Journal ArticleDOI
Information on grain sizes in gravel-bed rivers by automated image analysis
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In this paper, modified edge-detection algorithms combine edge seeding with an image porosity concept and partial watershed segmentation to reduce the time required in the field to characterize textural variation over gravel surfaces.Abstract:
The time required in the field to characterize textural variation over gravel surfaces can be reduced by taking vertical photographs for subsequent image analysis. We present modified edge-detection algorithms which combine edge seeding with an image porosity concept and partial watershed segmentation. The methods allow quick, reliable, and operator-independent size analysis from a wide range of vertical bed-surface images. They are tested using 24 naturally lit images of an exposed river bed with mixed lithologies and partial burial of gravel by sand. Grain-size percentiles derived by automated image analysis correlate closely with those from manual image analysis, with only small and consistent degrees of bias. They also correlate well with percentiles from field measurements with substantial bias, which, however, is consistent so that it can be corrected for, leaving a residual scatter of 0.25 (where = log2 mm = -) over a wide range of bed conditions. The bias depends somewhat on sand cover, and the biggest residual discrepancies are for tail percentiles.read more
Citations
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Journal ArticleDOI
An automated simple algorithm for realistic pore network extraction from micro-tomography images
TL;DR: A new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network and 3-D network is produced using city-block distance function and watershed segmentation algorithm.
Journal ArticleDOI
Automated Sizing of Coarse-Grained Sediments: Image-Processing Procedures
TL;DR: It is shown that neighborhood-based operations are the most powerful, and a morphological bottom-hat transform with a double threshold is optimal, and the optimal procedure is that which gives consistently good results across sites with dissimilar sedimentary characteristics.
Journal ArticleDOI
Terrestrial Laser Scanning of grain roughness in a gravel-bed river
David J. Milan,David J. Milan +1 more
TL;DR: In this paper, the application of terrestrial laser scanning (TLS) to determine the full population of grain roughness in gravel-bed rivers was demonstrated, where a total of 3.8 million data points were retrieved from a gravel bar surface at Lambley on the River South Tyne, UK.
Journal ArticleDOI
A transferable method for the automated grain sizing of river gravels
TL;DR: In this paper, an extremely rapid image-processing-based procedure for the measurement of exposed fluvial gravels and other coarse-grained sediments, defining the steps required to minimize the errors in the derived grain-size distribution.
Journal ArticleDOI
Grain size and topographical differences between static and mobile armour layers
TL;DR: In this paper, a series of laboratory flume experiments under conditions of sediment starvation (zero sediment feeding) and recirculation were conducted in order to identify the temporal evolution and surface properties of static and mobile armour layers.
References
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Journal ArticleDOI
Sampling surficial fluvial gravels; the precision of size distribution percentile sediments
Stephen P. Rice,Michael Church +1 more
TL;DR: In this article, the relative precision of the estimated percentiles to distribution shape is examined using synthetic skewed and bimodal grain size distributions, and it is shown that the absolute precision of percentile estimates varies with the grain size distribution of a particular sediment.
Journal ArticleDOI
Bed‐material transport estimated from channel surveys: Vedder River, British Columbia
Yvonne Martin,Michael Church +1 more
TL;DR: In this paper, the authors investigated the possibility to estimate bed-material transfer in gravel-bed rivers by analysis of morphological changes along Vedder River, British Columbia, using repeated cross-section surveys to estimate volume changes along the length of an 8 km reach.
Journal ArticleDOI
Photo‐sieving: A method for grain‐size analysis of coarse‐grained, unconsolidated bedding surfaces
TL;DR: The photo-sieving method as mentioned in this paper enables the grain-size analysis of particles > 10 mm from unconsolidated openwork bedding surfaces, which differs distinctly from point-counting techniques.
Journal ArticleDOI
Gravel Size Analysis from Photographs
TL;DR: In this article, the authors show that the grain size standard deviation from photographs are approximately equivalent to sieve values for sizes in phi units, but are offset by the same bias as the mean size.
Journal ArticleDOI
Estimating the size composition of sediment surfaces through image analysis
TL;DR: In this article, an edge-detection algorithm is used to obtain the particle boundaries and segment the image into individual grains, and further processing of the segmented image can result in detailed information about grain size, position, orientation and exposure.