Publisher's copyright statement:Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Turbidity of water due to the presence suspended sediment is measured and interpreted in a variety of ways, which can lead to the misinterpretation of data. This paper re-examines the physics of lightscattering in water, and exposes the extent to which the reporting of turbidity data is inconsistent. It is proposed that the cause of this inconsistency is the fact that the accepted turbidity standards USEPA Method 180.1, ISO 7027 and GLI Method 2 are mutually inconsistent, as these standards give rise to a large number of measurement units that are not based on the optical properties of light absorption and scattering by suspensions in water, but by the arbitrary definition of the degree of turbidity being due to a concentration of formazin or other similar polymerbased calibration standard. It is then proposed that all turbidity-measuring devices should be calibrated with precise optical attenuators such as ND filters. Such calibration would allow for the definition of a beam attenuation coefficient (BAC) for every turbidity measuring instrument which would be cross-comparable with any other instrument calibrated in the same way.The units for turbidity measurements should be based on attenuation and reported as dB m-1. It is also proposed that a new standard should be drafted according to this attenuation-based method, and this new standard should also define the nomenclature for reporting data collected at any specific scattering angle in terms of an attenuation in dB m-1. The importance of multi-parameter turbidity measurements for the improvement of the quality of turbidity data, and the application of parameter-rich data sets to new methods of sediment characterization are discussed. It is suggested that more research into multi-parameter turbidity measurements is needed, as these new methods will facilitate an increase in parity between turbidity and suspended sediment concentration (SSC), a relationship that is subjective.http://mc.manuscriptcentral.com/PiPG Progress in Physical Geography 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 Turbidity of water due to the presence suspended sediment is measured and interpreted in a variety of 2 ways, which can lead to the misinterpretation of data. This paper re-examines the physics of light-3 sc...

(2014) 'Experimental investigation into the impact of a liquid droplet onto a granular bed using three-dimensional, time-resolved, particle tracking.', Physical review E., 89 (3). 032201.Further information on publisher's website:http://dx.doi.org/10.1103/PhysRevE.89.032201Publisher's copyright statement:Reprinted with permission from the American Physical Society: Physical Review E 89, 032201 c 2014 by the American Physical Society. Readers may view, browse, and/or download material for temporary copying purposes only, provided these uses are for noncommercial personal purposes. Except as provided by law, this material may not be further reproduced, distributed, transmitted, modied, adapted, performed, displayed, published, or sold in whole or part, without prior written permission from the American Physical Society.Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. An experimental investigation into the interaction that occurs between an impacting water droplet and a granular bed of loose graded sand has been carried out. High-speed imaging, three-dimensional time-resolved particle tracking, and photogrammetric surface profiling have been used to examine individual impact events. The focus of the study is the quantification and trajectory analysis of the particles ejected from the sand bed, along with measurement of the change in bed morphology. The results from the experiments have detailed two distinct mechanisms of particle ejection: the ejection of water-encapsulated particles from the edge of the wetted region and the ejection of dry sand from the periphery of the impact crater. That the process occurs by these two distinct mechanisms has hitherto been unobserved. Presented in the paper are distributions of the particle ejection velocities, angles, and transport distances for both mechanisms. The ejected water-encapsulated particles, which are few in number, are characterized by low ejection angles and high ejection velocities, leading to large transport distances; the ejected dry particles, which are much greater in number, are characterized by high ejection angles and low velocities, leading to lower transport distances. From the particle ejection data, the momentum of the individual ballistic sand particles has been calculated; it was found that only 2% of the water-droplet momentum at impact is transferred to the ballistic sand particles. In addition to the particle tracking, surface profiling of the granular bed postimpact has provided detailed information on its morphology; these data hav...

[1] There are currently no process-based approaches that allow detailed spatial information on soil redistribution on hillslopes to be modeled at spatial scales that are appropriate for studying slope processes. In response, we developed a new type of soil-erosion model, a marker-in-cell model, which simulates the redistribution of soil during rainfall events. The model is a hybrid of cell-and particle-based techniques. A cell-based model is used to determine the hydrology and hydraulics occurring at the cellular scale on the hillslope. Markers, representing sediment, are then moved through the grid according to these properties. The spatial pattern of erosion is determined directly by the properties of the markers. The model allows two-dimensional spatial patterns of individual particle movement on a hillslope to be simulated within a computationally efficient framework. We have tested the model using data collected from a plot-scale, rainfall-simulation experiment. We measured the redistribution of 137 Cs-rich tracer soil to resolve the spatial patterns of erosion caused by a single, high-intensity, rainfall event. The model was able to recreate the key temporal and spatial aspects of the hydrology and hydraulics occurring on the plot, as well as the spatial redistribution of 137 Cs-rich tracer soil. The development of the model was used to probe our understanding of how to investigate soil-erosion processes. The lack of empirical underpinnings of the different model components highlighted the need to understand the spatiotemporal dynamics of soil erosion processes at the grain-scale so to provide a better process-based understanding of detachment and transport can be sought.

No abstract

No abstract