Thaw-driven mass wasting couples slopes with downstream systems, and effects propagate through Arctic drainage networks
Thaw-driven mass wasting couples slopes with downstream systems, and effects propagate through Arctic drainage networks
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DOI：
10.5194/tc-15-3059-2021
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发表时间：
2021-07-06
期刊：
影响因子：
5.2
通讯作者：
Zolkos, Scott
中科院分区：
文献类型：
--
作者：
Kokelj, Steven, V;Kokoszka, Justin;Zolkos, Scott
融化驱动的大量浪费的加剧正在改变冰川条件下的永久冻土地形，将斜坡与水生系统耦合在一起，并引发一系列下游影响。在近期快速演变的气候对多年冻土地形地貌的控制背景下，我们(A)量化了三维退行性融化崩塌扩大，并描述了斜坡与下游系统的耦合过程和阈值，(B)调查了坡面热岩溶影响的集水尺度模式及其地貌影响，以及(C)绘制了影响通过排干加拿大西北部永久冻土地形的水文网络的传播图。退行性融化崩塌面积与体积(R2=0.90)和多年冻土融化厚度(R2=0.63)之间的幂函数关系，结合1986年至2018年融化崩塌扰动面积的数十年增加，表明流域尺度的地貌活动和坡度与水文系统的耦合增加了2个数量级。主要影响是对一级和二级河流的影响，这些河流的泥沙输送通常由最近形成的碎屑舌沉积表示，通常比源头河流的输送能力高出数量级，表明下游系统受到百年至千年尺度的扰动。对水文网的评估表明，融化导致的大规模消融直接影响到994860公里(2)研究区域内5538公里的河段、889公里的海岸线和1379个湖泊。斜坡热岩溶的向下传播表明，受影响的湖泊数量可能增加至少4倍(n>；5692)，受影响的河流长度可能增加8倍(>；44343公里)，并确定了对湖泊、三角洲和沿海地区的几个主要影响区。威尔士亲王海峡的海洋环境极大地增加了从班克斯岛和维多利亚岛排水的众多受滑坡影响的水文网络中的沉积物和地球化学通量。皮尔河和麦肯齐河是斜坡热岩溶瀑布的全球重要传送带，为北美最大的北极三角洲和波弗特海带来了影响。气候驱动的多年冻土保存的冰川地形富冰斜坡的侵蚀，引发了下游效应的时间瞬变级联，标志着后冰川时期景观演变的复兴。冰川遗产、地面冰条件和大陆排水模式决定了加拿大西部北极的陆地、淡水、沿海和海洋环境将在未来数千年里成为融化驱动变化的相互关联的热点。
The intensification of thaw-driven mass wasting is transforming glacially conditioned permafrost terrain, coupling slopes with aquatic systems, and triggering a cascade of downstream effects. Within the context of recent, rapidly evolving climate controls on the geomorphology of permafrost terrain, we (A) quantify three-dimensional retrogressive thaw slump enlargement and describe the processes and thresholds coupling slopes to downstream systems, (B) investigate catchment-scale patterns of slope thermokarst impacts and the geomorphic implications, and (C) map the propagation of effects through hydrological networks draining permafrost terrain of northwestern Canada. Power-law relationships between retrogressive thaw slump area and volume (R-2 = 0.90), as well as the thickness of permafrost thawed (R-2 = 0.63), combined with the multi-decadal (1986-2018) increase in the areal extent of thaw slump disturbance, show a 2 order of magnitude increase in catchment-scale geomorphic activity and the coupling of slope and hydrological systems. Predominant effects are to first- and second-order streams where sediment delivery, often indicated by formation of recent debris tongue deposits, commonly exceeds the transport capacity of headwater streams by orders of magnitude, signaling centennial- to millennial-scale perturbation of downstream systems. Assessment of hydrological networks indicates that thaw-driven mass wasting directly affects over 5538 km of stream segments, 889 km of coastline, and 1379 lakes in the 994 860 km(2) study area. Downstream propagation of slope thermokarst indicates a potential increase in the number of affected lakes by at least a factor of 4 (n > 5692) and impacted stream length by a factor of 8 (> 44343 km), and it defines several major impact zones on lakes, deltas, and coastal areas. Prince of Wales Strait is the receiving marine environment for greatly increased sediment and geochemical fluxes from numerous slump-impacted hydrological networks draining Banks Island and Victoria Island. The Peel and Mackenzie rivers are globally significant conveyors of the slope thermokarst cascade, delivering effects to North America's largest Arctic delta and the Beaufort Sea. Climate-driven erosion of ice-rich slopes in permafrost-preserved glaciated terrain has triggered a time-transient cascade of downstream effects that signal the rejuvenation of post-glacial landscape evolution. Glacial legacy, ground-ice conditions, and continental drainage patterns dictate that terrestrial, freshwater, coastal, and marine environments of western Arctic Canada will be an interconnected hotspot of thaw-driven change through the coming millennia.