Runoff generation in thawing discontinuous permafrost terrains

融化的不连续永久冻土地形中径流的产生

• 批准号: RGPIN-2015-04719
• 负责人: Quinton, William
• 金额: $ 2.4万
• 依托单位: Wilfrid Laurier University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=613124
• 关键词: Runoff; generation; thawing; discontinuous; permafrost

The southern Taiga Plains ecoregion is one of the most rapidly warming regions on Earth, and is experiencing unprecedented rates of industrial expansion and related human disturbance. The permafrost in this region is relatively warm, thin and discontinuous. As a result, permafrost thaw is widespread and often leads to the transformation of forested permafrost terrains to permafrost-free, tree-less wetlands. Such permafrost thaw-induced landcover change has the potential to disrupt the hydrological cycle. However, the hydrological implications of this permafrost-thaw induced land cover transformation remain poorly understood despite its demonstrated pan-arctic occurrence. As a result, there is an urgent need for an improved understanding of, and ability to predict permafrost thaw and its hydrological consequences. My research programme will develop and mobilise new knowledge on permafrost thaw-induced land-cover change and the resulting hydrological impact; and use this new knowledge to develop a new suite of predictive hydrological modelling tools. Field measurements will concentrate on three observatories located along a ~300 km south-to-north transect extending over the peatland-dominated southern fringe of discontinuous permafrost. This transect is ideally suited for the study of permafrost thaw-induced changes to ecosystems and the resulting impacts on surface hydrology, since it covers a wide range of permafrost ecosystem characteristics along a climate gradient. The following specific objectives will be met at each node: 1) Map the changing spatial distribution of permafrost, wetland and forest coverage over the past 60 years; 2) For different ground thaw and moisture conditions, conduct field studies to improve the understanding of the volume and timing of runoff; 3) Simulate the major water flux and storage processes controlling runoff; 4) Improve the ability to characterize permafrost impacts at larger scales through field investigation and subsequent adaptation of a regional-scale permafrost model; and 5) Estimate future quantities of runoff and surface water storage under possible scenarios of climate warming and human disturbance. Improved knowledge and predictive capacity of permafrost thaw patterns, rates, impacts and feedbacks will improve water planning, management and security by reducing the uncertainty on the future availability of freshwater, and enable better mitigation strategies to offset negative impacts.

南部泰加平原生态区是地球上变暖最快的地区之一，正在经历前所未有的工业扩张速度和相关的人类干扰。该地区的多年冻土相对较暖、较薄且不连续。因此，多年冻土融化很普遍，常常导致有森林的永久冻土地带转变为无永久冻土、没有树木的湿地。这种由永久冻土融化引起的土地覆盖变化有可能扰乱水文循环。然而，这种永久冻土融化引起的土地覆盖变化的水文影响仍然鲜为人知，尽管它被证明存在于泛北极地区。因此，迫切需要提高对永久冻土融化及其水文后果的理解和预测能力。我的研究计划将发展和调动关于永久冻土融化引起的土地覆盖变化和由此产生的水文影响的新知识；并利用这些新知识开发一套新的预测水文模型工具。现场测量将集中在三个观测站上，这些观测站位于南向北约300公里的横断面上，横跨以泥炭为主的不连续永久冻土的南部边缘。这一样带非常适合研究多年冻土融化引起的生态系统变化及其对地表水文的影响，因为它涵盖了沿气候梯度的一系列永久冻土生态系统特征。将在每个节点实现以下具体目标：1)绘制过去60年来多年冻土、湿地和森林覆盖率变化的空间分布图；2)针对不同的地面融化和水分条件，进行实地研究，以增进对径流量和径流时间的理解；3)模拟控制径流的主要水通量和储存过程；4)通过实地调查和随后的区域尺度永冻模型调整，提高描述更大规模永冻土影响的能力；以及5)在气候变暖和人类干扰的可能情景下，估计未来的径流量和地表水储存量。提高对永久冻土融化模式、融化速度、影响和反馈的认识和预测能力，将减少未来淡水供应的不确定性，从而改善水规划、管理和安全，并使更好的缓解战略能够抵消负面影响。