Observations and Modelling of Freeze-up Processes in Rivers

河流冻结过程的观测和模拟

• 批准号: RGPIN-2020-04358
• 负责人: Loewen, Mark
• 金额: $ 3.13万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739916
• 关键词: Observations; Modelling; Freeze; up; Processes

Tiny ice particles, called frazil, form in the turbulent portions of the flow in northern rivers when the water supercools to just below zero degrees. Virtually all forms of river ice originate from frazil and its formation and evolution are the dominant river ice processes during freeze-up. Frazil particles in supercooled water readily adhere to natural and man-made surfaces. They may stick to the bed, forming anchor ice, or to each other, creating flocs that ultimately become large slush balls at the surface, freeze together into `frazil pans,' and eventually form the ice cover. Numerical river ice models include algorithms for simulating freeze-up processes but their accuracy is unknown due to a lack of field data to compare with. Although progress has been made in recent years to develop accurate measurement techniques there is still a great need for additional field measurements. To address this need, I propose an ambitious program of field measurements designed to significantly increase our knowledge of key freeze-up processes, and to use the resulting data to assess the accuracy of the algorithms currently used to model these processes. The long-term goal of the proposed research is to improve our understanding of how river ice forms, and its impacts on river ecology, hydraulics, and geomorphology. The short-term objectives of the proposed research program are to:    (1)Continue investigating the generation, transport, and fate of suspended frazil ice in rivers    (2)Investigate the properties of anchor ice and its impact on the ecology and hydraulics of rivers.    (3)Determine the impact of rafting of sediment by anchor ice on the sediment budget of rivers.    (4)Assess the ability of river ice process models to accurately model freeze-up. Three PhD and two MSc students will collaborate on the proposed research. The students will receive training on the use of a wide variety of sophisticated field instrumentation, advanced data processing methods and numerical modelling. Field measurements will be conducted over multiple winters on two rivers. River1D, a river ice processes model, will be applied to both rivers and its accuracy simulating freeze-up processes will be assessed by comparing model predictions to field measurements. The MSc students will gather digital images of surface ice conditions on the Peace River and analyze them using machine learning techniques. Their goal is to obtain accurate estimates of the amount of sediment transported by released anchor ice pans. Improving our ability to accurately monitor and predict freeze-up processes in rivers will have a significant impact on the planning, design, construction and operation of infrastructure built along rivers. It will also enhance our ability to assess the environmental impacts of cold region projects and more accurately assess the impact of climate change on freeze-up processes in northern rivers.

当水过冷至略低于零度时，北方河流的湍流部分会形成微小的冰颗粒，称为法拉齐尔。几乎所有形式的河冰都源自法拉齐尔，其形成和演化是冻结过程中主要的河冰过程。过冷水中的弗拉齐尔颗粒很容易粘附在天然和人造表面上，形成锚冰，或相互粘附，形成絮凝物，最终成为大的雪泥球。河冰数值模型包括模拟冻结过程的算法，但由于缺乏可比较的现场数据，其准确性尚不清楚，尽管已经取得了进展。近年来，为了开发精确的测量技术，仍然非常需要额外的现场测量。为了满足这一需求，我提出了一项雄心勃勃的现场测量计划，旨在显着增加我们对关键冻结过程的了解，并利用由此产生的结果。用于评估当前使用的算法的准确性的数据拟议研究的长期目标是提高我们对河流冰的形成及其对河流生态、水力学和地貌的影响的理解。拟议研究计划的短期目标是： （1）继续研究河流中悬浮碎冰的生成、迁移和归宿。 （2）研究锚冰的性质及其对河流生态和水力学的影响。 (3)确定锚冰漂流对河流沉积物预算的影响。(4)评估河流冰过程模型准确模拟冻结的能力三名博士生和两名硕士生将合作开展拟议的研究。学生将接受有关使用各种先进的现场仪器、先进的数据处理方法和数值模拟的培训，并将在两条河流上进行多个冬季的现场测量，这是一种河流冰过程模型。理学硕士学生将通过将模型预测与现场测量进行比较来评估两条河流的冰冻过程模拟的准确性，并使用机器学习技术对其进行分析。准确估计释放的锚冰盘输送的沉积物量，提高我们准确监测和预测河流冻结过程的能力，将对沿河基础设施的规划、设计、建设和运营产生重大影响。也增强了我们评估环境的能力寒区项目的影响，更准确地评估气候变化对北方河流结冰过程的影响。