Permafrost degradation mechanisms in organic-covered terrains and linkages to runoff production

近年来，前所未有的气候变暖和人为干扰导致有机覆盖的永久冻土带（包括加拿大北部大片地区的北极和高山冻土带、针叶林和北方地区）的永久冻土带严重退化。对于永久冻土退化的机制和速率，以及后者对排水和蓄水模式和过程的影响，仍然缺乏了解。因此，寒区水文学面临的主要挑战是如何根据冻土融化动态预测径流。这突出表明需要进行健全的科学研究，为北方水资源的知情和可持续管理提供知识。这项研究的目的是产生这些知识，并从中产生一套新的模型来预测永久冻土对气候变暖和人为干扰的反应，以便在永久冻土融化的背景下更自信地预测流域径流。短期目标是：1)记录过去半个世纪研究地点永久冻土分布的变化；2)建立关键水文过程的概念和数学模型，包括样地尺度的流量和主要地形类型之间的流量；3)研究多年冻土对上覆树冠变化的响应；4)识别控制可能导致多年冻土退化的优先解冻速率和模式的关键因素；5)建立了间断和连续冻土对气候变暖和人为干扰响应的新模式；6)结合水文和多年冻土模型，预测了气候变暖和人为干扰情景下的多年冻土空间分布和河流流量状况。由于数据档案丰富，基础设施和设备高度集中，以及当地社区的兴趣和支持，该研究将在西北地区Scotty Creek的不连续永久冻土层的湿地主导区进行。广泛的成本分摊和数据共享机会以及正在进行的免费研究项目也使Scotty Creek成为一个合乎逻辑的研究地点。然而，该项目的结果旨在转移到其他广泛存在的有机覆盖的永久冻土地形类型。

Unprecedented warming and human disturbance has led to substantial permafrost degradation in recent years in organic-covered permafrost terrains, including the arctic and alpine tundra, taiga and boreal regions that characterise vast areas of Canada's north. There remains a lack of understanding of the mechanisms and rates of permafrost degradation, and the influence of the latter on water drainage and storage patterns and processes. As a result, a major challenge of cold regions hydrology lies in predicting runoff dynamically with permafrost thaw. This underscores the need for sound scientific research to provide the knowledge for informed and sustainable management of northern water resources. This research aims to generate this knowledge, and from it produce a new suite of models for predicting the response of permafrost to climate warming and human disturbance so that basin runoff can be more confidently predicted in the context of thawing permafrost. The short-term objectives are: 1) document the change in permafrost distribution over the last half century at the study site; 2) develop conceptual and mathematical models of key hydrological processes, including plot-scale flows and flows among the major terrain types; 3) examine the permafrost response to changes in the overlying tree canopy; 4) identify the key factors controlling the rates and patterns of preferential thaw that may lead to permafrost degradation; 5) develop a new model that simulates the discontinuous and continuous permafrost response to climate warming and human disturbance; and 6) couple the hydrological and permafrost models to predict the spatial distribution of permafrost, and the river flow regime under scenarios of climate warming and human disturbance. The study will be conducted in the wetland-dominated zone of discontinuous permafrost at Scotty Creek, NWT, because of its rich data archive, high concentration of infrastructure and equipment, and local community interest and support. Extensive cost-sharing and data-sharing opportunities with on-going complimentary research projects also make Scotty Creek a logical study site. However, the project results are intended to be transferable to other widely-occurring organic-covered permafrost terrain types.