scholarly journals Sediment transport modelling in riverine environments: on the importance of grain-size distribution, sediment density and boundary conditions

2018 ◽  
Author(s):  
Jérémy Lepesqueur ◽  
Renaud Hostache ◽  
Núria Martínez-Carreras ◽  
Emmanuelle Montargès-Pelletier ◽  
Christophe Hissler
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Small Scale ◽  
Sediment Grain Size ◽  
Model Based

Abstract. Hydromorphodynamic models are powerful tools to predict the potential mobilization and transport of sediment in river ecosystems. Recent studies even showed that they are able to satisfyingly predict suspended sediment matter concentration in small river systems. However, modelling exercises often neglect suspended sediment properties (e.g. particle site distribution and density), even though such properties are known to directly control the sediment particle dynamics in the water column during rising and flood events. This study has two objectives. On the one hand, it aims at further developing an existing hydromorphodynamic model based on the dynamic coupling of TELEMAC-3D (v7p1) and SISYPHE (v7p1) in order to enable an enhanced parameterisation of the sediment grain size distribution with distributed sediment density. On the other hand, it aims at evaluating and discussing the added-value of the new development for improving sediment transport and riverbed evolution predictions. To this end, we evaluate the sensitivity of the model to sediment grain size distribution, sediment density and suspended sediment concentration at the upstream boundary condition. As a test case, the model is used to simulate a flood event in a small scale river, the Orne River in North-eastern France. The results show substantial discrepancies in bathymetry evolution depending on the model setup. Moreover, the sediment model based on an enhanced sediment grain size distribution (10 classes) and with distributed sediment density outperforms the model with only two sediment grain size classes in terms of simulated suspended sediment concentration.

scholarly journals Sediment transport modelling in riverine environments: on the importance of grain-size distribution, sediment density, and suspended sediment concentrations at the upstream boundary

2019 ◽  
Vol 23 (9) ◽  
pp. 3901-3915 ◽  
Author(s):  
Jérémy Lepesqueur ◽  
Renaud Hostache ◽  
Núria Martínez-Carreras ◽  
Emmanuelle Montargès-Pelletier ◽  
Christophe Hissler
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Sediment Grain Size ◽  
Model Based ◽  
Model Set

Abstract. Hydromorphodynamic models are powerful tools for predicting the potential mobilization and transport of sediment in river ecosystems. Recent studies have shown that they are able to predict suspended sediment matter concentration in small river systems satisfactorily. However, hydro-sedimentary modelling exercises often neglect suspended sediment properties (e.g. sediment densities and grain-size distribution), which are known to directly control sediment dynamics in the water column during flood events. The main objective of this study is to assess whether a better representation of such properties leads to an improved performance in the model. The modelling approach utilizes a fully coupled hydromorphodynamic model based on TELEMAC-3D (v7p1) and an enhanced version of the sediment transport module SISYPHE (based on v7p1), which allows for a refined sediment representation (i.e. 10-class sediment mixtures instead of 2-class mixtures and distributed sediment density instead of uniform). The proposed developments of the SISYPHE model enable us to evaluate and discuss the added value of sediment representation refinement for improving sediment transport and riverbed evolution predictions. To this end, we used several model set-ups to evaluate the influence of sediment grain-size distribution, sediment density, and suspended sediment concentration at the upstream boundary on model predictions. As a test case, we simulated a flood event in a small-scale river, the Orne river in north-eastern France. Depending on the model set-up, the results show substantial discrepancies in terms of simulated bathymetry evolutions. Moreover, the model based on an enhanced configuration of the sediment grain-size distribution (10 classes of particle sizes) and with distinct densities per class outperforms the standard SISYPHE configuration, with only two sediment grain-size classes, in terms of simulated suspended sediment concentration.

Influence of hydrological conditions and peat extraction operations on suspended sediment concentration and deposition in the East Branch Portage River, New Brunswick (Canada)

2013 ◽  
Vol 48 (4) ◽  
pp. 305-320 ◽  
Author(s):  
M. A. Es-Salhi ◽  
M. Clément ◽  
A. St-Hilaire ◽  
D. Caissie ◽  
S. C. Courtenay
Keyword(s):  
Grain Size ◽  
New Brunswick ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Suspended Sediment Concentration ◽  
Sediment Concentration ◽  
Organic Content ◽  
Sediment Type ◽  
Peat Extraction

Peat extraction activities often generate sediments that can be transported into streams and rivers. These sediments have sometimes been shown to negatively affect the natural environment. This study investigated the effects of peat production on the East Branch Portage River, New Brunswick (NB), Canada. Relationships between discharge, precipitation and suspended sediment concentration (SSC) were analysed. The effect of sedimentation pond maintenance activities on SSC was also studied. Finally, the grain size distribution and organic content of deposited sediments were quantified at five sites downstream of the pond. Three water quality stations were monitored during the ice-free period in 2007 and 2008. Results showed that SSC was not significantly correlated with precipitation and weakly correlated with discharge, although some of the high SSC events were triggered by high discharge and precipitation. Pond maintenance alone failed to ensure optimal sedimentation pond efficiency. In 2008, SSC increased a few days after pond maintenance. The NB SSC 25 mg/L guideline was exceeded at all stations in both years. Analysis of variance results showed that there were significant differences in the grain size distribution of deposited sediments at the five sampled sites. Sand was the prevailing sediment type deposited downstream of the sedimentation pond.

scholarly journals Fluvial morphology and sediment transport of the Malekhu Khola, Central Nepal Lesser Himalaya

2017 ◽  
Vol 18 ◽  
pp. 35-48
Author(s):  
Niraj Bal Tamang ◽  
Naresh Kazi Tamrakar ◽  
Milan Magar ◽  
Mahesh Raut
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Suspended Sediment ◽  
Cross Sections ◽  
Sediment Concentration ◽  
Mature Stage ◽  
Order Stream ◽  
Sediment Grain Size ◽  
Fluvial Morphology ◽  
Suspended Sediment Concentrations

Areas near the rivers and streams have been widely used for settlement, development works and agriculture due to availability of the resources such as water, aggregates and comparatively easier terrain. It is very important to understand prevailing fluvial conditions for sustainable output. The fluvial conditions of the Malekhu Watershed including the river characteristics, sediment transport and sediment dynamics were studied. Ten river transects and the corresponding segments of the Malekhu Khola were surveyed for cross-sections and longitudinal profiles. Samples were collected in each of the transects and were analysed for suspended sediment concentration. The riverbed sampling was made using Wolman’s pebble count for establishing grain size distribution. Manning’s roughness coefficients were determined to estimate discharge. The study shows that the Malekhu Khola is a sixth order stream. It has been classified into A4-, B4- and C4-type streams. The hypsometric analysis of the Malekhu Watershed shows that it is in mature stage of erosion. Sediment grain size slightly increases downstream but sorting remains extremely poor to moderately poor. The Malekhu Khola shows eroding tendency at 1.2 km, 16.6 km and 20 km from the origin and brings larger particles only during high flow period at the remaining transects. Mean Suspended Sediment Concentrations (SSC) for the Malekhu Khola was 72.14 mg/L, and it increases with increasing discharge and increasing watershed area and is related to velocity of the river, mining activities and local tributaries.Bulletin of the Department of Geology, Vol. 18, 2015, pp. 35-48

scholarly journals Surface sediment grain-size distribution and sediment transport in the subaqueous Mekong Delta, Vietnam

2017 ◽  
Vol 39 (3) ◽  
Author(s):  
Nguyen Trung Thanh ◽  
Karl Stattegger ◽  
Daniel Unverricht ◽  
Charles Nittrouer ◽  
Phung Van Phach ◽  
...  
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Surface Sediment ◽  
Mekong Delta ◽  
Sediment Grain Size

scholarly journals Variability of suspended sediment grain size distribution in winter floods

2016 ◽  
Vol 48 (2) ◽  
pp. 141-151
Author(s):  
Agnieszka Hejduk ◽  
Leszek Hejduk
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Standard Deviation ◽  
Size Distribution ◽  
Suspended Sediment ◽  
Grain Size Distribution ◽  
Sediment Grain Size ◽  
Mean Values ◽  
Average Value ◽  
Sediment Size

Abstract Variability of suspended sediment grain size distribution in winter floods. The work presents the results of research concern variability of suspended sediment grain size, transported during the winter floods in agricultural catchment, in the period of hydrological years 2012-2015. The information about grain size distribution from nine winter flood events were collected over the study period, which allowed to analyze the variability of suspended sediment particle size during the various events. Grain size of sediment was determined using a laser particle size analyzer Mastersizer Microplus from Malvern Instruments Ltd. Variability of individual particle size classes were observed in each flood. Sand fraction dominated in seven of nine measured events. There was no significant increase of suspended sediment size in relation to the maximum of discharge. It can be explain by a relatively low discharge of recorded events. The percentage of material classified as clay (<4 μm) ranged from 0.08 to 1.01%, silt-sized material (>4 and <63 μm) ranged between 9.31 and 67.17% and sand-size material (>63 μm) ranged from 32.01 to 90.61%. The relationship between the particle size and the discharge requires further studies. The diameter d10, d50 and d90 and a standard deviation were calculated for each flood. Mean values of d50 for individual flood ranged between 41.05 and 191.32 μm with average value of 99.01 μm and average standard deviation of 32.57.

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