Frazil Ice Formation and Evolution

弗拉齐尔冰的形成和演化

• 批准号: RGPIN-2015-04670
• 负责人: Loewen, Mark
• 金额: $ 2.04万
• 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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613099
• 关键词: Frazil; Ice; Formation; Evolution

Frazil ice particles are small, disc-shaped ice crystals that form in turbulent rivers once the water temperature has supercooled to a few hundredths of a degree below zero. Frazil ice particles are very adhesive in supercooled water and they readily stick to each other forming buoyant frazil flocs that rise to the surface where they form ‘frazil pans’ which then accumulate to form a full ice cover. Frazil particles easily adhere to almost any surface, such as screens and trash racks on water intakes, cutting off the water supplies to municipalities, industries, and power plants. It can also stick to the river bed, building up "anchor ice", which can be very harmful to fish. For example, in small rivers, anchor ice can fill up the entire channel in a single night, inhibiting habitat access for juvenile fish or blocking the oxygen supply to eggs buried in the stream bed. Despite the importance of frazil ice to the river freeze-up process and the consequences of its formation, little is known about its generation, transport and evolution. One reason for this is our current inability to accurately measure suspended frazil concentrations and size distributions in rivers. The long-term goal of the proposed research is to develop accurate methods for monitoring and predicting the formation of frazil ice in rivers and its subsequent transport and evolution during freeze-up. My research group has developed a unique digital imaging system that is designed to be deployed underwater in rivers at freeze-up and we propose to use this new technology to make the first accurate measurements of frazil ice properties in three Alberta rivers. We also propose to continue developing a sonar based system that can be used to continuously monitor river ice processes. In addition to this we will continue investigating the properties of frazil ice in the laboratory using our unique frazil ice generation tank. The data that we collect will have a tremendous impact because it will allow us and others to critically assess the accuracy of and improve numerical river ice models. Frazil ice formation and evolution is the dominant river ice process during freeze-up and therefore improving our ability to accurately monitor and predict it in rivers will have a significant impact on the planning design, construction and operation of infrastructure built along rivers.

脆弱的冰粒是微小的圆盘状冰晶，一旦水温过冷到零下几度，就会在湍急的河流中形成。脆弱的冰粒在过冷水中粘性很强，它们很容易相互粘连，形成漂浮的浮冰絮状物，在那里它们会上升到表面，在那里它们形成“Frazil pans”，然后积累形成完整的冰盖。脆性颗粒很容易附着在几乎任何表面，如取水口上的屏风和垃圾架，切断了市政、工业和发电厂的供水。它还会粘在河床上，形成“锚冰”，这对鱼类非常有害。例如，在小河中，锚冰可以在一夜之间填满整个海峡，阻碍幼鱼的栖息地，或者阻止埋藏在河床中的鱼卵的氧气供应。尽管碎冰对河流冻结过程及其形成的后果很重要，但人们对其产生、运输和演变知之甚少。其中一个原因是我们目前无法准确测量河流中的悬浮物浓度和粒度分布。拟议研究的长期目标是制定准确的方法，监测和预测河流中碎屑冰的形成及其随后在冻结期间的运输和演变。我的研究小组开发了一种独特的数字成像系统，旨在冰冻时部署在河流的水下，我们建议使用这项新技术对艾伯塔省三条河流的碎冰特性进行首次准确测量。我们还建议继续开发一种基于声纳的系统，可以用来连续监测河冰过程。除此之外，我们还将继续在实验室中使用我们独特的Frazil冰生成罐研究Frazil冰的特性。我们收集的数据将产生巨大的影响，因为它将使我们和其他人能够批判性地评估和改进河冰数值模型的准确性。碎冰的形成和演化是冰冻过程中的主导过程，因此，提高我们对河流中碎冰的准确监测和预测能力，将对沿江基础设施的规划设计、建设和运营产生重大影响。