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

近年来，史无前例的变暖和人类干扰导致了有机覆盖的永久冻土地带的实质性永久冻土退化，包括加拿大北部广大地区的北极和高山冻土带、泰加和北方地区。对多年冻土退化的机制和速率，以及后者对排水和储存模式和过程的影响，仍然缺乏了解。因此，寒区水文学面临的一个主要挑战是如何动态预测多年冻土融化的径流。这突出表明，必须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种知识，并由此产生一套新的模型来预测多年冻土对气候变暖和人类干扰的响应，以便在多年冻土融化的背景下更有信心地预测流域径流。短期目标是：1)记录研究地点在过去半个世纪中多年冻土分布的变化；2)建立关键水文过程的概念和数学模型，包括地块尺度的流动和主要地形类型之间的流动；3)研究冻土对覆盖树冠变化的响应；4)确定控制可能导致永久冻土退化的优先融化速度和模式的关键因素；5)开发一个新的模型，模拟不连续和连续的永久冻土对气候变暖和人类干扰的响应；将水文模型和多年冻土模型相结合，预测多年冻土的空间分布，以及气候变暖和人类干扰情景下的河流流态。这项研究将在西北地区Scotty Creek的湿地主导的不连续永久冻土地带进行，因为那里有丰富的数据档案，基础设施和设备高度集中，以及当地社区的兴趣和支持。广泛的成本分担和数据共享机会，加上正在进行的免费研究项目，也使Scotty Creek成为一个合理的研究地点。然而，该项目的成果意在转移到其他广泛出现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.