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

Winkels, T.G.; Stouthamer, Esther; Cohen, K.M.

doi:10.1111/sed.13022

Cited by 3 publications

(11 citation statements)

References 82 publications

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“…To assess the effect of simplifying subsurface architecture two subsurface schematizations of our study are considered with a different level of detail. The study area contains a geological architecture characteristic for the Rhine-Meuse delta and is mapped in high detail (Winkels et al, 2022). Given a subsurface schematization, 2D and 3D groundwater models are created.…”

Section: Methodsmentioning

confidence: 99%

“…The 2D and 3D subsurface schematizations for our analyses are based on a geological mapping (Cohen, 2017;Winkels et al, 2022) of the Stuivenberg channel belt (SCB). The SCB is a meandering channel belt in the central Rhine delta that was active between approximately 4300 and 3500 cal.…”

Section: Subsurface Scenariosmentioning

confidence: 99%

“…The SCB is a meandering channel belt in the central Rhine delta that was active between approximately 4300 and 3500 cal. yr BP (Winkels et al, 2022). Its internal architecture and lithology have been mapped in detail and includes an abandoned channel with a residual channel within the channel belt extent.…”

Section: Subsurface Scenariosmentioning

confidence: 99%

“…However, the shallow subsurface around lowland rivers in a deltaic setting is very heterogeneous, due to both the temporal evolution of the river system on antecedent stratigraphy (Geleynse et al, 2011) as the interplay between these rivers and coastal processes (Hoitink et al, 2017). In our study area (the Rhine-Meuse delta in the Netherlands) a large part of the delta consists of clay and peat deposits from river floodplains intersected by sandy deposits from their past and present river systems (Berendsen and Stouthamer, 2000;Bierkens, 1996;Winkels et al, 2022). Within the sandy channel belts from these often meandering river systems, units with different lithological characteristics are present, related to the meander dynamics and abandonment of these systems, such as abandoned and residual channels (Toonen et al, 2012;Winkels et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…In our study area (the Rhine-Meuse delta in the Netherlands) a large part of the delta consists of clay and peat deposits from river floodplains intersected by sandy deposits from their past and present river systems (Berendsen and Stouthamer, 2000;Bierkens, 1996;Winkels et al, 2022). Within the sandy channel belts from these often meandering river systems, units with different lithological characteristics are present, related to the meander dynamics and abandonment of these systems, such as abandoned and residual channels (Toonen et al, 2012;Winkels et al, 2022). The latter are often relatively small (tens of meters) and therefore may be overlooked or ignored in subsurface schematizations for groundwater models.…”

Section: Introductionmentioning

confidence: 99%

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Improving Dike Slope Failure Assessments related to Groundwater Hydrology

van Woerkom

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Dikes and dunes protect over 9 million in the Netherlands from floods due to extreme river water levels and coastal storms. According to the 2017 river flood protection assessment, all 3500 km of primary flood defenses must meet a new safety standard by 2050. Currently, 1500 km needs reinforcement. This evaluation aims to meet the new safety rules. Dike failure probability is seen as a mix of mechanisms, with dike slope instability being a key one – soil movement due to increased groundwater pressure. High water levels lead to heightened groundwater pressure through direct infiltration and subsurface flow. The current dike safety assessment uses an analytical approach for groundwater conditions, neglecting parameters like hydrological attributes, subsurface variability, and flood hydrograph shape. The diverse subsurface in the Rhine-Meuse delta impacts groundwater flow. Ignoring these parameters causes inaccurate safety estimates. The research's primary goal is to assess parameters affecting dike failure uncertainty due to groundwater variation in deltas. A groundwater model linked with a geomechanical model assessed dike slope stability, varying parameters that influence it via groundwater conditions. The significance of subsurface and geometry for dike slope stability under steady-state groundwater conditions was explored through a sensitivity analysis involving fifteen parameters related to geometry, drainage, and material properties. Dike slope and subsurface material type were pivotal factors, with complex connections influencing stability directly through geomechanical traits and indirectly through groundwater conditions. However, this assumes pressure conditions stabilize during high water events, which isn't always accurate. The significance of subsurface and geometry for dike slope stability was studied using a sensitivity analysis. Among fifteen parameters related to geometry, drainage, and materials, the dike slope and subsurface material had the greatest impact. Complex connections influence stability through geomechanical properties and groundwater conditions. Yet, this relies on pressure reaching equilibrium during high water events, which may not be consistent. Another uncertainty source is the heterogeneity in human-made river dikes and the natural subsurface. DETRIS, an object-based and process-based model, replicates material patterns in river dikes with historical cores. Incorporating heterogeneous DETRIS-simulated dikes into simulations yields a probabilistic assessment that accounts for internal dike heterogeneity. This approach reduces uncertainty by factoring in permeable layers or weak zones. In lowland deltas like the Rhine-Meuse delta, the natural subsurface's complexity includes sandy channel belts and clayey floodplain deposits. Current groundwater estimation practices oversimplify to two dimensions, but 2D models can underestimate when the river channel connects in three dimensions. A 2D groundwater model may underestimate dike slope stability compared to a 3D model. These uncertain factors merge to influence dike stability. The dike's interior composition significantly affects phreatic levels and heterogeneity. Material composition of the cover layer determines subsurface pressure. None of the factors – flood wave shape, dike interior, subsurface material, or groundwater model dimension – show a significantly greater impact on dike slope safety. Given climate change's potential extreme conditions and groundwater's role in dike failure, comprehensive guidelines for including groundwater uncertainty in safety assessments are advised.

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Section: Methodsmentioning

confidence: 99%

Section: Subsurface Scenariosmentioning

confidence: 99%

Section: Subsurface Scenariosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improving Dike Slope Failure Assessments related to Groundwater Hydrology

van Woerkom

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Stochastic Modeling of Thin Mud Drapes Inside Point Bar Reservoirs With ALLUVSIM‐GANSim

Hu,

Song,

Hou

et al. 2024

Water Resources Research

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Modeling inclined fine‐scale mud drapes inside point bars, deposited on accretion surfaces during stages of low energy or slack water, is critical to modeling fluid flow in complex sedimentary environments (e.g., fluvial and turbidity flows). These features have been modeled using deterministic or geostatistical modeling tools (e.g., object‐, event‐, and pixel‐based). However, this is a non‐trivial task due to the need to preserve geological realism (e.g., connectivity within sedimentary features and facies hierarchy), while being able to condition the generated models to point data (e.g., well data). Generative Adversarial Networks (GAN) have been successfully applied to reproduce several large‐scale scenarios (e.g., braided rivers and carbonate reservoirs), yet their potential for capturing small‐scale and hierarchical features remains largely unexplored. Here, we propose a geo‐modeling workflow for fast modeling of small‐scale conditional mud drapes based on ALLUVSIM and GANSim. Initially, improved ALLUVSIM produces realistic unconditional models of mud drapes along accretionary surfaces, serving as GAN training data. GANSim is then employed to achieve conditioning to well data and probability maps derived from geophysical modeling. Finally, temporal pressure data observed in wells are further conditioned via a Markov chain Monte Carlo sampling method. The proposed geo‐modeling workflow is validated in a two‐dimensional synthetic example as the pre‐trained generator extracts mud‐drapes‐features and generates multiple facies realizations conditioned to diverse information. A field application example in a modern meandering river verifies the effectiveness and practicability of the proposed workflow in real case application examples. The application examples illustrate the potential of the proposed method to predict mud drapes inside point bar reservoirs.

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Late‐Holocene counterpoint deposition in the Lower Rhine River

Boterman,

Candel,

Makaske

et al. 2024

Sedimentology

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Channel deposits from meandering rivers have proven to be far more complex than the well‐known lithofacies model consisting of coarse‐grained channel, gravelly channel‐lag and fine‐grained overbank deposits. Sharp bends in rivers are subject to different hydraulic processes than bends with lower curvatures, enabling erosion of inner banks and deposition of fine‐grained sediments in the outer bend, resulting in downstream migration of river bends. This phenomenon is known as counterpoint deposition, forming counterpoint bars. This research investigates whether scroll bars associated with a sharp bend in the Lower Rhine River, The Netherlands, are such a counterpoint‐bar deposit. A counterpoint bar is expected based on: (i) the surface morphology of the scroll bar; (ii) the confinement of the river course by an ice‐pushed ridge resulting in a sharp bend; and (iii) the archaeological context of successive Roman settlements atop the ice‐pushed ridge, potentially moving downstream with the migrating river bend. This hypothesis is tested through detailed borehole descriptions combined with optically stimulated luminescence dating, the latter being a novel approach to identifying counterpoint deposits. The deposits consist of clays and sandy clays with fine sand laminations, and sporadic larger sand bodies. Further upstream these deposits grade into channel deposits dominated by coarser sands with gravels. These lithologies are explained using earlier proposed mechanisms for counterpoint formation; substrata match those described in previously studied counterpoint deposits and their point bar counterparts. Optically stimulated luminescence dates indicate that the Lower Rhine River bend migrated downstream, confirming counterpoint deposition. A migration rate of 1.93 m/year was established through weighted linear regression. This study demonstrates the potential of optically stimulated luminescence dating to investigate counterpoint bar presence. The identified counterpoint bars and associated bend migration provide insight into meandering river dynamics that is crucial for river management and in aiding river restoration and rewilding initiatives.

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

Cited by 3 publications

References 82 publications

Improving Dike Slope Failure Assessments related to Groundwater Hydrology

Improving Dike Slope Failure Assessments related to Groundwater Hydrology

Stochastic Modeling of Thin Mud Drapes Inside Point Bar Reservoirs With ALLUVSIM‐GANSim

Late‐Holocene counterpoint deposition in the Lower Rhine River

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