Sand-mud Mixtures Research Articles

Salt marshes for nature-based flood defense: Sediment type, drainage, and vegetation drive the development of strong sediment beds

In face of sea-level rise and increasing risks for storm impacts on shorelines, there is a growing demand for developing nature-based flood defenses, for example by restoring or creating salt marshes in front of engineered structures such as dikes. However, salt marshes can only optimally provide flood defense if their sediment beds are erosion resistant, even under very high flow velocities. It remains unknown how fast sediment strength develops in marshes restored or created for nature-based flood defense. Therefore, this study investigated how 1) sediment type, 2) tidal drainage depth and duration, and 3) pioneer vegetation species drive the development rate of sediment strength. A controlled experiment was set up with pots filled with two sediment types, which were either left bare or planted with Spartina anglica or Scirpus maritimus, two dominant salt marsh pioneers in NW Europe. All treatments were subjected to four different tidal regimes with different tidal drainage depth and duration. The results showed that sandy mud (with a 37% silt and clay fraction) led to much stronger sediments than fine mud (with a 77% silt and clay fraction). Sediment strength was higher in the treatments with deeper tidal drainage depth and longer drainage duration. The presence of vegetation increased sediment strength and this effect was stronger with Scirpus maritimus than with Spartina anglica. Plant roots increased sediment strength directly, and the presence of vegetation also seemed to increase sediment strength through enhanced evaporation and transpiration. From these results it can be concluded that to restore or create erosion resistant salt marshes for flood defense, it is essential to ensure that marshes can form at relatively high elevations from well-draining sand-mud mixtures, thereby also ensuring vegetation growth.

Critical Shear Stress for Erosion of Sand-Mud Mixtures and Pure Mud

The erosion threshold of sand-mud mixtures is investigated by analyzing the momentum balance of a sand particle or a mud parcel in the mixture bed surface, and a formula for the critical shear stress of sand-mud mixtures is developed, which also applies for pure sand and mud. The developed formula suggests that the variation of the critical shear stress of sand-mud mixtures over mud content is mainly caused by the varying dry bulk density of the mud component in the mixture. The developed formula reproduces well the variation of the critical shear stress of sand-mud mixtures over mud content and can predict the critical shear stress of both sand-mud mixtures and pure mud in the process of consolidation. The developed formula promises to be convenient for application by relating the critical shear stress to mud content and the dry bulk density of sediment.

Evidence for better microphytobenthos dynamics in mixed sand/mud zones than in pure sand or mud intertidal flats (Seine estuary, Normandy, France).

Understanding the dynamics of microphytobenthos biomass and photosynthetic performances in intertidal ecosystems will help advance our understanding of how trophic networks function in order to optimize ecological management and restoration projects. The main objective of this study was to investigate microphytobenthic biomass and photosynthetic performances as a function of the sedimentary and environmental variabilities in the range of intertidal habitats in the downstream Seine estuary (Normandy, France). Our results highlight higher biomass associated with more stratified biofilms and better photosynthetic performances in areas characterized by a sand/mud mixture (40–60% of mud) compared to pure sand or pure mud environments. This type of sediment probably offers an efficient trade-off between the favorable characteristics of the two types of sediments (sand and mud) with respect to light penetration and nutrient accessibility. Moreover, the large quantities of exopolysaccharides produced in sand/mud mixtures emphasizes the functional role played by microphytobenthos in promoting sediment stability against erosion. This allows us to show that despite the strong increase in sand content of the downstream Seine estuary, intertidal flats are still productive since microphytobenthic biomass, photosynthetic performances and exopolysaccharides secretion are highest in sand-mud mixtures. This study also underlines the impact of ecosystem modifications due to human disturbance and climate change on the dynamics of key primary producers in estuaries.

Numerical modelling of the erosion of marsh boundaries due to wave impact

The study describes an improvement of the 1D version of the hydro-morphodynamic model XBeach to simulate the erosion of saltmarsh edges under wave attack. The effects of sand-mud mixture and characteristics of vegetation on the erosive processes are implemented, along with a nonlinear version of the Exner equation to better simulate the horizontal migration of a vertical bank profile due to wave impact. Numerical experiments reveal that the effect of soil composition is crucial for the development of bank morphology where steep scarps are associated with muddier soils while gently smoothed cross-shore profiles are associated with sandier soils. The effect of vegetation in controlling the morphodynamic evolution under wave attack is greater when the sand fraction increases, thus contributing to the development of small steep scarps. The model is further tested against field data of a saltmarsh bank profile and wind conditions collected before and after the passage of Hurricane Isaac in Lake Borgne, Louisiana. After validation of the hydrodynamics, a tuning procedure to match the final profile is carried out on the main model parameters. The results illustrate the potential utility of the model for application to geomorphic settings subjected to wave impact and characterized by high mud content and halophytic vegetation; yet, the model still has limitations and further improvements are needed. Finally, the results demonstrate the ability of saltmarshes to withstand erosion during the peak of large storms when the marsh is submerged, and highlight transient conditions as important drivers of geomorphic change during storms.

VALIDATION OF SAND-MUD MIXTURE TRANSPORT MODEL WITH FIELD AND FLUME EXPERIMENTS

In coastal and estuarine environments, sand-mud mixtures are often formed due to supply of various types of sediment discharge from rivers. For better prediction of the sediment transport patterns and the resultant bathymetry changes in these areas, it is important to apply a sediment transport model that can represent the behavior of sand-mud mixtures depending on the mud content to the simulation. This study aims at elucidating the effect of the mud content on the erosion processes of sand-mud mixtures under the combined wave and current forces through a field observation and flume experiments. A sand-mud mixture transport model was validated based on the field and experimental results.

Morphodynamic responses of Caofeidian channel-shoal system to sequential large-scale land reclamation

Understanding the influence of reclamation projects on a channel-shoal system is of vital importance regarding the management and sustainable development of coastal regions. This study addresses the issue by applying a processes-based morphological model to investigate hydro-morphodynamics of Caofeidian channel-shoal in five phases of large-scale reclamation project from year 2003 to 2020. Forced by the spring-neap tidal cycles and representative waves, the model considers multi-fraction sediment dynamics regarding strong spatial variations of mud-sand mixtures in the study area. The numerical results demonstrate that sequential large-scale land reclamation induces continuous loss of sediment volume of tidal flat by reducing its sediment storage capability. The morphodynamics of channels is complex in space and perturbation of reclamation location increases this complexity. For the channels in the western uninterrupted coast, reclamation affects their morphological evolution by damping the long-shore sediment transport. The tidal asymmetry is a key factor in the geomorphology of channels in the eastern inlet-interrupted coast (Laolonggou lagoon-inlet system), which is impacted by the reclamation location. Particularly, reclamation constricting the inlet dampens the flood tidal asymmetry and triggers the deepening of inlet, while tidal flats reclamation in lagoon enhances flood tidal asymmetry which induces the siltation of inlet. The model also reveals different behaviors of multi-fraction sediments, of which the silt with larger settling velocity is subject to the hydrodynamic change induced by reclamation. Although this study is site-specific, the finding provides valuable information for sustainable management of channel-shoal systems in muddy-silt coast under intermittent or sequential land reclamation.

Unified Formula for Critical Shear Stress for Erosion of Sand, Mud, and Sand–Mud Mixtures

AbstractResearch on erosion behavior of sediments usually treats sand and mud separately. However, natural soil often occurs as a sand–mud mixture. An expression for cohesive forces in sand–mud mix...

A hydro-morphodynamic model integrating extended sediment particle size distribution and flocculation processes for better simulating hydro-sedimentary fluxes

Many studies focusing on suspended sediment transport modelling in river systems only consider one class of sediment grain size. Rather recently, the SISYPHE sediment transport model has integrated sand-mud mixture transport processes using two classes of sediment. However, this new modelling framework still suffers from limitations, and increasing the number of sediment classes would arguably improve sediment transport and therefore riverbed evolution simulations. Moreover, current sediment transport models do not simulate sediment particle aggregation and disaggregation processes while these can play an important role in sediment transport. Integrating these new concepts would then contribute to significant improvements to river bed morphodynamics and sediment transport modelling. In this study, we further develop the SISYPHE model by extending the sediment particle size distribution to ten classes and integrating flocculation processes (coupling with the flocculation FLOCMOD model). The preliminary results we present in this paper are based on a large-scale flood event, which occurred in river Orne, north-eastern France. We clearly show that the proposed developments of SYSIPHE improves qualitatively and quantitatively the predictions of sediment transport and riverbed morphodynamics.

Process-based morphodynamic modeling of the Yangtze Estuary at a decadal timescale: Controls on estuarine evolution and future trends

Understanding the decadal morphodynamic evolution of estuaries and deltas and their controls is of vital importance regarding management for estuarine function and sustainable development. This work addresses this issue by applying a process-based model system (Delft3D) to hindcast and then forecast the morphodynamic evolution of the Yangtze Estuary at a decadal timescale. Forced by the river and tides, the model considers sand-mud mixture and the variations of river water discharge and sediment discharge. The morphodynamic model is validated against three periods, i.e., an accretion period (1958–1978), an erosion period (1986–1997) and a recent accretion period with human activities (2002−2010). Model results show good performance with respect to spatial erosion and deposition patterns, sediment volume changes, and hypsometry curves. The model reveals quite different behaviors for mud transport between the dry and wet seasons, which is subject to the prescription of river boundary conditions and bed composition. We define six scenarios to project evolution to the year 2030 under decreased river inputs and increased relative sea level. The simulations reveal that overwhelming amount of erosion will likely occur in the inner and mouth bar area of the estuary. Particularly, the mouth zone will shift from net deposition before 2010 to net erosion by 2030, mainly because of decreasing sediment supply. Changes in water discharge have minor effects on the projected trend. Net erosion will be considerable when the sediment supply is extremely low (100Mtyr−1) due to the abundance of erodible modern sediment in the Yangtze Estuary. Erosion within the mouth bar area may be unexpected, including the deepening of the tidal inlet at East Chongming mudflat and the formation of a flood channel on the seaward side of Jiuduansha Shoal. Overall, the model results provide valuable information for sustainable delta management under changing conditions for both the Yangtze system and other similar estuaries and deltas with diminishing sediment supplies.

Monitoring and characterisation of sand-mud sedimentation processes

Estuaries and tidal inlets are often characterised by the presence of both cohesive and non-cohesive sediments. Knowledge of the sedimentation behaviour of sand-mud mixtures is therefore crucial to the understanding and prediction of the time-dependent structure (i.e. mixed or segregated), composition and erodibility of sediment bed deposits developing within these environments. In the current study, a series of settling column tests are conducted to investigate the hindered settling and initial bed consolidation phases of a range of sand-clay mixtures to determine the parametric conditions under which bed segregation occurs. A new, non-invasive, electrical resistivity measurement technique is employed to capture both temporal and spatial changes in the density, porosity and composition of the evolving sand-clay bed deposits, complimented by time-lapsed images of the sedimentation process within the column. The results show that the formation of segregated (sand-clay) bed layers with bed deposits is largely controlled by the initial fractional composition (i.e. relative sand and clay concentrations). Specifically, mixtures with low clay contents are shown to form well-defined (sand-clay) layer segregation within the resulting deposits, while higher clay contents result in more transitional segregation patterns or no layer segregation (for very high clay concentrations). The physical mechanisms under which these different segregation types can be generated are illustrated through predictions from an existing polydisperse hindered settling model. This model indicates that the degree of bed segregation, and time scale over which this occurs, correlates well with the difference in predicted hindered settling characteristics and upward displacements associated with the sand and clay fractions, respectively. In this regard, the new experimental dataset provides validation for the polydisperse model (for the first time), with the combined data and model predictions providing new insight into mixed (sand-clay) sedimentation processes.

A one-dimensional biomorphodynamic model of tidal flats: Sediment sorting, marsh distribution, and carbon accumulation under sea level rise

We develop a biomorphodynamic model to investigate sediment and vegetation dynamics on a schematic intertidal flat characterized by an initially well-mixed sand-mud mixture. Major interactions between tides, wind waves, salt marshes, sediment transport and sea level rise (SLR) are taken into account. For a bare flat under only tidal action, the model predicts a convex cross-shore profile with the surficial distribution of mud and sand on the upper and lower part of the intertidal flat, respectively. When wind waves are strong, the intertidal flat is highly eroded resulting in a concave profile near the high water mark. This behavior is pronouncedly altered when the intertidal flat is vegetated with the presence of salt marshes. Numerical results suggest that a considerable amount of mud can still remain in the vegetated region even when wave action is strong. A steeper transition zone forms at the boundary between salt marshes and bare flats because of the differential sediment deposition in the two neighboring regions. The inclusion of wind waves is found to considerably enhance the size of the marsh-edge transition zone. For the numerical experiments designed in this study, the profile shape and sediment sorting behavior of tidal flats are not significantly modified by a gradual rising sea level. However, the impacts of SLR on vegetated tidal flats are still manifold: (a) driving the landward migration of intertidal zone and salt marshes; (b) enhancing sediment erosion on intertidal flats; and (c) drowning salt marshes under limited sediment supply with the constrain of seawalls. Finally, model results suggest that organic carbon accumulation on marshlands may be enhanced with an increasing SLR rate provided that salt marshes are not drowned.

Impact of sediment grain-size and biofilm age on epipelic microphytobenthos resuspension

Intertidal zones are dynamic areas, where tidal currents and wind-induced waves are responsible of resuspension of the sediment and associated microphytobenthos (MPB). Sediment composition (mud–sand mixtures) and MPB biofilm age are two major components involved in resuspension of epipelic microphytobenthos in muddy areas. However, their relative role in resuspension phenomenon must be better understood in controlled conditions. In this study, three mud–sand mixtures (Pure mud M1, 75% mud/25% sand M2 and 50% mud/50% sand M3) were tested with an epipelic MPB biofilm of different ages (3, 6 and 9days after inoculum) using an erodimeter flume. The biofilm biomass, physiological state, photosynthetic parameters and Extracellular Polymeric Substances (EPS) were surveyed as well as water content and ammonium concentration in the sediment. Chl a content and Suspended Particular Inorganic Matter (SPiM) erodability differed between treatments, biofilm being able to be eroded before sediment when it is well constituted (especially in pure mud M1). Between day 3 and day 9 of culture, biofilm age did significantly affect critical thresholds for Chl a erosion and sediment resuspension for mud–sand mixtures (M2 and M3). Sediment resuspension seemed to be also driven by physical constraints like differential compaction and vertical sand segregation as a function of mud content. Indeed, grain-size was the main factor involved in MPB resuspension phenomenon, with an optimum reached near a equilibrate ratio between mud and sand (50% mud–50% sand). Proteins of the EPS bound fraction (extracted with dowex resin) appeared to have a critical role in the pioneering stages of biofilm installation, allowing its formation in a less favorable environment caused by sand enrichment (mixtures M2 and M3). This effect of bound EPS must be mediated by an increasing cohesion and lowering sediment permeability. Carbohydrate content of the bound EPS fraction was directly related to the sediment (SPiM) erodability, independently from mixture type or biofilm age.

Mixed-sediment transport modelling in Scheldt estuary with a physics-based bottom friction law

In this study, the main object is to investigate the performance of a few new physics-based process models by implementation into a numerical model for the simulation of the flow and morphodynamics in the Western Scheldt estuary. In order to deal with the complexity within the research domain, and improve the prediction accuracy, a 2D depth-averaged model has been set up as realistic as possible, i.e. including two-way hydrodynamic-sediment transport coupling, mixed sand–mud sediment transport (bedload transport as well as suspended load in the water column) and a dynamic non-uniform bed composition. A newly developed bottom friction law, based on a generalised mixing-length (GML) theory, is implemented, with which the new bed shear stress closure is constructed as the superposition of the turbulent and the laminar contribution. It allows the simulation of all turbulence conditions (fully developed turbulence, from hydraulic rough to hydraulic smooth, transient and laminar), and the drying and wetting of intertidal flats can now be modelled without specifying an inundation threshold. The benefit is that intertidal morphodynamics can now be modelled with great detail for the first time. Erosion and deposition in these areas can now be estimated with much higher accuracy, as well as their contribution to the overall net fluxes. Furthermore, Krone’s deposition law has been adapted to sand–mud mixtures, and the critical stresses for deposition are computed from suspension capacity theory, instead of being tuned. The model has been calibrated and results show considerable differences in sediment fluxes, compared to a traditional approach and the analysis also reveals that the concentration effects play a very important role. The new bottom friction law with concentration effects can considerably alter the total sediment flux in the estuary not only in terms of magnitude but also in terms of erosion and deposition patterns.

Numerical modelling of mixed-sediment consolidation

Sediment transport modelling in estuarine environments, characterised by cohesive and non-cohesive sediment mixtures, has to consider a time variation of erodibility due to consolidation. Generally, validated by settling column experiments, mud consolidation is now fairly well simulated; however, numerical models still have difficulty to simulate accurately the sedimentation and consolidation of mixed sediments for a wide range of initial conditions. This is partly due to the difficulty to formulate the contribution of sand in the hindered settling regime when segregation does not clearly occur. Based on extensive settling experiments with mud-sand mixtures, the objective of this study was to improve the numerical modelling of mixed-sediment consolidation by focusing on segregation processes. We used constitutive relationships following the fractal theory associated with a new segregation formulation based on the relative mud concentration. Using specific sets of parameters calibrated for each test—with different initial sediment concentration and sand content—the model achieved excellent prediction skills for simulating sediment height evolutions and concentration vertical profiles. It highlighted the model capacity to simulate properly the segregation occurrence for mud-sand mixtures characterised by a wide range of initial conditions. Nevertheless, calibration parameters varied significantly, as the fractal number ranged from 2.64 to 2.77. This study investigated the relevance of using a common set of parameters, which is generally required for 3D sediment transport modelling. Simulations were less accurate but remained satisfactory in an operational approach. Finally, a specific formulation for natural estuarine environments was proposed, simulating correctly the sedimentation-consolidation processes of mud-sand mixtures through 3D sediment transport modelling.

A STUDY ON THE SAND-MUD MIXTURE AT NORTH-WEST OF THE PERSIAN GULF

A numerical model is used for simulating the transportation process of sand-mud mixture at Shah-Abdollah Port located on the north-western shoreline of the Persian Gulf. Available hindcast wave data were adopted in combination with tidal water level variations as the boundary conditions of the numerical model. The existing extracted shoreline changes around Shah-Abdollah Port through GIS analysis of satellite images were used to assess the general morphological changes in the study area. The modeling results of sediment transport shows that the net longshore sediment transport at both sides of the port reduces to very small values near the port location implying that this location is acting as a null net drift point dividing the eastern sandy and western muddy coastlines.

Modeling Tidal Bedding In Distributary-Mouth Bars

Abstract Distributary-mouth bars are important morphological units of deltas which develop under a wide range of wave, tidal, and riverine conditions, and are known to form highly productive subsurface oil and gas reservoirs. This paper extends previous work on purely fluvial mouth bars, to mixed systems where tides are also present. Under these conditions mouth bars can display alternate layers of mud and sand that can ultimately determine their vertical permeability. Herein we propose an analytical, process-based model to explain characteristics of tidal bedding and quantify their extent in mouth bars. Findings from our analytical model are compared with results from the numerical model Delft3D. From landward to seaward and in the absence of tides, our analysis shows that a sand-dominated zone is followed by a depositional environment made of sand and mud mixtures, and finally by mud-dominated areas. With increasing tidal amplitude, the sand–mud mixture zone is gradually replaced by a lamination zone characterized by alternate tidal bedding. Bedding characteristics in mouth bars are defined using the extension of the lamination area and the difference in mud content between coarse and fine sediment layers. Both quantities tend to increase with increasing tidal amplitude. The lamination zone grows while the difference in mud content decreases for small ratios of mud to sand settling velocity and mud to sand concentration. Bottom friction strongly affects tidal bedding by reducing the length of the zone where lamination occurs and increasing differences in mud content between successive layers.

Processes and products of turbidity currents entering soft muddy substrates

New laboratory experiments reveal that cohesionless turbidity currents are able to enter cohesive soft muddy substrates without losing their shape. These intrabed currents are driven by bed shear stress exceeding bed cohesive strength, and by flow density exceeding bed den - sity. The flows produce unique turbidites with internal mud layers, mixed cohesive-nonco - hesive sediment layers, and flame and load structures. A depositional model for intrabed (I) turbidites is proposed, comprising, from base to top: I1�sand-bearing mud, with a scoured base, dispersed mud, and mud clasts; I2�muddy sand from the intrabed portion of the tur - bidity current; I3�sandy mud with a speckled appearance; and I4�mud-poor sand from the suprabed portion of the flow. Complete I1�I4 turbidites are inferred to dominate loca - tions in nature where the currents mix with the bed and deep erosional scours form, filled with deformed or chaotic sand-mud mixtures. Further downflow, base-missing I2�I4 and I4 sequences signify gradual deceleration, loss of erosivity, and termination of intrabed flow

The settling dynamics of flocculating mud and sand mixtures: part 2—numerical modelling

Estuarine and coastal sediment transport is characterised by the transport of both sand-sized particles (of diameter greater than 63 μm) and muddy fine-grained sediments (silt, diameter less than 63 μm; clay, diameter less than 2 μm). These fractions are traditionally considered as non-cohesive and cohesive, respectively, because of the negligible physico-chemical attraction that occurs between sand grains. However, the flocculation of sediment particles is not only caused by physico-chemical attraction. Cohesivity of sediment is also caused by biology, in particular the sticky extra-cellular polymeric substances secreted by diatoms, and the effect of biology in binding sediment particles can be much larger than that of physico-chemical attraction. As demonstrated by Manning (2008) and further expanded in part 1 of this paper (Manning et al., submitted), the greater binding effect of biology allows sand particles to flocculate with mud. In many estuaries, both the sand and fine sediment fractions are transported in significant quantities. Many of the more common sediment transport modelling suites now have the capability to combine mud and sand transport. However, in all of these modelling approaches, the modelling of mixed sediment transport has still essentially separated the modelling of sand and mud fractions assuming that these different fractions do not interact except at the bed. However, the use of in situ video techniques has greatly enhanced the accuracy and reliability of settling velocity measurements and has led to a re-appraisal of this widely held assumption. Measurements of settling velocity in mixed sands presented by Manning et al. (2009) have shown strong evidence for the flocculation of mixed sediments, whilst the greater understanding of the role of biology in flocculation has identified mechanisms by which this mud-sand flocculation can occur. In the first part of this paper (Manning et al., submitted), the development of an empirical flocculation model is described which represents the interaction between sand and mud particles in the flocculation process. Measurements of the settling velocity of varying mud-sand mixtures are described, and empirical algorithms governing the variation of settling velocity with turbulence, suspended sediment concentration and mud-sand content are derived. The second part of this paper continues the theme of examination of the effects of mud-sand interaction on flocculation. A 1DV mixed transport model is developed and used to reproduce the vertical transport of mixed sediment fractions. The 1DV model is used to reproduce the measured settling velocities in the laboratory experiments described in the part 1 paper and also to reproduce measurements of concentration of mixed sediments in the Outer Thames. In both modelling exercises, the model is run using the algorithms developed in part 1 and repeated using an assumption of no interaction between mud and sand in the flocculation process. The results of the modelling show a significant improvement in the ability of the 1DV to reproduce the observed sediment behaviour when the empirical equations are used. This represents further strong evidence of the interaction between sand and mud in the flocculation process.

The settling dynamics of flocculating mud-sand mixtures: Part 1—Empirical algorithm development

The settling dynamics of flocculating mud-sand mixtures: Part 1—Empirical algorithm development

Erosion threshold of sand–mud mixtures

Results of a large number of erosion tests on artificially generated and relatively dense sand–mud mixtures are presented. Soil sample compositions are varied concerning clay–silt and sand–silt ratio, and clay mineralogy. The experimental set-up consists of a re-circulating small-scale rectangular erosion flume with unidirectional flow conditions. The erosion threshold and erosion rate are studied through step by step increasing the flow rate during a test. Results clearly indicate time-decreasing erosion during which individual flocs are randomly eroded, and time-independent (steady) erosion during which both sand and mud particles are continuously and uniformly eroded. These two erosion types appear to be floc and surface erosion, respectively ( Winterwerp and Van Kesteren, 2004). Floc erosion relates to the stochastic character of both the flow conditions and (surficial) sediment strength, whereas surface erosion relates to the plasticity index, which is a bulk soil mechanical parameter characterizing cohesiveness. The surface erosion threshold is discussed following a geotechnical approach, which argues that surface erosion is a drained process. This implies that cohesiveness rather than packing density is important for the erosion threshold, which is confirmed by the experimental data. Simultaneously with the erosion tests, also the undrained shear strength of the applied soil samples was determined. A model is proposed and validated to predict the undrained shear strength as function of the granular porosity in combination with the plasticity index. The comparison of the undrained shear strength with the surface erosion threshold further confirms the applicability of a geotechnical approach to understand the erosion of mixed sediments. Finally, the study provides a valuable data set that can be used as a reference for future research on erosion behavior of (natural) sediment mixtures.