Erosion pattern of artificial gravel deposits

Friedl, Fabian; Weitbrecht, Volker; Boes, Robert M.

doi:10.1016/j.ijsrc.2017.08.003

Cited by 10 publications

(15 citation statements)

References 46 publications

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“…Based on the observations from the laboratory experiments, the angle of repose for dry and wet elements γ dry and γ wet was 40 • and 30 • , respectively. The initial bank slope of the gravel deposits was 35 • , and bank collapse was immediately observed in the experiments [44], resulting in smaller bed slopes for the submerged material and steeper slopes for the dry material due to apparent cohesion. Note that all values of the calibrated parameters are within the application range of the respective approaches according to the literature (see Section 2.1).…”

Section: Expmentioning

confidence: 91%

“…A flow separation was observed at the end of the gravel deposit. Hence, a recirculation zone established downstream of the gravel deposit [44]. Despite some limitations in reproducing recirculation and 3D flow structures, the depth-averaged numerical model was able to reproduce the evolution of the sediment deposition dynamics well (Figure 17).…”

Section: Erosion Processmentioning

confidence: 97%

“…Friedl performed laboratory experiments on the erosion of artificial gravel deposits in a trapezoidal flume with fixed bed and fixed embankments [27,44]. The experimental setup is shown in Figure 5 for both the trapezoidal and rectangular geometry of the gravel deposit.…”

Section: Erosion Of Artificial Gravel Depositsmentioning

confidence: 99%

“…This corresponds to a duration between 2.5 and 15 h in prototype scale. The topography was measured with a Laser Distance Measurement Sensor (LDMS) with an accuracy of <1 mm [44] in cross-sections at a distance of half a meter at irregular time intervals. Based on this, the downstream sediment supply Q b,sup was evaluated for 4-5 time steps depending on the experimental run.…”

Section: Expmentioning

confidence: 99%

“…Based on the above findings gained from the simulation of Ikeda's experiments, the numerical model was first calibrated as described in Section 2.2.2 and then tested against data from Friedl's laboratory experiments on the erosion process of artificial gravel deposits [27,44]. In the following, we first compare the simulation results with the reference data of a single experiment based on two cross-sections.…”

Section: Erosion Of Artificial Gravel Depositsmentioning

confidence: 99%

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Modeling Streambank and Artificial Gravel Deposit Erosion for Sediment Replenishment

Vonwiller

Vetsch

Boes

2018

Water

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Sediment replenishment by artificial gravel deposits is a measure to increase sediment supply in gravel-bed rivers. Thereby, streambank erosion is the dominant process for gravel entrainment. In this contribution, we quantitatively validate a numerical morphodynamic 2D model and the relevant model approaches to reproduce non-cohesive streambank erosion. Therefore, a calibration and a sensitivity analysis of the relevant model approaches and parameters are carried out based on a reference laboratory experiment on streambank erosion in a straight channel from the literature. The relevant model approaches identified to successfully reproduce lateral streambank erosion are the gravitational bank collapse, the lateral bed slope effect on the bed load transport direction and the local bed slope effect on the critical Shields stress. Based on these findings, the numerical model was compared against data from laboratory experiments on gravel deposit erosion. Thereby, the focus was on the influence of the hydraulic discharge, the grain size distribution of the sediment and the geometrical quantities of the gravel deposits, such as the width, height and length of the deposit. It is shown that the dynamics of the erosion process were well reproduced by the numerical model using non-uniform sediment. Furthermore, the erosion rates were in good agreement with the laboratory experiments, except for the initial phase of the experiments, where the erosion rates were highest and settling of the gravel deposit was observed in the laboratory experiments. Overall, the numerical model proved to be a suitable tool to predict the erosion process of artificial gravel deposits, and hence, can be recommended for the design of sediment replenishment measures.

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Section: Expmentioning

confidence: 91%

Section: Erosion Processmentioning

confidence: 97%

Section: Erosion Of Artificial Gravel Depositsmentioning

confidence: 99%

Section: Expmentioning

confidence: 99%

Section: Erosion Of Artificial Gravel Depositsmentioning

confidence: 99%

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Modeling Streambank and Artificial Gravel Deposit Erosion for Sediment Replenishment

Vonwiller

Vetsch

Boes

2018

Water

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Erosion, transport and deposition of a sediment replenishment under flood conditions

Stähly

Franca

Robinson

et al. 2020

Earth Surf Processes Landf

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River reaches downstream of dams with constant residual discharge often lack sediment supply and periodic high flows due to dam sediment retention and flow regulation, respectively. To test a novel multi-deposit methodology for defining environmental flows for activating the dynamics of the river morphology downstream of dams, a flood was released from Rossens Dam in Switzerland. This event was combined for the first time with a multi-deposit configuration of sediment replenishment consisting of four artificial deposits allocated as alternate bars along the riverbanks as a restoration measure. To validate the sediment transport behaviour observed in laboratory tests, stones were equipped with radiofrequency identification (RFID) passive integrated transponder (PIT) tags, a fixed antenna was installed at the river bed and a mobile antenna was used to enable the investigation of the erosion, transport and deposition of replenished sediments. The duration of the erosion period was determined for the tracked stones, and average transport velocities were found to be on the order of 10-3 m/s. To estimate the erosion efficiency of the flood, defined as the eroded tagged stones compared with the released water volume, the hydrograph was divided into different periods: rising limb, constant peak discharge, decreasing limb. During the rising limb of the flood, which lasted for 20% of the total flood duration, more than 40% of the PIT tags were transported. The defined erosion efficiency is a measure to support the hydrographic design of artificial flood releases from dams. The deposition of tagged stones resulted in a repeating cluster formation, as expected from previous laboratory experiments, creating an increase in hydraulic habitat diversity. Comparison of the results obtained in the field and from laboratory experiments confirmed the robustness of the multi-deposit sediment replenishment method. Combined with the knowledge gained on the erosion efficiency, these results could motivate further applications and research into multi-deposit sediment replenishment techniques as a habitat-oriented river restoration measure.

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Time‐average stochastic control based on a singular local Lévy model for environmental project planning under habit formation

Yoshioka

Tsujimura

Hamagami

et al. 2023

Math Methods in App Sciences

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This study applies the theory of stochastic control to an environmental project planning to counteract against the sediment starvation problem in river environments. This can be considered as a time-average inventory problem to time-discretely control a continuous-time system driven by a non-smooth jump process under habit formation disturbing project implementation. The system is modeled such that the sediment storage dynamics are physically consistent with certain experimental results. Further, the habit formation is modeled as simple linear dynamics and serves as a constraint related to the replenishment amount of the sediment. We show that the time-average control problem is not necessarily ergodic. Consequently, the effective Hamiltonian may become a non-constant. Thereafter, ratcheting cases as extreme cases of the irreversible habit formation are considered, owing to them being unique exactly solvable non-ergodic control problems. The optimality equation associated with a regularized and hence well-defined control problem is verified. Furthermore, a finite difference scheme is examined against the exactly solvable case and then applied to more complicated cases.

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Erosion pattern of artificial gravel deposits

Cited by 10 publications

References 46 publications

Modeling Streambank and Artificial Gravel Deposit Erosion for Sediment Replenishment

Modeling Streambank and Artificial Gravel Deposit Erosion for Sediment Replenishment

Erosion, transport and deposition of a sediment replenishment under flood conditions

Time‐average stochastic control based on a singular local Lévy model for environmental project planning under habit formation

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