Fluid and sediment dynamics in sand-bedded river systems

沙层河流系统中的流体和沉积物动力学

• 批准号: 341862-2012
• 负责人: Venditti, Jeremy
• 金额: $ 2.33万
• 依托单位: Simon Fraser University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=595502
• 关键词: Fluid; sediment; dynamics; sand; bedded

The objective of this research program is to advance our knowledge of the mechanics of sand-bedded river channels and, in particular, to develop physically-based tools to assist in the prediction of sediment movement between their source and ultimate sink in the ocean. The program uses the sand-bedded reach of the lower Fraser River as a natural laboratory to investigate and quantify processes. The Fraser also serves as inspiration (and in some cases the prototype) for more detailed observations in the River Dynamics Laboratory (RDL) flume channel at SFU. The mechanisms responsible for moving sediment through the 85 km river reach that passes through British Columbia's Lower Mainland are understood only conceptually, but the dynamics of the sediment control how the river responds to flood flows and the quality of aquatic habitat in the channel, delta, and tidal flat environments. Empirical methods for estimating sediment movement based on historical data collection programs are no longer reliable because of ongoing adjustment of the river to dredging required to maintain the Port of Vancouver. A physically-based modeling approach for sediment routing is required to make reliable predictions of how the sand-bedded channel and the delta environments will respond to various perturbations (e.g. a warmer climate, changes in water flux, changes in sediment flux associated with land use practices and contemporary variation in sea level). This research focuses on establishing methods to monitor suspended sediment delivery to the sand-bedded lower Fraser River, development of models for predicting suspended sediment transport based on the physical interactions between large-scale turbulent motions in the water column and examination of bedform response to variable flows (hydrographs or tides). There is a pressing need to make predictions of sediment transport in sand-bedded rivers that empty into the sea, such as the lower Fraser River, because they are often sites of intense urban development world-wide and the dynamics of these natural landscape processes significantly affect the socio-economic viability of this development.

这项研究计划的目的是提高我们对砂层河道力学的认识，特别是开发基于物理的工具，以帮助预测海洋中沉积物在源头和最终汇之间的运动。该项目利用弗雷泽河下游的沙质河床作为自然实验室来调查和量化过程。弗雷泽河也为SFU河流动力学实验室（RDL）水槽通道的更详细观察提供了灵感（在某些情况下是原型）。在流经不列颠哥伦比亚省低陆平原的85公里河段中，泥沙移动的机制仅在概念上得到了理解，但泥沙的动力学控制着河流对洪水的反应以及河道、三角洲和潮滩环境中水生栖息地的质量。基于历史数据收集程序估计沉积物运动的经验方法不再可靠，因为为了维持温哥华港，河流需要不断进行疏浚调整。为了可靠地预测砂层河道和三角洲环境将如何对各种扰动（如气候变暖、水通量变化、与土地利用做法有关的沉积物通量变化和当代海平面变化）作出反应，需要一种基于物理的沉积物路径建模方法。本研究的重点是建立监测向沙层状下游弗雷泽河输送悬浮泥沙的方法，根据水柱中大规模湍流运动之间的物理相互作用，开发预测悬浮泥沙输送的模型，以及检查河床对可变流量（水文或潮汐）的响应。迫切需要对流入海洋的沙层河流（如弗雷泽河下游）的沉积物运输进行预测，因为它们通常是世界范围内密集城市发展的地点，这些自然景观过程的动态显著影响这种发展的社会经济可行性。