Prediction of Dynamic Ice Processes in Complex River Systems

河流冻结和破碎过程是非常动态的，极大地影响了河流系统的水文、形态和生态过程。其中一个过程是锚冰的演变，当湍流的水冷却到略低于0°C时，锚冰就会在河床上形成。它往往是短暂的，并可能对鱼类栖息地和水资源基础设施（如水力发电设施）产生不利影响。另一个动态过程是冰塞的形成。冰塞是由厚厚的碎冰堆积而成的，它限制了河流的流动，因此经常与高洪水风险联系在一起。多水道系统，如河流三角洲和汇合处，特别容易发生冰堵。例如，最近麦克默里堡的洪水是由于阿萨巴斯卡-克利尔沃特河汇合处形成的冰堵塞。冰与水流和河流形态相互作用的复杂方式，使得观察和预测这些动态冰事件变得非常困难。在多航道系统中，锚冰演化和冰塞形成的过程仍有许多未解之谜。我们非常需要提高对这些动态冰事件的预测能力。气候变化使这一问题变得更加紧迫，因为预计这些冰事件的时间、频率和严重程度都将发生变化。基于物理的数值模型提供了强大的预测工具，当与良好的实验室和现场数据一起使用时，还可以提供对这些复杂过程的深刻见解。因此，我提出了一项研究计划，通过开发基于物理的建模方法、进行实验室实验和/或利用现场数据来解决与冰塞和锚冰过程相关的知识空白。长期目标是显著提高我们对复杂河流环境中动态冰过程的理解和预测能力。研究的短期目标是：(1)研究河流三角洲在冰阻塞过程中发生的动力过程。(2)建立易发生冰塞的多航道系统洪水风险预测的业务模型。(3)确定控制锚冰形成的气象水文因素及其释放机制。(4)评估和改进现有河流冰模型的锚冰算法。拟议的研究计划将提高对冰塞和锚冰事件的理解和预测能力。它将大大有利于水资源基础设施的开发和运行，并通过减少这些冰事件的不利影响具有显著的经济价值。通过提供可靠的洪水预报工具和减少洪水损失，它将立即有益于公众安全。这项研究将产生一个增强的、基于物理的河流冰数值模型，这将为评估人类活动或气候变化对北部河流冰况的影响提供一个重要工具。该项目还将为研究生和本科生团队提供高质量的培训。

Ice processes during river freeze-up and breakup can be very dynamic, greatly affecting the hydrological, morphological, and ecological processes in river systems. One such process is the evolution of anchor ice, which forms on the riverbeds when turbulent water cools to just below 0°C. It is often ephemeral and can adversely impact fish habitat and water resources infrastructure (e.g. hydropower facilities). Another dynamic process is the formation of ice jams. Ice jams are thick accumulations of broken ice that constrict river flow and thus are often associated with high flood risks. Multi-channel systems such as river deltas and confluences are particularly prone to ice jams. For example, the recent Fort McMurray flood was due to an ice jam formed at the Athabasca-Clearwater River confluence. The complex ways that ice interacts with the flow and river morphology, makes observing and forecasting these dynamic ice events very difficult. There are still many unanswered questions regarding the processes of anchor ice evolution and ice jam forming in multi-channel systems. There is a great need for improving our predictive ability of these dynamic ice events. Climate change makes this even more urgent as the timing, frequency and severity of these ice events are all expected to change. Physics-based numerical models provide powerful forecasting tools, and when used with good laboratory and field data, can also provide great insights into these complex processes. Therefore, I am proposing a research program to address the knowledge gaps related to ice jam and anchor ice processes by developing physics-based modelling methods, conducting laboratory experiments, and/or utilizing field data. The long-term goal is to significantly improve our understanding of, and ability to predict, dynamic ice processes in complex river environments. The short-term objectives are to:     (1)Investigate the dynamic processes occurring in river deltas during ice jamming.     (2)Develop an operational model for predicting flood risk of ice jam prone multi-channel systems.     (3)Determine the meteo-hydrological factors controlling anchor ice formation and release mechanisms.     (4)Assess and improve anchor ice algorithms of existing river ice models. The proposed research program will lead to improved understanding and predictive ability of ice jam and anchor ice events. It will greatly benefit the development and operation of water resources infrastructure and have significant economic value by reducing the adverse impacts of these ice events. It will immediately benefit public safety by providing reliable flood forecasting tool and reducing flood damage. The research will produce an enhanced, physics-based river ice numerical model, which will provide an essential tool to assess the impacts of human activities or climate change on ice regime of northern rivers. This program will also provide high-quality training to a team of graduate and undergraduate students.