Enrichment of Organic Carbon in Sediment Transport by Interrill and Rill Erosion Processes

Gully erosion occurs by the combined action of splash, sheetwash and rill-wash (interrill and rill erosion). These erosion processes have a great capacity for both sediment production and sediment transport. The objectives of this experiment were to evaluate hydrological and sediment transport in a degraded area, severely dissected by gullies; to assess the hydraulic flow characteristics and their aggregate transport capacity; and to measure the initial splash erosion rate. In the study area in Guarapuava, State of Paraná, Brazil (lat 25º 24' S; long 51º24' W; 1034 m asl), the soil was classified as Cambissolo Húmico alumínico, with the following particle-size composition: sand 0.116 kg kg-1; silt 0.180 kg kg-1; and clay 0.704 kg kg-1. The approach of this research was based on microcatchments formed in the ground, to study the hydrological response and sediment transport. A total of eight rill systems were simulated with dry and wet soil. An average rainfall of 33.7 ± 4.0 mm was produced for 35 to 54 min by a rainfall simulator. The equipment was installed, and a trough was placed at the end of the rill to collect sediments and water. During the simulation, the following variables were measured: time to runoff, time to ponding, time of recession, flow velocity, depth, ratio of the initial splash and grain size. The rainsplash of dry topsoil was more than twice as high as under moist conditions (5 g m-2 min-1 and 2 g m-2 min-1, respectively). The characteristics of the flow hydraulics indicate transition from laminar to turbulent flow [Re (Reynolds number) 1000-2000]. In addition, it was observed that a flow velocity of 0.12 m s-1 was the threshold for turbulent flow (Re > 2000), especially at the end of the rainfall simulation. The rill flow tended to be subcritical [Fr (Froude Number) < 1.0]. The variation in hydrological attributes (infiltration and runoff) was lower, while the sediment yield was variable. The erosion in the rill systems was characterized as limited transport, although the degraded area generated an average of 394 g m-2 of sediment in each simulation.

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Sediment transport modelling in a distributed physically based hydrological catchment model

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-7-7591-2010 ◽

2010 ◽

Vol 7 (5) ◽

pp. 7591-7631 ◽

Cited By ~ 1

Author(s):

M. Konz ◽

M. Chiari ◽

S. Rimkus ◽

J. M. Turowski ◽

P. Molnar ◽

...

Keyword(s):

Sediment Transport ◽

Hydrological Model ◽

Transport Model ◽

Water Cycle ◽

Transport Processes ◽

Distributed Hydrological Model ◽

Water Fluxes ◽

Transport Modelling ◽

Erosion Processes ◽

Grid Level

Abstract. Sediment transport and erosion processes in channels are important components of water induced natural hazards in alpine environments. A distributed hydrological model, TOPKAPI, has been developed to support continuous simulations of river bed erosion and deposition processes. The hydrological model simulates all relevant components of the water cycle and non-linear reservoir methods are applied for water fluxes in the soil, on the surface and in the channel. The sediment transport simulations are performed on a sub-grid level, which allows for a better discretization of the channel geometry, whereas water fluxes are calculated on the grid level in order to be CPU efficient. Flow resistance due to macro roughness is considered in the simulation of sediment transport processes. Several transport equations as well as the effects of armour layers on the transport threshold discharge are considered. The advantage of this approach is the integrated simulation of the entire water balance combined with hillslope-channel coupled erosion and transport simulation. The comparison with the modelling tool SETRAC and with LiDAR based reconstructed sediment transport rates demonstrates the reliability of the modelling concept. The modelling method is very fast and of comparable accuracy to the more specialised sediment transport model SETRAC.

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The history of the Nahariya Submarine Canyon, offshore northern Israel, from sedimentary down core records and foraminiferal analyses

10.5194/egusphere-egu21-9674 ◽

2021 ◽

Author(s):

Naomi Moshe ◽

Oded Katz ◽

Adi Torfstein ◽

Mor Kanari ◽

Pere Masque ◽

...

Keyword(s):

Sediment Transport ◽

Eastern Mediterranean ◽

Transport Processes ◽

Mass Wasting ◽

Submarine Canyons ◽

Last Glacial ◽

Erosion Processes ◽

Foraminiferal Species ◽

Continental Slopes ◽

The Last Glacial

Submarine canyons are prominent features in continental slopes. They play an important role in sediment transport to the deep sea, as they form conduits for turbidity currents and cause landslides due their steep slopes. Such mass transport events could create geo-hazards, which compromise infrastructures along the continental slope.Our research focuses on the Nahariya Canyon, which is part of a series of submarine canyons located along the continental slopes of the eastern Mediterranean, offshore northern Israel. This canyon is incised into the slope and does not reach the shelf. Here, we report the results from a study of two piston cores sampled in the canyon at water depths of 650m (NAC650, ~2.5m long) and 915m (NAC915, ~6m long). Chronologies were established based radiocarbon dating using slope foraminiferal shells, in addition to 210Pb and OSL dating of bulk sediment. The sediments were characterized by major and trace element concentrations, mineralogy, grain size, and dead foraminiferal assemblages. We further identified the living (Rose-Bengal stained) foraminiferal species at three depths habitats (200m 650m and 915m water depth).Our results show that both piston cores are comprised of a capping ~40 cm thick interval of fine laminated mud, deposited over the last ~150-200 years, apparently reflecting hemipelagic sedimentation. This capping interval unconformably overlays a consolidated sequence in both cores, which indicates a major sediment removal. The consolidated sequence in NAC650 is mostly homogenous and dates to the previous glacial (>140 ka), and in NAC915 the upper 70 cm of the consolidated sequence consists mud clasts dated to 27-46 ka that overlay an &#8216;S shape&#8217; shear zone, which is a result of a down canyon mass wasting (debrite). Below that debrite, the sediment is mostly homogenous and dates to the last glacial (>25 ka). Broken shells of shallow benthic foraminiferal species such as Ammonia spp., Asterigerinata mamilla, Miliolids, Rosalina spp. and Sorites orbiculus are found abundantly throughout both piston-cores, varying between in-core intervals, indicating that allochthonous sediments are prevalent at those cores. Same shallow species are found also in the surface (living) assemblages, mixed with slope deep foraminiferal species. Moreover, the deep living foraminiferal shells are well preserved, in contrast to the shallow living species. Taken together, these indicate that sediment transport processes along the canyon exist to this day.The cores suggest that the canyon is an erosive environment at least since the last glacial maximum, when the last significant mass wasting deposit is recorded. The Holocene is not represented in the records, probably due to the dominance of erosion processes, except for a thin layer of sediment deposited over the last two centuries that prevails along the entire canyon.

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Estimating rill erosion and sediment transport processes along a saturated purple soil slope

Canadian Journal of Soil Science ◽

10.1139/cjss-2020-0119 ◽

2021 ◽

Author(s):

Han Zhen ◽

Xiaoyan Chen ◽

Yanhai Li ◽

Shiqi Chen ◽

Xiaojie Gu ◽

...

Keyword(s):

Sediment Transport ◽

Sediment Concentration ◽

Transport Processes ◽

Purple Soil ◽

Rill Erosion ◽

Soil Slope ◽

Sediment Transportation ◽

Erosion Models ◽

Increasing Trend ◽

Soil Slopes

A plough pan with reduced permeability always accumulates inﬁltrated water along slopes then saturates the cultivated layer under continuous rain. Topsoil saturation is a frequent phenomenon and an important process of the special soil slopes. A methodology and device system was used in this study to keep cultivated purple soil saturated. Strands of scouring tests were developed to quantify the rill erosion and sediment transport processes along a saturated purple soil slope at four experiment slopes (5°, 10°, 15°, and 20°) and three flow discharges (2, 4 and 8 L min−1). The experimental results indicated that the sediment transport capacity on a saturated purple soil slope ranged from 0.03 to 1.56 kg s−1 m−1 with the increasing trend along the slope gradient and flow discharge, and the increasing trend could be well matched by a nonlinear multivariable equation. The sediment concentration of the saturated purple soil slope exponentially increased with rill length and decreased with the increment rate and the maximum sediment concentrations observed in this study in different hydraulic events ranged from 108.13 to 1174.20 kg m-3. Saturated and non-saturated purple soil slopes erode differently with the maximum sediment concentration of saturated purple soil slope recorded at approximately 1.42-2.10 times the values for non-saturated purple soil slope. The findings of this research help illustrate the sediment transportation and erosion behaviors of a saturated purple soil slope, and serve as the basis for determining the parameters in the erosion models of the purple soil slope.

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Organic Carbon Cycling During Himalayan Erosion: Processes, Fluxes and Consequences for the Global Carbon Cycle

Climate Change and Food Security in South Asia ◽

10.1007/978-90-481-9516-9_12 ◽

2010 ◽

pp. 163-181

Author(s):

Valier Galy ◽

Christian France-Lanord ◽

Olivier Beyssac ◽

Bruno Lartiges ◽

Mustafizur Rhaman

Keyword(s):

Organic Carbon ◽

Carbon Cycle ◽

Carbon Cycling ◽

Global Carbon Cycle ◽

Erosion Processes ◽

Organic Carbon Cycling ◽

Global Carbon

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Sediment transport modelling in a distributed physically based hydrological catchment model

Hydrology and Earth System Sciences ◽

10.5194/hess-15-2821-2011 ◽

2011 ◽

Vol 15 (9) ◽

pp. 2821-2837 ◽

Cited By ~ 8

Author(s):

M. Konz ◽

M. Chiari ◽

S. Rimkus ◽

J. M. Turowski ◽

P. Molnar ◽

...

Keyword(s):

Sediment Transport ◽

Hydrological Model ◽

Transport Model ◽

Water Cycle ◽

Ground Surface ◽

Distributed Hydrological Model ◽

Water Fluxes ◽

Transport Modelling ◽

Erosion Processes ◽

Grid Level

Abstract. Bedload sediment transport and erosion processes in channels are important components of water induced natural hazards in alpine environments. A raster based distributed hydrological model, TOPKAPI, has been further developed to support continuous simulations of river bed erosion and deposition processes. The hydrological model simulates all relevant components of the water cycle and non-linear reservoir methods are applied for water fluxes in the soil, on the ground surface and in the channel. The sediment transport simulations are performed on a sub-grid level, which allows for a better discretization of the channel geometry, whereas water fluxes are calculated on the grid level in order to be CPU efficient. Several transport equations as well as the effects of an armour layer on the transport threshold discharge are considered. Flow resistance due to macro roughness is also considered. The advantage of this approach is the integrated simulation of the entire basin runoff response combined with hillslope-channel coupled erosion and transport simulation. The comparison with the modelling tool SETRAC demonstrates the reliability of the modelling concept. The devised technique is very fast and of comparable accuracy to the more specialised sediment transport model SETRAC.

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Spatial variability of biogenic elements and organic carbon content in the tributaries of Lake Baikal

E3S Web of Conferences ◽

10.1051/e3sconf/202016305012 ◽

2020 ◽

Vol 163 ◽

pp. 05012

Author(s):

Ekaterina Sharapova ◽

Ludmila Efimova ◽

Irina Denisova ◽

Aida Ermekova ◽

Mikhail Lychagin ◽

...

Keyword(s):

Organic Carbon ◽

Spatial Variability ◽

Lake Baikal ◽

Aquatic Vegetation ◽

Chemical Elements ◽

Organic Phosphorus ◽

Biogenic Elements ◽

Organic Carbon Content ◽

Mineral Phosphorus ◽

Erosion Processes

The article considers the features of biogenic elements and organic carbon (Corg) content spatial variability in the Lake Baikal tributaries. The role of hydrological conditions and landscape-geochemical features in the chemical elements flow formation is shown. It was found that organic carbon in the river waters is represented mainly by its dissolved form. In the lower reaches of the Selenga, erosion processes and economic activity in the catchment area increase the proportion of suspended forms of organic carbon and mineral phosphorus. In the river delta under the influence of the sedimentation and the intake of organic matter formed during aquatic vegetation decomposition, the content of dissolved Corg increases with a contemporary decrease in its suspended form. As a result of intensification of production and destruction processes in well-heated areas of the delta, a significant decrease in the concentrations of mineral phosphorus and an increase in organic phosphorus occur.

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