Modeling Bed-Surface Dynamics In Gravel-Bed Rivers

砾石河床河床表面动力学建模

• 批准号: 0106561
• 负责人: Peter Wilcock
• 金额: $ 20.5万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-15 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0106561&HistoricalAwards=false
• 关键词: Modeling; Bed; Surface; Dynamics; Gravel

0106561WilcockBed surface coarsening, broadly termed armoring, is a pervasive feature ofgravel rivers. Armoring strongly influences channel hydraulics, determinesthe population of grains available for transport, and defines the habitatfor aquatic invertebrates, salmonid spawning, and juvenile fish. A generaland predictive understanding of flow, transport, and benthic ecology ingravel-bed rivers requires an ability to predict the bed surfacecomposition as a function of water and sediment supply. In general, the bedsurface is not in equilibrium with contemporary conditions, so cause andeffect cannot be deduced from simple correlations of field observations.Instead, we turn to the laboratory for controlled observations and tocomputational models to capture the varied and transient conditions in thefield.Observations of armoring have been made for decades and algorithms capableof predicting armoring have been developed. Key elements are missing inboth data and models, however, and the empirical and the theoretical havenot yet merged into a complete model. This work aims to bridge that gap bybuilding from both sides. On the empirical side, we will use a laboratoryflume to make coupled observations of flow, transport, and bed surfacecomposition in order to describe the evolution of surface and subsurfacegrain sizes with unprecedented spatial and temporal detail. On thetheoretical side, we will develop a transport and armoring model thatincludes size-dependent vertical transfer of grains between surface andsubsurface (kinematic sorting). This mechanism can be incorporated incurrent models, but the necessary transfer functions remain undefined andwill be identified using the data from the experimental portion of thisproject. Testing of the model will be based on internal comparisonsbetween different sediment supply configurations and a set of runs withprogressive bed aggradation and degradation. The result will be aphysically-based, tested model capable of predicting transport and armoringunder the complex, transient conditions typical of the field.

0106561 WILCOCKBED表面变厚，广泛称为装甲，是Gravel Rivers的普遍特征。装甲强烈影响液压通道，确定可用于运输的谷物种群，并定义了水生无脊椎动物，鲑鱼产卵和少年鱼的栖息地。对流动，运输和底栖生态学的河流河流的一般和预测性理解，需要能够预测床表面成分作为水和沉积物供应的函数。通常，床表面与现代条件不处于平衡状态，因此不能从现场观察的简单相关性中推导出效果。但是，关键要素缺少嵌入数据和模型，但是经验和理论尚未合并为完整的模型。这项工作旨在弥合双方的差距旁路。在经验方面，我们将使用实验室来对流动，运输和床表面组成的观察结果进行耦合，以描述具有前所未有的空间和时间细节的表面和地下尺寸的演变。 在这方面，我们将开发一个运输和装甲模型，其中包括晶粒在表面和浅面之间的尺寸依赖性垂直转移（运动学排序）。可以将这种机制纳入刚有模型，但是使用来自该项目的实验部分的数据确定必要的传输函数，并将确定不确定的模型。 该模型的测试将基于不同的沉积物供应构型与一组具有良好床促进和降解的运行之间的内部比较。 结果将是基于身体的，测试的模型，能够预测运输和装甲的典型磁场的复杂，瞬态条件。