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1

Estimation of Long-Term Suspended Sediment Yield from a Small Agricultural Catchment

Krajewski Adam, Banasik Kazimierz, Hejduk Leszek

Journal of Ecological Engineering

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2024

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Vol. 25, nr 1

99--107

EN

Predicting and estimating sediment yield from the catchment is crucial for the effective management of water resources and controlling soil erosion. Universal Soil Loss Equations (USLE) and their modifications have been appreciated and commonly applied among many methods. The idea of this work is to use the ESDAC database (a web platform hosting a series of pan-European and global datasets on soil erosion) to build the modified form of the USLE for the Zagożdzonka catchment, a small agricultural area located in central Poland. The calculated sediment yield is compared with the one determined based on the reservoir survey. The conducted analyses show that the average annual suspended sediment yield from the study catchment estimated using the MUSLE equation accounts for 201 Mg and is close to that determined based on the reservoir survey, i.e., 248 Mg. However, MUSLE, with the initially proposed parameters, will overpredict sediment transport at the study site. The ESDAC database may support local studies concerning soil erosion and sediment transport. The research is helpful for policymakers, planners, and engineers.

2

Ocena transportu osadu wzdłuż zachodniego wybrzeża Polski

Szmytkiewicz Piotr, Stella-Bogusz Magdalena, Bojan Michał, Piłczyński Krzysztof, Szmytkiewicz Marek, Schonhofer Jan

Inżynieria Morska i Geotechnika

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2024

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nr 6

250--257

PL

Obliczenia wzdłużbrzegowego transportu osadu dla klimatu falowego od 1993 do 2024 r. Wypadkowy wzdłużbrzegowy transport osadu na zachodnim wybrzeżu Polski skierowany z wschodu na zachód.

EN

Calculations for longshore sediment transport carried out for wave climate data from 1993 to 2024. The resultant longshore sediment transport along the western Polish coast directed from east to west.

3

Transport i depozycja sedymentu w zbiorniku zaporowym Dobczyce - implementacja podejścia Lagrange'a

Szlapa Monika

Gospodarka Wodna

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2024

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Nr 2

2--8

PL

Praca przedstawia możliwości, jakie daje zastosowanie modelu PTM opartego na podejściu Lagrange'a do transportu sedymentu. Przykładowe wyniki modelowania przedstawiono dla Zbiornika Dobczyckiego. W pracy skupiono się na maksymalnych możliwych zasięgach transportu sedymentu wnoszonego przez rzekę Rabę dla przepływów wysokich. Wyniki symulacji odwzorowały w sposób zadowalający założony fragment rzeczywistości. Przedstawiono możliwości obliczeniowe, wynikające z podejścia Lagrange'a, które pomagają w lepszym zarządzaniu zbiornikiem zaporowym, ale także trudności i ograniczenia związane ze stosowaniem tej techniki.

EN

The study presents possibilities offered by the application of the PTM model based on the Lagrange approach to sediment transport. The author presents examples of the modelling results for the Dobczycki reservoir. The article focuses on the maximum possible reach of the sediment transport carried by the Raba River at high water levels. The results of simulation recreate the assumed fragment of reality to a satisfactory degree. The author presents calculation possibilities, resulting from the Lagrange approach, contributing to a better management of the dam reservoir, as well as difficulties and limitations related to the application of this technique.

4

Quantitative Evaluation to the Sediment Load at a Part of Euphrate River in Center of Iraq

Al Bayaty Majd A., Al Zubaidy Riyath Z., Almansory Nisren J.

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 6

159--171

EN

Estimates sediment transport in Iraqi Rivers are essential for effective rivers management, particularly when delivery rates is potential threat to environment and ecological systems. Therefore, this research was performed for estimating sediment transport rates in a certain reach from Euphrates River downstream Al Hindiyah Barrage and examine the stat of Entrainment Rate Esi of bed sediments under a unsteady stream flow. In spite of complexity and the difficulty of conducting measurements, the sediment load were measured with satisfactory perfection to achieve acceptable results for monitoring this river reach. The acoustic Doppler current profiler (ADCP) technique were used to measure velocity distribution, cross section profiles, and using (Helley-Smith) sampler to collect bed load samples from twenty cross sections downstream Al Hindiya Barrage. The investigation of suspended sediment concentration in vertical profiles has consisted of using an Entrainment rate relation (Esi), also for evaluating materials concentration near the bed and the upward, the vertical distribution of material particles was examine in the water column. The measurement results are clarified that there are many regions of river covered with high sedimentation, but the suspended load is prevalent mode of transport with average value 97.313%. The observed suspended sediment yield in the river reach was ranged from 386.645 ton/day to 6588.58 ton/day during the drought condition and low level of water discharge and may change with discharge change. While bed load yield ranged between 0.270 ton/day to 5.394 ton/day. The investigation is represented a non-equilibrium condition in sediment transport is prevalent circumstance in channel system. It is tested the relation of Ei against limited grainsizes data and skin shear velocity U*skin then analyzed the regression. The result is shown that near-bed entrainment, evaluated at 15% of the flow depth, decreases with the ratio of settling velocity to skin-friction shear velocity due to its role in determining bed load-layer concentrations. The fit relation for R2 = 0.48 and correlation r = -0.55 are shown that outstanding an association between maximal flow resistance and sediment diffusivities, this is probably because bed-form prompt by turbulence flow which caused nonlinear dependence.

5

Hybrid Modelling Using Lattice Boltzmann and Finite Difference Methods of Dikes Effect on Sediment Transport and Morphological Processes with a Quasi-Tridimensional Approach

Machrouhi Khalil, Bendaraa Anass, Charafi My Mustapha, Hasnaoui Abdellatif

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 11

146--162

EN

This paper presents the development of a quasi-three-dimensional model that utilizes an equilibrium technique to investigate the morphological change of a channel focused on transport of sediment. The authors developed a computational algorithm that integrates two numerical techniques, specifically the Lattice Boltzmann Method (LBM) and the finite-difference method (FDM), to perform a hybrid calculation. The aforementioned algorithm was employed to investigate the impact of dykes on the dynamics of channel flow, sediment transport, and bed evolution. To derive the three-dimensional velocity field, the Boltzmann lattice method is employed to compute the two horizontal components of the vertically integrated velocity. Subsequently, these two components are combined with a logarithmic vertical profile. The process of sediment particle transport can be divided into two components: the bed load transport rate and the suspended load transport rate. The latter determination is achieved through the computation of the equilibrium flow rate of suspended sediment, which is derived from the equilibrium concentrations and logarithmic velocities. by comparing its outputs to previous research on constant width channels and horizontal beds, especially in dykes, the model was validated. This model accurately predicts sediment transport as bed load and suspended load, which is important for understanding sediment dynamics around such structures. the model’s ability to anticipate sediment erosion and deposition across the channel, providing crucial insights into river detours and other sedimentary processes.

6

Numerical Modeling of Sediment Transport and Bed Evolution in Nonuniform Open-Channel Flows

Zerihun Yebegaeshet T.

Archives of Hydro-Engineering and Environmental Mechanics

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2024

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Vol. 71, nr 1

1--26

EN

The shallow-water and multilayer hydrostatic models have been commonly used to analyze the problems of a sediment-laden, plane open-channel flow. The models are adequate to solve a quasi-hydrostatic flow problem, but their accuracy deteriorates as the effects of the vertical acceleration gain in significance. Herein, a higher-order numerical model for treating the problems of unsteady, plane open-channel flow over a movable bed is proposed. In this model, the flow hydrodynamics is governed by the depth-averaged Boussinesq-type equations, and the bed morphodynamics is determined by an Exner-type equation and additional equations describing the non-equilibrium transports of suspended load and bed load. A hybrid finite-volume and finite-difference scheme was used to discretize and solve the governing equations, yielding solutions that are in satisfactory agreement with the experimental data. Overall, the results of the proposed model for the temporal free-surface profile and bed evolution were fairly adequate. For the two particular cases considered, however, the quality of its results was moderately affected by the effects of the three-dimensional characteristics of the dam-break flow and the sliding of the dike body due to sub-surface flow. The results of this investigation highlight the importance of including a higher-order Boussinesq-type correction for refining sediment transport computations.

7

Experimental investigation for the local scour around V-shaped spur-dikes

Alasadi Layth Abdul Rasool, Khlif Tagreed Hameed, Hassan Fadhel Abdulabbas

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2023

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Vol. 32, No. 1

68--86

EN

Spur-dikes are efficient hydraulic structures that are made for numerous purposes. They have one end on the stream bank and another extending into the current. As a result of the existing spur-dikes in the stream course, the local scour phenomena usually occur around them, leading to several predicaments which have been of great concern to the hydraulic engineers. For the present work, laboratory experiments were carried out to measure the scour depths around several spur-dikes located at different distances for the V-shaped one. The experiments were conducted using physical models installed in a non-curved flume with a bed with uniform cohesion-less sediment of a medium particle size (d50 = 0.7 mm). All the models were operated under the subcritical flow of clear-water conditions. The investigations include three spur-dikes (1, 2 and 3) and three distances between them (1, 1.5 and 2 of spur-dike length) as two countermeasures to minimize the local scour depths. The results showed that an increasing number of spur-dikes and the distances between them would decrease the scour depths within the limit of the present study. The experimental data were used to create a new formula of R = 0.954 that reflects a good agreement with the experimentally observed results.

8

Natural and anthropogenic influences on the development of mud depocenters in the southwestern Baltic Sea

Porz Lucas, Zhang Wenyan, Schrum Corinna

Oceanologia

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2023

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No. 65 (1)

182--193

EN

The morphological evolution of two mud depocenters in the southwestern Baltic Sea is investigated by comparison of numerical model results to geological and oceanographic data. The pathways of dense currents during episodic dense-water inflows from the North Sea are shown to correspond to current pathways inferred from contouritic depositional geometries in the flow-confining channels within the study area. A favorable comparison of model results to published current speed observations shows that the mesoscale dynamics of individual inflow events are reproduced by the model, indicating that external forcing and basin geometry rather than internal dynamics control the mesoscale dynamics of inflow events. The bottom current directions during inflows show high stability in the flow-confining channels and explain the contouritic depositional geometries. Asymmetric depositional features in the channels are qualitatively reproduced in the model. Bottom currents are less stable in areas without contouritic features, possibly resulting in an overall diffusive effect on sediment distribution in those areas. In a simulation of resuspension by bottom-contacting fishing gear, inter-basin sediment transport is increased by 4–30%, depending on the area, compared to the case of natural hydrodynamic resuspension. The model predicts an increased winnowing of the finest sediment fraction due to bottom trawling, leading to an overall coarsening-to-fining trend in the direction of net sediment transport. The results show that rather than hemi-pelagic background sedimentation, episodic events with high bottom current velocities as well as bottom-trawling induced resuspension are responsible for the present-day and future morphological configuration of the mud depocenters in the southwestern Baltic Sea.

9

Two-Dimensional Numerical Modeling of Morphodynamic Evolution in Bouregreg Estuary (Morocco)

El Assaoui Naïma, Sadok Abdelaziz, Bendaraa Anass, Charafi Moulay Mustapha

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 5

217--230

EN

The Bouregreg valley, located on the Atlantic coast of Morocco, has been subject to several anthropogenic and natural impacts that disturb the proper functioning of the estuary’s ecosystem. Important dredging operations influenced by both tides and freshwater inflows have created a significant variation of estuary’s morphology characterized by a sand bar developed at the mouth. The main objective of this study is to investigate the Morphodynamic processes of the estuary and in particular the impact of dredging operations using a two-dimensional horizontal numerical (2DH) modeling approach based on the shallow water equations. Several numerical tests have been carried out to calibrate the model and to investigate the hydrodynamic and morphological aspects of the estuary. For this technical solution, the modelling simulations show that in addition to the quantities of sand that will be dredged initially, the maintenance of the channel will facilitate a better water circulation between the Bouregreg valley and the Atlantic Ocean and improve the stability of the civil engineering structures and the neighbouring monuments. In addition, this water circulation will guide the river flow in the ebb phase of the tide. The model results show a reduction of about 30% in the impact of erosion, observed before the digging of the canal.

10

Analysis and Mapping of Water Erosion Vulnerability Using GIS for the Mghila Watershed, Northwest of Algeria

Ratiat Abdelkader, Haddad Ali, Bouaichi Ilham, Matene Chahrazed Naziha

Archives of Hydro-Engineering and Environmental Mechanics

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2023

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Vol. 70, nr 1

71--87

EN

Intensification of extreme rainfall-runoff events in arid and semi-arid regions because of climate change induce the water erosion that contributes considerably to the loss of vegetal layers of soils and reduce the storage capacity of dams by silting of transported sediments from the watershed to the impoundment. This paper aims at proposing means for protecting the Mghila dam against silting by identification and delimitation of vulnerable areas to water erosion. This dam, built in the North-West of Algeria, ensures irrigated cultivation. Topographical, geological, and land use characteristics of the watershedwere analyzed using the geographic information system (GIS). Analysis of results has allowed the identification by area percentage four-vulnerability classes with sensitivity to the water erosion: low (18.89%), medium (13.08%), high (65.05%) and very high (8.38%). The spatial distribution of the lithological substratum friability, the vegetation cover and slope degrees have led to the development of an efficient strategy for the watershed management in order to reduce the effect of water erosion on soil degradation and silting of the Mghila dam.

11

Semi-theoretical model for mean sediment resting time of spherical particles: the role of hydrodynamic impulses and sphere size nonuniformity

Wyssmann Micah A., Papanicolaou Athanasios N., Kyriakopoulos Theodoros

Acta Geophysica

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2023

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Vol. 71, no. 6

2883--2904

EN

Prediction of bedload rates in gravel-bed rivers at low-to-moderate flow conditions, where bedload movement is intermittent, remains a challenging problem. While the virtual velocity concept provides a useful approach to bedload rate estimation in the intermittent movement regime, virtual velocity estimation remains hindered by a lack of tools for predicting mean sediment resting time. As a first step toward sediment resting time estimation in gravel beds, the present study develops a semi-theoretical resting time model applicable to nonuniform gravel-sized spherical particles. The model is based on the consideration that interactions of near-bed flow with bed material lead to mobilization of individual resting particles during hydrodynamic momentum transfer events (i.e., impulses). Thus, resting time is affected by impulse magnitude and timing. The primary premise underpinning model development is that an instantaneous velocity time-series generation approach based on the velocity spectrum can be used to mimic hydrodynamic impulses and simulate resting times. Based on past findings, two model parameters are considered important to advancing resting time predictions in gravel beds. First, the relative particle size allows size-fractional resting time predictions for a nonuniform sediment mixture. Second, the hindrance coefficient accounts for hiding effects and enables resting time predictions for different bed structure types. To provide calibration and verification data, laboratory experiments documenting impulse statistics and mean resting times for a range of flow and relative particle size conditions were also performed. The verified model exhibits mean resting times with similar magnitude and trends with increasing stress compared with experimental verification data.

12

A coupled model for sediment transport dynamics and prediction of seabed morphology with application to 1DH/2DH coastal engineering problems

Afentoulis Vasileios, Papadimitriou Andreas, Belibassakis Kostas, Tsoukala Vasiliki

Oceanologia

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2022

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No. 64 (3)

514--534

EN

Coastline retreat poses a threat to nearshore environment and the assessment of erosion phenomena is required to plan the coastal engineering works. The hydro-morphodynamic response of a beach to natural and artificial forcing factors differ considerably, as the nearshore processes are especially complex and depended on a multitude of parameters, including prevailing wave and hydrodynamic conditions, beach topography, sediment characteristics and the presence of coastal protection works. The present study serves the purpose of numerically evaluating nearshore morphological processes and ultimately assessing the capacity of coastal defence structures to control beach erosion. For this reason, a new sediment transport model including unsteady effects and swash zone morphodynamics, was coupled to the highly nonlinear Boussinesq wave model FUNWAVE-TVD, providing integrated predictions of bed level evolution, across various timescales of interest. The compound model was validated thoroughly against laboratory data and other numerical investigations. Overall, a good agreement between experimental and numerical results was achieved for a number of test cases, investigating the effects of different types of shore protection structures. The proposed integrated model can be a valuable tool for engineers and scientists desiring to obtain accurate bed level predictions, over complex mildly and steeply sloping sea bottoms composed of non-cohesive sediment particles.

13

Wpływ zbiornika retencyjnego Jeziorsko na układ dna i transport rumowiska na odcinku od zapory czołowej do Uniejowa

Hämmerling Mateusz, Kałuża Tomasz, Zawadzki Paweł, Zaborowski Stanisław

Gospodarka Wodna

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2022

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Nr 9

13--17

PL

Przegrodzenie rzeki ułatwia gospodarowanie wodą na danym odcinku cieku. Budowa zbiornika retencyjnego jest bardzo korzystna, ponieważ umożliwia zwiększenie retencji, przyczynia się do ochrony przeciwpowodziowej, umożliwia korzystanie ze zgromadzonych wód przez różnych użytkowników. Wpływ zbiornika retencyjnego na warunki przepływu wody oraz środowisko jest zagadnieniem wieloaspektowym. Dlatego w badaniach przedstawionych w niniejszym artykule skupiono się głównie na wpływie piętrzenia na warunki przepływu wody i transport rumowiska na dolnym stanowisku budowli. W artykule przedstawiono analizę zmian poziomów dna, zwierciadła wody oraz rumowiska poniżej zbiornika Jeziorsko na rzece Warcie. Ocenę skutków procesu erozji koryta rzeki Warty wykonano na podstawie sondowań dna, pomiarów zwierciadła wody oraz składu granulometrycznego pobranych próbek rumowiska wykonanych w latach 1975-2010.

EN

Building dams on rivers facilitates water management in a given section of the river. Building a retention reservoir brings a lot of benefits, as it increases retention, contributes to flood protection, gives different users the possibility to benefit from the accumulated water. Impact of a retention reservoir on the water flow conditions and the environment is a complex issue. Therefore, the study presented in this article focuses mainly on the effect of damming on the water flow conditions and sediment transport in the lower station of the construction. The article presents an analysis of the Warta River bottom, water table and sediment levels changes downstream of the reservoir. The assessment of the Warta riverbed erosion process impact was made based on the bottom probing, water table levels measurement and granulometric composition of sediment samples collected in the years 1975-2010.

14

Numerical Calculations with a Multi-layer Model of Mixed Sand Transport Against Measurements in Wave Motion and Steady Flow

Kaczmarek Leszek M., Radosz Iwona, Zawisza Jerzy

Rocznik Ochrona Środowiska

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2021

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Tom 23

629--641

EN

A multi-layer model is used to calculate time-dependent sediment velocity and concentration vertical profiles. This model, in which the differences in sediment transport at different distances from the bed are considered is intended both for the wave motion and steady flow. Numerical calculations were carried out for sediment transport during the wave crest and trough and total sediment transport as a sum of their absolute values. The model concept of variation in shear stress from the skin stress value above the bed to the stress value at the bed previously proposed for steady flow is extended here for the wave motion and verified by direct stress measurements. The calculations were carried out for mixed sand sediments with different grain size distributions including semi-uniform and poorly sorted grains. Comparison with the available small- and large-scale data from flumes and oscillating tunnels yields agreement typically within plus/minus a factor two of measurements.

15

The impact of Klaipėda Port entrance channel dredging on the dynamics of coastal zone, Lithuania

Žilinskas Gintautas, Janušaitė Rasa, Jarmalavičius Darius, Pupienis Donatas

Oceanologia

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2020

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No. 62 (4PA)

489--500

EN

Dredging entrance channels to ports on open littoral drift seashores often causes major morphological changes to the shoreline. This study aims to assess the impact of dredging the Port of Klaipėda's entrance channel and the construction of the jetties on the coastal zone. Based on an analysis of cartographic material collected between 1835 and 2017, and on field data (bathymetric surveys and cross-shore profile levelling), changes to the coastal zone in the area nearest to the port were evaluated. The dominant longshore sediment transport on the Lithuanian nearshore runs from south to north. Thus, based on established patterns, intensive accretion could have been expected to take place on the southern side of the port jetties and erosion on their northern side. However, in the case of the Port of Klaipėda, in the area nearest to the port on the updrift side of the port jetties, where accretion would have been expected to take place, the nearshore depth increased throughout the 20th century (when the length and configuration of the jetties did not change). The shoreline shifted landward instead of moving further out to sea. The present study shows that the intensive dredging of the entrance channel caused nearshore and shore erosion on the updrift side of the port jetties, even while a sufficient sediment load was being transported by the longshore drift.

16

Influence of the climatic variations in the wind waves parameters on the alongshore sediment transport

Divinsky Boris V., Kosyan Ruben D.

Oceanologia

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2020

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No. 62 (2)

190--199

EN

The purpose of this work was to analyze the influence of climatic variability of wind waves and swell parameters in the coastal zone on the sediment transport and to assess the contribution of the swell to the formation of alongshore fluxes. The object of research is the Anapa bay-bar (the Black Sea). Mathematical modeling has shown that in the Anapa bay-bar area the average annual wind waves and swell powers have significant interannual variability. For the period from 1979 to 2017, in the southern part of the bay-bar, there was a statistically significant decrease in the share of swell in the alongshore transport, directed from NW to SE, in the central part – an increase in the contribution of swell to the total sediment flow from SE to NW, in the northern part – probable increase in flows to NW and decrease – to SE. Such a dynamic is consistent, in general, with experimental observations of the processes of erosion and accumulation of beach-forming material along the Anapa bay-bar coastline. A separate description of the bottom sediment fluxes under the influence of wind waves and swell made it possible to explain the fluctuations of the coastline over a climatic period.

17

Grain-size characteristics and net transport patterns of surficial sediments in the Zhejiang nearshore area, East China Sea

Liang Juan, Liu Jian, Xu Gang, Chen Bin

Oceanologia

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2020

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No. 62 (1)

12--22

EN

Spatial variations in grain-size parameters can reflect sediment transport patterns and depositional dynamic environments. Therefore, 616 surficial sediment samples taken from the Zhejiang nearshore area in the East China Sea were analyzed to better understand the net sediment transport pattern in this region. The study area is generally dominated by clayey silt and has relatively coarse mud sediment in the southeast. The sorting coefficient of surface sediment is higher than 1.4, and sediment is poorly sorted throughout the study area. The skewness has a strong correlation with the mean grain-size diameter. The net sediment transport pathways obtained by the grain-size trend analysis indicate several distinct characteristics of the surficial sediment transport. The sediment is transported southward under the action of the stronger southward Zhejiang-Fujian Coastal Current (ZMCC) in winter in the upper part of the nearshore area. Influenced by the obstruction of the Taiwan Warm Current (TWC) and the tidal current, surficial sediment transport vectors display two areas of grain-size trend convergence and indicate the net deposition environment has a high sedimentation rate. However, the transport is mainly toward the north under the control of the prevailing northward ZMCC and the strong TWC in the summer. The sedimentary rate is closely related to the processes of the sediment transport. On the one hand, sediment transportation affects the depositional rate in a different environment. On the other hand, the modern sedimentary rate can reflect indirectly the sediment source and sediment transportation.

18

Features of the Sediment Runoff Regime Downstream the Ile River

Duskayev Kassym, Myrzakhmetov Akhan, Zhanabayeva Zhanar, Klein Igor

Journal of Ecological Engineering

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2020

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Vol. 21, nr 2

117--125

EN

This paper is devoted to study on the sediment runoff of the Ile River downstream. The article analyses the Kapshagai reservoir impact on the regime and characteristics of the sediment runoff in the Ile River downstream before and after construction of the reservoir in 1970. Along with the calculation of characteristics of sediment runoff, an assessment of the amount of the suspended sediment, which is in the bowl of the reservoir, was shown. Furthermore, the impact reservoir on the granulometric composition of the suspended and bed sediment of Ile River was calculated.

19

A new mathematical model to calculate the equilibrium scour depth around a pier

Gazi Ainal Hoque, Afzal Mohammad Saud

Acta Geophysica

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2020

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Vol. 68, no. 1

181--187

EN

This paper sheds light on the formulation of a new equilibrium local scour depth equation around a pier. The total bed materials removed from the scour hole due to the force exerted by the fowing fuid after colliding with the pier in the fow feld are estimated. At the equilibrium condition, the shape of the scour hole around the pier may take any form, viz. linear, circular, parabolic, triangular, or combination of diferent shapes. To consider that, two functions are assumed at the stoss and the lee sides of the pier. The total volume of bed materials removed from the scour hole of an arbitrary shape at the stoss and the lee sides of the pier is obtained by integrating the two functions. The equilibrium scour depth is formed by applying the energy balance theorem. An example problem is illustrated and the results are compared with the equations presented by Melville and Coleman (Bridge scour. Water Resources Publication, Colorado, 2000) and HEC-18 (Richardson and Davis in Evaluating scour at bridges, HEC-18. Technical report no. FHWA NHI, 2001).

20

Use of modelling for the renovation of drainage channels – The case of the Bouteldja plain in northeastern Algeria

Sennaoui Foued, Benabdesselam Tamara, Saihia Abdallah

Journal of Water and Land Development

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2019

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no. 43

1--8

EN

Agricultural drainage has become a priority in agriculture and the economic development of the state. Algeria has launched several agro-economic projects pertaining to natural resources and human potential for development in agricultural areas. Our aim is to model the morphological evolution of open drainage channels, under the influence of sedimentary transport processes. The application of the Hydrologic Engineering Center’s River Analysis System (HEC-RAS) software is to examine two-phase mathematical models. In our case it is the flow and the sedimentary charge along a trapezoidal earth channel of a wetland north east of Algeria. The results of these models were validated by actual data obtained during the observation period from 2017 to 2018, for various rainy events. The solid transport and sedimentation velocity equations of Engelund and Hansen and Van Rijn respectively used by this model, give Nash performance criteria equal to 0.95 and determination coefficient R2 equal to 0.91. On the other hand, the laying of a coarse gravel layer of median diameter of the grains d50% = 60 mm on the bottom of the channels reduces the rate of sedimentation by about 32% over an 11-year period. This satisfying objective study of the modelling allows to obtain an approach to the renovation and a plan for new design of drainage systems, that participates to the sustainable development in the agricultural field.

PL

Drenowanie stało się priorytetem w rolnictwie i gospodarczym rozwoju kraju. W Algierii uruchomiono kilka programów rolniczych odnoszących się do zasobów naturalnych i potencjału rozwojowego obszarów wiejskich. Naszym celem było modelowanie zmian morfologicznych w otwartych kanałach drenarskich pod wpływem procesów transportu zawiesiny. W dwufazowym modelu matematycznym wykorzystano program HEC-RAS (Hydrologic Engineering Center’s River Analysis System). Zmiennymi w modelu były przepływ i ładunek zawiesiny wzdłuż ziemnego kanału o trapezoidalnym przekroju w środowisku podmokłym północnowschodniej Algierii. Wyniki modelu porównano z rzeczywistymi danymi opadowymi pozyskanymi w różnych okresach w latach 2017 i 2018. Równania Engelunda i Hansena (transport zawiesiny) i Van Rijna (tempo sedymentacji) użyte w modelu dały w wyniku kryterium Nasha równe 0,95 i współczynnik determinacji R2 równy 0,91. Warstwa grubego żwiru o medianie średnic ziaren d50% = 60 mm na dnie kanału spowalniała tempo sedymentacji o ok. 32% w ciągu 11 lat. Przedstawione badania umożliwiają nowe podejście do renowacji istniejących i projektowania nowych systemów drenarskich, które przyczyniają się do zrównoważonego rozwoju rolnictwa.