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首页> 外文期刊>Hydrological Processes >Tracking hydrological responses of a thermokarst lake in the Old Crow Flats (Yukon Territory, Canada) to recent climate variability using aerial photographs and paleolimnological methods
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Tracking hydrological responses of a thermokarst lake in the Old Crow Flats (Yukon Territory, Canada) to recent climate variability using aerial photographs and paleolimnological methods

机译：跟踪旧乌鸦公寓（Yukon Territory，Canada）的水文反应以使用空中照片和古胃癌方法的最近气候变异性

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Recent studies using remote sensing analysis of lake-rich thermokarst landscapes have documented evidence of declining lake surface area in response to recent warming. However, images alone cannot identify whether these declines are due to increasing frequency of lake drainage events associated with accelerated thermokarst activity or to increasing evaporation in response to longer ice-free season duration. Here, we explore the potential of combining aerial photograph time series with paleolimnological analyses to track changes in hydrological conditions of a thermokarst lake in the Old Crow Flats (OCF), Canada, and to identify their causes. Images show that the water level in lake OCF 48 declined markedly sometime between 1972 and 2001. In a sediment core from OCF 48, complacent stratigraphic profiles of several physical, geochemical, and biological parameters from ∼1874–1967 indicate hydro-limnological conditions were relatively stable. From ∼1967–1989, declines in organic matter content, organic carbon isotope values, and pigment concentrations are interpreted to reflect an increase in supply of minerogenic sediment, and subsequent decline in aquatic productivity, caused by increased thermo-erosion of shoreline soils. Lake expansion was likely caused by increased summer rainfall, as recorded by increased cellulose-inferred lake-water oxygen isotope compositions. Stratigraphic trends defining the lake expansion phase terminated at ∼1989, which likely marks the year when the lake drained. Above-average precipitation during the previous year probably raised the lake level and promoted further thermo-erosion of the shoreline soils that caused the lake to drain. These are meteorological conditions that have led to other recent lake-drainage events in the OCF. Thus, the decline in lake level, evident in the aerial photograph from 2001, is unlikely to have been caused by evaporation, but rather is a remnant of a drainage event that took place more than a decade earlier. After drainage, the lake began to refill, and most paleolimnological parameters approach levels that are similar to those during the stable phase. These findings indicate that combined use of aerial images and paleolimnological methods offers much promise for identifying the hydrological consequences of recent climatic variations on thermokarst lakes. Copyright © 2011 John Wiley & Sons, Ltd.
机译：最近利用富有湖泊的Thermokarst景观景观分析的研究记录了湖面区域下降的证据，以应对最近的变暖。然而，单独的图像无法识别这些下降是否是由于与加速热潮流活动相关的湖排水事件的频率增加或响应于较长的冰季持续时间而增加蒸发。在这里，我们探讨了与古胃癌的空中照片时间序列组合的潜力，以跟踪旧乌鸦单位（OCF），加拿大的热能湖水文条件的变化，并识别其原因。图片显示，OCF 48湖中的水位在1972年和2001年之间有时拒绝。在OCF 48的沉积物核心中，来自〜1874-1967的几种物理，地球化学和生物参数的自满地层概况表明水利灭血条件相对稳定的。从〜1967-1989中，有机质含量下降，有机碳同位素值和颜料浓度被解释为反映了内源性沉积物供应的增加，随后的水生生产率下降，由海岸线土壤的热侵蚀增加引起的。由于脂肪纤维素推断的湖水同位素组合物增加，夏季降雨量增加，湖膨胀可能会增加。定义湖膨胀阶段的地层趋势终止于〜1989，这可能标志着湖泊排水的年份。前一年的平均降水量可能提高了湖泊水平，并促进了导致湖泊的海岸线土壤的进一步热侵蚀。这些是导致OCF中其他最近湖排水事件的气象条件。因此，从2001年开始的湖面水平的下降不太可能是由蒸发引起的，而是蒸发引起的，而且是一项以上持续十年的排水事件的残余。排水后，湖泊开始重新填充，最古代学参数接近水平与稳定期间的水平相似。这些调查结果表明，航空图像和古肿瘤方法的结合使用为识别近期气候变化的水文后果提供了许多关于热汗湖的水文后果。版权所有©2011 John Wiley＆Sons，Ltd。

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