Efficacité et résistance de techniques de protection de berges en génie végétal

Peeters, Alexandre; Houbrechts, Geoffrey; Hallot, Éric; Campenhout, Jean Van; Verniers, Gisèle; Petit, François

doi:10.4000/geomorphologie.11927

Cited by 6 publications

(8 citation statements)

References 25 publications

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“…This result is consistent with Watson et al [1997], who found that a Rc/W value of 2 could be a lower limit for willow post soil bioengineering structures. Note that the bend curvature was also observed to be critical for other soil bioengineering structures such as combs [Peeters et al, 2018], which suggests that the explanation driving this process should be sought elsewhere.…”

Section: Discussionmentioning

confidence: 99%

“…To finish, surrogates are often used to simulate in a more or less realistic manner some of the components of the problem studied [Maike et al, 2016]. Here we used nylon threads to simulate the use of anti-scouring twigs (Figure 3), a promising and soft solution sometimes encountered in the field [Peeters et al, 2018]. The difficulty of course is to ensure a realistic stiffness of the surrogate.…”

Section: Scalingmentioning

confidence: 99%

“…European Union Water Framework Directive) and river managers now seek to preserve bank erosion within a defined erodible corridor as much as possible [Piegay et al, 2005]. However, despite this evolution in restauration policy and practices, the protection of key assets still requires locally limiting bank erosion [Peeters et al, 2018] and the use of soil bioengineering techniques appears to be an appropriate option. The objective of these techniques (fascines, brush mattresses, brush layers, wattles, cuttings and plantings, and seedlings [Zeh, 2007]) is to use the natural properties (resistance, resilience, stiffness) of living native species to mimic naturally stable banks consolidated by vegetation; the aim is to fulfil erosion control functions as well as to recover the riverbank's ecological functions [Li and Eddleman, 2002;Cavaillé et al, 2018].…”

Section: Introductionmentioning

confidence: 99%

“…Information consists essentially in observation of the structures' evolution a few years after their construction, considering the type of flow encountered and whether the structure remained intact or failed. Unfortunately, despite a growing effort to valorise post-project data [Batier, 2004;Leblois et al, 2016;Peeters et al, 2018], in the case of structure destruction we have almost no information on the mechanisms that resulted in the structure's failure, because we still crudely lack insitu evaluation of project performance over time [Buchanan et al, 2014;Pinto et al, 2016].…”

Section: Introductionmentioning

confidence: 99%

“…Ensuring the success of a bank protection with soil bioengineering techniques requires accounting for all these erosion processes. This is particularly true during the early stages of vegetation establishment, as water erosion rates decrease exponentially with increasing root mass [Gyssels et al, 2005]: as long as the root system is under development (usually the first 2 years), the bank is highly vulnerable [Henderson, 1986;Watson et al, 1997;Anstead and Boar, 2010] and it is recommended to assist the structure to resist erosion, for instance by solidifying the toe of the bank with protections allied with bank grading [Thorne, 1990;Shields et al, 1995;Peeters et al, 2018]. However, riverbank stabilisation structures are often designed to address only fluvial erosion, and feedback concerning internal processes (mass wasting) are still missing [Florsheim et al, 2008].…”

Section: Introductionmentioning

confidence: 99%

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Design of fascines for riverbank protection in alpine rivers: Insight from flume experiments

Recking

Piton

Montabonnet

et al. 2019

Ecological Engineering

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We present the results of flume experiments specifically designed to investigate the conditions required for successful bank protection using fascines, considered in the early and critical stage of their installation (no developed root system), in the alpine context. A total of 145 runs were performed with erodible banks, considering different combinations of protection design (no protection, rip-raps, twigs), bed mobility (with or without bedload), discharge (from low to exceptional floods), and bend curvature radius. None of the runs showed any direct fascine grabbing by the flow observed; all destruction was the consequence of bank scouring, erosion and collapse around the structure. In all cases, most destructive effects resulted from water recirculation inside the bank. Thus, we conclude that all measures aiming to reduce water circulations during the first stage of the fascine construction and development are recommended. This include large bend curvature radii (when possible), fining of the filling material, use of antiscouring twigs, optimisation of the programming of the works with consideration of the hydrology (shape of hydrographs) and regular survey of the structure. Our experiments show that anti-scouring twigs have a real protective effect by modifying the local hydraulics and promoting sediment deposition at the bank toe.

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Section: Discussionmentioning

confidence: 99%

Section: Scalingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Design of fascines for riverbank protection in alpine rivers: Insight from flume experiments

Recking

Piton

Montabonnet

et al. 2019

Ecological Engineering

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Riverbank fascines mostly fail due to scouring: Consistent evidence from field and flume observations

Leblois,

Piton,

Recking

et al. 2024

River Research & Apps

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The willow fascine soil bioengineering technique is commonly used worldwide in river restoration projects to stabilize riverbanks, thanks to high theoretical shear stress resistance and adaptable configuration. Fascines are composed of bundles of living branches fixed between stakes. When positioned in meanders at bank toe, they are subjected to strong hydraulic constraints. Here, we present the field back‐analysis of 470 willow fascines alongside experiments in a small‐scale model (scale 1:25). We describe the dynamics of failure in various situations. The field analysis revealed that 78% of fascines present no signs of bank instability. No fascines were pulled out, and they rarely showed signs of destruction once vegetation had established. Flume experiments confirmed that the main mechanical process of failure is erosion at fascine toe and extremities (9% and 3% of occurrence in the field, respectively). The dynamics of failure occur through: (i) erosion at the fascine toe, removing materials under the bundle; (ii) bank sediments, sliding underneath the fascine; (iii) scouring, leaving stakes exposed to falling into the river. Based on these observations, the fascine toe should be protected sufficiently deeply against undermining to keep sediments in place while vegetation is established. Bank slopes should be reduced as far as possible to decrease scouring. Finally, the mean shear stress values used as reference when designing bioengineering techniques do not capture the local and continuous scouring processes leading to failure. Thus, bend curvature, degradation, grain sizes, and level of fascine implementation should be considered when adapting design.

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Estimation of the area-specific suspended sediment yield from discrete samples in different regions of Belgium

et al. 2021

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PurposeSuspended sediment transport, which represents the majority of the sediment load, has been studied across very different scales and in a wide variety of regions and climates. Despite numerous studies, data for European watersheds are generally limited and correspond to large rivers systems. Especially, in Belgium, little data is available outside the Belgian loess belt. Moreover, the high heterogeneity of soil erosion and sediment transport makes it difficult to measure or model at watershed scale. The purpose of this research is to estimate the median sediment yields in different geographical regions and to detect their explanatory variables.Materials and methodsGathering data from 1994 to 2016, more than 2000 measurements of suspended sediment concentration at 72 river stations mainly located in South-Belgium were sampled according to a flood-event-based manual methodology. This allowed fast acquisition of data in watersheds ranging from 7 to 3600 km 2 in different geographical regions. Median area-specific sediment yields (SSY) were calculated at watershed scale while looking for regional differences.Results and discussionMedian area-specific sediment yields computed for the period 1996-2018 show regional differences: 19.2 t km −2 year −1 on sandy substrate (Lorraine), 24.9 t km −2 year −1 on schisto-sandstone substratum (Ardenne), and up to 119 t km −2 year −1 in the loamy Brabant plateau, with a link to the agricultural land cover and, to a lesser extent, to the watershed slope. The high temporal and spatial variability of rainfall has great effects on the SSY, necessitating the gathering of more than 20 years of data to smooth the high variability of SSY. A multiple correlation of land cover variables and the average slope of the watershed with SSY managed to explain 48% of the variance within the SSY observations.ConclusionsThe agricultural land cover has an important effect on median SSY values. While the regionalization of Belgium is largely based on lithology, soils, and altitude, the land use resulting from these physical and climatic characteristics explains the differences in SSY. Field values of clogged dams and waterways confirm the matching of the SSY computation from discrete samples, despite the high temporal variability of sediment transport. KeywordsSediment yield • Suspended sediment concentration • Soil erosion rate • Meuse basin • Scheldt basin

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Efficacité et résistance de techniques de protection de berges en génie végétal

Cited by 6 publications

References 25 publications

Design of fascines for riverbank protection in alpine rivers: Insight from flume experiments

Design of fascines for riverbank protection in alpine rivers: Insight from flume experiments

Riverbank fascines mostly fail due to scouring: Consistent evidence from field and flume observations

Estimation of the area-specific suspended sediment yield from discrete samples in different regions of Belgium

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