Deriving high-resolution sediment load data using a nonlinear deterministic approach

2004 ◽  
Vol 40 (5) ◽  
Author(s):  
Bellie Sivakumar ◽  
Wesley W. Wallender
Keyword(s):  
High Resolution ◽  
Sediment Load ◽  
Deterministic Approach

The Significance of Erosion Channels on Gold Metallogeny in the Witwatersrand Basin (South Africa): Evidence from the Carbon Leader Reef in the Carletonville Gold Field

2020 ◽  
Author(s):  
G. T. Nwaila ◽  
J. E. Bourdeau ◽  
Z. Jinnah ◽  
H. E. Frimmel ◽  
G. M. Bybee ◽  
...  
Keyword(s):  
South Africa ◽  
High Resolution ◽  
Mass Balance ◽  
Closed System ◽  
Seismic Data ◽  
Crucial Role ◽  
Sediment Load ◽  
Witwatersrand Basin ◽  
Petrographic Analyses ◽  
Group A

Abstract Within the eastern portion of the Carletonville gold field, the gold- and uranium-rich Carbon Leader reef of the Central Rand Group (Witwatersrand Supergroup) is truncated by an erosion channel. This channel is asymmetrical and lenticular in shape, measuring 150 to 180 m in width and up to 100 m in depth. High-resolution seismic data show that the erosion channel cuts from the Carbon Leader reef into all older units of the Central Rand Group down to the Roodepoort Formation of the underlying West Rand Group. A total of seven bore-holes were drilled into the channel, revealing that it is composed of quartzite at its base (9 m thick), overlain by deformed (lower) and laminated (upper) chloritoid-bearing shale (21 m thick) and quartzite (18 m thick). The Carbon Leader reef is highly enriched in gold (5–40 g/t Au), whereas the gold tenor of the erosion channel fill is in general much lower (<1 g/t Au), although locally grades of as much as 3.8 g/t Au are reached. Detailed seismic, sedimentological, and petrographic analyses revealed that the channel was filled with locally sourced sediments from the Main Formation. A closed-system mass balance further demonstrates that gold in the erosion channel could have been entirely sourced from the Carbon Leader reef. Sediment load played a crucial role in the distribution of gold in the channel, thus supporting a stratigraphically controlled modified placer model for the origin of gold in the Carbon Leader reef.

Diffused and localized sediment production processes in a distributed transport model

2020 ◽  
Author(s):  
Giulia Battista ◽  
Peter Molnar ◽  
Fritz Schlunegger ◽  
Paolo Burlando
Keyword(s):  
Surface Roughness ◽  
High Resolution ◽  
Overland Flow ◽  
Sediment Load ◽  
Transport Model ◽  
Sediment Sources ◽  
Local Surface ◽  
Sediment Production ◽  
Production Processes ◽  
Spatially Distributed

<p>The identification of preferential sediment production areas within a river basin is essential to improve predictions of sediment load and its sources, and to identify sources of potential water pollution. The role of these localized sediment sources is especially relevant in the sediment budget of alpine basins, where erosion in highly non-uniform and mass movements play a major role in the mobilization of sediments. While sediment tracers are useful to assess the origin of river-borne sediments, currently very few spatially distributed sediment transport models include the sediment production from a variety of sources and track sediment from source to outlet.</p><p>In this work, we present a new approach to include the production of sediment from localized sources, in addition to diffusive overland flow erosion, in a spatially distributed sediment production and transport model. This extension of the hydrological model Topkapi-ETH simulates the mobilization of sediments by (i) overland flow erosion, (ii) sediment pickup from landsliding areas by overland flow and (iii) river discharge, and (iv) sediment pickup from deeply incised valleys by channel flow. Landslides and incised valleys were identified from geological/geomorphological maps and a high resolution DEM of the study basin. To model the contribution of landslides, we introduce a parameter λ for gully competence, which describes the effectiveness of overland flow in mobilizing the sediments. Overall, λ affects the contributions of the different sediment production processes to the modelled sediment load at the basin outlet. To estimate a value of λ for the case study, we propose the local surface roughness to quantify the gully development onto the landslide surfaces. Additionally, we use available <sup>10</sup>Be measurements across the basin to assign a concentration to each sediment production process and select the end member value of λ that best reproduces the observed <sup>10</sup>Be concentrations at the outlet.</p><p>Our simulations indicate that including the production of sediments from localized sources with processes (ii) to (iv) is essential to capture the highest observed concentrations with the model. Moreover, the same observed suspended sediment concentrations at the outlet may be obtained with different combinations of sediment production processes in function of the gully competence. Finally, the local surface roughness analysis and the use of <sup>10</sup>Be concentration as a sediment tracer suggest that channel processes are dominant over hillslope sediment production in the study basin.</p><p>In conclusion, our work shows that combinations of physically-based sediment transport modelling with geomorphological mapping of localized sediment sources, high-resolution topographic information and point measurements of cosmogenic radionuclide concentrations allow to infer the dominant sediment production processes in river basins.</p>

scholarly journals Monitoring Geomorphic Change and Catchment Sediment Production to Understand the Erosive Dynamics in a Gullied Channel by Means of High-Resolution DEMs

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 56
Author(s):  
Alberto Alfonso-Torreño ◽  
Álvaro Gómez-Gutiérrez ◽  
Susanne Schnabel ◽  
J. Francisco Lavado Contador ◽  
Manuel Pulido Fernández ◽  
...  
Keyword(s):  
High Resolution ◽  
Soil Loss ◽  
Sediment Load ◽  
Gully Erosion ◽  
Negative Consequences ◽  
Inference System ◽  
Erosion Processes ◽  
Agrosilvopastoral Systems ◽  
Positive Balance ◽  
The Relationship

Gully erosion in valley bottoms is a frequent process with negative consequences in the dehesa environment. Soil loss, decrease of soil and descend in biomass are among the negative aftereffect of gully erosion processes. Studies conducted in agrosilvopastoral systems described the dynamics of gullied channels by means of fixed topographic cross sections or with low spatial resolution Digital Elevation Models (DEMs). Currently, high spatial and temporal resolution DEMs can be produced with spatially distributed information due to the development of new systems, platforms and sensors. Additionally, the rainfall and sediment discharge could also be monitored. This control allows us to relate gully erosion with catchment hydrology. The goals are (1) to quantify the sediment budgets by the spatio-temporal distribution of erosion and/or deposition in the gullied channel, (2) to interpret the geomorphic processes driving erosion and deposition and (3) to analyze the relationship between the morphological change and the catchment runoff and the sediment load. The studied area is a gullied channel located in the SW Iberian Peninsula and developed over a recent sedimentary deposit. The channel reaches an extension of 1 km in length and 2 m in depth. The methodology included the following steps: (1) flying the same study area with different time periods using a fixed-wing small Unmanned Aerial System (sUAS) to capture high-resolution aerial images and surveying Ground Control Points (GCPs) using a GNSS, (2) Structure-from-Motion photogrammetry processing using the acquired images and the GCPs to produce high-resolution DEMs for each date, (3) Applying the DEMs of difference approach to estimate topographic changes and to quantify the sediment budget and finally (4) analyzing the relationship between rainfall events, discharge, sediment load and changes in the channel previously estimated. Resulting DEMs and orthophotographs showed a Ground Sampling Distance of 0.02 m with a georeferencing Root Mean Square Error of 0.03 m. A spatially variable threshold (to differentiate actual geomorphic change from noise or errors) was produced using a Fuzzy Inference System and considering photogrammetric errors, slope and vegetation as factors. The applied method proved to be suitable to interpret the geomorphic changes for the gullied channel. For the 2016–2018 period, the gully showed a positive balance indicating accumulation of sediments coming from the hillslopes of the catchment. It is the period with the highest rainfall when numerous events generated runoff. On the contrary, for the period 2018–2019 a total soil loss of −119 m3 was estimated.

scholarly journals Observed runoff, jökulhlaups and suspended sediment load from the Greenland ice sheet at Kangerlussuaq, West Greenland, 2007 and 2008

2009 ◽  
Vol 55 (193) ◽  
pp. 855-858 ◽  
Author(s):  
Sebastian H. Mernild ◽  
Bent Hasholt
Keyword(s):  
High Resolution ◽  
Suspended Sediment ◽  
Sediment Load ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Suspended Sediment Load ◽  
Degree Days ◽  
West Greenland ◽  
Sheet Surface ◽  
Positive Degree

AbstractThis study fills the gap in hydrologic measurements of runoff exiting a part of the Greenland ice sheet (GrIS), the Kangerlussuaq drainage area, West Greenland. The observations are of value for obtaining knowledge about the terrestrial freshwater and sediment output from part of the GrIS and the strip of land between the ice sheet and the ocean, in the context of varying ice-sheet surface melt and influx entering the ocean. High-resolution stage, discharge and suspended sediment load show a decrease in runoff of ∼25% and in sediment load of ∼40% from 2007 to 2008 in response to a decrease in the summer accumulated number of positive degree-days. During the 2007 and 2008 runoff seasons, jökulhlaups were observed at Kangerlussuaq, drained from an ice-dammed lake at the margin of the GrIS.

Observations of the spatial structure of interstellar hydrogen

1967 ◽  
Vol 31 ◽  
pp. 45-46
Author(s):  
Carl Heiles
Keyword(s):  
High Resolution ◽  
Spatial Structure ◽  
Velocity Dispersion ◽  
Temperature Variations

High-resolution 21-cm line observations in a region aroundlII= 120°,b11= +15°, have revealed four types of structure in the interstellar hydrogen: a smooth background, large sheets of density 2 atoms cm-3, clouds occurring mostly in groups, and ‘Cloudlets’ of a few solar masses and a few parsecs in size; the velocity dispersion in the Cloudlets is only 1 km/sec. Strong temperature variations in the gas are in evidence.

Combining integrated systems-biology approaches with intervention-based experimental design provides a higher-resolution path forward for microbiome research

2019 ◽  
Vol 42 ◽  
Author(s):  
J. Alfredo Blakeley-Ruiz ◽  
Carlee S. McClintock ◽  
Ralph Lydic ◽  
Helen A. Baghdoyan ◽  
James J. Choo ◽  
...  
Keyword(s):  
Systems Biology ◽  
High Resolution ◽  
Experimental Design ◽  
Integrated Systems ◽  
Microbiome Research ◽  
Constructive Criticism

Abstract The Hooks et al. review of microbiota-gut-brain (MGB) literature provides a constructive criticism of the general approaches encompassing MGB research. This commentary extends their review by: (a) highlighting capabilities of advanced systems-biology “-omics” techniques for microbiome research and (b) recommending that combining these high-resolution techniques with intervention-based experimental design may be the path forward for future MGB research.

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

Microcalorimeters for X-Ray Spectroscopy

1988 ◽  
Vol 102 ◽  
pp. 41
Author(s):  
E. Silver ◽  
C. Hailey ◽  
S. Labov ◽  
N. Madden ◽  
D. Landis ◽  
...  
Keyword(s):  
High Resolution ◽  
High Efficiency ◽  
Thermal Response ◽  
Low Noise ◽  
High Resolution Spectroscopy ◽  
Superconducting Transition ◽  
Sapphire Substrates ◽  
Laboratory Plasmas ◽  
Adiabatic Demagnetization ◽  
Theoretical Predictions

The merits of microcalorimetry below 1°K for high resolution spectroscopy has become widely recognized on theoretical grounds. By combining the high efficiency, broadband spectral sensitivity of traditional photoelectric detectors with the high resolution capabilities characteristic of dispersive spectrometers, the microcalorimeter could potentially revolutionize spectroscopic measurements of astrophysical and laboratory plasmas. In actuality, however, the performance of prototype instruments has fallen short of theoretical predictions and practical detectors are still unavailable for use as laboratory and space-based instruments. These issues are currently being addressed by the new collaborative initiative between LLNL, LBL, U.C.I., U.C.B., and U.C.D.. Microcalorimeters of various types are being developed and tested at temperatures of 1.4, 0.3, and 0.1°K. These include monolithic devices made from NTD Germanium and composite configurations using sapphire substrates with temperature sensors fabricated from NTD Germanium, evaporative films of Germanium-Gold alloy, or material with superconducting transition edges. A new approache to low noise pulse counting electronics has been developed that allows the ultimate speed of the device to be determined solely by the detector thermal response and geometry. Our laboratory studies of the thermal and resistive properties of these and other candidate materials should enable us to characterize the pulse shape and subsequently predict the ultimate performance. We are building a compact adiabatic demagnetization refrigerator for conveniently reaching 0.1°K in the laboratory and for use in future satellite-borne missions. A description of this instrument together with results from our most recent experiments will be presented.

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