LL
L. Li
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6 records found
1
Process-based numerical models are increasingly used to study the evolution of marine and terrestrial depositional environments. Whilst a detailed description of small-scale processes provides an accurate representation of reality, application on geological timescales is restrained by the associated increase in computational time. In order to reduce the computational time, a number of acceleration methods are combined and evaluated for a schematic supply-driven delta (static base level) and an accommodation-driven delta (variable base level). The performance of the combined acceleration methods is evaluated by comparing the morphological indicators such as distributary channel networking and delta volumes derived from the model predictions for various levels of acceleration. The results of the accelerated models are compared to the outcomes from a series of simulations to capture autogenic variability. Autogenic variability is quantified by re-running identical models on an initial bathymetry with 1 cm added noise. The overall results show that the variability of the accelerated models fall within the autogenic variability range, suggesting that the application of acceleration methods does not significantly affect the simulated delta evolution. The Time-scale compression method (the acceleration method introduced in this paper) results in an increased computational efficiency of 75% without adversely affecting the simulated delta evolution compared to a base case. The combination of the Time-scale compression method with the existing acceleration methods has the potential to extend the application range of process-based models towards geologic timescales.
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Process-based numerical models are increasingly used to study the evolution of marine and terrestrial depositional environments. Whilst a detailed description of small-scale processes provides an accurate representation of reality, application on geological timescales is restrained by the associated increase in computational time. In order to reduce the computational time, a number of acceleration methods are combined and evaluated for a schematic supply-driven delta (static base level) and an accommodation-driven delta (variable base level). The performance of the combined acceleration methods is evaluated by comparing the morphological indicators such as distributary channel networking and delta volumes derived from the model predictions for various levels of acceleration. The results of the accelerated models are compared to the outcomes from a series of simulations to capture autogenic variability. Autogenic variability is quantified by re-running identical models on an initial bathymetry with 1 cm added noise. The overall results show that the variability of the accelerated models fall within the autogenic variability range, suggesting that the application of acceleration methods does not significantly affect the simulated delta evolution. The Time-scale compression method (the acceleration method introduced in this paper) results in an increased computational efficiency of 75% without adversely affecting the simulated delta evolution compared to a base case. The combination of the Time-scale compression method with the existing acceleration methods has the potential to extend the application range of process-based models towards geologic timescales.
Abstract
(2018)
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Helena van der Vegt, Joep Storms, Dirk-Jan Walstra, Liang Li, Kjetil Nordahl, Allard Martinius, N.C. Howes
In deltaic deposits, the largest volumes of sandy deposits occur at the delta top (as channel accretion, overbank deposits) and as distinct or amalgamated sandy mouth bars in the upper delta front. We use process-based models to study the sediment distribution in four evolving deltas, each with a different input sediment profile. We show how the mouthbar deposits can preserve a large proportion of the sand preserved in the sedimentary record of deltaic systems.
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In deltaic deposits, the largest volumes of sandy deposits occur at the delta top (as channel accretion, overbank deposits) and as distinct or amalgamated sandy mouth bars in the upper delta front. We use process-based models to study the sediment distribution in four evolving deltas, each with a different input sediment profile. We show how the mouthbar deposits can preserve a large proportion of the sand preserved in the sedimentary record of deltaic systems.
Abstract
(2017)
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Helena van der Vegt, Joep Storms, Dirk-Jan Walstra, Liang Li, N.C. Howes, Kjetil Nordahl, Allard Martinius
Geological models are generated by interpretation and interpolation of sparse data. To limit uncertainty, relevant analogues are used to extrapolate knowledge of previously studied, well understood systems. However, these analogues only provide a snapshot of deposition. During delta progradation, sediment will not only be deposited, but is also reworked resulting in unique preserved sediment distribution patterns for each delta. We show how process-based models can be used to study the evolution of deltaic sediment distribution in four dimensions. Grain-size distribution trends are extracted from preserved deposits in synthetic analogues of prograding deltas.
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Geological models are generated by interpretation and interpolation of sparse data. To limit uncertainty, relevant analogues are used to extrapolate knowledge of previously studied, well understood systems. However, these analogues only provide a snapshot of deposition. During delta progradation, sediment will not only be deposited, but is also reworked resulting in unique preserved sediment distribution patterns for each delta. We show how process-based models can be used to study the evolution of deltaic sediment distribution in four dimensions. Grain-size distribution trends are extracted from preserved deposits in synthetic analogues of prograding deltas.
Abstract
(2017)
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Helena van der Vegt, Joep Storms, Dirk-Jan Walstra, Liang Li, Kjetil Nordahl, Allard Martinius, Nick Howes
Conference paper
(2016)
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Joep Storms, Dirkjan Walstra, Liang Li, Helena van der Vegt, N.C. Howes, W de Boer, H van Putten, Andrea Forzoni
New developments are currently being undertaken to develop a new open source web-based modelling system based on the process-based model Delft3D. This modelling systems (Delft3D-GeoTool) aims to provide non-modeling specialists (as wel as specialists) in the field of sedimentary geology and reservoir geology with tools to easily set up their own model simulations and scenarios, perform post-processing analyses and store the results in a database.
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New developments are currently being undertaken to develop a new open source web-based modelling system based on the process-based model Delft3D. This modelling systems (Delft3D-GeoTool) aims to provide non-modeling specialists (as wel as specialists) in the field of sedimentary geology and reservoir geology with tools to easily set up their own model simulations and scenarios, perform post-processing analyses and store the results in a database.
Process-based numerical models are increasingly used to study landscape evolution. Whilst a detailed description of small scale processes provides an accurate representation of reality, direct simulation on relevant time scales constitutes an unfeasible computational effort. Therefore, most process-based forward morphological models incorporate techniques that accelerate the morphological and stratigraphic development. This so-called morphological acceleration utilizes the difference between hydrodynamic and morphological response time scales. This imposes an upper limit of typically thousand years of time scale for these type of forward models. Given the relevance of base-level variations for whose period is more than thousand years, the development of additional acceleration techniques is required. Here we propose a new acceleration technique to facilitate the modeling the evolution of deltaic systems on the time scales of more than thousand years. The effect of the acceleration technique is analyzed for accommodation-driven deltas. The results show that as long as the [A]/[S] ratio is honored for the acceleration technique, the morphological indicators for the delta-plain geometries are well reproduced for accommodation-driven deltas. In conclusion, the usage of additional acceleration technique enables process-based models to reach long time-scales.
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Process-based numerical models are increasingly used to study landscape evolution. Whilst a detailed description of small scale processes provides an accurate representation of reality, direct simulation on relevant time scales constitutes an unfeasible computational effort. Therefore, most process-based forward morphological models incorporate techniques that accelerate the morphological and stratigraphic development. This so-called morphological acceleration utilizes the difference between hydrodynamic and morphological response time scales. This imposes an upper limit of typically thousand years of time scale for these type of forward models. Given the relevance of base-level variations for whose period is more than thousand years, the development of additional acceleration techniques is required. Here we propose a new acceleration technique to facilitate the modeling the evolution of deltaic systems on the time scales of more than thousand years. The effect of the acceleration technique is analyzed for accommodation-driven deltas. The results show that as long as the [A]/[S] ratio is honored for the acceleration technique, the morphological indicators for the delta-plain geometries are well reproduced for accommodation-driven deltas. In conclusion, the usage of additional acceleration technique enables process-based models to reach long time-scales.