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21 pages, 3784 KB

Open AccessArticle

Reconstruction of the Evolution of the Hydro-Sedimentary Signal to the Sea from the Study of the Sedimentary Archives: Case of the Wadi Cheliff, Algeria

by Ali Hadour, Gil Mahé, Mohamed Meddi and Laurent Dezileau

Water 2025, 17(23), 3378; https://doi.org/10.3390/w17233378 - 26 Nov 2025

Viewed by 264

Abstract

This work focuses on the study of several fluvial cores to help better understand the contribution of rainfall and large dams in the decline of sedimentary inputs of the Wadi Cheliff at its outlet. Therefore, three sediment cores, sampled in the lower Cheliff [...] Read more.

This work focuses on the study of several fluvial cores to help better understand the contribution of rainfall and large dams in the decline of sedimentary inputs of the Wadi Cheliff at its outlet. Therefore, three sediment cores, sampled in the lower Cheliff valley, downstream of dams, were studied through the paleohydrological approach. Then, the granulometric and geochemical profiles obtained were correlated with ¹³⁷Cs profiles, hydrological data of the Wadi Cheliff at the station closest to the Sea, Sidi bel Attar, the evolution of the rainfall signal and the data on the large dams. Such an examination aims, on the one hand, to establish a chronology of depositional accumulation and, on the other hand, to evaluate the ability of the information contained in the sedimentary archive to transcribe the evolution of the hydro-sedimentary signal and the fluctuations of the controlling factors. The results reveal a strong variation in the granulometric distribution of the deposits and a progressive decline in the rate of sediment accumulation. Thus, the upper part of the core is mainly made of particles belonging to the silt and clays granulometric classes that have accumulated with an average rate of about 1.31 cm.y⁻¹, contrary to the deposits in the lower part of the core composed of a succession of sand and finer sedimentary layers, and showing an accumulation rate much more superior, which value is evaluated to 16 cm.y⁻¹. However, the fluctuations observed in the granulometric composition, and the accumulation rate of the deposits correlated strongly with the evolution of the rainfall signal and/or the multiplication of the number of large dams. Indeed, frequent sand deposits and a higher accumulation rate correspond to the wet period before 1980. Then, the decrease in rainfall has been accompanied by a lower accumulation rate, and deposits composed mainly of clay and silt particles. In addition, the recently built dams have a drastic effect on the deposition process. Thus, the accumulation rate has been strongly slowed, and the deposits are short of the sand fraction. This study shows that the deposition process is closely linked to the hydro-sedimentary yield of the Wadi Cheliff to the sea, as it shows that the information present in the sediment archive accurately reflects the evolution of rainfall signal and the effect of large dams on the decline of sedimentary inputs from the Wadi Cheliff to the sea. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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22 pages, 8689 KB

Open AccessArticle

Site-Specific Net Suspended Sediment Flux and Turbidity–TSM Coupling in a UNESCO Tidal Flat on the Western Coast of Korea: High-Resolution Vertical Observations

by Jun-Ho Lee, Hoi Soo Jung, Keunyong Kim, Yeongjae Jang, Donguk Lee and Joo-Hyung Ryu

Water 2025, 17(23), 3361; https://doi.org/10.3390/w17233361 - 25 Nov 2025

Viewed by 517

Abstract

Understanding suspended sediment transport in macrotidal embayments is crucial for assessing water quality, ecosystem function, and long-term morphological stability. This study provides a high-resolution, localized estimate of suspended sediment flux and examines the empirical relationship between turbidity (NTU, nephelometric turbidity unit) and total [...] Read more.

Understanding suspended sediment transport in macrotidal embayments is crucial for assessing water quality, ecosystem function, and long-term morphological stability. This study provides a high-resolution, localized estimate of suspended sediment flux and examines the empirical relationship between turbidity (NTU, nephelometric turbidity unit) and total suspended matter (TSM, mg·L⁻¹) in the main tidal channel of Gomso Bay, a UNESCO-designated tidal flat on the west coast of Korea. A 13 h high-resolution fixed-point observation was conducted during a semi-diurnal tidal cycle using a multi-instrument platform, including an RCM, CTD profiler, tide gauge, and water sampling for gravimetric TSM analysis. Vertical measurements at the surface, mid, and bottom layers, taken every 15–30 min, revealed a strong linear correlation (R² = 0.94) between turbidity and TSM, empirically validating the use of optical sensors for real-time sediment monitoring under the highly dynamic conditions of Korean west-coast tidal channels. The net suspended sediment transport load was estimated at approximately 5503 kg·m⁻¹, with ebb-dominant residual currents indicating a net seaward sediment flux at the observation site. Residual flows over macrotidal channels are known to vary laterally, with landward fluxes often occurring over shoals. Importantly, the results from this single-station, short-duration observation indicate a predominantly seaward suspended sediment transport during the study period, which should be interpreted as a localized and time-specific estimate rather than a bay-wide characteristic. Nevertheless, these findings provide a baseline for assessing sediment flux and contribute to future applications in digital twin modeling and coastal management. Gomso Bay is part of the UNESCO-designated ‘Getbol, Korean Tidal Flats’, underscoring the global significance of preserving and monitoring this dynamic coastal system. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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19 pages, 5873 KB

Open AccessArticle

Seasonal Variations in Riverine Sediment Transport Timescales in the Pearl River Estuary

by Rong Lu, Huizhong He, Anyuan Xie, Xi He, Cong Peng, Zhengyuan Li and Hao Zheng

Water 2025, 17(19), 2805; https://doi.org/10.3390/w17192805 - 24 Sep 2025

Viewed by 1059

Abstract

Understanding sediment transport timescales is essential for predicting morphological evolution, pollutant accumulation, and ecosystem health in estuaries. This study examines seasonal hydrodynamics and sediment transport in the Pearl River Estuary using a well-calibrated numerical model. The results indicate that plume dynamics largely control [...] Read more.

Understanding sediment transport timescales is essential for predicting morphological evolution, pollutant accumulation, and ecosystem health in estuaries. This study examines seasonal hydrodynamics and sediment transport in the Pearl River Estuary using a well-calibrated numerical model. The results indicate that plume dynamics largely control sediment transport in both the wet and dry seasons. During the wet season, sediments are exported along both estuary flanks with the expanding freshwater plume. Under the combined effects of topography and the Coriolis force, a greater proportion of sediments exits via the confluence of the West Channel and West Shoal. In the dry season, prevailing northeasterly winds suppress sediment export along the East Channel, redirecting most of the riverine sediment westward. Sediment transport timescales, quantified by sediment age, further show that, during the wet season, export via the East Channel requires approximately 30 days, whereas export along the western flank takes about 45 days due to the weaker dynamics over the West Shoal. Reduced river discharge in the dry season increases sediment age overall; offshore delivery within the plume region takes roughly 50 days, while transport via the East Channel may require an additional 30–60 days. Comparative simulations with and without wind forcing reveal that southerly winds during the wet season weaken plume intensity and prolong transport timescales, whereas northeasterly winds in the dry season enhance plume dynamics, accelerating sediment export from the estuary. Collectively, these findings clarify the mechanisms underlying the seasonal variability in sediment transport and provide a scientific basis for estuarine management and engineering. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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38 pages, 11886 KB

Open AccessArticle

The Estimation of Suspended Solids Concentration from an Acoustic Doppler Current Profiler in a Tidally Dominated Continental Shelf Sea Setting and Its Use as a Numerical Modelling Validation Technique

by Shauna Creane, Michael O’Shea, Mark Coughlan and Jimmy Murphy

Water 2025, 17(12), 1788; https://doi.org/10.3390/w17121788 - 14 Jun 2025

Viewed by 1596

Abstract

Reliable coastal and offshore sediment transport data is a requirement for many engineering and environmental projects including port and harbour design, dredging and beach nourishment, sea shoreline protection, inland navigation, marine pollution monitoring, benthic habitat mapping, and offshore renewable energy (ORE). Novel sediment [...] Read more.

Reliable coastal and offshore sediment transport data is a requirement for many engineering and environmental projects including port and harbour design, dredging and beach nourishment, sea shoreline protection, inland navigation, marine pollution monitoring, benthic habitat mapping, and offshore renewable energy (ORE). Novel sediment transport numerical modelling approaches allow engineers and scientists to investigate the physical interactions involved in these projects both in the near and far field. However, a lack of confidence in simulated sediment transport results is evident in many coastal and offshore studies, mainly due to limited access to validation datasets. This study addresses the need for cost-effective sediment validation datasets by investigating the applicability of four new suspended load validation techniques to a 2D model of the south-western Irish Sea. This involves integrating an estimated spatial time series of suspended solids concentration (

{S S C}_{s o l i d s}

) derived from acoustic Doppler current profiler (ADCP) acoustic backscatter with several in situ water sample-based

{S S C}_{s o l i d s}

datasets. Ultimately, a robust spatial time series of ADCP-based

{S S C}_{s o l i d s}

was successfully calculated in this offshore, tidally dominated setting, where the correlation coefficient between estimated

{S S C}_{s o l i d s}

and directly measured

{S S C}_{s o l i d s}

is 0.87. Three out of the four assessed validation techniques are deemed advantageous in developing an accurate 2D suspended sediment transport model given the assumptions of the depth-integrated approach. These recommended techniques include (i) the validation of 2D modelled suspended sediment concentration (

{S S C}_{s e d i m e n t}

) using water sample-based

{S S C}_{s o l i d s}

, (ii) the validation of the flood–ebb characteristics of 2D modelled suspended load transport and

{S S C}_{s e d i m e n t}

using ADCP-based datasets, and (iii) the validation of the 2D modelled peak

{S S C}_{s e d i m e n t}

over a spring–neap cycle using the ADCP-based

{S S C}_{s o l i d s}

. Overall, the multi-disciplinary method of collecting in situ metocean and sediment dynamic data via acoustic instruments (ADCPs) is a cost-effective in situ data collection method for future ORE developments and other engineering and scientific projects. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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24 pages, 2798 KB

Open AccessArticle

On the Origin of Sediment Ripples

by Ulrich Zanke and Markus J. Kloker

Water 2025, 17(5), 681; https://doi.org/10.3390/w17050681 - 26 Feb 2025

Cited by 1 | Viewed by 1243

Abstract

As soon as a granular sediment has been set in motion by the currents of droppable fluids or by wind, sand waves form as smaller ripples or larger dunes. The relevance of this phenomenon lies in the roughness effect against the currents and [...] Read more.

As soon as a granular sediment has been set in motion by the currents of droppable fluids or by wind, sand waves form as smaller ripples or larger dunes. The relevance of this phenomenon lies in the roughness effect against the currents and the influence on sediment loads. Likewise, their physical understanding helps us to estimate past flow conditions by means of fossilized sand waves, as well as those on distant planets with proven ripples and dunes, such as Mars and Titan. In the literature, diagrams exist based on observations for the conditions under which the various forms of sand waves develop. However, the cause of their formation is unclear. Various theories have been discussed regarding the further development of ripples once they have formed, but none of them explains the fundamental mechanism that generates the very first ripples. These occur simultaneously over a large area and almost instantly, with a fairly even distance from crest to crest. This contribution presents a solution for how this is possible based on hydrodynamic instability. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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22 pages, 7209 KB

Open AccessArticle

Beyond Water Surface Profiles: A New Iterative Methodology for 2D Model Calibration in Rivers Using Velocity Data from Multiple Cross-Sections

by Fabian Rivera-Trejo, Gabriel Soto-Cortes, Kory M. Konsoer, Eddy J. Langendoen and Gaston Priego-Hernandez

Water 2025, 17(3), 377; https://doi.org/10.3390/w17030377 - 30 Jan 2025

Viewed by 1737

Abstract

Observed longitudinal water-surface profiles are commonly used to calibrate river hydrodynamic models, relying on assumptions of lateral uniformity in water surface elevation and velocity distribution. While suitable for 1D models, this approach has limitations in regard to 2D model calibration. When 2D flow [...] Read more.

Observed longitudinal water-surface profiles are commonly used to calibrate river hydrodynamic models, relying on assumptions of lateral uniformity in water surface elevation and velocity distribution. While suitable for 1D models, this approach has limitations in regard to 2D model calibration. When 2D flow measurements are available, a more robust quantitative evaluation is necessary to assess model accuracy. This study introduces a novel methodology to improve 2D model calibration and evaluate performance. High-resolution bathymetric and hydrodynamic data collected with a multibeam echosounder (MBES) and acoustic Doppler current profiler (ADCP) were aligned to compare observed and simulated flow velocities at matching spatial locations. Statistical metrics, including relative mean absolute error and root-mean-square error, were employed to assess hydrodynamic modeling. The methodology was tested using MBES and ADCP measurements alongside TELEMAC-2D simulations of a dynamic neck cutoff on the White River, Arkansas, USA. This approach provides a 2D calibration process, enhancing model accuracy and informing parameter selection, such as channel boundary roughness and downstream boundary water surface elevation. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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21 pages, 12487 KB

Open AccessArticle

The Impact of Foreshore Slope on Cross-Shore Sediment Transport and Sandbar Formation in Beach Berm Nourishment

by Xinglu Liu, Xiaofeng Luo, Chuanteng Lu, Gongjin Zhang and Wei Ding

Water 2024, 16(15), 2212; https://doi.org/10.3390/w16152212 - 5 Aug 2024

Cited by 2 | Viewed by 2768

Abstract

Foreshore slope is crucial in designing beach berm nourishment schemes and understanding coastal responses to wave forces. Beach berm nourishment often suffers from a high loss rate, necessitating theoretical research and design parameter comparison to mitigate these losses early on. This study uses [...] Read more.

Foreshore slope is crucial in designing beach berm nourishment schemes and understanding coastal responses to wave forces. Beach berm nourishment often suffers from a high loss rate, necessitating theoretical research and design parameter comparison to mitigate these losses early on. This study uses Bagnold’s energy conservation method and the small-angle approximation method to establish a relationship between cross-shore sediment transport and foreshore slope. The feedback mechanism between these factors shows that when the foreshore slope is fewer than 10 degrees, a smaller initial slope results in a reduced rate of sediment transport. Over time, the foreshore slope decreases and eventually reaches equilibrium, promoting the formation of an offshore sandbar, which helps reduce sediment loss. Using data from Guanhu Beach in Dapeng Bay, this study constructs a realistic numerical beach model to simulate the dynamic behavior of beach profiles with varying foreshore slopes under the influence of monsoon waves and storm surges. The simulation results support the feedback mechanism findings, demonstrating that profiles with minimal foreshore slopes experience the least initial sediment loss, thus facilitating sandbar formation more effectively. These insights can inform beach berm nourishment strategies, emphasizing early-stage efforts to expand beach areas and reduce sediment loss. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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25 pages, 5907 KB

Open AccessArticle

Modelling of Granular Sediment Transport in Steady Flow over a Mobile Sloped Bed

by Jarosław Biegowski, Magdalena Pietrzak, Iwona Radosz and Leszek M. Kaczmarek

Water 2024, 16(14), 2022; https://doi.org/10.3390/w16142022 - 17 Jul 2024

Cited by 1 | Viewed by 1878

Abstract

This paper introduces a three-layer system, proposing a comprehensive model of granular mixture transport over a mobile sloped bed in a steady flow. This system, consisting of the bottom, contact, and upper zones, provides complete, continuous sediment velocity and concentration vertical profiles. The [...] Read more.

This paper introduces a three-layer system, proposing a comprehensive model of granular mixture transport over a mobile sloped bed in a steady flow. This system, consisting of the bottom, contact, and upper zones, provides complete, continuous sediment velocity and concentration vertical profiles. The aim of this study is to develop and experimentally verify this model for sediment transport over a bottom locally sloping in line with or opposite the direction of sediment flow. The model considers gravity’s effect on sediment transport in the bottom (dense) layer when the component of gravity parallel to the bottom acts together with shear stresses associated with water flow. This is a crucial factor often overlooked in previous studies. This effect causes an increase in velocity in the mobile sublayer of the dense layer and significantly affects the vertical distributions of velocity and concentration above this layer. The proposed shear variation due to the interaction between fractions and an intensive sediment mixing and sorting process over a mobile sloped bed adds to the novelty of our approach. The data sets used for the model’s validation cover various conditions, including slopes, grain diameters, densities, and grain mobility conditions, from incipient motion to a fully mobilized bed. This extensive validation process instils confidence in the theoretical description and its applicability to real-world scenarios in the design of hydraulic infrastructure, such as dams, barrages, bridges, and irrigation, and flood control systems. Full article

(This article belongs to the Special Issue Rivers, Estuaries, and Coastal Zones: Sediment Transport and Morphodynamical Models)

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