ASSESSING THE ANTHROPOGENIC IMPACTS ON THE FLUVIAL WATER AND SEDIMENT FLUXES INTO THE THERMAIKOS GULF, NORTHERN GREECE

<p>Bacterial communities are essential to the biogeochemical cycle in riverine ecosystems. However, the integrated biogeography and assembly process of planktonic and sedimentary bacterial communities in large rivers is still poorly understood. Here, the study provided the spatiotemporal pattern of bacterial communities in the Yangtze River of 4300 km continuum, which is the largest river in Asia. We found that the taxa in sediments are the main contributors to the bacterial diversity of the river ecosystem since sediments sub-group took 98.8% of the total 38, 904 Operational Taxonomic Units (OTUs) observed in 280 samples. Seasonal differences in bacterial communities were statistically significant in water, whereas bacterial communities in both water and sediment were geographically clustered according to five types of landforms: mountain, foothill, basin, foothill-mountain, and plain. Interestingly, the presence of two huge dams resulted in a drastic fall of bacterial taxa in sediment immediately downstream due to severe riverbed scouring. The integrity of the biogeography was satisfactorily interpreted by the combination of neutral and species sorting perspectives in meta-community theory for bacterial communities in flowing water and sediment. Although deterministic process had dominant influence on assembly processes in water and sediment communities, homogeneous selection was the main contributor in water, while combination of homogeneous selection and variable selection contributed selection process in sediment. In addition, homogenizing dispersal played more important role in community assembly process in sediment than water. Our study fills a gap in understanding of biogeography and assembly process of bacterial communities in one of the world&#8217;s largest river and highlights the importance of both planktonic and sedimentary communities to the integrity of bacterial biogeographic patterns in a river subject to varying natural and anthropogenic impacts.</p>

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Application of a hydrological-hydraulic modelling cascade in lowlands for investigating water and sediment fluxes in catchment, channel and reach

Journal of Hydrology and Hydromechanics ◽

10.2478/johh-2013-0042 ◽

2013 ◽

Vol 61 (4) ◽

pp. 334-346 ◽

Cited By ~ 15

Author(s):

Jens Kiesel ◽

Britta Schmalz ◽

Gary L. Brown ◽

Nicola Fohrer

Keyword(s):

Model Performance ◽

Hydraulic Model ◽

Sediment Fluxes ◽

Erosion Processes ◽

Water And Sediment ◽

Sensitivity Tests ◽

Domain Models ◽

One Year ◽

Data Improvement ◽

Future Work

Abstract This study shows a comprehensive simulation of water and sediment fluxes from the catchment to the reach scale. We describe the application of a modelling cascade in a well researched study catchment through connecting stateof- the-art public domain models in ArcGIS. Three models are used consecutively: (1) the hydrological model SWAT to evaluate water balances, sediment input from fields and tile drains as a function of catchment characteristics; (2) the onedimensional hydraulic model HEC-RAS to depict channel erosion and sedimentation along a 9 km channel onedimensionally; and (3) the two-dimensional hydraulic model AdH for simulating detailed substrate changes in a 230 m long reach section over the course of one year. Model performance for the water fluxes is very good, sediment fluxes and substrate changes are simulated with good agreement to observed data. Improvement of tile drain sediment load, simulation of different substrate deposition events and carrying out data sensitivity tests are suggested as future work. Main advantages that can be deduced from this study are separate representation of field, drain and bank erosion processes; shown adaptability to lowland catchments and transferability to other catchments; usability of the model’s output for habitat assessments.

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Seasonal variation in water and sediment fluxes of the Yangtze River under precipitation change and human interference

10.5194/egusphere-egu21-1880 ◽

2021 ◽

Author(s):

Yao Yue ◽

Yuanfang Chai ◽

Shitian Xu ◽

Xiaofeng Zhang

Keyword(s):

Yangtze River ◽

Sediment Load ◽

Water Discharge ◽

Water Flux ◽

Precipitation Change ◽

The Yangtze River ◽

Human Interference ◽

Sediment Fluxes ◽

Water And Sediment ◽

Sediment Reduction

<p>Seasonal change of water and sediment fluxes is an important issue in flood/drought control and ecosystem protection. Based on trend analysis in dry and flood seasons during 1960&#8211;2014 at six major gauging stations on the Yangtze River, the largest river in China, significant homogenization of intra-year water discharge was found, while sharp decrease of sediment load in both seasons was tested. By reconstructing water and sediment series without the human interference, contributions of precipitation change, large dam constructions on the mainstream, and other human activities in each of the sub-basins of the Yangtze River were separated and quantified. It shows that precipitation change attributed for 9.5&#8211;23.6% to discharge homogenization in the middle and lower reaches of the Yangtze River, and increased sediment yield by 1.9&#8211;25.5% in both dry and flood seasons. Being the largest hydraulic project in the world, the Three Gorges Dam only explains 17.5&#8211;27.2% of the downstream homogenization in water flux, and 3.2&#8211;23.9% of sediment reduction in both seasons. Relatively small but massive human interference in the sub-basins was recognized as the primary factor, contributing over 60% to discharge homogenization and over 70% to seasonal sediment reduction, most notably in the Hanjiang sub-basin for water flux and in the Jianglingjiang sub-basin for sediment load.</p>

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BP Model Applied to Forecast the Water and Sediment Fluxes in the Yellow River Mouth

2009 2nd International Congress on Image and Signal Processing ◽

10.1109/cisp.2009.5303781 ◽

2009 ◽

Cited By ~ 1

Author(s):

Jun Yan ◽

Yanfang Liu ◽

Jun Wang ◽

Hui Cao ◽

Haibin Zhao

Keyword(s):

Yellow River ◽

River Mouth ◽

The Yellow River ◽

Sediment Fluxes ◽

Water And Sediment ◽

Yellow River Mouth ◽

Bp Model

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Water and sediment fluxes on the Ebro Delta shoreface: on the role of low frequency currents

Marine Geology ◽

10.1016/s0025-3227(98)00153-4 ◽

1999 ◽

Vol 157 (3-4) ◽

pp. 219-239 ◽

Cited By ~ 20

Author(s):

J.A. Jiménez ◽

J. Guillén ◽

V. Gracia ◽

A. Palanques ◽

M.A. Garcı́a ◽

...

Keyword(s):

Low Frequency ◽

Ebro Delta ◽

Sediment Fluxes ◽

Water And Sediment

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Optimizing the Operation of a Multiple Reservoir System in the Eastern Nile Basin Considering Water and Sediment Fluxes

10.1201/9781003097792 ◽

2021 ◽

Author(s):

Reem Fikri Mohamed Osman Digna

Keyword(s):

Nile Basin ◽

Sediment Fluxes ◽

Reservoir System ◽

Water And Sediment ◽

Multiple Reservoir

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A comparative study of the flux and fate of the Mississippi and Yangtze river sediments

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-367-312-2015 ◽

2015 ◽

Vol 367 ◽

pp. 312-319 ◽

Cited By ~ 2

Author(s):

K. Xu ◽

S. L. Yang

Keyword(s):

Anthropogenic Impacts ◽

River Sediments ◽

Large River ◽

Sediment Discharge ◽

Dispersal Patterns ◽

Sediment Dispersal ◽

River Deltas ◽

Water And Sediment ◽

Continental Shelves ◽

Global Oceans

Abstract. Large rivers play a key role in delivering water and sediment into the global oceans. Large-river deltas and associated coastlines are important interfaces for material fluxes that have a global impact on marine processes. In this study, we compare water and sediment discharge from Mississippi and Yangtze rivers by assessing: (1) temporal variation under varying climatic and anthropogenic impacts, (2) delta response of the declining sediment discharge, and (3) deltaic lobe switching and Holocene sediment dispersal patterns on the adjacent continental shelves. Dam constructions have decreased both rivers’ sediment discharge significantly, leading to shoreline retreat along the coast. The sediment dispersal of the river-dominated Mississippi Delta is localized but for the tide-dominated Yangtze Delta is more diffuse and influenced by longshore currents. Sediment declines and relative sea level rises have led to coastal erosion, endangering the coasts of both rivers.

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