scholarly journals Inferring Sediment Transport Capacity from Soil Microtopography Changes on a Laboratory Hillslope

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 929
Author(s):  
Sayjro Nouwakpo ◽  
Chi-hua Huang ◽  
Laura Bowling ◽  
Phillip Owens ◽  
Mark Weltz
Keyword(s):  
Experimental Data ◽  
Sediment Transport ◽  
Transport Processes ◽  
Transport Capacity ◽  
Erosion Modeling ◽  
Subsurface Hydrology ◽  
Concentrated Flow ◽  
Erosion Models ◽  
Flow Hydraulics ◽  
The Impact

In hillslope erosion modeling, the Transport Capacity (Tc) concept describes an upper limit to the flux of sediment transportable by a flow of given hydraulic characteristics. This widely used concept in process-based erosion modeling faces challenges due to scarcity of experimental data to strengthen its validity. In this paper, we test a methodology that infers the exceedance of transport capacity by concentrated flow from changes to soil surface microtopography sustained during rainfall-runoff events. Digital Elevation Models (DEMs) corresponding to pre- and post-rainfall events were used to compute elevation change maps and estimate spatially-varying flow hydraulics ω taken as the product of flow accumulation and local slope. These spatial data were used to calculate a probability of erosion PE at regular flow hydraulics intervals. The exceedance of Tc was inferred from the crossing of the PE = 0.5 line. The proposed methodology was applied to experimental data collected to study the impact of soil subsurface hydrology on soil erosion and sediment transport processes. Sustained net deposition occurred under drainage condition while PE for seepage conditions mostly stayed in the net erosion regime. Results from this study suggest pulsating erosion patterns along concentrated flow networks with intermittent increases in PE to local maxima followed by declines to local minima. These short-range erosion patterns could not be explained by current Tc-based erosion models. Nevertheless, Tc-based erosion models adequately capture observed decline in local PE maxima as ω increased. Applying the proposed approach suggests a dependence of Tc on subsurface hydrology with net deposition more likely under drainage conditions compared to seepage conditions.

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

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.

3D numerical studies on stratification and mixing processes affecting fine sediment transport in the pre-dam of the Dhünn reservoir in Germany

2020 ◽  
Author(s):  
Wendy Gonzalez ◽  
Irina Klassen ◽  
Anne Jakobs ◽  
Frank Seidel
Keyword(s):  
Sediment Transport ◽  
Input Data ◽  
Measurement Data ◽  
Fine Sediment ◽  
Transport Processes ◽  
Transport Modeling ◽  
Wind Effects ◽  
Sediment Distribution ◽  
Vertical Diffusivity ◽  
The Impact

<p>Fine sediment transport processes and the thermodynamics in reservoirs are key processes governing the water quality of reservoirs. With regard to a sustainable sediment management of reservoirs, the prediction of sediment transport and deposition is becoming increasingly important.</p><p>The subject of the present work was the 3D numerical simulation of fine sediment transport in a reservoir taking into account stratification and mixing effects which in turn are caused by temperature gradients and wind effects. In order to understand and investigate the driving factors for stratification processes and their impact on fine sediment distribution, the great pre-dam of the Dhünn reservoir in Germany served as case study. The investigations were conducted in sensitivity analyses adopting a 3D sediment transport model with Delft 3D. The impact of various physical and numerical parameters on temperature and fine sediment transport modeling was examined: the number of vertical layers, the input data for the heat model (e.g. relative humidity, air temperature, cloud coverage, solar radiation), the vertical diffusivity and wind effects. The sensitivity studies showed that the input data for the heat model have a minor impact on the temperature and sediment transport modeling within the tested range of parameters. However, the vertical diffusivity and especially the inclusion of wind showed a greater influence on the simulated temperature and suspended sediment concentration gradients. The temperature modeling results by inclusion/exclusion of wind were qualitatively compared with temperature data from literature and with measurement data over a period of one month. Hereby, the simulations showed a good agreement with measurement data by exclusion of wind effects.</p><p>The results of the studies provide a solid basis for the development of further models in fields where fine sediment transport is affected by stratification processes and can also be very useful in terms of a better understanding of the interactions between temperature, wind and fine sediment transport.</p>

scholarly journals Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter

2012 ◽  
Vol 9 (12) ◽  
pp. 18211-18252 ◽  
Author(s):  
J. Martín ◽  
X. Durrieu de Madron ◽  
P. Puig ◽  
F. Bourrin ◽  
A. Palanques ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Sediment Transport ◽  
Transport Processes ◽  
Depth Range ◽  
Shelf Water ◽  
Head Region ◽  
Deep Basin ◽  
Remarkable Feature ◽  
The Impact ◽  
Southern Flank

Abstract. Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the deep basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of a mild and wet 2010–2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed to study the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms of significant wave heights = 4–4.5 m. During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of CCC in an approximate depth range of 150–350 m. The density of this water mass only reached ~ 28.78 kg m−3, indicating that it did not cascade into the canyon and that merely downwelled into it forced by the accumulation of seawater along the coast during the storms and by the subsequent strong cyclonic circulation induced over the shelf. Suspended sediment load in this turbid intrusion was comparable at three heights above bottom where turbidimeters were installed (10, 75 and 115 m above bottom) on the southern canyon flank and oscillated between 10 and 50 mg L−1. Current speeds were also comparable in the depth range profiled by ADCPs (40 to 150 mab) and reached values up to 90 cm s−1 during the peak of the strongest storm (13 March, Hs = 4.5 m). Sediment transport at 75 mab on the southern canyon flank was estimated at 1–1.5 t m−2 for the entire deployment while very close to the bottom (5 m above) in the canyon head it was less than 0.6 t m−2 during the same period. We provide a rough estimation of 105 t of sediment transported through the canyon along its southern wall during a 3 day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated to eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200–300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea.

Analysis of geometric relationships of bedrock and alluvial channels: a comparison between rivers from the Scottish Highlands and San Gabriel Mountains (USA)

2021 ◽  
Author(s):  
Mel O. Guirro ◽  
Rebecca A. Hodge ◽  
Fiona Clubb ◽  
Laura Turnbull
Keyword(s):  
Sediment Transport ◽  
Transport Processes ◽  
Sediment Supply ◽  
Spatial Distributions ◽  
Alluvial Channels ◽  
Transport Capacity ◽  
Alluvial Rivers ◽  
Bedrock Rivers ◽  
San Gabriel Mountains ◽  
Scottish Highlands

<p>Sediment transport in rivers depends on interactions between sediment supply, topography, and flow characteristics. Erosion in bedrock rivers controls topography and is paramount in landscape evolution models. The riverbed cover indicates sediment transport processes: alluvial cover indicates low transport capacity or high sediment supply, and bedrock cover demonstrates high transport capacity or low sediment supply. This study aims to evaluate controls on the spatial distributions of bedrock and alluvial covers, by analysing scaling geometric relations between bedrock and alluvial channels. A Principal Component Analysis (PCA) was conducted to evaluate correlations between river slope, depth, width, and sediment size. The two principal components were used to implement a clustering analysis in order to identify differences in alluvial and bedrock sections. Spatial distributions of mixed bedrock-alluvial sections were investigated from two datasets - Scottish Highlands (Whitbread 2015) and the San Gabriel Mountains in the USA (Dibiase 2011)-, representing different environmental conditions, such as erosion rates, lithology, tectonics, and climate. The rock strength of both areas is high, and therefore it is excluded as a factor that explains the difference between the areas. The results of the cluster analysis were different in each environment. The main sources of variation among river sections identified by PCA were slope and width for the San Gabriel Mountains, and drainage area and depth for the Scottish Highlands. The rivers in the Scottish Highlands formed clusters that differentiate bedrock and alluvial patches, showing a clear geometric distinction between channels. However, the river analysis from the San Gabriel Mountains showed no clusters. Bedrock rivers are typically described as narrower and steeper than alluvial rivers, as demonstrated by rivers in the Scottish Highlands (e.g. slope was around 0.1 m/m for bedrock sections and 0.01 m/m for alluvial sections). However, this may not be always the case: both bedrock and alluvial sections in San Gabriel Mountains presented similar slope around 0.1 m/m. The inability to demonstrate significant geometry differences in bedrock and alluvial sections in the San Gabriel Mountains may be due to the frequency and magnitude of sediment supply of that region, which are influenced by tectonics and climate. A major difference in the supply of sediment in rivers of the San Gabriel Mountains is the frequent occurrence of debris flow. Non-linear interactions between hydraulic and sediment processes may constantly modify the geometry of bedrock-alluvial channels, increasing the complexity of analysis at larger temporal and spatial scales. This study is part of the i-CONN project, which links connectivity in different scientific disciplines. A sediment connectivity assessment in different environments and scales may be useful to evaluate the controls on the spatial distribution of bedrock and alluvial rivers.</p><p> </p><p>Dibiase, R.A. 2011. Tectonic Geomorphology of the San Gabriel Mountains, CA. PhD Thesis. Arizona State University, Phoenix, 247pp.</p><p>Whitbread, K. 2015. Channel geometry data set for the northwest Scottish Highlands. British Geological Survey Open Report, OR/15/040. 12pp.</p>

scholarly journals Sediment transport along the Cap de Creus Canyon flank during a mild, wet winter

2013 ◽  
Vol 10 (5) ◽  
pp. 3221-3239 ◽  
Author(s):  
J. Martín ◽  
X. Durrieu de Madron ◽  
P. Puig ◽  
F. Bourrin ◽  
A. Palanques ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Sediment Transport ◽  
Transport Processes ◽  
Depth Range ◽  
Shelf Water ◽  
Head Region ◽  
Remarkable Feature ◽  
Vertical Profiling ◽  
The Impact ◽  
Southern Flank

Abstract. Cap de Creus Canyon (CCC) is known as a preferential conduit for particulate matter leaving the Gulf of Lion continental shelf towards the slope and the basin, particularly in winter when storms and dense shelf water cascading coalesce to enhance the seaward export of shelf waters. During the CASCADE (CAscading, Storm, Convection, Advection and Downwelling Events) cruise in March 2011, deployments of recording instruments within the canyon and vertical profiling of the water column properties were conducted to study with high spatial-temporal resolution the impact of such processes on particulate matter fluxes. In the context of the mild and wet 2010–2011 winter, no remarkable dense shelf water formation was observed. On the other hand, the experimental setup allowed for the study of the impact of E-SE storms on the hydrographical structure and the particulate matter fluxes in the CCC. The most remarkable feature in terms of sediment transport was a period of dominant E-SE winds from 12 to 16 March, including two moderate storms (maximum significant wave heights = 4.1–4.6 m). During this period, a plume of freshened, relatively cold and turbid water flowed at high speeds along the southern flank of the CCC in an approximate depth range of 150–350 m. The density of this water mass was lighter than the ambient water in the canyon, indicating that it did not cascade off-shelf and that it merely downwelled into the canyon forced by the strong cyclonic circulation induced over the shelf during the storms and by the subsequent accumulation of seawater along the coast. Suspended sediment load in this turbid intrusion recorded along the southern canyon flank oscillated between 10 and 50 mg L−1, and maximum currents speeds reached values up to 90 cm s−1. A rough estimation of 105 tons of sediment was transported through the canyon along its southern wall during a 3-day-long period of storm-induced downwelling. Following the veering of the wind direction (from SE to NW) on 16 March, downwelling ceased, currents inside the canyon reversed from down- to up-canyon, and the turbid shelf plume was evacuated from the canyon, most probably flowing along the southern canyon flank and being entrained by the general SW circulation after leaving the canyon confinement. This study highlights that remarkable sediment transport occurs in the CCC, and particularly along its southern flank, even during mild and wet winters, in absence of cascading and under limited external forcing. The sediment transport associated with eastern storms like the ones described in this paper tends to enter the canyon by its downstream flank, partially affecting the canyon head region. Sediment transport during these events is not constrained near the seafloor but distributed in a depth range of 200–300 m above the bottom. Our paper broadens the understanding of the complex set of atmosphere-driven sediment transport processes acting in this highly dynamic area of the northwestern Mediterranean Sea.

scholarly journals Modelling the effects of ice transport and sediment sources on the form of detrital thermochronological age probability distributions from glacial settings

2020 ◽  
Vol 8 (4) ◽  
pp. 931-953
Author(s):  
Maxime Bernard ◽  
Philippe Steer ◽  
Kerry Gallagher ◽  
David Lundbek Egholm
Keyword(s):  
Sediment Transport ◽  
Sampling Site ◽  
Age Distribution ◽  
Morphological Characteristics ◽  
Transport Processes ◽  
Surface Erosion ◽  
Sediment Sources ◽  
Sediment Particles ◽  
The Impact ◽  
Local Sampling

Abstract. The impact of glaciers on the Quaternary evolution of mountainous landscapes remains controversial. Although in situ or bedrock low-temperature thermochronology offers insights on past rock exhumation and landscape erosion, the method also suffers from potential biases due to the difficulty of sampling bedrock buried under glaciers. Detrital thermochronology attempts to overcome this issue by sampling sediments at e.g. the catchment outlet, a component of which may originate from beneath the ice. However, detrital age distributions not only reflect the catchment exhumation, but also spatially variable patterns and rates of surface erosion and sediment transport. In this study, we use a new version of a glacial landscape evolution model, iSOSIA, to address the effect of erosion and sediment transport by ice on the form of synthetic detrital age distributions. Sediments are tracked as Lagrangian particles formed by bedrock erosion, and their transport is restricted to ice or hillslope processes, neglecting subglacial hydrology, until they are deposited. We base our model on the Tiedemann Glacier (British Columbia, Canada), which has simple morphological characteristics, such as a linear form and no connectivity to large tributary glaciers. Synthetic detrital age distributions are generated by specifying an erosion history, then sampling sediment particles at the frontal moraine of the modelled glacier. Results show that sediment sources, reflecting different processes such as glacier and hillslope erosion, can have distinct bedrock age distribution signatures, and estimating such distributions should help to identify predominant sources in the sampling site. However, discrepancies between the detrital and bedrock age distributions occur due to (i) the selective storage of a large proportion of sediments in small tributary glaciers and in lateral moraines, (ii) the large range of particle transport times due to varying transport lengths and strong variability of glacier ice velocity, (iii) the heterogeneous pattern of erosion, and (iv) the advective nature of glacier sediment transport along ice streamlines. This last factor leads to a poor lateral mixing of particle detrital signatures inside the frontal moraine, and then local sampling of the frontal moraine is likely to reflect local sources upstream. Therefore, sampling randomly across the moraine is preferred for a more representative view of the catchment age distribution. Finally, systematic comparisons between synthetic (U-Th)/He and fission track detrital ages, with different bedrock age-elevation profiles and different relative age uncertainties, show that the nature of the age-elevation relationship and age uncertainties largely control the ability to track sediment sources in the detrital record. However, depending on the erosion pattern spatially, qualitative first-order information may still be extracted from a thermochronological system with high uncertainties (>30 %). Overall, our results demonstrate that detrital age distributions in glaciated catchments are strongly impacted not only by erosion and exhumation but also by sediment transport processes and their spatial variability. However, when combined with bedrock age distributions, detrital thermochronology offers a novel means to constrain the transport pattern and time of sediment particles.

scholarly journals Response of tidal flow regime and sediment transport in North Malé Atoll, Maldives, to coastal modification and sea level rise

Ocean Science ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 319-334
Author(s):  
Shuaib Rasheed ◽  
Simon C. Warder ◽  
Yves Plancherel ◽  
Matthew D. Piggott
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Sea Level Rise ◽  
Sea Level ◽  
Land Reclamation ◽  
Transport Processes ◽  
Sediment Grain Size ◽  
Sediment Distribution ◽  
Time Periods ◽  
The Impact

Abstract. Changes to coastlines and bathymetry alter tidal dynamics and associated sediment transport processes, impacting upon a number of threats facing coastal regions, including flood risk and erosion. Especially vulnerable are coral atolls such as those that make up the Maldives archipelago, which has undergone significant land reclamation in recent years and decades and is also particularly exposed to sea level rise. Here we develop a tidal model of Malé Atoll, Maldives, the first atoll-scale and multi-atoll-scale high-resolution numerical model of the atolls of the Maldives and use it to assess potential changes to sediment grain size distributions in the deeper atoll basin, under sea level rise and coastline alteration scenarios. The results indicate that the impact of coastline modification over the last two decades at the island scale is not limited to the immediate vicinity of the modified island but can also significantly impact the sediment grain size distribution across the wider atoll basin. Additionally, the degree of change in sediment distribution which can be associated with sea level rise that is projected to occur over relatively long time periods is predicted to occur over far shorter time periods with coastline changes, highlighting the need to better understand, predict and mitigate the impact of land reclamation and other coastal modifications before conducting such activities.

scholarly journals The effects of ice and hillslope erosion and detrital transport on the form of detrital thermochronological age probability distributions from glacial settings

2020 ◽  
Author(s):  
Maxime Bernard ◽  
Philippe Steer ◽  
Kerry Gallagher ◽  
David L. Egholm
Keyword(s):  
Sediment Transport ◽  
Particle Transport ◽  
Large Range ◽  
Probability Distributions ◽  
Age Distribution ◽  
Morphological Characteristics ◽  
Transport Processes ◽  
Surface Erosion ◽  
Sediment Particles ◽  
The Impact

<p>The impact of glaciers on the Quaternary evolution of mountainous landscapes remains controversial. While in-situ low-temperature thermochronology offers insights on past rock exhumation and landscape erosion, it also suffers from biases due to the difficulty of sampling bedrocks buried under the ice of glaciers. Detrital thermochronology attempts to bypass this issue by sampling sediments at, e.g. the catchment outlet, that may originate from beneath the ice. However, the age distribution resulting from detrital thermochronology does not only inform on the catchment exhumation, but also on the patterns and rates of surface erosion and sediment transport. In this study, we use a new version of a glacial landscape evolution model, iSOSIA to address the role of erosion and sediment transport by the ice on the form of synthetic detrital age distributions and thus, for inferred catchment erosion from such data. Sediments are tracked as Lagrangian particles that can be formed by bedrock erosion, transported by ice or hillslope processes and deposited. We apply our model to the Tiedemann glacier (British Columbia, Canada), which has simple morphological characteristics, such as a straight form and no connectivity with large tributary glaciers. Synthetic detrital age distributions are generated by specifying an erosion history, then sampling sediment particles at the frontal moraine of the modelled glacier. The detrital ages are represented as synoptic probability density functions (SPDFs).</p><p>A characterization of sediment transport shows that 1500 years are required to reach an equilibrium for detrital particles age distributions, due to the large range of particle transport times from their sources to the frontal moraine. Second, varying sampling locations and strategies at the glacier front lead to varying detrital SPDFs, even at equilibrium. These discrepancies are related to (i) the selective storage of a large proportion of sediments in small tributary glaciers and in lateral moraines, (ii) the large range of particle transport times, due to varying transport lengths and to a strong variability of glacier ice velocity, (iii) the heterogeneous pattern of erosion, (iv) the advective nature of glacier sediment transport along ice streamlines that leads to a poor lateral mixing of particle detrital signatures inside the frontal moraine. Third, systematic comparisons between (U-Th)/He and fission track detrital ages, with different age-elevation profiles and relative age uncertainties, show that (i) the age increasing rate with elevation largely controls the ability to track sediment sources, and (ii) qualitative first-order information about distribution of erosion may still be extracted from thermochronological system with high variable uncertainties (> 30 %). Overall, our distributions in glaciated catchments are strongly impacted by erosion and transport processes and by their spatial variability. Combined with bedrock age distributions, detrital thermochronology can offer a means to constrain the transport pattern and time of sediment particles. However, results also suggest that detrital age distributions of glacial features like frontal moraines, are likely to reflect a transient case as the time required to reach detrital thermochronological equilibrium is of the order of the short-timescale glaciers dynamic variability, as little ice ages or recent glaciers recessions.</p>

scholarly journals Evaluating sediment transport capacity relationships for use in ephemeral gully erosion models

2015 ◽  
Vol 367 ◽  
pp. 128-133 ◽  
Author(s):  
E. J. Langendoen ◽  
R. R. Wells ◽  
M. E. Ursic ◽  
D. A. N. Vieira ◽  
S. M. Dabney
Keyword(s):  
Sediment Transport ◽  
Aggregate Size ◽  
Gully Erosion ◽  
Transport Capacity ◽  
Large Aggregate ◽  
Size Classes ◽  
Sediment Transport Capacity ◽  
Ephemeral Gully ◽  
Erosion Models ◽  
Deposition Depth

Abstract. On cropland, ephemeral gully erosion in the USA may contribute up to 40% of the sediment delivered to the edge of the field. Well-tested, physically- and process-based tools for field and watershed scale prediction of gully erosion are lacking due to the fact that the complex nature of migrating headcuts is poorly understood. Understanding sediment transport capacity downstream of migrating headcuts is essential, as sediment deposition often leads to temporary storage that controls downstream water elevation, which in turn affects the rate of headcut migration. Current process-based gully erosion prediction technology used by the Agricultural Research Service (ARS) is based on characterizing the headcut migration rate, which requires the deposition depth as input to the model. Alternatively, the deposition depth can be calculated if downstream sediment transport capacity can be predicted. Data collected at the ARS-National Sedimentation Laboratory were used to test existing sediment transport relationships for the five sediment size classes (clay, silt, sand, small aggregates, large aggregates) typically used in ARS soil erosion models. The results show that the transport rate can be satisfactorily predicted for sand and large aggregate size fractions using common transport relationships based on unit stream power theory. The fractional content of the sand and large aggregate size classes can be computed using standard relationships, which are based on soil texture, previously developed by ARS. The transport of clays, silts and small aggregates is detachment limited and must therefore be computed using improved soil detachment relationships for ephemeral gullies.

Experimental Study on Sediment Transport Capacity Model of Slope Runoff Based on ANN

2014 ◽  
Vol 1010-1012 ◽  
pp. 1149-1152
Author(s):  
Peng Jiao ◽  
Pei Qing Xiao ◽  
Xin Xin Hou ◽  
Dan Zhang
Keyword(s):  
Sediment Transport ◽  
Impact Factors ◽  
Transport Capacity ◽  
Adaboost Algorithm ◽  
Sediment Transport Capacity ◽  
Erosion Prediction ◽  
Capacity Model ◽  
Input Variables ◽  
The Impact ◽  
Slope Runoff

Sediment transport capacity of slope runoff is an important hydrodynamic parameter in the establishment of soil erosion prediction model. According to simulated runoff-scouring experiments, sediment transport capacity of slope runoff under different conditions is calculated. The impact factors of sediment transport capacity of slope runoff were analyzed by the method of Mean Impact Value, and then the input variables including dry bulk density, slope, Inlet flow, outlet flow, hydraulic radius, flow rate were determined. GRNN model was established and optimized by Adaboost algorithm to forecast Sediment transport capacity of slope runoff. The validation results showed that the GRNN model was applied to Sediment transport capacity forecasting of slope runoff. In conditions of experimental training samples, GRNN model had better computed results compared to BP Neural network model, and Adaboost algorithm could effectively decrease error of GRNN model.

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