Trajectoire d'évolution d'un cours d'eau à très faible énergie : le cas de la Charente entre Angoulême et Saintes (Ouest de la France)

Duquesne, Amélie; Plumejeaud-Perreau, Christine; Carozza, Jean‐Michel

doi:10.4000/geomorphologie.14411

Cited by 4 publications

(16 citation statements)

References 59 publications

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“…The fluvial pattern of the Charente River undergoes changes along its course. It starts as an irregular incised single channel from its source to Civray, transitions to a highly anastomosed pattern with 2-13 channels between Civray and Angoulême, becomes discontinuous and weakly anastomosed with 3-5 channels from Angoulême to Cognac, and finally takes on a meandering-to-sinuous single-channel form from Cognac to the estuary [34][35][36][37].…”

Section: Study Areamentioning

confidence: 99%

“…Field observations within the study area indicate a predominant fine suspended load and a limited bedload consisting mainly of sandy sediments, particularly upstream from Cognac. Duquesne et al [34,35] have shown that fluvial forms have very limited mobility in the medium term (around 150 years) due to the natural characteristics of the river such as its very low slope and flood flows with minimal morphogenic effects. Additionally, there is minimal change in the number of islands, except for those influenced by human activities [36].…”

Section: Study Areamentioning

confidence: 99%

“…Duquesne et al [34,35] have shown that fluvial forms have very limited mobility in the medium term (around 150 years) due to the natural characteristics of the river such as its very low slope and flood flows with minimal morphogenic effects. Additionally, there is minimal change in the number of islands, except for those influenced by human activities [36].…”

Section: Study Areamentioning

confidence: 99%

“…These values classify this section of the river as an "anastomosed river, organic flood plains type C2a" according to the classification by Nanson and Croke [42]. The landscape is characterized by a network of interconnected channels (2-5 channels), which are separated by large, elongated, and vegetated islands [36]. The width of the alluvial plain ranges from 1 to 2 km.…”

Section: Study Areamentioning

confidence: 99%

“…The width of the alluvial plain ranges from 1 to 2 km. The channels have a low sinuosity (approximately 1.05) and moderate width-depth ratios (around 15) and are bordered by natural low levees [34,35].…”

Section: Study Areamentioning

confidence: 99%

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Improving Grain Size Analysis to Characterize Sedimentary Processes in a Low-Energy River: A Case Study of the Charente River (Southwest France)

Duquesne

Carozza

2023

Applied Sciences

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The recognition and quantification of fluvial transport and depositional processes has widely been studied. However, few works have focused on the interpretation and quantification of sedimentary processes in low-energy fluvial environments. This paper features and compares the results of five methods of grain size data processing (statistic moments, textural analysis, multivariate statistics combining Principal Component Analysis and hierarchical cluster analysis, and CM image and end-member modeling analysis) and discusses their efficiencies in characterizing low-energy alluvial plain deposits. These environments are characterized by fine grain size, high-homogeneity deposits at the macroscopic scale, and low grain size variability, hence presenting a difficulty in identifying and splitting an apparently homogeneous sedimentary record into sedimentary sequences. These statistical methods are applied on a ~9 m long core extracted from the fluvial island of la Baine located in the downstream section of the Charente River (Chaniers, Charente-Maritime, France). In the light of these results, elementary statistical parameters (statistical moments, modes, and sorting index) have limited interest in the sedimentary description and interpretation of fine fluvial deposits. Textural analyses are more informative but highly dependent on the classification scheme. Only the multivariate statistics approach and end-member modeling analysis present interesting results and allow the robust identification of sub-units. However, multivariate statistics results are dependent on the choice of input variables and do not support non-zero values, while the second method, the most recent and complex one, needs further developments to clearly connect end-member classes to sedimentary processes.

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

See 3 more Smart Citations

Improving Grain Size Analysis to Characterize Sedimentary Processes in a Low-Energy River: A Case Study of the Charente River (Southwest France)

Duquesne

Carozza

2023

Applied Sciences

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Historical geomorphological adjustments of an Upper Rhine sub-tributary over the two last centuries (

Jautzy¹,

Schmitt²,

Rixhon³

2022

geomorphologie

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Reconstructing evolutionary trajectories of river systems gives valuable insights into the main drivers (i.e. hydroclimatic versus anthropogenic) of their historical morphodynamics. Understanding past and modern adjustments of hydrosystems is therefore a key for appropriate sustainable management schemes. In this respect, the historical evolution (~150 years) of a 6 km dynamic reach of an Upper Rhine sub-tributary, the Bruche River, is thoroughly studied using a wide array of planimetric and topographic data (ancient maps and longitudinal profile, orthophotos, LiDAR). The primary aim is to precisely quantify the lateral and vertical mobility, taking uncertainties into account. Lateral mobility is studied using a specifically designed indicator, the Aggregated Migration rate Index (AMI), which enables precise assessment of planform changes in m.yr -1 on elementary sub-reaches (~100 m). A twofold decrease in mean lateral mobility in the mid-20 th century, most probably related to functional channel modifications associated with the installation of an underground pipeline, represents the most striking result. Vertical mobility is analysed through the comparison of diachronic LiDAR data (decadal timescale) and historical archive (secular timescale). From the mid-20 th century onwards, an unexpected general aggradation of the riverbed (~0.6 m) has occurred, for which several explanations are discussed (i.e. bank erosion, deforestation, sediment release following weir lowering), though remaining speculative. Overall, our results show that historical geomorphological adjustments are primarily controlled by various anthropogenic factors. As the Bruche hosts one of the highest concentrations of spawning beds of emblematic fish species in the French Upper Rhine, this study lays the foundation for future restoration strategies.

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L’anastomose du fleuve Charente : apports de la quantification des formes fluviales à la connaissance des processus géomorphologiques et des facteurs de contrôle

Carozza,

Duquesne,

Vayssière

2023

geomorphologie

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Ce travail se propose de déduire les processus géomorphologiques actifs et les facteurs de contrôle de l’anastomose du fleuve Charente à partir d’une approche quantitative de l’organisation de son paysage fluvial sur un linéaire de près de 55 km entre Ambérac et Angoulême. Peu de travaux de ce type ont été réalisés jusqu’à présent pour cette famille de cours d’eau. La description de l’organisation du paysage fluvial repose sur la caractérisation morphométrique des chenaux et des îles. Cette approche permet de mettre en évidence l’existence d’une segmentation en sous-ensembles qui pourrait refléter des processus et/ou des trajectoires d’évolution distincts. Le linéaire a été découpé en 4 tronçons homogènes caractérisés par une complexité variable, mesurée par l’indice d’anastomose (Ia). L’analyse de la variabilité spatiale de l’organisation de l’anastomose montre une corrélation positive mais faible avec les variables de contrôle (pente et largeur de la plaine) qui suggère l’existence d’autres processus dans l’apparition et le maintien de l’anastomose.

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Trajectoire d'évolution d'un cours d'eau à très faible énergie : le cas de la Charente entre Angoulême et Saintes (Ouest de la France)

Abstract: Articles sous presse Trajectoire d'évolution d'un cours d'eau à très faible énergie : le cas de la Charente entre

Cited by 4 publications

References 59 publications

Improving Grain Size Analysis to Characterize Sedimentary Processes in a Low-Energy River: A Case Study of the Charente River (Southwest France)

Improving Grain Size Analysis to Characterize Sedimentary Processes in a Low-Energy River: A Case Study of the Charente River (Southwest France)

Historical geomorphological adjustments of an Upper Rhine sub-tributary over the two last centuries (

L’anastomose du fleuve Charente : apports de la quantification des formes fluviales à la connaissance des processus géomorphologiques et des facteurs de contrôle

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