Multiple frazil ice blockages at a water intake in the St. Lawrence River
Multiple frazil ice blockages at a water intake in the St. Lawrence River
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DOI：
10.1016/j.coldregions.2007.10.003
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发表时间：
2008-07
影响因子：
4.1
通讯作者：
M. Richard;B. Morse
中科院分区：
文献类型：
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作者：
M. Richard;B. Morse
本文介绍了位于加拿大魁北克市圣劳伦斯河北岸的一个市政取水口的多重碎石冰堵塞的现场研究结果。使用的仪器包括一个气象站、一个带有长焦镜头的数码相机、四个水温探头、一个光学后向散射系统、一个压力传感器和一个声学传感器(冰廓线系统)。背景冰数据是由直升机每两周一次的观测提供的，当地的水流速度是通过分析数字照片上浮冰的运动和进行一维和三维数值模拟获得的。该市提供了进水口流量和水头损失的数据，并由作者进行了分析。这个地点是独一无二的，因为这条河通过商业航运人为地保持了整个冬天的开放。它也是独一无二的，因为进水口位于潮汐河段，因此受到广泛的上下游流速的影响。由于其地理位置，进水口有时受到边界冰的保护或部分受到保护。随着半日潮的每一次变化，完全新的水和冰到达该地点。有大约100个活跃的冰川和锚冰事件的详细数据，导致进水口发生35次堵塞事件。在介绍了冬季环境状况的全球概要和阻塞事件的概要统计之后，详细介绍了选定的四个事件。讨论的项目是形成脆性冰的临界温度和取水口堵塞作为一天中的时间、潮汐条件和表面冰类型的函数。堵塞事件的特点还包括发展所需的时间、严重程度和持续时间。
This paper presents the results of a field study of multiple frazil ice blockages of a municipal water intake located on the north shore of the St. Lawrence River at Québec City, Canada. Instrumentation used includes a weather station, a digital camera with a telephoto lens, four water temperature probes, an Optical Backscatter System, a pressure sensor and an acoustic sensor (Ice Profiling System). Background ice data is provided by bi-weekly helicopter observations and local water velocity was obtained by analysing surface ice floes movement on digital photos and by performing 1-D and 3-D numerical modeling. Data on flow rates and head losses through the intake were provided by the City and analysed by the authors. The site is unique because the river is artificially kept open all winter by commercial shipping. It is also unique because the intake is located in a tidal reach and is therefore subject to a wide range of upstream and downstream flow velocities. Due to its location, the intake is, at times, sheltered or partially sheltered by border ice. With each change in the semi-diurnal tide, totally new water and ice reach the site. Detailed data is available for about 100 active frazil and anchor ice events leading to 35 blockage events at the intake. After presenting a global summary of the winter's environmental conditions and after presenting summary statistics on blockage events; four selected events are presented in detail. Items discussed are critical temperatures for the formation of frazil ice and the blockage of the intake as a function of time of day, tidal condition and surface ice type. Blockage events are also characterized in terms of the time required for them to develop, their severity and their duration.