Mountain stream adjustments to changes in flow and sediment supply regimes

山间溪流对流量和沉积物供应状况变化的调整

• 批准号: RGPIN-2017-03834
• 负责人: Hassan, Marwan
• 金额: $ 2.84万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=687389
• 关键词: Mountain; stream; adjustments; changes; flow

Mass movements in mountainous regions often deliver sediment directly to the stream network, resulting in coupled conditions that can trigger immediate channel responses during relatively large delivery events. Notably, delivery events can reset the local channel profile and govern construction and maintenance of channel-bed architecture downstream of delivery points. The local response rate and trajectory following a sediment delivery event is a function of the prevailing watershed flow regime, the event magnitude, gradients in channel width, and in some instances the activity concentration of aquatic species such as salmon. Whereas lowland river systems have been the focus of a substantial body of research, much less work has been carried out within mountain streams and little concerning mountain channel responses to changes in flow or sediment supply regimes.****The objective of my research program is to help build a more complete knowledge base of mountain stream systems, and my principle interest is to examine how these systems respond to changes in streamflow and sediment supply. Changes in either or both streamflow and sediment supply physically manifests itself as a response in local rates and magnitudes of bedload sediment transport. As a result, the central emphasis of my work is sediment transport and, ultimately, I would like to develop predictive capabilities of channel response trajectories under a broad range of conditions, incorporating adequate physical descriptions of sediment transport and channel properties (morphology, texture, structure). Predictive capabilities can serve as a basic tool for natural resource managers and are urgently needed as stream ecosystems face increasingly frequent and/or extreme landscape disturbances due to climate and land use changes.****Looking forward to the next five years of my research program, and within the context described above, I propose to conduct flume experiments and numerical simulations to: (1) describe particle entrainment, travel distance and rest period of individual grains, (2) analyze the development and maintenance of pool-riffle morphologies in response to changes in flow regime and sediment supply (texture and amount), and (3) to study the impact of hydrograph shape and sediment feed regime on sediment transport and bed surface evolution. Experiments conducted in the CFI-funded Mountain Channel Hydraulic Experimental Laboratory provide detailed descriptions of physical processes that are difficult to obtain in a field setting, and numerical simulations are used to further explore responses of the fluvial system across plausible control regimes. The proposed project will substantially develop our understanding of channel stability in mountain streams, which is a critical issue on many fronts - theoretical, management, restoration, conservation - and an emerging frontier topic in fluvial geomorphology.***

山区的质量运动通常会直接传递到流网络，从而导致耦合条件，可以在相对较大的交付事件中触发立即的通道响应。值得注意的是，交付事件可以重置本地频道概况，并控制交付点下游的渠道床位建筑的构建和维护。沉积物输送事件发生后的局部响应率和轨迹是流行流动状态，事件幅度，通道宽度的梯度以及在某些情况下的水生物种（如鲑鱼）的活动浓度的函数。尽管低地河流系统一直是大量研究的重点，但在山流中进行的工作少了，几乎没有关于山区通道对流动或沉积物供应方案变化的响应的响应。水流和沉积物供应的变化在物理上表现为局部速率和床负载沉积物传输幅度的响应。结果，我工作的主要重点是沉积物的运输，最终，我想在广泛的条件下发展通道响应轨迹的预测能力，并结合了对沉积物传输和通道特性（形态，质地，结构）的足够物理描述。预测能力可以作为自然资源管理人员的基本工具，并且由于溪流生态系统面临越来越频繁的和/或由于气候和土地利用变化而引起的越来越频繁和/或极端的景观干扰。以及响应流动状态和沉积物供应（质地和量）的变化，以及（3）研究水力学形状和沉积物对沉积物传输和床表面演化的影响的影响，以及（3）研究池 - 裂片形态的维持。在CFI资助的山通道液压实验室中进行的实验提供了对物理过程的详细描述，这些过程在现场设置中难以获得，并使用数值模拟来进一步探索跨普利亚控制控制方案的河流系统的响应。拟议的项目将大大发展我们对山流中的渠道稳定性的理解，这在许多方面是一个关键问题 - 理论，管理，恢复，保护 - 以及河流地貌学中新兴的边界主题。*** ***