Predicting the future hydrology of Arctic watersheds dominated by thermokarst lakes

在北极的广大地区，流域由数量庞大的湖泊所主导，这些湖泊覆盖了多达50%的陆地面积，并以复杂的水流网络连接在一起。在冻土层富含冰的地方，这些湖泊中有许多是存在于封闭洼地中的热岩溶湖，这些洼地是在富含冰的冻土层融化的早期阶段由地面沉降形成的。随着北极变暖和降水量的变化，这些湖泊及其相连的径流网络正进入一个快速而戏剧性的转变的新阶段。虽然气候是这些网络水文的强大驱动力，但变化也受到不断变化的植被、积雪、富冰永冻层融化和相关地表沉降之间的相互作用和反馈的驱动。这些变化正在进行，湖泊不断生长，缩小，形成;并完全从景观中移除。了解这些系统正在发生的变化是非常困难的，超出了我们目前的建模能力。这两种变化预计将在未来十年内发生，但也在未来几个世纪的变化，植被和永久冻土继续将继续在全球温度稳定后很长一段时间，因为植被，永久冻土和水文慢慢平衡与新的气候。我们需要新一代的预测方法来开发这种长期变化的情景，并使我们能够解决与这些系统对北方社会、土著土地所有权地区、野生动物栖息地和气候反馈的重要性相关的关键问题。这一知识对于指导必要的决定至关重要，这些决定是为了满足加拿大的国家和国际协定，将温室气体排放限制在确保长期保护这些独特的北极生态系统的水平。我们现有的预测这些系统水文的能力非常差，包括：整个北极的水文和气候数据非常稀少，质量往往很低，而且没有空间分布;这些北极流域的极端空间异质性记录不足，挑战了我们测量和模拟这些系统的能力;现有的水文模型不能很好地反映这种变化，因为它们没有整合地表和地下水文、湖泊、植被和永久冻土;地面热/水文模型不包括地面沉降和与积雪有关的反馈。该DG将解决我的总体，数十年的北极研究计划中的关键问题，该计划侧重于解决这些知识和建模限制，总体目标是进行变革性水文研究，以记录加拿大北极水文过去的变化，提供未来气候变化情景下北极水文变化的现实情景。

Across extensive areas of the Arctic, watersheds are dominated by immense numbers of lakes that cover up to 50% of the land area and are linked together in complex streamflow networks. Where the permafrost is ice rich, many of these lakes are thermokarst lakes that exist in closed depressions formed by settlement of the ground during earlier episodes of thawing of ice rich permafrost. These lakes and their linked streamflow networks are entering a new stage of rapid and dramatic transformation as the Arctic warms and precipitation changes. Although climate is a strong driver of the hydrology of these networks, changes are also driven by interactions and feedbacks between changing vegetation, snowcover, ice rich permafrost thaw, and related ground surface subsidence. These changes are ongoing with lakes growing, shrinking, forming; and completely being removed from the landscape. Understanding ongoing changes to these systems is extremely difficult and beyond our current modelling ability. This is true for both changes expected to occur over the next decade, but also over the coming centuries as changes to vegetation and permafrost continue will continue long after the global temperature is stabilized, as the vegetation, permafrost and hydrology slowly equilibrate with the new climate. We require a new generation of predictive methods to develop scenarios of such long-term change and allow us to address key issues related to the importance of these systems to northern society, indigenous land claims regions, wildlife habitat, and climate feedbacks. This knowledge is essential to guide decisions needed to meet Canada's national and international agreements to limit greenhouse gas emissions to a level that will ensure the long-term preservation of these unique Arctic ecosystems. Our existing ability to predict the hydrology of these systems is extremely poor, including: hydrologic and climate data across the Arctic is extremely sparse, often of low quality, and not spatially distributed; the extreme spatial heterogeneity of these Arctic watersheds is poorly documented and challenges our ability to measure and model these systems; existing hydrologic models poorly represent this variability as they don't integrate surface and subsurface hydrology, lakes, vegetation, and permafrost; and ground thermal/hydrologic models do not include ground subsidence and feedbacks related to snow accumulation. This DG will address key issues in my overarching, multiple-decade Arctic research program that is focussed on addressing these knowledge and modelling limitations, with the overall goal to undertake transformative hydrological research to document past changes to the hydrology of the Canadian Arctic, provide realistic scenarios of the changes in Arctic hydrology under future climate change scenarios.