Critical Shear Stress Values Research Articles

On local scouring downstream small water structures.

BackgroundIn order to regulate water flow, hydraulic structures such as weirs or checks, frequently equipped with gates, are used. Water can flow below or over the gate or, simultaneously, over and below the gate. Both diversifications of hydraulic gradient, being an effect of damming up a river by the structure and shear stresses at the bed, which exceeds the critical shear stress value, invoke the local scouring downstream the structure. This phenomenon has been studied in laboratory and field conditions for many years, however Researchers do not agree on the parameters that affect the size of the local scour and the intensity of its formation. There are no universal methods for estimating its magnitude However, solutions are sought in the form of calculation formulas typical for the method of flow through the structure, taking into account the parameters that characterize a given structure. These formulas are based on factors that affect the size of the local scours, that is, their dimensions and location. Examples of such formulas are those contained in this article: Franke (1960), Straube (1963), Tarajmovič (1966), Rossinski & Kuzmin (1969) equations. The need to study this phenomenon results from the prevalence of hydrotechnical structures equipped with gates (from small gated checks to large weirs) and from potential damage that may be associated with excessive development of local erosion downstream, including washing of foundations and, consequently, loss of stability of the structure.MethodsThis study verifies empirical formulas applied to estimate the geometry parameters of a scour hole on a laboratory model of a structure where water is conducted downstream the gate with bottom reinforcements of various roughness. A specially designed remote-controlled measuring device, equipped with laser scanner, was applied to determine the shape of the sandy bottom. Then the formula optimization is conducted, using Monte Carlo sampling method, followed by verification of field conditions.ResultsThe suitability of a specially designed device, equipped with laser scanner for measuring the bottom shape in laboratory conditions was demonstrated. Simple formula describing local scour geometry in laboratory conditions was derived basing on the Straube formula. The optimized formula was verified in field conditions giving very good comparative results. Therefore, it can be applied in engineering and designing practices.

Numerical analysis of twin-precipitate interactions in magnesium alloys

The present paper performs a two-dimensional numerical study of the interactions between {101¯2} tensile twin and precipitates aligned along basal planes in magnesium alloys. The model consists of an elliptical twin placed in between two rectangular precipitates. Material behavior is modeled using anisotropic elasticity and crystal plasticity. The model represents the situation at the onset of twinning when twins are small and fit in between the precipitates. The results show that precipitates influence the shear stress necessary to accommodate twin by changing the slip critical resolved shear stress (CRSS) values and by acting as obstacles. Thin twins (aspect ratio <0.05) are influenced by both effects while thick twins (aspect ratio >0.1) are influenced by slip CRSS changes. The precipitate thickness plays a crucial role in twin thickening and propagation. Increasing precipitate thickness increases shear stress necessary to accommodate twin and also decreases stress beyond the precipitate which hinders sequential twin propagation.

In Situ Characterization of the Effect of Twin-Microstructure Interactions on {1 0 1 2} Tension and {1 0 1 1} Contraction Twin Nucleation, Growth and Damage in Magnesium

Through in situ electron backscatter diffraction (EBSD) experiments, this paper uncovers dominant damage mechanisms in traditional magnesium alloys exhibiting deformation twinning. The findings emphasize the level of deleterious strain incompatibility induced by twin interaction with other deformation modes and microstructural defects. A double fiber obtained by plane-strain extrusion as a starting texture of AM30 magnesium alloy offered the opportunity to track deformation by EBSD in neighboring grains where some undergo profuse {1 0 1 2} twinning and others do not. For a tensile loading applied along extrusion transverse (ET) direction, those experiencing profuse twinning reveal a major effect of grain boundaries on non-Schmid behavior affecting twin variant selection and growth. Similarly, a neighboring grain, with its ⟨c⟩-axis oriented nearly perpendicular to tensile loading, showed an abnormally early nucleation of {1 0 1 1} contraction twins (2% strain) while the same {1 0 1 1} twin mode triggering under ⟨c⟩-axis uniaxial compression have higher value of critical resolved shear stress exceeding the values for pyramidal ⟨c + a⟩ dislocations. The difference in nucleation behavior of contraction vs. compression {1 0 1 1} twins is attributed to the hydrostatic stresses that promote the required atomic shuffles at the core of twinning disconnections.

Plastic behavior of the [formula omitted] phase in Ti-6Al-4V alloys

Plastic deformation of α′ martensite phase in Ti-6Al-4V alloy is investigated by performing tensile tests in a Scanning Electron Microscope (SEM). Electron Backscatter Diffraction (EBSD) analysis is used to determine the slip modes activated in α′ martensite depending on the crystallographic orientation of the laths. As in the α phase, mostly basal and prismatic slip modes are identified. The weighted Schmid analysis applied using the critical resolved shear stress (CRSS) values of the α phase performs well in the description of the behavior of the α′ phase.

Molecular dynamics simulation of the interactions between screw dislocation and stacking fault tetrahedron in Fe–10Ni–20Cr and Ni

Radiation-induced defects are the significant cause of radiation damage in austenitic stainless steels. In this work, the interactions between a screw dislocation and stacking fault tetrahedrons (SFTs) are studied in Fe–10Ni–20Cr (a model alloy of austenitic stainless steel) and Ni, using molecular dynamics simulations. Four interaction processes were primarily found, including (1) partial absorption, (2) sheared, (3) bypassing, and (4) restored through double cross-slip. In Fe–10Ni–20Cr alloys, there is almost no correlation between the critical resolved shear stress (CRSS) value and SFT size, but the intersection position largely impacts the results. And the CRSS value decreases with temperature increasing in Fe–10Ni–20Cr. The occurrence of cross-slip has a significant effect on the interactions, and there exist greater CRSS value in the interactions of cross-slipping. Besides, the occurrence of the cross-slip is linked to the stacking fault energy and the distribution of solute atoms of the alloys.

Micropillar compression deformation of single crystals of the intermetallic compound Γ-Fe4Zn9

The plastic deformation behavior of single crystals of the Γ (Fe4Zn9) phase compound in the Fe−Zn system, which has been believed to be the most detrimental phase causing brittle failure in the coating layer (such as powdering) on galvannealed (GA) steels, has been investigated by micropillar compression tests at room temperature as a function of crystal orientation and specimen size. All micropillar specimens exhibit rich deformability in compression. Two distinct slip systems, {1¯01}<111> and {1¯01}<010>, are observed to operate. The critical resolved shear stress (CRSS) values for {1¯01}<111> and {1¯01}<010> both obey an inverse power-law scaling against the micropillar size with an exponent of -0.245 and -0.046, respectively. The bulk CRSS values for these two slip systems are estimated respectively to be 238 and 649 MPa by considering the specimen size effects of CRSS. The crystal orientation range for the operation of {1¯01}<010> slip is limited to the vicinity of 〈111〉 because of the considerable difference in the CRSS values for these two slip systems. Dislocations with b (Burgers vector) = 〈010〉 dissociate into two partial dislocations, while those with b = 1/2<111> do not show any dissociation, both of which are consistent with the result of theoretical calculation of the generalized stacking fault energy on the {1¯01} slip plane. Possible reasons for brittle failure related to the Γ phase occurring in the coating layer on GA steels are discussed based on the results obtained.

Critical role of wave–seabed interactions in the extensive erosion of Yellow River estuarine sediments

Integrating field observations in the high-erosion rate region of the Chinese coastal zone (northern estuary of the Yellow River) were used to investigate the role of wave–seabed interactions in seabed erosion, combined with laboratory erosion experiments on the variations in sediment erodibility due to cyclic wave loading. The field results highlight a strong erosive event that occurred in the presence of high waves, during which the seawater turbidity increased sharply from 50 FTU to 600–800 FTU and the bed elevation decreased by 7.7 mm/h over 27 h. The laboratory results attribute this type of erosion to the contribution of wave actions on seabed sediments, where the waves probably acted as a plough and reduced the threshold velocity and critical shear stress values, thus enhancing sediment transport that also occurs due to the shear effect of near-bed currents during fair-weather conditions. Wave-induced liquefaction, characterised by the uneven build-up of excess pore pressures at different buried depths, may also enhance sediment erosion by generating vertical pore water seepage within the sediment and inducing internal sediment re-suspension. The field observations allowed us to construct a regional mathematical model of seabed erosion that parameterises the wave–seabed interactions, as well as to explore the implications of this model for extensive erosion of Yellow River estuarine sediments. This research represents a major step towards validating the critical role of wave-induced interactions in extensive sediment erosion events within a shallow estuarine system.

Modeling the initiation of sediment motion under a wide range of flow conditions using a Geno-Mamdani Fuzzy Inference System method

The current study introduces a novel approach to estimate the incipient motion of sediments under a wide range of flow regimes by developing a fuzzy model with a fuzzy-band that refers to a transition from weak motion to general motion of sediment. The partial sediment entrainment is defined by fuzzy sets considering the uncertainty related to the individual ratio of inertia to viscous forces which is the definition of shear Reynolds number. In the current study, the Mamdani Fuzzy Inference System (Mamdani FIS) is used to develop a comprehensive fuzzy model of the incipient motion of sediment. The Mamdani FIS has a shortcoming regarding the training of the fuzzy model. To estimate the dimensionless shear stress, a new method is developed by combining a genetic algorithm with the fuzzy approach which is named the Geno-Mamdani Fuzzy Inference System (GMFIS) method. The performance of the GMFIS model is evaluated using experimental data by considering root mean square error (RMSE), Nash-Sutcliffe coefficient of efficiency (CE), degree of robustness (Dr), and concordance coefficient (CC) as evaluation criteria. The GMFIS model performed very well based on the RMSE, CE, Dr, and CC values and satisfactorily represented the three types of incipient motion. Finally, a new range of fuzzy, dimensionless, critical shear stress values is established in all flow conditions from weak to general sediment entrainment.

Linear complementarity solution of 2D boundary slip EHL contact

Recent researches proved that bearing friction can be largely reduced with an oleophilic (no-slip) surface sliding against an oleophobic (slip) surface. The present work investigates the applicability of the slip/no-slip concept to 2D elastohydrodynamic lubrication (EHL) problems. Numerical analysis of isothermal EHL point contact is conducted under pure rolling conditions with the critical shear stress slip model. The challenge of determining the slip direction upon the attainment of the critical shear stress value in 2D problems is resolved by using a linear complementarity principle. The effect of boundary slip on bearing performance in terms of film thickness and friction is evaluated.

Understanding the Role of Local Texture Variation on Slip Activity in a Two-Phase Titanium Alloy

During plastic deformation of engineering alloys with a hcp crystal structure, slip systems with different critical resolved shear stresses can be activated. In the case of a two-phase titanium alloys such as Ti-6Al-4V, it is well established that various [[EQUATION]] and [[EQUATION]] type slip systems can be activated in the α-phase, which dominates this alloy. However, their relative likelihood is less well established particularly when comparing prismatic [[EQUATION]] and basal [[EQUATION]] slip which are known to have similar critical resolved shear stress values. By combining EBSD-based grain orientation mapping and high-resolution digital image correlation, grain specific shear strain mapping and Burgers vector direction analysis was carried out after small levels of plasticity in two differently microtextured Ti-6Al-4V samples. This enabled the different types of strain heterogeneity and strain patterns to be linked to the underlying microstructure and microtexture. The detailed analysis shows that the dominance of a particular [[EQUATION]] type slip mode greatly varies with the local texture and that shear strain patterns extend across many grains when soft macrozones (clusters of similarly orientated grains) are present. The work highlights that the relative displacement ratio analysis significantly improves slip trace analysis in hcp crystals by reducing the cases of ambiguous solutions and that grain neighbourhood can have a greater impact on slip system activation than Schmid factor.

Numerical simulation of hydrodynamic characteristics and bedload transport in cross sections of two gravel-bed rivers based on one-dimensional lateral distribution method

Accurate evaluation and prediction of bedload transport are crucial in studies of fluvial hydrodynamic characteristics and river morphology. This paper presents a one-dimensional numerical model based on the one-dimensional lateral distribution method (1D-LDM) and six classic bedload transport formulae that can be used to simulate hydrodynamic characteristics and bedload transport discharge in cross sections. Two gravel-bed rivers, i.e. the Danube River located approximately 70 km downstream from Bratislava in Slovakia and the Toltén River in south of Chile are used as examples. In the 1D-LDM, gravity, bed shear stress, turbulent diffusion, and secondary flow are included to allow for accurate predictions of flow velocity and consequently bed shear stress in the cross sections. Six classic formulae were applied to evaluate the non-dimensional bedload transport rate, and the bedload transport discharge through a river cross section is obtained by integrating the bedload transport rate over the width of the cross section. The results show that the root mean square error (RMSE) and mean absolute error (MAE) of velocity and water discharge were less than 8% of the observed magnitude, while the correlation coefficient between model predictions and observations was close to unity. The formulae proposed by Ashida and Michiue (1972), in which particle collision with the bed is taken into account, and by Camenen and Larson (2005), which allows for yielding a non-zero bedload transport rate even when the bed shear stress is smaller than the critical bed shear stress value, appeared to be more appropriate for predicting the observed bedload transport rate in the studied cross sections of two gravel-bed rivers. If non-uniform sediment mixtures were considered, the bedload transport discharge through a cross-section could change considerably by up to 22.5% of the observed magnitude. The relations proposed by Ashida and Michiue (1972) and Egiazaroff (1965) for parameterizing the hiding factor yielded more realistic model predictions in comparison with observations for the measured data set collected for the Toltén River, while the one proposed by Wilcock and Crowe (2003) performs the best for the data set measured for the Danube River.

Application of parameters and paradigms of the erosion and deposition for cohesive sediment transport modelling in the Lingdingyang Estuary, China

Suspended sediment and the surficial sediment in most estuaries throughout the world consist of fine particles. Modelling cohesive sediment transport is an important way to explore the morphological evolution of estuaries where cohesive sediment is dominant. Various values for critical shear stress and deposition paradigms for cohesive sediment transport were evaluated here by analysis of field samples combined with numerical simulation in the Lingdingyang (LD) estuary in China. A UMCES-Gust Erosion Microcosm System (U-GEMS) experiment using field samples suggests that the experimental average value of critical shear stress for erosion (τce) is 0.26 N/m2. Two conflicting paradigms, i.e. mutually exclusive versus simultaneous erosion and deposition, are commonly used for cohesive sediment transport. Simulations of tidal currents and sediment transport during the wet season of 2007 and dry season of 2016 in the LD estuary were conducted under these two paradigms using the TELEMAC-2D hydrodynamic module and the sediment module SISYPHE in the TELEMAC model. Model verification under these two paradigms was carried out, and the τce parameters in the TELEMAC model were revised based on a U-GEMS experiment. The results showed the following. (1) The simulation results of the model in the LD estuary were satisfactory when an experimental average τce value of 0.26 N/m2 was used. (2) The simultaneous paradigm using a τce value of 0.26 N/m2 well explained the changes in the field-observed depth-averaged suspended sediment concentrations under all tidal regimes during the dry season, whereas the simultaneous paradigm using a τce of 0.15 N/m2 was more similar to observations in the LD estuary during the wet season.

Assessment of surface and bulk-dominated methodologies to measure critical resolved shear stresses in hexagonal materials

Crystallographic slip in hexagonal metals involves a number of geometrically distinct slip families characterized by their slip direction and slip plane (basal, prismatic, and pyramidal). Owing to the low symmetry of hexagonal lattices, each of these slip families only have a few symmetrically equivalent slip systems (family members). Furthermore, different slip families become active at different resolved shear stress, i.e., they have different critical resolved shear stress values (CRSS). The plastic anisotropy of hexagonal materials makes the numerical prediction of their plastic behavior challenging and depends critically on the knowledge of CRSS values. The present contribution assesses the reliability of three proposed methods (with additional variations) to quantify CRSS values of the different hexagonal slip families. Those methods (a to c) rely on: (a) the statistics of observed surface slip traces in a (slightly) deformed polycrystal; (b) an iterative adjustment of CRSS values until a simulated single crystal indentation matches the corresponding experiment in terms of load–displacement response and residual surface topography of the indent; (c) in-situ high-energy X-ray diffraction to measure the evolution of resolved stress (from lattice strains) in grains for which single-family slip is probable based upon specific lattice reorientation conditions. Virtual experiments are performed on synthetic microstructures such that the (extracted) CRSS values resulting from simulating the different methodologies can be rigorously compared against the (target) CRSS values that are installed in the phenomenological constitutive material description used in the simulations. The resulting CRSS values of methods (a) exhibit a strong dependence on, and deterioration with, decreasing level of slip trace observability, which is an uncertain quantity in experimental measurements. For the inverse indentation method (b), the predicted CRSS values are within 8 % of their reference CRSS values for the two investigated cases. The high-energy X-ray diffraction method (c) most reliably determines CRSS values for basal and prism slip, but lacks a strict grain selection criterion to assess pyramidal slip.

Method for determination of optimal geometrical parameters of a unit cell of X-shaped truss cores

Recently, in order to develop high-strength lightweight core materials of sandwich structures for multi-functional applications, a large number of truss structures have been created, including pyramidal and tetrahedral truss cores. In this paper, a new truss structure is developed to be used as core material in sandwich panels. The X-shaped truss core consists of discrete hourglass-shaped unit cells formed by the groove-to-groove connection of two flat X-shaped truss elements made by metal plate cutting. In order to determine optimal geometrical parameters of a unit cell of X-shaped truss core, in this work it is proposed to plot the diagrams of relative density versus the angle of the rods for the required values of equivalent critical compression and lateral shear stresses, and for the required values of equivalent compression and shear stiffness of the unit cell of X-shaped truss core. The results show that with the same mechanical characteristics, the relative density of the optimal X-shaped truss core is less than the relative density of optimal pyramidal and tetrahedral truss cores.

Inversion of polyphase calcite twin data for deviatoric stress tensors: 1. A novel numerical approach

A new inversion method is developed in this paper to estimate deviatoric stress tensors from a certain population of polyphase calcite twins. It is both to minimize the number of the common incompatible (twinned and untwinned) e-planes and to maximize the sum of the resolved shear stresses along the compatible twinned e-planes under each reduced stress. The genetic algorithm is employed to resolve this optimization problem. A series of two-phase, equally-mixed artificial datasets, generated under the prescribed stresses, were taken to demonstrate the feasibility of this method. Results indicate a strong tendency to have an increasing accuracy of reduced stress with the ascent of the prescribed maximum differential stress, the difference between the prescribed stresses, and the number of twinned calcite crystals, respectively. What is more, the maximum differential stress becomes sufficiently large to permit an accurate estimate of reduced stress, even though the prescribed stresses are intermediately similar to each other. However, the method assumes a constant critical resolved shear stress value to rescale the stress tensors, and does not consider the influence on the critical resolved shear stress value of strain hardening, grain size, and temperature. It takes an enormous amount of time in calculation.

A new technology for suspended sediment simulation in Lake Taihu, China: Combination of hydrodynamic modeling and remote sensing

Sediment resuspension is closely related to the endogenetic release of nutrients in Lake Taihu. Thus, understanding the factors associated with sediment resuspension is important. In this study, a new technology, which integrates a hydrodynamic model and remote sensing techniques, was applied to derive the distribution of the erosion flux and obtain the spatially variable critical shear stress. Then, the spatially variable critical shear stress was used in the sediment simulations at Lake Taihu. Compared to the traditional model, based on uniform values of critical shear stress, the new method, using variable values of critical shear stress calibrated from the Geostationary Ocean Color Imager (GOCI) data, significantly improved the sediment simulations at Lake Taihu. Based on the erosion flux from August 6-8, 2013, the correlations between erosion and wind speed, wind fetch, mud depth, and water depth were analyzed for different subsections and spots in Lake Taihu. The potential sources of error were also addressed. Further improvement of the model is necessary.

Briefing: Improving erosion resistance of sand using nano-silica additive

This briefing paper examines the improvement in the hydraulic erosion resistance of medium silica sand achieved using 1–4% nano-silica (NS) additive. The erodibility of the different soil blends (prepared by mixing NS solutions prepared at required concentrations with the dry test sand) was investigated at bench scale by testing compacted treated sand specimens using the erosion-function apparatus. The NS addition produced a viscous gel property for the soil mixtures, allowing the mobilisation of an effective cohesion (surface bond strength). A 1·5% NS addition was identified as the optimum amount in terms of the greatest erosion resistance for the particular sand investigated; that is, a 92% reduction in the erodibility coefficient value and an approximately six-fold increase in the critical shear stress value were achieved relative to the untreated sand. Further, these improvements in the erosion-resistance properties of the compacted sand–NS mixtures were achieved within a significantly shorter time period (i.e. 1 d specimen curing period adopted in the current investigation) when compared with that typically required for traditional cement and lime additives.

Development of fly ash reinforced nanocomposite preformed particle gel for the control of excessive water production in the mature oil fields

One of the appropriate methods to minimize water production and increase sweep efficiency is the utilization of Preformed Particle Gel (PPG) in the mature oil fields. In this paper, a new fly ash reinforced nanocomposite PPG was developed by the reaction of acrylamide as monomer, N,N′-Methylenebis (acrylamide) as crosslinker and nano fly ash in presence of Potassium Persulfate as initiator and it was compared with a conventional PPG which was designed without nano fly ash. On the incorporation of nano fly ash, swelling performance and thermal stability of PPG had increased significantly. Rheological data revealed that dynamic moduli (G′ and G″) of fly ash reinforced nanocomposite PPG has improved viscoelastic properties with a higher value of critical shear stress as compared to conventional PPG. The single sandpack flow experiment has shown the injectivity of nanocomposite PPG into the sandpack with a maximum resistance factor of 60.57. However, parallel-sandpack flow experiment showed that the newly developed nano fly ash reinforced nanocomposite PPG has a profile improvement rate of 92.98% and 97.83% for the permeability contrast of 2.16 and 4.14 respectively and hence it may be a promising agent in reducing excessive water production in mature oil fields.

Assessment of Surface and Bulk-Dominated Methodologies to Measure Critical Resolved Shear Stresses in Hexagonal Materials

Crystallographic slip in hexagonal metals involves a number of geometrically distinct slip families characterized by their slip direction and slip plane (basal, prismatic, and pyramidal). Owing to the low symmetry of hexagonal lattices, each of these slip families only have a few symmetrically equivalent slip systems (family members). Furthermore, different slip families become active at different resolved shear stress, i. e., they have different critical resolved shear stress values (CRSS). The plastic anisotropy of hexagonal materials renders the numerical prediction of their plastic behavior challenging and depends critically on the knowledge of CRSS values. The present contribution assesses the reliability of three proposed methods (with additional variations) to quantify CRSS values of the different hexagonal slip families. Those methods (a to c) rely on: (a) the statistics of observed surface slip traces in a (slightly) deformed polycrystal; (b) an iterative adjustment of CRSS values until a simulated single crystal indentation matches the corresponding experiment in terms of load-displacement response and residual surface topography of the indent; (c) in-situ high-energy X-ray diffraction to measure the evolution of resolved stress (from lattice strains) in grains for which single family slip can be deduced from specific lattice reorientation conditions. Virtual experiments are performed on synthetic microstructures to assess how reliably each method recovers prescribed CRSS values using a phenomenological constitutive material description. The resulting CRSS values of methods (a) exhibit a strong dependence on, and deteriorates with decreasing level of slip trace observability, which is an uncertain quantity in experimental measurements. For the inverse indentation method (b), the predicted CRSS values are within 8% of their reference CRSS values for the two investigated cases. The high-energy X-ray diffraction method (c) most reliably determines CRSS values for basal and prism slip, but lacks a strict grain selection criterion to assess pyramidal slip.

Bedrock erosion and changes in bed sediment lithology in response to an extreme flood event: The 2013 Colorado Front Range flood

In this study, we use before and after flood observations of bed sediment lithology to determine how the lithological composition of bed sediment changes in response to an extreme flood event and use the post-flood measurements and observations to estimate values of critical shear stresses needed to erode shale bedrock and protective bank vegetation in the study streams. We present results from measurements of bed sediment lithology taken after the 2013 Colorado Front Range flood and compare these results with the same measurements taken before the flood. These two data sets provide a unique opportunity to determine how bed sediment lithology changes following an extreme flood event and allows insight into sources of channel bed sediment. After the flood, bed sediment lithology shifted distinctly towards the lithological distribution of the total catchment. Before the flood, bed sediment in most locations was primarily composed of granitic material, while after the flood, the streams were more likely to have metamorphic, volcanic, or sedimentary rocks in the bed sediment, reflecting more input from more non-local hillslopes compared to before the flood. Our post-flood measurements and observations allowed us to estimate threshold critical shear stress for the plucking of shale bedrock (212 Pa) and the removal of large cottonwood trees (364 Pa) in downstream sections of the study streams. Bank vegetation plays a critical role in protecting bedrock banks from lateral erosion, such that only the largest flood events can remove vegetation and expose bedrock on channel banks to potential erosion. We found that this large flood event plucked shale bedrock from both the channel bed and banks and that the shale bed sediment then quickly breaks down and is transported away by small flows. As such, this data set allowed us to make conclusions about the effect of large flood events on the long-term evolution of lateral and vertical erosion in bedrock rivers.