The hydrologic impacts of a subarctic landscape in transition

亚北极景观转型的水文影响

• 批准号: RGPIN-2022-04007
• 负责人: Lemieux, JeanMichel
• 金额: $ 2.62万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765425
• 关键词: hydrologic; impacts; subarctic; landscape; transition

Temperatures in the Arctic and subarctic are rising faster than the global average. Predictions suggest that by 2050, near-surface permafrost (permanently frozen soils) will have decreased by about 35% compared to current conditions. One documented consequence of permafrost degradation is a transformation of the hydrological cycle from a surface-water to a groundwater-dominated system-a shift which would significantly modify the terrestrial (not atmospheric) portion of the water cycle. The transition toward groundwater-dominated hydrological systems has the potential to greatly impact the water supplies of communities in northern Canada. Currently, these communities primarily rely on surface water bodies, such as rivers and lakes, for their water supplies. While these sources of water can be abundant, the water quality and volume is often variable, as they are easily contaminated and may freeze or dry up during the winter. In contrast, groundwater is generally less vulnerable to contamination and usually requires only minimal treatment. Yet because groundwater is currently stored as ground ice in permafrost, access to groundwater has historically been limited for most northern communities. While continued permafrost degradation is increasing the availability of groundwater in these areas, how the reactivation of these groundwater flow systems will impact the water cycle (and, by extension, the water supplies of northern communities) is still not well understood. Understanding the hydrological implications of continued permafrost degradation is further complicated by the extensive geomorphological and ecological transformations that often occur simultaneously with permafrost thaw. A prominent example of these linked phenomena is the impact that the greening of the tundra due to the expansion of shrubs has on groundwater recharge. The expansion of shrub populations strongly influences snow distribution; as taller vegetation traps more snow than bare land. Since the spring snowmelt is the main groundwater recharge event in subarctic environments, changes in vegetation cover are likely to alter the spatial distribution of groundwater recharge. Yet despite recent work, our ability to predict how a changing landscape will influence local hydrology is limited, due to both the complexity of the northern water cycle, as well as challenges associated with accessing the territory. This research program aims to improve our understanding of the hydrological cycle in the subarctic, in order to anticipate how climate warming and landscape evolution will impact the availability of groundwater and surface water. The research will rely on field observations in a subarctic watershed as well as advanced computer simulations. The results of this research will contribute to the sound and sustainable management of freshwater resources in northern environments, and may help northern Canadian communities to gain access to safer, more reliable drinking water supplies.

北极和亚北极地区的气温上升速度快于全球平均水平。预测表明，到2050年，近地表永久冻土（永久冻土）将比目前的状况减少约35%。有文献记载的永久冻土层退化的一个后果是水循环从地表水系统向地下水系统的转变——这种转变将显著改变水循环的陆地部分（而非大气部分）。向以地下水为主导的水文系统过渡有可能极大地影响加拿大北部社区的供水。目前，这些社区主要依靠地表水，如河流和湖泊，作为他们的水供应。虽然这些水源可能很丰富，但水质和水量往往不稳定，因为它们很容易受到污染，冬天可能会结冰或干涸。相比之下，地下水通常不太容易受到污染，通常只需要最少的处理。然而，由于地下水目前以地下冰的形式储存在永久冻土中，因此对大多数北方社区来说，地下水的获取一直受到限制。虽然持续的永久冻土退化正在增加这些地区地下水的可用性，但这些地下水流动系统的重新激活将如何影响水循环（进而影响北部社区的供水）仍然没有得到很好的理解。广泛的地貌和生态变化往往与永久冻土融化同时发生，这使理解永久冻土持续退化的水文含义变得更加复杂。这些相互联系的现象的一个突出的例子是由于灌木的扩大而使冻土带变绿对地下水补给的影响。灌木种群的扩张强烈影响积雪分布；因为较高的植被比裸露的土地能吸收更多的雪。由于春季融雪是亚北极地区地下水补给的主要事件，植被覆盖的变化可能会改变地下水补给的空间分布。然而，尽管最近开展了一些工作，但由于北部水循环的复杂性，以及与进入该地区相关的挑战，我们预测不断变化的景观将如何影响当地水文的能力有限。这项研究计划旨在提高我们对亚北极水文循环的理解，以预测气候变暖和景观演变将如何影响地下水和地表水的可用性。这项研究将依靠在亚北极流域的实地观测以及先进的计算机模拟。这项研究的结果将有助于对北部环境中的淡水资源进行健全和可持续的管理，并可能帮助加拿大北部社区获得更安全、更可靠的饮用水供应。