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）将比目前减少约35%。一个记录的永久冻土退化的后果是从地表水到地下水占主导地位的系统的水文循环的转变，这将显着修改陆地（而不是大气）部分的水循环。 过渡到地下水为主的水文系统有可能大大影响社区的供水在加拿大北方。目前，这些社区主要依靠河流和湖泊等地表水体供水。虽然这些水源可能是丰富的，但水质和水量往往是可变的，因为它们很容易受到污染，并可能在冬季冻结或干涸。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，由于地下水目前作为地冰储存在永久冻土中，历史上大多数北方社区对地下水的利用一直受到限制。虽然永久冻土的持续退化正在增加这些地区地下水的可用性，但这些地下水流系统的重新激活将如何影响水循环（进而影响北方社区的供水），目前仍不清楚。了解水文影响的持续冻土退化是进一步复杂的广泛的地貌和生态变化，往往同时发生的冻土融化。这些相关现象的一个突出例子是，由于灌木的扩张，冻土带的绿化对地下水补给产生了影响。灌木种群的扩张强烈地影响了雪的分布;因为较高的植被比裸露的土地捕获更多的雪。由于春季融雪是亚北极环境中主要的地下水补给事件，植被覆盖的变化可能会改变地下水补给的空间分布。然而，尽管最近的工作，我们的能力，以预测如何变化的景观将影响当地水文有限，由于两个复杂的北方水循环，以及与访问的领土相关的挑战。 该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。这项研究将依赖于亚北极流域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北方环境中淡水资源的健全和可持续管理，并可能帮助加拿大北方社区获得更安全、更可靠的饮用水供应。