The Impact of Different Design Approaches on Fine Sediment Transport in Gezira Scheme, Sudan

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.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 Dh&#252;nn 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.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.

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The impact of a convectional summer rainfall event on river flow and fine sediment transport in a highly urbanised catchment: Bradford, West Yorkshire

The Science of The Total Environment ◽

10.1016/s0048-9697(03)00070-6 ◽

2003 ◽

Vol 314-316 ◽

pp. 495-512 ◽

Cited By ~ 45

Author(s):

G OLD ◽

G LEEKS ◽

J PACKMAN ◽

B SMITH ◽

S LEWIS ◽

...

Keyword(s):

Sediment Transport ◽

River Flow ◽

Summer Rainfall ◽

Fine Sediment ◽

Rainfall Event ◽

The Impact

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Assessing the impact of fine sediment on high status river sites

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.143895 ◽

2021 ◽

Vol 759 ◽

pp. 143895

Author(s):

Gabriel Gaffney ◽

Karen Daly ◽

Philip Jordan

Keyword(s):

Fine Sediment ◽

High Status ◽

The Impact

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The impact of storms and stratification on sediment transport in the Rhine region of freshwater influence

Journal of Geophysical Research Oceans ◽

10.1002/2016jc012362 ◽

2017 ◽

Vol 122 (5) ◽

pp. 4456-4477 ◽

Cited By ~ 5

Author(s):

Raúl P. Flores ◽

Sabine Rijnsburger ◽

Alexander R. Horner-Devine ◽

Alejandro J. Souza ◽

Julie D. Pietrzak

Keyword(s):

Sediment Transport ◽

Freshwater Influence ◽

The Impact

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Analyzing the impact of wooden debris on scour and sediment transport

River Flow 2020 ◽

10.1201/b22619-105 ◽

2020 ◽

pp. 743-750

Author(s):

T. Johannsen ◽

M. Weber ◽

N. Saenger

Keyword(s):

Sediment Transport ◽

The Impact

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Numerical modelling of sediment transport in the Adriatic Sea

Ocean Science Discussions ◽

10.5194/osd-11-1391-2014 ◽

2014 ◽

Vol 11 (3) ◽

pp. 1391-1433 ◽

Cited By ~ 1

Author(s):

A. Guarnieri ◽

A. J. Souza ◽

N. Pinardi ◽

P. Traykovski

Keyword(s):

Sediment Transport ◽

Adriatic Sea ◽

Transport Model ◽

Data Availability ◽

Western Coast ◽

Po River ◽

Northern Adriatic ◽

Coastal Belt ◽

Italian Coasts ◽

The Impact

Abstract. A new sediment transport model, considering currents, tides and waves is presented for the Adriatic Sea basin. The simulations concentrate on the winter of 2002–2003 because of field data availability and interesting intermittent processes occurrence. A process oriented analysis is performed to investigate the impact that Sirocco and Bora wind regimes have on sediment transport. The comparisons of the simulations with the observed data show that the model is capable to capture the main dynamics of sediment transport along the Italian coasts and the sediment concentration within the water column. This latter can reach values up to several g L−1, especially within the first centimetres above the bottom. The sediments are transported mainly southwards along the Italian coasts, consistently with the known literature results, except during Sirocco wind events, which can be responsible for reversing the coastal circulation in the northern area of the basin, and consequently the sediment transport. The resuspension of sediments is also related to the specific wave regimes induced by Bora and Sirocco, the former inducing resuspension events near the coasts while the latter causing a more diffused resuspension regime in the Northern Adriatic basin. Beside the realistic representation of short timescales resuspension/deposition events due to storms, the model was also used to investigate persistent erosion or deposition areas in the Adriatic Sea. Two main depocenters were identified: one, very pronounced, in the surroundings of the Po river delta, and another one a few kilometres off the coast in front of the Ancona promontory. A third region of accumulation, even if less intense, was found to be offshore the southernmost limit of the Gargano region. On the contrary the whole western coast within a distance of a few kilometres from the shore was found to be subject to prevailing erosion. The comparison with observed accumulation and erosion data shows that the model captures well the main depocenters in the domain and the erosion within the very coastal belt of the western side of the basin, but seems to be too erosive in a few areas, in particular those where the contribution of sediment inflow to the sea of some minor but intermittently important rivers is not considered in a realistic way as input to the model.

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Effects of Cascade Reservoir Systems on the Longitudinal Distribution of Sediment Characteristics: A Case Study of the Heihe River Basin

10.21203/rs.3.rs-189115/v1 ◽

2021 ◽

Author(s):

Yu Wang ◽

Bao-long Li ◽

Juan-juan Liu ◽

Qi Feng ◽

Wei Liu ◽

...

Keyword(s):

Grain Size ◽

Sediment Transport ◽

Longitudinal Distribution ◽

Heihe River ◽

Hydrodynamic Conditions ◽

Sediment Grain Size ◽

Cascade Reservoirs ◽

Grain Size Distributions ◽

Transport Patterns ◽

The Impact

Abstract Spatial variations in grain-size parameters can reflect river sediment transport patterns and depositional dynamics. Therefore, 22 surficial sediment samples taken from the Heihe River and its cascade reservoirs were analyzed to better understand the impact of cascade reservoir construction on sediment transport patterns in inland rivers in China. The results showed that the longitudinal distribution of sediment grain size in the Heihe River was significantly affected by the influence of the cascade reservoirs. The grain size of the reservoir sediments within the cascade reservoir system was much lower than that of sediments in the natural river section, and the sediments in the natural river were well sorted, exhibiting leptokurtosis and positive or very positive skew. The lower reaches of the dammed river experienced strong erosion, and the grains of the bed sediments were coarse and poorly sorted; the grain-size distributions were more positively skewed and exhibited leptokurtosis. The backwater zone of the reservoir was influenced by both backwater and released water, and the sediment grain size was between the grain size of the natural river and that of the lower reaches of the dam; these sediments were moderately well sorted and had a positively skewed, leptokurtic grain-size distribution. Sedimentary environmental analysis revealed that the characteristics of the sediment grain size in an upstream tributary of the Heihe River were more influenced by source material than by hydrodynamic conditions, while the grain-size characteristics of the mainstream sediments were controlled mainly by hydrodynamic conditions.

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Gravel Bed Composition in Oregon Coastal Streams

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f80-196 ◽

1980 ◽

Vol 37 (10) ◽

pp. 1514-1521 ◽

Cited By ~ 68

Author(s):

J. N. Adams ◽

R. L. Beschta

Keyword(s):

Regression Analysis ◽

Fine Sediment ◽

Low Flow ◽

Coast Range ◽

Oregon Coast Range ◽

Oregon Coast ◽

Gravel Bed ◽

Fine Sediments ◽

High Flows ◽

The Impact

The amount of fine sediments (generally < 1 mm in diameter) in gravel bedded streams is often used as an indicator of habitat quality and also as a measure of the impact from accelerated sedimentation resulting from land disturbance. Five streams in the Oregon Coast Range were studied to evaluate temporal and spatial variability of streambed composition, as well as the factors affecting the amount of fine sediment within the bed. The amount of fine sediments (< 1 mm) contained in frozen streambed cores and expressed as a percentage (by weight) of the total sample proved highly variable in time and space. During a 19-mo sampling period, temporal variability was caused by an occasional flushing of fines from the gravel beds during high flows. Percent fines also varied greatly between streams, between locations in the same stream, and between locations in the same riffle. Streams on 21 Coast Range watersheds were sampled during summer low flow. The amount of fines averaged 19.4% for all watersheds and ranged from 10.6 to 29.4% for streams on undisturbed watersheds. Regression analysis indicated that the watershed slope, area, relief, and land use influenced the amount of fine sediment in the bed. Bed composition varied greatly between locations in the same stream with about 75% of the within-stream comparisons indicating a significant (α = 0.05) difference. Within a single stream, gravel bed composition correlated significantly with channel sinuosity and bank-full stage. Regression analysis and field observations suggested that road construction and logging operations can increase the amount of fines; however, such increases may be temporary if high flows flush the gravelsKey words: bed sediments, forest harvesting, Oregon Coast Range, sedimentation, spawning gravels, stream channels, water quality

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