A Study of the Nature and Incidence of Density Currents in a Shallow Glacial Lake
A Study of the Nature and Incidence of Density Currents in a Shallow Glacial Lake
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浅冰湖密度流的性质和发生率的研究
DOI：
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
F. Weirich
中科院分区：
文献类型：
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作者：
F. Weirich
本文概述了对一个浅冰湖沉积过程研究的结果，在该研究中，一个集成的、全流域的仪器网络、一个多维水下传感器阵列和一个中央快速扫描数据记录系统被用于获取湖内和湖周围过程的详细信息。本文的研究结果集中在两个季节的密度流的性质和发生上。该系统的总体特征包括基本等温的湖泊环境，水停留时间仅为8-12天，以及相当大的输沙量，超过30%的入沙负荷通过该系统。缺乏显著的热分层和一般等压条件的趋势排除了传统的密度流的过流、间流和下流模式。相反，具有同型混合的上下流模型似乎更为合适。溢流是经常发生的事件，主要是由风引起的，偶尔也会发生由风引起的溢流。密度差低至0.19 kg m-3的底流也很频繁，其速度可能达到能够侵蚀较细材料的程度。核心数据支持仪器网络的许多发现。最后，研究结果指出，需要仔细测量输入和输出变量，以及即使入口条件的微小变化对湖泊沉积过程的重要性。
This paper outlines the findings of a study of sedimentation processes in a shallow glacial lake in which an integrated, basinwide instrumentation network, a multidimensional underwater sensor array, and a central rapid scan data-recording system were employed to obtain detailed information on processes both in and around the lake. The results presented here focus upon the nature and occurrence of density currents in the lake over a two-season period. The general character of the system includes a largely isothermal lake environment, water residency times of only 8–12 days, and considerable sediment throughput with over 30 percent of the incoming sediment load moving through the system. The lack of significant thermal stratification and the tendency toward generally isopycnal conditions precludes a conventional over-, inter-, and underflow model of density currents. It appears instead that an over- and underflow model with homopycnal mixing is more appropriate. The overflows, largely wind driven, are frequent events, and on occasion wind-driven translake overflows occur. Underflows, occurring with density differences as low as 0.19 kg m-3, are also frequent and may reach velocities capable of eroding the finer materials. Core data support many of the findings from the instrumentation network. Finally, the results point to the need for careful measurement of both input and output variables and the significance of even small variations in the entrance conditions on sedimentation processes in the lake.