The Impact of Damming the Ord River on the Fine Sediment Budget in Cambridge Gulf, Northwestern Australia

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

Water Resources in Arid Lands: Management and Sustainability - Advances in Science, Technology & Innovation ◽

10.1007/978-3-030-67028-3_5 ◽

2021 ◽

pp. 55-72

Author(s):

Awad M. Ali ◽

Ishraga S. Osman ◽

Hozaifa Khalid ◽

Maab Albager ◽

Amal Ibrahim

Keyword(s):

Sediment Transport ◽

Fine Sediment ◽

The Impact

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The impact of significant input of fine sediment on benthic fauna at tributary junctions: a case study of the Bermejo-Paraguay River confluence, Argentina

Ecohydrology ◽

10.1002/eco.1511 ◽

2014 ◽

Vol 8 (2) ◽

pp. 340-352 ◽

Cited By ~ 14

Author(s):

Martín C. M. Blettler ◽

Mario L. Amsler ◽

Inés Ezcurra de Drago ◽

Luis A. Espinola ◽

Eliana Eberle ◽

...

Keyword(s):

Benthic Fauna ◽

Fine Sediment ◽

Paraguay River ◽

River Confluence ◽

The Impact

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

10.5194/egusphere-egu2020-20418 ◽

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

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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Reduced fine sediment flux in response to the managed diversion of an upland river channel

Earth Surface Dynamics Discussions ◽

10.5194/esurfd-3-1179-2015 ◽

2015 ◽

Vol 3 (4) ◽

pp. 1179-1220

Author(s):

M. T. Perks ◽

J. Warburton

Keyword(s):

Suspended Sediment ◽

Fine Sediment ◽

Sediment Flux ◽

Analysis Of Covariance ◽

Before And After ◽

Suspended Sediment Concentrations ◽

Sediment Transfer ◽

The Uk ◽

The Impact ◽

B Coefficients

Abstract. This paper describes the implementation of a novel mitigation approach and subsequent adaptive management, designed to reduce the transfer of fine sediment in Glaisdale Beck; a small upland catchment in the UK. Hydro-meteorological and suspended sediment datasets are collected over a two year period spanning pre- and post-diversion periods in order to assess the impact of the channel reconfiguration scheme on the fluvial suspended sediment dynamics. Analysis of the river response demonstrates that the fluvial sediment system has become more restrictive with reduced fine sediment transfer. This is characterised by reductions in flow-weighted mean suspended sediment concentrations from 77.93 mg L−1 prior to mitigation, to 74.36 mg L−1 following the diversion. A Mann–Whitney U test found statistically significant differences (p < 0.001) between the pre- and post-monitoring median SSCs. Whilst application of one-way analysis of covariance (ANCOVA) on the coefficients of sediment rating curves developed before and after the diversion found statistically significant differences (p < 0.001), with both Log a and b coefficients becoming smaller following the diversion. Non-parametric analysis indicates a reduction in residuals through time (p < 0.001), with the developed LOWESS model over-predicting sediment concentrations as the channel stabilises. However, the channel is continuing to adjust to the reconfigured morphology, with evidence of a headward propagating knickpoint which has migrated 120 m at an exponentially decreasing rate over the last 7 years since diversion. The study demonstrates that channel reconfiguration can be effective in mitigating fine sediment flux in upland streams but the full value of this may take many years to achieve whilst the fluvial system, slowly readjusts.

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