Curvas-chave de descargas de sedimentos em suspensão no Baixo São Francisco

RESUMOO conhecimento da análise quantitativa das concentrações de sedimentos em suspensão transportados pelo rio São Francisco bem como sua relação com as vazões é de muita importância, pois pode auxiliar na identificação dos efeitos da intervenção humana e ou ocasionados pelas condições naturais da região. As regiões a jusante dos barramentos no rio São Francisco apresentam como principal consequência a regularização das vazões e a diminuição das concentrações de sedimentos. O objetivo da pesquisa foi determinar as curvas-chave de sedimentos em suspensão (CCS) nas estações fluviométricas instaladas no Baixo São Francisco (BSF) após a barragem de Xingó. Para o estabelecimento dessas curvas foram utilizados dados de vazão e concentração de sedimentos em suspensão, obtidos do sistema Hidroweb no site da Agência Nacional da Água (ANA) no período de 1999 a 2018. Foram obtidas CCS para todo o trecho do BSF as quais apresentaram bons coeficientes de determinação. Na análise dos dados também foi possível perceber que nos últimos anos, desde 2013 houve redução gradativa das vazões disponibilizadas na barragem de Xingó. Consequentemente, houve também a redução gradativa das cargas de sedimentos em suspensão geradas nas estações de Piranhas, Traipu e Propriá, ou seja, os menores valores já registrados no BSF correspondendo as menores séries históricas tanto de vazão como de sedimentos em suspensão. Keys curves of sediment discharges in suspension in the Lower São Francisco A B S T R A C TThe knowledge of the quantitative analysis of suspended sediment concentrations carried by the São Francisco River as well as its relation with the flows is of great importance, since it can help in the identification of the effects of human intervention and/or caused by the natural conditions of the region. In the downstream regions of the São Francisco riverbanks, the main consequence was the regularization of flow rates and the reduction of sediment concentrations. The objective of the research was to determine the key curves of suspended sediments (CCS) at the fluviometric stations installed in the lower São Francisco river after Xingó dam. For the evaluation, flow data and suspended sediment concentration were used. These data were obtained from the Hidroweb system on the website of the National Water Agency (ANA) from 1999 to 2018. CCS were plotted for all stretches and presented good coefficients of determination (R2). Based on the analysis of the data it was also possible to notice that in recent years, since 2013 there has been a gradual reduction of the flows available in the Xingó dam. Consequently, there was also a gradual reduction of suspended sediment loads generated at the Piranhas, Traipu and Propriá stations, that is, the lowest values already recorded in lower São Francisco, corresponding to the lower historical series of both discharge and suspended sediments.Keywords: dam, flow, sediments

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Impact of Chelicorophium curvispinum on the concentration-discharge response of suspended sediment in the Rhine River

10.5194/egusphere-egu21-9199 ◽

2021 ◽

Author(s):

Marcel van der Perk

Keyword(s):

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Sediment Concentration ◽

Sudden Increase ◽

Rhine River ◽

Rating Curve ◽

Independent Evidence ◽

Sediment Rating Curve ◽

Suspended Sediment Concentrations

In an ongoing study to the decline in suspended sediment concentrations and loads in the Rhine river since the mid-1950s, the temporal changes in the power-law sediment rating curve parameters were examined. This revealed that the rating exponent of the rating curve increased substantially between the early and late 1980s. Until the early 1980s, the ratings curves were relatively flat with values of the rating exponent b varying around 0.2. In the mid-1980s, the exponent suddenly increased to a value between 0.4 and 0.6 and since then has remained within this range. This change in the rating exponent was mainly caused by a decrease in suspended sediment concentrations during low discharges. During high discharges, the suspended sediment concentration initially increased during the late 1980s, but this increase was nullified soon afterwards due to the declining trend in suspended sediment concentration.The sudden increase of the rating exponent coincided with the period that the Ponto-Caspian Chelicorophium curvispinum (Caspian mud shrimp) invaded the Rhine river basin. This suggests that this suspension-feeder species bears the prime responsibility for this increase, although this hypothesis requires further independent evidence. The sudden increase in the rating exponent does however not manifest itself in the long-term gradual trend of declining suspended sediment concentrations and vice versa. Apparently, the sequestration of sediment by Chelicorophium curvispinum is only temporary: the suspended sediment sequestered during periods of relatively low discharges is likely remobilised again during periods of high discharge. This implies that the invasion of Chelicorophium curvispinum has not played a significant role in the decline of suspended sediment concentrations. The precise reasons for the gradual long-term decline in suspended sediment concentration remain yet unknown.

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Transport Mechanism of Suspended Sediments and Migration Trends of Sediments in the Central Hangzhou Bay

Water ◽

10.3390/w12082189 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2189

Author(s):

Zekun Song ◽

Weiyong Shi ◽

Junbiao Zhang ◽

Hao Hu ◽

Feng Zhang ◽

...

Keyword(s):

Sediment Transport ◽

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Suspended Sediments ◽

Sediment Concentration ◽

Hangzhou Bay ◽

The South ◽

Transport Mode ◽

Tidal Pumping ◽

The North

Based on the 2013 field survey data of hydrology, suspended sediments and bottom sediments in the Central Hangzhou Bay, this paper explores the dynamic mechanism of suspended sediments in Hangzhou Bay by employing material flux decomposition. Meanwhile, the migration trends of bed sediments are also investigated by analyzing grain size trends. The results show that during an ebb or flood tide, the hydrograph of suspended sediment concentration of Hangzhou Bay is dominated by an M shape (bimodal), which is attributed primarily to the generation of a soft mud layer and a separate fluid mud layer. Laterally, the distribution of suspended sediment concentration is high in the south and low in the north. From a macroscopic perspective, the net sediment transport in the study area displays a “north-landward and south-seaward” trend, presenting a “C”-shaped transport mode. That is, the sediments are transported from the bay mouth to the bay head on the north side and from the bay head to the bay mouth on the south side. The sediment transports by advection and tidal pumping are predominant, while the sediment transport by vertical circulation makes little contribution to the total sediment transport. Moreover, the sediment transport in the center of the reach area is dominated by advection, whereas that near both sides of the banks is controlled by tidal pumping. The asymmetry of the tides, i.e., flood-dominance in the north and ebb-dominance in the south, is the primary cause of the dynamic mechanism for the overall “C”-shaped transport mode in Hangzhou Bay. Additionally, coupled with the narrow-head wide-mouth geomorphology, Hangzhou Bay remains evolving by south shore silting and north shore scouring.

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Sediment Load and Suspended Sediment Concentration Prediction

Soil and Water Research ◽

10.17221/6502-swr ◽

2013 ◽

Vol 1 (No. 1) ◽

pp. 23-31 ◽

Cited By ~ 2

Author(s):

Bečvář Martin

Keyword(s):

Suspended Sediment ◽

Sediment Yield ◽

Suspended Sediment Concentration ◽

Sediment Load ◽

Sediment Concentration ◽

River Basins ◽

River Systems ◽

Sediment Yields ◽

Suspended Sediment Concentrations ◽

Annual Sediment

Sediment is a natural component of riverine environments and its presence in river systems is essential. However, in many ways and many places river systems and the landscape have been strongly affected by human activities which have destroyed naturally balanced sediment supply and sediment transport within catchments. As a consequence a number of severe environmental problems and failures have been identified, in particular the link between sediments and chemicals is crucial and has become a subject of major scientific interest. Sediment load and sediment concentration are therefore highly important variables that may play a key role in environment quality assessment and help to evaluate the extent of potential adverse impacts. This paper introduces a methodology to predict sediment loads and suspended sediment concentrations (SSC) in large European river basins. The methodology was developed within an MSc research study that was conducted in order to improve sediment modelling in the GREAT-ER point source pollution river modelling package. Currently GREAT-ER uses suspended sediment concentration of 15 mg/l for all rivers in Europe which is an obvious oversimplification. The basic principle of the methodology to predict sediment concentration is to estimate annual sediment load at the point of interest and the amount of water that transports it. The amount of transported material is then redistributed in that corresponding water volume (using the flow characteristic) which determines sediment concentrations. Across the continent, 44 river basins belonging to major European rivers were investigated. Suspended sediment concentration data were collected from various European basins in order to obtain observed sediment yields. These were then compared against the traditional empiric sediment yield estimators. Three good approaches for sediment yield prediction were introduced based on the comparison. The three approaches were applied to predict annual sediment yields which were consequently translated into suspended sediment concentrations. SSC were predicted at 47 locations widely distributed around Europe. The verification of the methodology was carried out using data from the Czech Republic. Observed SSC were compared against the predicted ones which validated the methodology for SSC prediction.

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Dynamics of Suspended Sediments Related to Fine Particles in Lower Mekong River

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.446-447.1528 ◽

2013 ◽

Vol 446-447 ◽

pp. 1528-1533

Author(s):

Sarunya Promkotra

Keyword(s):

Shear Stress ◽

Flow Velocity ◽

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Fine Particles ◽

Suspended Sediments ◽

Sediment Concentration ◽

Mekong River ◽

Fall Velocity ◽

Stream Discharge

Analytical results are considered the factors of suspended sediment concentration, fall velocity, dimensionless shear stress, transportation rate and stream discharge. As a result of suspended sediments of Loei, Huang and Mekong River, fine particles account for the applicability in sediment deposits. Floating suspended sediments explicit more clay minerals than suspended sediments. Suspended sediment concentration (SSC) in the estuarine of Loei River and Huang River are moderately less than Mekong River. Flow directions of the interconnected rivers to the mainstream-Mekong River lead to the quantity of SSC. Sediment concentrations attain to the dynamic response. Dimensionless shear stress relates to shear velocity, geometry and grain size of particles, and difference of flow velocity. This shear stress is directly comparative to flow velocity and clay mineral concentrations. The transport rate involves in the flow velocity, SSC and depth of the river. Moreover, stream discharge can be presumed by the geometry of the river and topography of sampling locations.

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Sampling strategies to estimate suspended sediment concentration for turbidimeter calibration

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/1807-1929/agriambi.v21n12p884-889 ◽

2017 ◽

Vol 21 (12) ◽

pp. 884-889 ◽

Cited By ~ 2

Author(s):

Leandro Dalbianco ◽

Rafael Ramon ◽

Claudia A. P. de Barros ◽

Jean P. G. Minella ◽

Gustavo H. Merten ◽

...

Keyword(s):

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Suspended Sediments ◽

Sediment Concentration ◽

Rainfall Event ◽

Sampling Strategies ◽

Southern Brazil ◽

Rainfall Events ◽

Insufficient Amount ◽

Indirect Relationship

ABSTRACT The influx of sediments carried by rivers can be measured continuously using a turbidimeter through the indirect relationship between turbidity and suspended sediment concentration (SSC). However, this process is dependent on obtaining water samples with suspended sediments to calibrate the turbidimeter. Sampling can be carried out through different methods, resulting in errors and uncertainties in estimating the SSC. Four different possibilities for the composition of the calibration curve were tested in order to evaluate the effectiveness of the turbidimeter calibration for different sampling strategies. The study was conducted in 2012 and 2013 in two catchments in southern Brazil that had a strong sediment yield impact. The results indicate that sampling during rainfall events generate a significant and representative SSC for the turbidimeter calibration. The use of an integrating sampler for synthetic samples provides an effective calibration, but overestimates SSC compared to calibration from rainfall event sampling. The samples collected at fixed intervals - weekly and daily - generated an insufficient amount of data and are not representative of real sediment concentrations of the catchments.

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Calibrations of Suspended Sediment Concentrations in High-Turbidity Waters Using Different In Situ Optical Instruments

Water ◽

10.3390/w12113296 ◽

2020 ◽

Vol 12 (11) ◽

pp. 3296

Author(s):

Yunwei Wang ◽

Yun Peng ◽

Zhiyun Du ◽

Hangjie Lin ◽

Qian Yu

Keyword(s):

Suspended Sediment ◽

Inflection Point ◽

Suspended Sediment Concentration ◽

Sediment Concentration ◽

Fluid Mud ◽

Optical Instruments ◽

Suspended Sediment Concentrations ◽

High Turbidity ◽

The Right

In environments of high suspended sediment concentration (SSC > 1 kg/m3), efficient measurements of SSC through accurate calibration relationships between turbidity and SSC are necessary for studies on marine sediment dynamics. Here, we investigated the performance of three types of optical instrument (OBS-3A, AQUAlogger 310TY, and RBRsolo3Tu with Seapoint sensor) in observations carried out at the middle of the Jiangsu coast, China. These instruments were calibrated in the lab using the water and suspended sediment samples collected from the observation site. It was found that both the calibration curves of OBS-3A and RBRsolo3Tu have an inflection point (at SSC of ca. 15 kg/m3 for OBS-3A and ca. 2 kg/m3 for RBRsolo3Tu), on either side of which turbidity increases (the left side) or decreases (the right side) with the increasing SSC. Only under SSCs smaller than the inflection point can OBS-3A and RBRsolo3Tu be applied to continuous SSC measurements at a fixed point. However, the turbidity output of AQUAlogger 310TY has always a positive correlation with SSC, which applies for SSC up to 40 kg/m3; thus, three fluid-mud events are quantified during this observation. AQUAlogger 310TY has important prospects for field applications in high-SSC environments.

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Indirect Estimation of Flow and Suspended-sediment Concentration and Load in Small Mountain Streams: an Exploratory Study in Ribeira Seca Stream, Madeira Island

WSEAS TRANSACTIONS ON ENVIRONMENT AND DEVELOPMENT ◽

10.37394/232015.2020.16.89 ◽

2021 ◽

Vol 16 ◽

Keyword(s):

Suspended Sediment ◽

Exploratory Study ◽

Suspended Sediment Concentration ◽

Suspended Sediments ◽

Sediment Concentration ◽

Suspended Sediment Transport ◽

Measurement Campaign ◽

Indirect Determination ◽

Madeira Island ◽

The North

The aim of this study was to assess the applicability of indirect techniques for streamflow and suspended sediment concentration estimation and their use in the calculation of suspended sediment transport rate in the small mountain watersheds of Madeira Island, Portugal. Emphasis was given to the application of salt dilution gauging to the indirect determination of the flow rate and the use of water turbidity data to estimate the concentration of suspended sediments. The field and laboratory work carried out are briefly described, and the main experimental results and the field data from the short measurement campaign performed in the Ribeira Seca stream in Faial, on the north side of the island, are presented and discussed. Whilst the measurement campaign carried out was temporally and spatially limited, it was pioneering for Madeira and allowed to verify the applicability of the indirect hydrometric and sedimentometric techniques used in this exploratory study.

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Prediction and classification of suspended sediment and zooplankton signals from acoustic Doppler current profiler backscatter data using artificial neural networks

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/944/1/012014 ◽

2021 ◽

Vol 944 (1) ◽

pp. 012014

Author(s):

A Dwinovantyo ◽

S Solikin ◽

H M Manik ◽

T Prartono ◽

Susilohadi

Keyword(s):

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Acoustic Doppler Current Profiler ◽

Suspended Sediments ◽

Sediment Concentration ◽

Optimal Number ◽

Environmental Data ◽

Zooplankton Abundance ◽

Current Profiler ◽

Artificial Neural

Abstract Characterization of each underwater object has its challenges, especially for small objects. The process of quantifying acoustic signals for these small objects can be done using high-frequency hydroacoustic instruments such as an acoustic Doppler current profiler (ADCP) combined with the artificial intelligence (AI) technique. This paper presents an artificial neural network (ANN) methodology for classifying an object from acoustic and environmental data in the water column. In particular, the methodology was tuned for the recognition of suspended sediments and zooplankton. Suspended sediment concentration and zooplankton abundance, which extracted from ADCP acoustic data, were used as input in the backpropagation method along with other environmental data such as effects of tides, currents, and vertical velocity. The classifier used an optimal number of neurons in the hidden layer and a feature selection based on a genetic algorithm. The ANN method was also used to estimate the suspended sediment concentration in the future. This study provided new implications for predicting and classifying suspended sediment and zooplankton using the ADCP instrument. The proposed methodology allowed us to identify the objects with an accuracy of more than 95%.

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Monitoring of seasonally variability and movement of suspended sediment concentration along Thiruvananthapuram coast using OLI sensor

10.5194/os-2017-86 ◽

2018 ◽

Author(s):

Bismay Ranjan Tripathy ◽

Kaliraj Seenipandi ◽

Haroon Sajjad ◽

Pawan Kumar Joshi ◽

Bhagwan Singh Chaudhary ◽

...

Keyword(s):

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Suspended Sediments ◽

Analysis Data ◽

Sediment Concentration ◽

Landsat 8 ◽

Wave Direction ◽

High Concentration ◽

Littoral Current ◽

Lower Depth

Abstract. In the recent decades hydrologists, geologists, and stream ecologists have shown substantial interest in analyzing suspended sediments in water. Extracting information like suspended sediment concentration (SSC) in coastal waters is very important for assessment and monitoring of coastal settings and their effects on their ecology. This article demonstrates importance of Landsat 8 Operational Land Imager (OLI) for monitoring seasonal variation in SSC and movement (pre and post monsoon) along Thiruvananthapuram Coast in India. The data was converted into marine reflectance after correcting due atmospheric errors. SSC was extracted using spectral analysis data analysis. Movement of SSC was monitored using wave direction and significant wave height data. The results revealed that the SSC decreased rapidly with the increase in distance from the beach and depth of the seabed. Wave with higher frequency in deeper water caused sparely circulation of sediments and their concentration at the lower depth in high bathymetry. Thus, the suspended sediments were indirectly proportional to bathymetry and distance from the shoreline and directly proportion to wave direction and littoral current at off-shore. High concentration of sediments was found to be accumulated at shallow depth (

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Sediment Concentration in Melt Waters as an Indicator of Erosion Processes Beneath an Alpine Glacier

Journal of Glaciology ◽

10.1017/s0022143000029877 ◽

1979 ◽

Vol 23 (89) ◽

pp. 247-257 ◽

Cited By ~ 72

Author(s):

David N. Collins

Keyword(s):

Suspended Sediment ◽

Suspended Sediment Concentration ◽

Sediment Concentration ◽

Water Volume ◽

Alpine Glacier ◽

Erosion Processes ◽

Rate Of Increase ◽

Before And After ◽

Suspended Sediment Concentrations ◽

Ice Water

Abstract Suspended-sediment concentrations in melt waters from the Gornera, Gornergletscher, Switzerland, were determined at hourly intervals for periods during the ablation seasons of 1974 and 1975. Rapid erratic fluctuations of suspended-sediment concentration produced peaks which occurred both before and after highest daily flows. Clockwise daily hysteresis rating loops between sediment concentration and discharge included many involutions. Suspended-sediment-concentration-discharge rating curves were different for rising and falling limbs of individual diurnal hydrographs and varied from day to day. Close-interval measurements of sediment concentration and discharge records allow interpretation of the nature of ice–water–sediment interactions at the bed of an Alpine glacier. At Gornergletscher, subglacial sediment is delivered to melt waters flowing in the smaller basal conduits, which often change course suddenly, entraining unworked sediment stored at the bed. During diurnal discharge maxima, sediment concentration in the Gornera is reduced because the rate of increase of water volume outstrips the rate of supply of sediment. The drainage of the ice-dammed lake Gornersee, producing exceptionally high flows, extended the drainage network over large areas of the glacier bed, and evacuated much sediment.

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