Fluid and sediment dynamics in sand-bedded river systems

这项研究计划的目的是促进我们对沙层河道力学的了解，特别是开发基于物理的工具，以帮助预测沉积物在其源头和海洋中的最终下沉之间的运动。该计划将弗雷泽河下游的沙层河段作为一个天然实验室来调查和量化过程。弗雷泽还作为灵感(在某些情况下是原型)，在SFU的河流动力学实验室(RDL)水槽中进行了更详细的观测。通过流经不列颠哥伦比亚省下大陆的85公里河段的泥沙运动机制仅在概念上被理解，但泥沙的动态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。根据历史数据收集方案估计泥沙运动的经验方法不再可靠，因为维护温哥华港需要不断调整河流以进行疏浚。需要一种基于物理的泥沙路线模拟方法，以可靠地预测沙层河道和三角洲环境将如何应对各种扰动(例如，气候变暖、水通量的变化、与土地利用做法有关的泥沙通量的变化以及当代海平面的变化)。这项研究的重点是建立监测沙质层弗雷泽河下游悬沙输移的方法，建立基于水体大尺度湍流运动物理相互作用的悬沙输移预报模型，以及考察河床对变化的水流(水文或潮汐)的响应。迫切需要对流入大海的沙床河流(如弗雷泽河下游)的泥沙输送进行预测，因为这些河流往往是世界各地密集的城市发展地点，这些自然景观过程的动态对这种发展的社会经济可行性有重大影响。

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.