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)将比目前条件减少约35%。多年冻土退化的一个有据可查的后果是水文循环从地表水转变为以地下水为主的系统--这一转变将显著改变水循环的陆地部分(而不是大气部分)。向以地下水为主的水文系统的过渡有可能极大地影响加拿大北部社区的供水。目前，这些社区的供水主要依靠河流和湖泊等地表水体。虽然这些水源可能很丰富，但水质和水量往往是不同的，因为它们很容易受到污染，在冬天可能会结冰或干涸。相比之下，地下水一般不太容易受到污染，通常只需要最低限度的处理。然而，由于地下水目前以地面冰的形式储存在永久冻土中，从历史上看，大多数北方社区获取地下水的机会一直受到限制。虽然永冻层的持续退化增加了这些地区地下水的可获得性，但这些地下水流动系统的重新启动将如何影响水循环(进而影响北部社区的供水)仍不是很清楚。由于经常与永久冻土融化同时发生的广泛的地貌和生态变化，对永冻层持续退化的水文影响的理解进一步复杂化。这些相互关联的现象的一个突出例子是，由于灌木的扩张而导致的苔原绿化对地下水补给的影响。灌木种群的扩张强烈地影响了雪的分布；因为更高的植被比裸露的土地捕获了更多的雪。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，尽管最近开展了工作，但由于北部水循环的复杂性以及与进入该领土相关的挑战，我们预测不断变化的地形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了解，以便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获得性。这项研究将依赖于对亚北极分水岭的实地观察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。