identical to those observed in the associated fluorite, showing consistent salinities of 24.6–25.0 wt% (NaCl+CaCl2) and homogenization temperatures of 150 to 155 °C. Moreover, the trace element abundances determined by the LA-ICPMS analyses show a composition similar to other inclusions observed in the common mineralization in the mining district, including elevated Pb (>5000 μg/g) and Zn (>2000 μg/g) concentrations at low Cl/Br mass ratios, and sulfur contents mostly below the limits of detection. The results suggest fluid mixing between a continental basement brine and a redbed-derived fluid from the Triassic Buntsandstein. Therefore, the formation of the rare fluorite-hematite veins was probably triggered by a change of the sedimentary fluid endmember representing a shift from the Middle Triassic Muschelkalk fluid, which drove the more common Pb + Zn + Ag mineralization, towards fluids derived from the Buntsandstein. Furthermore, the absence of sulfur is interpreted to have precluded base metal sulfide precipitation, and the formation of hematite points to unusually oxidized conditions and hence towards a lack of a reducing agent, which would also have been required to generate a mineralization of base metal sulfides.

Numerical simulation of scour and flow field over movable bed induced by a submerged wall jet

Abstract Dam construction continues its rapid expansion around the world primarily for the purpose of hydropower generation. One important consequence of such projects is local scour at the downstream of the dam caused by outflow of excess reservoir water through spillways or bottom outlets that is associated with high velocities. The scour development endangers the dam foundation and river banks and undermines the stability of the hydraulic structures. In this study, a detailed three-dimensional (3D) flow simulation is conducted to investigate the complex fluid–sediment interactions leading to the formation of the scour hole and ridge systems downstream of a near-bottom jet. Three different bed-load equations, including Meyer-Peter–Müller, Nielsen, and Van Rijn formulas, are applied for calculating the bed-load transport rate. Comparison with a series of available experimental data shows that the Meyer-Peter–Müller equation results in better predictions than the two other relations. The performance of different turbulence models to reproduce vertical profiles of velocity and scour characteristic against the experimental data were evaluated. The vertical and horizontal profiles of the scour hole-ridge system are also compared with the corresponding experimental ones. The numerical model satisfactorily reproduces the geometric parameters representing the scour hole. However, the model overestimates the length of the scour hole.

Influence of anthropogenic landscape modifications and infrastructure on the geological characteristics of liquefaction

Abstract Many large cities worldwide are built on natural and engineered geological materials that are highly susceptible to liquefaction and associated ground failure in earthquakes. Constitutive equations describing relationships between sediment geotechnical characteristics, seismological parameters, and liquefaction susceptibility of natural and engineered sediments are well established. What is less understood is the role of anthropogenic landscape modifications (e.g., river channel modifications, sediment engineering and re-distribution) and infrastructure (e.g., buildings, buried infrastructure such as drainage systems) on the spatial distributions and severity of liquefaction and ground deformation. Here we use stratigraphic studies, ground penetrating radar (GPR), and analyses of high-resolution aerial photographs to evaluate surface and subsurface geological manifestations of recurrent liquefaction in anthropogenically-modified landscapes during the 2010–2011 Canterbury earthquake sequence in New Zealand. Engineered fill layers provided low density, high permeability traps that captured fluidized sediment and promoted the formation of a unique assemblage of liquefaction-induced sediment intrusions that differ from those preserved in proximal natural sediment. Subsurface drainage systems imparted significant influence on the location, size and orientations of liquefaction ejecta features. Sediments adjacent to engineered stream channels experienced large lateral strains that are unlikely to have occurred in the absence of channel modifications. Spatial variations in naturally-formed topography and liquefaction-susceptible sediments exerted strong influence on the characteristics of liquefaction hazards, even in highly engineered environments. Collectively, these observations highlight important interactions between natural and engineered environments that should be carefully considered when interpreting the geologic effects of contemporary earthquakes and / or using prehistoric geological records to forecast future hazards.

Brittle tectonics and fluids overpressure during the early stage of the Bay of Biscay opening in the Jard-sur-Mer area, (northern Aquitaine Basin, France)

Ba, F, Pb, Ag, Zn mineral deposits are widespread at the northern and eastern boundaries of the Aquitaine Basin. In most cases, they are hosted within high permeability carbonates that rest over the Hercynian basement and below an impermeable layer. Such a position suggests a Mississippi Valley Type (MVT) model for the formation of these deposits. This model is characterized by the lateral flow of sedimentary fluids expelled from the deeper part of the basin and mixed with other sources of water as they reach the basin boundaries. In the Jard-sur-Mer area, which sits in the north of the Basin, these deposits are also found higher in the sedimentary series suggesting that fluids have flown through the impermeable layer. Our field observations demonstrate that a brittle deformation episode, compatible with an upper-Jurassic N-S direction of extension, occurred as the mineralizing fluids were over pressured. The overpressure was the result of a large input of hydrothermal water ascending along inherited faults affecting the Hercynian basement and released at the onset of the tectonics event. When compared with the rest of the basin, these new results at the northern boundary suggests that the Aquitaine Basin recorded several stages of fluid overpressure both at the onset and during the opening of the Bay of Biscay.

Effect of Aerosil and Oleic Acid on Sedimentation of Magnetorheological Fluid

Magnetorheological Fluids (MRFs) are considered as smart fluids because they control viscosity using external magnetic field. It contains ferro-magnetic powder which are aligned in magnetic flux lines. The magnetic force between particles are controlled by magnetic field intensity. This controllable viscosity makes them acceptable in many mechanical applications, but due to difference in density between suspended particles and carrier fluid sedimentation is bound to occur. This thus creates the need of some additives. In our study, silica Nano particles (commercially known as Aerosil 200) is used as stabilizer and Oleic Acid is used as surfactant and their effect on sedimentation is studied in this article. Some other synthesis parameters like particle concentration, stirring duration and material loading also cause some change in sedimentation rate.

On the implicit immersed boundary method in coupled discrete element and lattice Boltzmann method

SummaryThe coupled discrete element method and lattice Boltzmann method (DEMLBM) has increasingly drawn attention of researchers in geomechanics due to its mesoscopic nature since 2000. Immersed boundary method (IBM) and immersed moving boundary (IMB) are two popular schemes for coupling fluid particle in DEMLBM. This work aims at coupling DEM and LBM using the latest IBM algorithm and investigating its accuracy, computational efficiency, and applicability. Two benchmark tests, interstitial fluid flow in an ideal packing and single particle sedimentation in viscous fluid, are carried out to demonstrate the accuracy of IBM through semi‐empirical Ergun equation, finite element method (FEM), and IMB. Then, simulations of particle migration with relatively large velocity in Poiseuille flow are utilized to address limitations of IBM in DEMLBM modeling. In addition, advantages and deficiencies of IBM are discussed and compared with IMB. It is found that the accuracy of IBM can be only guaranteed when sufficient boundary points are used and it is not suitable for geomechanical problems involving large fluid or particle velocity.

Simulating particle sedimentation in a flowing fluid using an immersed boundary–lattice Boltzmann method

ABSTRACTA combination of the lattice-Boltzmann and immersed-boundary methods is used to simulate the behaviour of circular particles in fluids, including their behaviour in stationary and flowing fluids. This method simulates the fluid domain with a regular Eulerian grid, and the non-grid uniform boundaries with a Lagrangian grid. The no-slip boundary condition of the fluid and particle boundaries is enforced by interpolating boundary forces. This simulation uses a direct-force method to achieve a slight deformation of solid particles. The correctness of the method is validated using simulations of the flow past an impulsive cylinder. Finally, the method is used to compare the particles’ behaviour in stationary and flowing fluids. The result shows that a well-known ‘drafting, kissing, and tumbling’ (DKT) case occurs in the particle sedimentation in the stationary viscous fluid. In contrast, kissing occurs in the moving fluid, but no separating.

Detection of EGFR gene mutation status from pleural effusions and other body fluid specimens in patients with lung adenocarcinoma.

BackgroundEpidermal growth factor receptor (EGFR) gene mutation status is essential to the optimal management of lung adenocarcinoma. Liquid biopsy has advantages such as noninvasiveness, speediness, and convenience. This study aimed to detect EGFR gene mutations using next‐generation sequencing (NGS) from different types of body fluids from patients with lung adenocarcinoma.MethodsThis was a prospective study of 20 patients with lung adenocarcinoma recruited between January 2017 and December 2018 at the Beijing Hospital. All patients had adenocarcinoma with confirmed sensitizing EGFR mutations. Body fluid specimens included pleural effusion, ascites, pericardial effusion, and cerebrospinal fluid. NGS was conducted to test for nine lung cancer‐related gene in body fluid supernatant free DNA, sedimentary tumor cells, and plasma free DNA.ResultsThe EGFR gene mutation abundance of body fluid supernatant free DNA was higher than that of body fluid sedimentary tumor cells and plasma free DNA specimens (100% vs. 90% vs. 80%, respectively, all P < 0.05). The results of EGFR mutation from the body fluid supernatants were consistent with the results from the tissue biopsy.ConclusionsThis study showed that compared with body fluid sediment tumor cells and plasma free DNA samples, body fluid supernatant free DNA has a higher detection rate and sensitivity of tumor‐specific mutations. Free DNA obtained from body fluid supernatants could be used as high‐quality specimens for gene mutation detection in patients with lung cancer. This could be applied in treatment decisions and patient management.

A smoothed particle hydrodynamics (SPH) formulation of a two-phase mixture model and its application to turbulent sediment transport

A Smoothed Particle Hydrodynamics (SPH) formulation and implementation of the classical two-phase mixture model are reported, with a particular focus on the turbulent sediment transport and the sediment disturbances generated by moving equipment operating near or on the seabed. In the mixture model, the fluid-particle system is considered to be an equivalent medium whose evolution is described by a set of equations for the mixture continuity and momentum conservation, with the particle volume fraction being tracked by a transport equation. The governing equations are adapted to a Lagrangian, weakly-compressible SPH framework, the turbulence is modeled by a Reynolds-averaged Navier-Stokes approach, and adaptive boundary conditions for shear stress and turbulent quantities are implemented to account for laminar or turbulent local flow conditions. The complex rheological behavior of clay sediment/water mixtures is modeled using a volume fraction, shear rate-dependent viscosity which accounts for the existence of a yield stress. Hence, the proposed work encompasses several challenging modeling aspects: turbulence, non-Newtonian fluid behavior, sediment transport, and fluid-structure interactions. It is then illustrated on diverse cases of interest: a fluid-particle mixture column release, its subsequent turbulent transport and return to a hydrostatic equilibrium, the settling of particle clouds and two cases of particle-driven gravity currents, and their comparisons with available results. Finally, SPH simulation results for the disturbance of a bed of clay sediment/water mixture induced by a moving plate are reported and compared with experiments performed in our laboratory. The proposed SPH two-phase mixture model agrees well with the existing results considered in this study.

Semianalytical Solution for Simultaneous Distribution of Fluid Velocity and Sediment Concentration in Open-Channel Flow

AbstractTo understand the sediment-transport process in an open-channel turbulent flow, the time-averaged profiles of streamwise fluid velocity and volumetric particle concentration in suspension m...

Synsedimentary glacitectonic deformation within a glacilacustrine-esker sequence, Teesdale, Northern England

In glacial sedimentology there has been a recent improvement in the understanding of both progressive and polyphase deformation of glacigenic sequences, and the role played by water during these complex deformation histories. However, the processes occurring during the detachment and transport of sediment blocks during ice-marginal glaciotectonic thrusting remain poorly understood. This lack of understanding is addressed in detail through a macro- and microscale study of the deformation structures in the glacigenic sequence exposed at Hayberries, Teesdale, County Durham (UK), where esker sands and gravels and associated tills truncate and overlie a sequence of rhythmically bedded glacilacustrine sands, silts and clays. Thrusts within the glacilacustrine and glacifluvial sediments appear to be relatively sharp, planar structures. However, orientated thin sections reveal that these bedding-parallel detachments are marked by a thin layer of massive to foliated sand. The geometry of both meso and small-scale folds and sense of displacement on the thrusts is consistent with both brittle and ductile structures having formed in response to ice-push from the N/NW. Detailed analysis of the thin sections reveals that initial folding and thrusting was followed by the liquefaction and injection of a massive, matrix poor sand along the propagating thrust. Evidence for liquefaction and injection (sand-filled veins) increases towards the NW consistent with fluid flow and sediment injection accompanying SE-directed ice-push. These results suggest that the introduction of pressurised meltwater and sediment along the thrusts during deformation may facilitate decoupling and displacement along these detachments by thrust gliding.

Comparison of fluid processes in coexisting wolframite and quartz from a giant vein-type tungsten deposit, South China: Insights from detailed petrography and LA-ICP-MS analysis of fluid inclusions

Abstract Granite-related wolframite-quartz veins are the world's most important tungsten mineralization and production resource. Recent progress in revealing their hydrothermal processes has been greatly facilitated by the use of infrared microscopy and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of both quartz- and wolframite-hosted fluid inclusions. However, owing to the paucity of detailed petrography, previous fluid inclusion studies on coexisting wolframite and quartz are associated with a certain degree of ambiguity. To better understand the fluid processes forming these two minerals, free-grown crystals of intergrown wolframite and quartz from the giant Yaogangxian W deposit in South China were studied using integrated in situ analytical methods including cathodoluminescence (CL) imaging, infrared microthermometry, Raman microspectroscopy, and fluid inclusion LA-ICP-MS analysis. Detailed crystal-scale petrography with critical help from CL imaging shows repetition of quartz, wolframite, and muscovite in the depositional sequence, which comprises a paragenesis far more complex than previous comparable studies. The reconstruction of fluid history in coexisting wolframite and quartz recognizes at least four successive fluid inclusion generations, two of which were entrapped concurrently with wolframite deposition. Fluctuations of fluid temperature and salinity during precipitation of coexisting wolframite and quartz are reflected by our microthermometry results, according to which wolframite-hosted fluid inclusions do not display higher homogenization temperature or salinity than those in quartz. However, LA-ICP-MS analysis shows that both primary fluid inclusions in wolframite and quartz-hosted fluid inclusions associated intimately with wolframite deposition are characterized by strong enrichment in Sr and depletion in B and As compared to quartz-hosted fluid inclusions that are not associated with wolframite deposition. The chemical similarity between the two fluid inclusion generations associated with wolframite deposition implies episodic tungsten mineralization derived from fluids exhibiting distinct chemical signatures. Multiple chemical criteria including incompatible elements and Br/Cl ratios of fluid inclusions in both minerals suggest a magmatic-sourced fluid with the possible addition of sedimentary and meteoric water. Combined with microthermometry and Raman results, fluid chemical evolution in terms of B, As, S, Sr, W, Mn, Fe, and carbonic volatiles collectively imply fluid phase separation and mixing with sedimentary fluid may have played important roles in wolframite deposition, whereas fluid cooling and addition of Fe and Mn do not appear to be the major driving factor. This study also shows that fluid inclusions in both wolframite and coexisting quartz may contain a substantial amount of carbonic volatiles (CO2 ± CH4) and H3BO3. Ignoring the occurrence of these components can result in significant overestimation of apparent salinity and miscalculation of LA-ICP-MS elemental concentrations. We suggest that these effects should be considered critically to avoid misinterpretation of fluid inclusion data, especially for granite-related tungsten-tin deposits.

Evolution of serpentinite from seafloor hydration to subduction zone metamorphism: Petrology and geochemistry of serpentinite from the ultrahigh pressure North Qaidam orogen in northern Tibet

Serpentinite from the North Qaidam ultrahigh pressure metamorphic belt in northern Tibet is studied to provide insight into petro-geochemical evolution of serpentinite from seafloor hydration to subduction zone metamorphism. The North Qaidam serpentinite can be divided into undeformed lizardite serpentinite that was not severely overprinted during subduction and deformed antigorite serpentinite that was well recrystallized during subduction. Petrological and geochemical analyses demonstrate that the serpentinite was originally melt-percolated refractory abyssal harzburgite. Considering the local geodynamic setting, it is inferred that the serpentinite probably originated from the oceanic lithosphere that subducted before continental subduction. Relatively uniform low δ18O (4.0‰–4.5‰) of the antigorite serpentinite indicates high temperature hydrothermal alteration of protolith harzburgite by seawater. In contrast, much lower δ18O (0.6‰–2.7‰) of the lizardite serpentinite is ascribed to exchange with meteoric water at the Earth’s surface. Relict serpentinization textures are well preserved in the lizardite serpentinite, with reactions of olivine to lizardite and magnetite, pyroxenes to talc, tremolite, and lizardite, and spinel to chromite and chlorite. The replacement of lizardite by antigorite during subduction mostly initiates along grain boundaries and interconnecting veinlets, implying fluid-assisted transformation of lizardite into antigorite. Partial decomposition of antigorite produces magnesian secondary olivine in the antigorite serpentinite, while direct breakdown of metastable lizardite generates ferroan secondary olivine in the lizardite serpentinite. The serpentinite is enriched in fluid-mobile elements, with U primarily accumulated during seafloor alteration and alkalis notably introduced by sedimentary fluids at bending faults or in accretionary wedge. Infiltration by fluids equilibrated with sediments is also supported by highly elevated 87Sr/86Sr of the serpentinite. Moreover, 87Sr/86Sr of the antigorite serpentinite (0.710649–0.713996) is higher than that of the lizardite serpentinite (0.707184–0.708502), which implies more intense interaction of sedimentary fluids with the former than the latter. However, the lizardite serpentinite contains more alkalis and less U than the antigorite serpentinite, which indicates that large proportions of alkalis were lost during partial dehydration of serpentinite, while U was not released.

A dynamic multilayer shallow water model for polydisperse sedimentation

A multilayer shallow water approach for the approximate description of polydisperse sedimentation in a viscous fluid is presented. The fluid is assumed to carry finely dispersed solid particles that belong to a finite number of species that differ in density and size. These species segregate and form areas of different composition. In addition, the settling of particles influences the motion of the ambient fluid. A distinct feature of the new approach is the particular definition of the average velocity of the mixture. It takes into account the densities of the solid particles and the fluid and allows us to recover the global mass conservation and linear momentum balance laws of the mixture. This definition motivates a modification of the Masliyah–Lockett–Bassoon (MLB) settling velocities of each species. The multilayer shallow water model allows one to determine the spatial distribution of the solid particles, the velocity field, and the evolution of the free surface of the mixture. The final model can be written as a multilayer model with variable density where the unknowns are the average velocities and concentrations in each layer, the transfer terms across each interface, and the total mass. An explicit formula of the transfer terms leads to a reduced form of the system. Finally, an explicit bound of the minimum and maximum eigenvalues of the transport matrix of the system is utilized to design a Harten–Lax–van Leer (HLL)-type path-conservative numerical method. Numerical simulations illustrate the coupled polydisperse sedimentation and flow fields in various scenarios, including sedimentation in a type of basin that is used in practice in mining industry and in a basin whose bottom topography gives rise to recirculations of the fluid and high solids concentrations.

Seismic evidence for repeated vertical fluid flow through polygonally faulted strata in the Canterbury Basin, New Zealand

Abstract Seismic imaging techniques are widely used to determine fluid migration pathways in the subsurface. Understanding the timing and distribution of focused fluid migration pathways is important for assessing reservoir seal quality and hydrocarbon exploration risk, as well as seafloor biogeochemical processes in the case of fluid venting from the seafloor. The frontier Canterbury Basin southeast of New Zealand is well studied, but questions remain regarding the dynamic movement of fluids through the basin. Using 3D seismic data combined with high-resolution boomer seismic data, we characterise focused fluid migration and sediment remobilisation events in the Canterbury Basin. We show how polygonal fault formation and nucleation is affected in the vicinity of vertically ascending fluids and sediments. A cylindrical region devoid of polygonal faulting around the feeder system of a buried sediment volcano points to the possible existence of an axisymmetrical stress field induced by upward migrating fluids and sediments. Sediment remobilisation and intrusions of permeable stingers (i.e. sand injectites) could enable dewatering of their host strata and thereby prevent polygonal faults from nucleating. Amplitude variations with angle (AVA) and a detailed analysis of two tiers of polygonal faults reveal three phases of fluid migration and sediment remobilisation and intrusion through, and into, low permeability sediments. Our integrated conceptual model provides insights into vertical fluid migration mechanisms and the implications for polygonal fault formation.

Sediment transport problems by the particle finite element method (PFEM)

This paper presents a particle finite element model for the numerical simulation of sediment transport problems. Fluid motion and sediment motion are coupled in a two-way manner, through boundary shear stress field and through flow domain mesh deformation. Solution of equations for fluid and sediment flows is performed by an explicit particle Lagrangian procedure (PFEM-2), including a fractional step strategy for the fluid flow equations. Previous particle finite element techniques concentrate on the simulation of erosion by removing elements. Here, transport problem includes erosion, saltation, deposition, and avalanche of grains. Numerical tests explore the efficiency of the methodology, either quantitatively or qualitatively.

Soft-sediment deformation structures as a tool to recognize synsedimentary tectonic activity in the middle member of the Bakken Formation, Williston Basin, North Dakota

Abstract The Bakken Formation (uppermost Devonian-Lower Carboniferous) in North Dakota consists of black shales with a middle member composed of mixed siliciclastics and carbonates. Millimeter to decimeter-scale soft-sediment deformation structures (SSDS) are common in the upper third to quarter of the middle member, having been observed in sixty-three out of ninety cores studied. The nine categories identified herein reflect brittle and ductile deformation and loss of sediment shear in compressional and extensional settings. They are interpreted to form due to seismically-induced folding, liquefaction and fluidization of unconsolidated sediment, as well as microfaulting and brecciation of consolidated sediment, and reflect synsedimentary tectonic movements, e.g. along faults that were active during deposition. The distribution of SSDS follows the orientation of the major structural elements rooted in the basement of the Williston Basin. The stratigraphic and spatial distribution of SSDS suggests variable tectonic activity: cores near the most active fault systems have the highest net thickness of units with SSDS, whereas those farther from the most active faults exhibit only a few deformed units. The predominance of SSDS in the upper portion of the middle member suggests there was a change from relative tectonic quiescence to a more active regime which in turn led to modifications of basin geometry and new accommodation patterns. Synsedimentary deformation might have had a positive effect on reservoir quality in deformed units by increasing porosity and permeability as a result of cohesion loss and rearrangement of grains. Additionally, multiple injection structures and complexes of small-scale normal and reverse faults could contribute to better connectivity of reservoir units.

Formation of water-escape structure during shock-induced fluidization: The role of permeability contrast

Water-escape structure is considered to be a product of fluidization. The exact mechanism of formation of this structure has, however, not been adequately addressed. In the present study, laboratory experiments were carried out to observe the effect of cyclic loading on water-saturated sediment in a close system, with an objective to decipher the specific mechanism of formation of water-escape structure. Present study reveals that an optimum permeability contrast between the successive sedimentary layers of a fining upward succession is the prerequisite for formation of water-escape structures. The onset of fluidization comes into existence when at a critical minor principal stress condition during shearing, the underlying coarse-grained layer attains drained contractive state and the overlying finer-grained layer retains the undrained dilative state. In the contractive layer the sediments tend to become more compact through rearrangements of the particles and displacement of the interstitial fluid. The pore fluid is squeezed out and the sand structure suffers volume contraction. As the upwelling fluid is obstructed by the dilative layer, water-filled cavities are formed at the interface. On progressive shaking these water-filled cavities keep on enlarging and finally the expelled water ruptures through the overlying sand layer resulting water-escape structure. This study also depicts that no influx of external fluid is essential in fluidization of sediments, as was believed earlier.

Fixed-Bed and Mobile-Bed Resistance of Channels with Steep Gradients in Mountainous Areas

Flood discharge and sediment transport are closely linked to channel resistance in steep mountain streams. Previous research has mainly focused on the resistance of fixed-bed channels with steep gradients and mobile-bed channels in alluvial rivers. The present study performs an experiment and establishes a calculation method for the fixed-bed resistance of mountain channels. The basic expression of the mobile-bed resistance of steep mountain channels is derived by determining the controlling factors of the bed load movement on the riverbed resistance. The proposed formula can accurately predict the variation of the bed load resistance. The results of the present research improve the understanding of fluid dynamics and sediment transport in steep mountain channels.

Encyclopedia of Geochemistry

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