Morphodynamics of gravel-bed rivers

砾石床河流的形态动力学

• 批准号: 41186-2012
• 负责人: Ashmore, Peter
• 金额: $ 3.35万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=521538
• 关键词: Morphodynamics; gravel; bed; rivers

The overall research goal is to analyze the dynamics of rivers to contribute to understanding of the response of rivers to environmental change and human modification, and to the development of methods for restoration of impacted rivers. This requires an understanding of the processes that create particular types of river form and dynamics. At the heart of this is the idea that rivers are transporters of sediment and that this sediment transport also creates the river form. If we can understand these sediment transport processes we can explain why rivers with different morphology occur and how rivers change in morphology over time. The classical approach to analysis of sediment transport is to develop mathematical functions that predict transport rate from the hydraulics of the flow. But this hydraulically-based analysis does not directly explain differences in river form and the local processes creating this form, and ignores the possibility that there are elements of the transport process that are not directly related to local hydraulics but are inherent properties of morphological instability. I am exploring an alternative approach which is to measure rates and 'styles' of morphological development - morphodynamics - that are the outcome, and driver, of spatial and temporal patterns of sediment transport. By measuring the morphological change we can make a direct link between the sediment transport processes and differences in river form and dynamics. This also leads to development of new methods for predicting sediment transport rate in rivers. Because the morphological dynamics of rivers is relatively slow we use small-scale physical models in an experimental flume to observe the development of channel morphology, measure rates of change and the volumes of erosion and deposition (using photogrammetry to map bed topography), and observe the way in which morphology develops from the statistics of the collective displacement of bed material particles. The outcome of the research will be a new way of analyzing river morphology and sediment transport, and of understanding variations in river morphology and morphological change, with practical application in river management and fluvial sedimentology.

总体研究目标是分析河流的动态，以帮助理解河流对环境变化和人类改造的响应，并开发受影响河流的恢复方法。这就需要了解创造特定类型河流形态和动力学的过程。其核心思想是河流是沉积物的运输者，这种沉积物的运输也创造了河流的形态。如果我们能够理解这些沉积物的输运过程，我们就可以解释为什么会出现不同形态的河流，以及河流的形态如何随着时间的推移而变化。泥沙输移分析的经典方法是建立数学函数，根据水流的水力学特性预测输移率。但是，这种基于水力学的分析并不能直接解释河流形态的差异以及形成这种形态的局部过程，并且忽略了这样一种可能性，即运输过程中存在与局部水力学不直接相关的元素，但这些元素是形态不稳定的固有属性。我正在探索一种替代方法，这是测量率和“风格”的形态发展- morphodynamics -这是结果，和驱动程序，沉积物运输的空间和时间模式。通过测量形态的变化，我们可以在沉积物输运过程与河流形态和动力学差异之间建立直接联系。这也导致了预测河流输沙率的新方法的发展。由于河流的形态动力学是相对缓慢的，我们使用小规模的物理模型在实验水槽中观察通道形态的发展，测量变化率和侵蚀和沉积量（使用摄影测量绘制河床地形），并观察形态发展的方式从河床物质颗粒的集体位移的统计。该研究成果将为分析河流形态和泥沙输移、了解河流形态变化和形态变化提供新的途径，并在河流管理和河流沉积学中得到实际应用。