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.***

山区的物质运动通常会将沉积物直接输送到河流网络，从而导致在相对较大的输送事件期间可能触发即时通道响应的耦合条件。值得注意的是，输送事件可以重置本地通道配置文件，并管理输送点下游通道床架构的构建和维护。沉积物输送事件后的当地响应率和轨迹是当前流域流态、事件幅度、通道宽度梯度以及某些情况下鲑鱼等水生物种活动浓度的函数。尽管低地河流系统一直是大量研究的焦点，但在山区溪流中开展的工作要少得多，而且很少涉及山区河道对水流或沉积物供应状况变化的反应。我的研究计划的目标是帮助建立一个更完整的知识库的山溪系统，我的主要兴趣是研究这些系统如何响应流量和沉积物供应的变化。水流和泥沙供应的变化在物理上表现为对当地推移质输沙率和量级的响应。因此，我的工作的中心重点是泥沙输运，并最终，我想开发预测能力的通道响应轨迹在广泛的条件下，结合适当的物理描述泥沙输运和通道特性（形态，纹理，结构）。预测能力可以作为自然资源管理者的基本工具，并且由于气候和土地使用变化，河流生态系统面临日益频繁和/或极端的景观干扰，因此迫切需要预测能力。展望我的研究计划的未来五年，在上述背景下，我建议进行水槽实验和数值模拟，以：（1）描述颗粒的夹带、运动距离和单个颗粒的静止期;（2）分析池槽形态的发展和维持对水流状态和泥沙供应的响应（3）研究了过程线形状和输沙状况对泥沙输移和床面演变的影响。在CFI资助的山区通道水力实验室进行的实验提供了物理过程的详细描述，很难获得在现场设置，和数值模拟被用来进一步探索整个合理的控制制度的河流系统的响应。拟议的项目将大大提高我们对山区溪流通道稳定性的理解，这是理论、管理、恢复、保护等许多方面的关键问题，也是河流地貌学的一个新兴前沿课题。