Geophysical tomography as a tool to estimate the geometry of soil layers: relevance for the reliability assessment of dikes

Olalla, J.F. Chavez; Winkels, T.G.; Ngan-Tillard, D.J.M.; Heimovaara, T.J.

doi:10.1080/17499518.2021.1971252

Cited by 7 publications

(4 citation statements)

References 22 publications

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“…Geophysical imagery is often affected by a lack of resolution, and the geometry of interfaces is directly estimated by these methods, which inherently lack accuracy. In addition to EMI and ERT, results of geotechnical investigations, e.g., Cone Penetration Test (CPT), core sampling and borehole drilling logs, should be used to directly identify interfaces between soil layers [35].…”

Section: Numerical Modeling: Example Of Results and Comments On Hydra...mentioning

confidence: 99%

On Internal Erosion of the Pervious Foundation of Flood Protection Dikes

Girolami,

Bonelli,

Valois

et al. 2023

Water

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This work focuses on the mechanisms that trigger internal erosion of the pervious foundation of flood protection dikes. The origin of these permeable layers is generally attributed to the presence of a paleo-valley and paleo-channels filled with gravelly-sandy sediments beneath the river bed and dikes. These layers may extend into the protected area. Visual observations of leaks, sand boils and sinkholes in the protected area testify to internal erosion processes in the underground soil. Local geological conditions are part of the information to be sought to explain these processes: presence of permeable soils and position of interfaces. Results obtained on Agly dikes (France), using two classical geophysical methods (EMI and ERT), were analyzed using cored soils and showed that it is not enough to simply conclude to the presence of backward erosion piping. The possibility of internal erosion, such as suffusion or contact erosion, must also be considered as the cause of leaks, sand boils and sinkholes. As the results obtained are explained by the presence of a paleo-valley and paleo-channels beneath the river bed and dikes—commonly encountered in this context—the methodology presented and the results obtained are likely to be relevant for many dikes.

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Section: Numerical Modeling: Example Of Results and Comments On Hydra...mentioning

confidence: 99%

On Internal Erosion of the Pervious Foundation of Flood Protection Dikes

Girolami,

Bonelli,

Valois

et al. 2023

Water

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“…Like conditioning on g point data, adding conditional probabilities to represent inter‐layer dependencies can result in more realistic dike buildup realizations. The use of recent developments in continuous geophysical data interpretation, such as electrical resistivity tomography (Chavez Olalla et al, 2021) or ground penetrating radar (Di Prinzio et al, 2010) are promising to increase the availability of ground truth data too. In addition, coupling our object‐based model to other geostatistical methods, such as multiple‐point geostatistics (Tahmasebi, 2018) can provide more detailed indications of material uncertainty across but also along the dike.…”

Section: Discussionmentioning

confidence: 99%

Assessing lithological uncertainty in dikes: Simulating construction history and its implications for flood safety assessment

Woerkom

Beek

Middelkoop

et al. 2022

J Flood Risk Management

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Dikes often have a long history of reinforcement, with each reinforcement adding new material resulting in a heterogeneous dike. As data on the dike internal heterogeneity is sparse, it is generally overlooked in the stability assessment of dikes. We present an object-based and process-based model simulating dike construction history on archeological dike cross, yielding similar patterns of heterogeneity as observed in real dikes, and apply it in a dike safety assessment. Model predictions improve when being based on more accurate statistics of dike buildup, or when being conditioned to ground truth data. When incorporated in a dike stability assessment, multiple model runs can be coupled to hydrological simulations and dike slope stability calculations, resulting in a probabilistic stability assessment considering internal dike heterogeneity. While high-resolution observations are still sparse, good model accuracies can be reached by combining regional information on dike buildup with local point observations and this model provides a parsimonious basis to include information of internal dike heterogeneity in safety assessments.

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“…The abandonment stage upper sands appear to have a higher percentage of admixture of silt‐sized grains (Supinfo S2) that regular point bar deposits have not, which would decrease their hydraulic conductivity. Experimental ERT geophysical measurements (Olalla et al ., 2021, their fig. 6) return relatively lower resistivity values in this part of cross‐section B (their BH2 is 2017 01 002 herein), which supports the deviating sedimentary characteristics of these sands.…”

Section: Discussionmentioning

confidence: 99%

Planform architecture, meander evolution and grain‐size variability of a deltaic channel belt in the Rhine‐Meuse delta, The Netherlands

2022

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In the unconstrained, low gradient setting of major delta plains, individual meander belts tend to function for relatively short periods of time due to repeated channel avulsion. Their short lifetime makes ‘deltaic’ channel belts suitable to study the products of steady meander evolution as the deposits and internal architectural elements preserved are often without complications of repeated bend cutoffs. This study investigated how sedimentary characteristics as preserved from subsequent stages of activity differ within the Stuivenberg channel belt. The Stuivenberg channel belt is a long‐studied example in the Holocene Rhine‐Meuse delta, The Netherlands, for which the meander evolution, i.e. geometry and dimensions through initiation, main activity and abandonment stages and durations of activity involved, was reconstructed. Mapping of the channel belt started from established coring based and LiDAR‐aided methods. Explorative approaches were used to assess active channel width at the onset of abandonment, and to reconstruct meander positions during earlier stages. The migration history of five consecutive meanders is revealed from convex and concave ridge‐and‐swale scrolls. Analysis identifies them to be the product of translation, expansion and rotation trajectories during a period of 800 years. Grain‐size composition throughout the sand body is interpreted given these positional contexts, with special attention to local coarsening of upper point bar facies in deltaic meander belts. The findings emphasize: (i) the need to separate abandonment stage from main activity stage when analysing three‐dimensional channel belt architectures; and (ii) the influence of meander evolution on lithological characteristics of initial stage versus mature stage parts of deltaic channel belt sands.

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Geophysical tomography as a tool to estimate the geometry of soil layers: relevance for the reliability assessment of dikes

Cited by 7 publications

References 22 publications

On Internal Erosion of the Pervious Foundation of Flood Protection Dikes

On Internal Erosion of the Pervious Foundation of Flood Protection Dikes

Assessing lithological uncertainty in dikes: Simulating construction history and its implications for flood safety assessment

Planform architecture, meander evolution and grain‐size variability of a deltaic channel belt in the Rhine‐Meuse delta, The Netherlands

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