A reduced-complexity model for river delta formation – Part 1: Modeling deltas with channel dynamics
A reduced-complexity model for river delta formation – Part 1: Modeling deltas with channel dynamics
复制标题
河流三角洲形成的复杂性降低模型 - 第 1 部分：利用河道动力学对三角洲进行建模
DOI：
10.5194/esurf-3-67-2015
复制
发表时间：
2014
期刊：
影响因子：
3.9
通讯作者：
C. Paola
中科院分区：
文献类型：
--
作者：
M. Liang;V. Voller;C. Paola
摘要。在这项工作中，我们开发了一种用于河流三角洲形成的低复杂度模型（以下简称DeltaRCM）。它是一种基于规则的元胞形态动力学模型，与基于详细计算流体动力学的还原论模型不同。该模型（DeltaRCM）的基本框架包括基于随机地块的水和泥沙元胞路径规划方案，以及一套泥沙沉积和侵蚀的现象学规则。该模型的输出包括随时间演变的深度平均流场、水面高程和河床地形。结果表明，DeltaRCM能够（1）解决多种河道动力学问题——包括伸长、分叉、改道和迁移——以及（2）生成多种三角洲，如冲积扇三角洲和具有多级分叉的三角洲。我们还展示了一个简单的地层记录组件，它可以追踪粗细物质的分布以及沉积物的年龄。低复杂度三角洲模型必须包含的基本过程包括引导泥沙输运的深度平均流场、考虑至少在主河道中回水效应的非平凡水面剖面、推移质和悬移质泥沙输运以及泥沙输运的地形导向。
Abstract. In this work we develop a reduced-complexity model (RCM) for river delta formation (referred to as DeltaRCM in the following). It is a rule-based cellular morphodynamic model, in contrast to reductionist models based on detailed computational fluid dynamics. The basic framework of this model (DeltaRCM) consists of stochastic parcel-based cellular routing schemes for water and sediment and a set of phenomenological rules for sediment deposition and erosion. The outputs of the model include a depth-averaged flow field, water surface elevation and bed topography that evolve in time. Results show that DeltaRCM is able (1) to resolve a wide range of channel dynamics – including elongation, bifurcation, avulsion and migration – and (2) to produce a variety of deltas such as alluvial fan deltas and deltas with multiple orders of bifurcations. We also demonstrate a simple stratigraphy recording component which tracks the distribution of coarse and fine materials and the age of the deposits. Essential processes that must be included in reduced-complexity delta models include a depth-averaged flow field that guides sediment transport a nontrivial water surface profile that accounts for backwater effects at least in the main channels, both bedload and suspended sediment transport, and topographic steering of sediment transport.