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首页> 外文期刊>Computers & geosciences >Modeling a dynamically varying mixed sediment bed with erosion, deposition, bioturbation, consolidation, and armoring
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Modeling a dynamically varying mixed sediment bed with erosion, deposition, bioturbation, consolidation, and armoring

机译：用侵蚀，沉积，生物扰动，固结和装甲为动态变化的混合沉积物床建模

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Erosion and deposition of bottom sediments reflect a continual, dynamic adjustment between the fluid forces applied to a sediment bed and the condition of the bed itself. Erosion of fine and mixed sediment beds depends on their composition, their vertical structure, their disturbance/recovery history, and the biota that inhabit them. This paper presents a new one-dimensional (ID), multi-layer sediment bed model for simulating erosion and deposition of fine and mixed sediments subject to consolidation, armoring, and bioturbation. The distinguishing characteristics of this model are a greatly simplified first-order relaxation treatment for consolidation, a mud erosion formulation that adapts to both Type I and II erosion behavior and is based directly on observations, a continuous deposition formulation for mud that can mimic exclusive erosion and deposition behavior, and straightforward inclusion of bioturbation effects. Very good agreement with two laboratory data sets on consolidation effects is achieved by adjusting only the first-order consolidation rate r_c. Full model simulations of three idealized cases based on upper Chesapeake Bay, USA observations are presented. In the mud only case, fluid stresses match mud critical stresses at maximum erosion. A consolidation lag results in higher suspended sediment concentrations after erosional events. Erosion occurs only during accelerating currents and deposition does not occur until just before slack water. In the mixed mud and sand case without bioturbation, distinct layers of high and low sand content form and mud suspension is strongly limited by sand armoring. In the mixed mud and sand Case with bioturbation, suspended mud concentrations are greater than or equal to either of the other cases. Low surface critical stresses are mixed down into the bed, constrained by the tendency to return towards equilibrium. Sand layers and the potential for armoring of the bed develop briefly, but mix rapidly. This model offers a relatively simple and robust tool for simulating the complex interactions that can affect muddy and mixed sediment bed erodibility.
机译：底部沉积物的侵蚀和沉积反映了作用于沉积物床的流体力与床本身状况之间的连续动态调节。细沙床和混合沙床的侵蚀取决于它们的组成，垂直结构，扰动/恢复历史以及栖息在其中的生物群。本文提出了一种新的一维（ID）多层沉积物床模型，用于模拟受固结，装甲和生物扰动作用的精细和混合沉积物的侵蚀和沉积。该模型的显着特征是大大简化了用于固结的一阶松弛处理，一种泥浆冲蚀配方，它可以同时适应I型和II型冲蚀行为，并且直接基于观测结果；可以模拟唯一排蚀的泥浆连续沉积配方。和沉积行为，并直接包含生物扰动效应。通过仅调整一阶合并率r_c，可以使两个实验室数据集对合并效果达成很好的一致性。提出了基于美国切萨皮克湾上层观测的三种理想情况的全模型模拟。在仅泥浆的情况下，流体应力与泥浆临界应力匹配，且侵蚀最大。固结滞后导致侵蚀事件后悬浮泥沙浓度升高。侵蚀仅在加速电流期间发生，直到水松弛之前才发生沉积。在没有生物扰动的泥沙混合情况下，形成高沙含量和低沙含量的独特层以及泥沙悬浮受到防砂能力的强烈限制。在带有生物扰动的泥沙混合案例中，悬浮泥浓度大于或等于其他任何一种情况。低表面临界应力向下混合到床层中，受返回到平衡趋势的限制。沙层和床的装甲潜力会短暂发展，但会迅速混合。该模型提供了一个相对简单而强大的工具，用于模拟可能影响泥质和混合沉积床侵蚀性的复杂相互作用。

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