Image analysis for measuring stratigraphy in sand-gravel laboratory experiments

Abstract. Measurements of spatial and temporal changes in the grain size distribution are crucial to improving the modelling of sediment transport and associated grain size-selective processes. We present three complementary techniques to determine such variations in the grain size distribution in sand-gravel laboratory experiments, as well as the resulting stratigraphy: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratigraphy measurement method has been evaluated in two sets of experiments. In both sets three grain size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, i.e. the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e., grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also observing and understanding grain size-selective processes. The stratigraphy based on areal fractions is measured with sufficient accuracy. Other advantages of the proposed stratigraphy measurement technique are: (a) rapid collection and processing of a large amount of data, (b) very high spatial density of information on the grain size distribution (so far unequalled in other methods), (c) the lack of disturbances to the bed surface, (d) only minor disturbances to the substrate due to the removal of sediment layers, and (e) the possibility to return a sediment layer at its original elevation and continue the flume experiment. The areal fractions can be converted into volumetric fractions using a conversion model. The proposed empirical conversion model is based on a comparison between the photogrammetry results and dry sieve analysis.

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Image analysis for measuring the size stratification in sand–gravel laboratory experiments

Earth Surface Dynamics ◽

10.5194/esurf-2-217-2014 ◽

2014 ◽

Vol 2 (1) ◽

pp. 217-232 ◽

Cited By ~ 6

Author(s):

C. Orrú ◽

V. Chavarrías ◽

W. S. J. Uijttewaal ◽

A. Blom

Keyword(s):

Grain Size ◽

Image Analysis ◽

Size Distribution ◽

Grain Size Distribution ◽

Measurement Method ◽

Laboratory Experiments ◽

Size Fraction ◽

Sediment Layer ◽

Areal Fraction ◽

Sediment Layers

Abstract. Measurements of spatial and temporal changes in the grain-size distribution of the bed surface and substrate are crucial to improving the modelling of sediment transport and associated grain-size selective processes. We present three complementary techniques to determine such variations in the grain-size distribution of the bed surface in sand–gravel laboratory experiments, as well as the resulting size stratification: (1) particle colouring, (2) removal of sediment layers, and (3) image analysis. The resulting stratification measurement method was evaluated in two sets of experiments. In both sets three grain-size fractions within the range of coarse sand to fine gravel were painted in different colours. Sediment layers are removed using a wet vacuum cleaner. Subsequently areal images are taken of the surface of each layer. The areal fraction content, that is, the relative presence of each size fraction over the bed surface, is determined using a colour segmentation algorithm which provides the areal fraction content of a specific colour (i.e. grain size) covering the bed surface. Particle colouring is not only beneficial to this type of image analysis but also to the observation and understanding of grain-size selective processes. The size stratification based on areal fractions is measured with sufficient accuracy. Other advantages of the proposed size stratification measurement method are (a) rapid collection and processing of a large amount of data, (b) a very high spatial density of information on the grain-size distribution, (c) the lack of disturbances to the bed surface, (d) only minor disturbances to the substrate due to the removal of sediment layers, and (e) the possibility to return a sediment layer to its original elevation and continue the flume experiment. The areal fractions are converted into volumetric fractions using an existing conversion model.

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The Influence of Grain Size Distribution on the Hydraulic Gradient for Initiating Backward Erosion

Water ◽

10.3390/w12092644 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2644 ◽

Cited By ~ 1

Author(s):

Willem-Jan Dirkx ◽

Rens Beek ◽

Marc Bierkens

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Laboratory Experiments ◽

Hydraulic Gradient ◽

Concentrated Flow ◽

Pipe Formation ◽

Novel Method ◽

Flow Through ◽

The Stability

Backward erosion by piping is one of the processes that threaten the stability of river embankments in the Netherlands. During high river stages, groundwater flow velocities underneath the embankment increase as a result of the steepened hydraulic gradient. If a single outflow point exists or forms, the concentrated flow can entrain soil particles, leading to the formation of a subsurface pipe. The processes controlling this phenomenon are still relatively unknown due to their limited occurrence and because piping is a subsurface phenomenon. To study the initiation of piping, we performed laboratory experiments in which we induced water flow through a porous medium with a vertically orientated outflow point. In these experiments, we explicitly considered grain size variations, thus adding to the existing database of experiments. Our experiments showed that the vertical velocity needed for the initiation of particle transport can be described well by Stokes’ law using the median grain size. We combine this with a novel method to relate bulk hydraulic conductivity to the grain size distribution. This shows that knowledge of the grain size distribution and the location of the outflow point are sufficient to estimate the hydraulic gradient needed to initiate pipe formation in the experiment box.

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Development of Image Analysis Tools to Evaluate In-Situ Evolution of the Grain Size Distribution in Sand Subjected to Breakage

Springer Series in Geomechanics and Geoengineering - Bifurcation and Degradation of Geomaterials in the New Millennium ◽

10.1007/978-3-319-13506-9_36 ◽

2014 ◽

pp. 253-258 ◽

Cited By ~ 2

Author(s):

Marios Gkiousas-Kapnisis ◽

Edward Andò ◽

Alessandro Tengattini ◽

Itai Einav ◽

Gioacchino Viggiani

Keyword(s):

Grain Size ◽

Image Analysis ◽

Size Distribution ◽

Grain Size Distribution ◽

Analysis Tools

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Fluctuations of bed load solid discharge and grain size distribution on steep slopes with image analysis

Experiments in Fluids ◽

10.1007/s00348-003-0707-9 ◽

2003 ◽

Vol 35 (6) ◽

pp. 589-597 ◽

Cited By ~ 31

Author(s):

P. Frey ◽

C. Ducottet ◽

J. Jay

Keyword(s):

Grain Size ◽

Image Analysis ◽

Size Distribution ◽

Grain Size Distribution ◽

Bed Load ◽

Solid Discharge ◽

Steep Slopes

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Assessment and Analysis of Precambrian Basement Soil Deposits Using Grain Size Distribution

Materials and Geoenvironment ◽

10.2478/rmzmag-2019-0019 ◽

2020 ◽

Vol 66 (4) ◽

pp. 235-243

Author(s):

Gideon Layade ◽

Charles Ogunkoya ◽

Victor Makinde ◽

Kehinde Ajayi

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Textural Properties ◽

Soil Samples ◽

Sieve Analysis ◽

Precambrian Basement ◽

Statistical Parameters ◽

Fine Grained ◽

Transportation History

AbstractThe article presents the grain size distribution of soil samples from the Precambrian basement within the purview of the textural properties, deduced transportation history and the numerical assessments using statistical parameters. The fourteen soil samples collected from the study area were subjected to sieve analysis in the laboratory for the determination of their grain size distribution. The statistical parameters’ study includes the graphic mean, skewness, sorting and kurtosis. The result of the analysis of the soil samples ranged from coarse to fine-grained samples, moderately and poorly sorted, positively and negatively skewed and the kurtosis also shows leptokurtic as the most dominant which suggests the samples poorly distributed and moderately sorted at the centre of the grain size distribution. These results also suggest the geological environment of the soil samples could be responsible for the poorly and moderately sorted exhibited by the samples deposited in the location.

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