Abstract Daily time lapse imagery and pixel tracking was used to monitor and track spatial and temporal changes in sediment-mantled hillslopes, during and immediately after glacier retreat in the Fox Glacier/Te Moeka o Tuawe valley, New Zealand. Observations from 2014 to 2018 of the Fox Glacier and surrounding hillslopes show hillslope failure is primarily coincident with, and triggered by, glacier retreat with rainfall accelerating movement of the hillslope. During glacier retreat, failure of the hillslope primarily occurred through sediment sliding, internal deformation of the sediment and occasional surficial debris falls, flows and avalanches delivering approximately 9.2 M m3 of sediment directly to the underside of the glacier over the study period with a maximum daily averaged movement of 0.4 m per day of the main sediment mass. Following debuttressing, hillslope failure became dominated by localised rainfall-induced debris flows which initiated gullying of the sediment-mantled slope. Ongoing instability of the slope and associated movement is maintained by toe erosion from the Fox River and melting dead ice, while continued rapid failure is facilitated through localised debris flows. The tracking of temporal and spatial changes of sediment-mantled hillslopes during glacier retreat has shown broad-scale hillslope response to occur quickly within days of rainfall or accelerated glacier retreat, particularly during summer. Debris flows, commonly thought to be a dominant erosion process within paraglacial environments, only occur following complete debuttressing and are supply-limited, only occurring after sediment sliding has occurred. Unlike many other case studies, sediment connectivity immediately following glacier retreat is high due to a lack of storage space and high rainfall inducing mass movements, efficiently delivering hillslope sediments to the proglacial stream channel. Attempts to quantify displaced volumes of sediment from paraglacial systems are likely underestimated due to a) a lack of focus on the early and latter stages of debuttressing b) a reliance on debris flows being a primary transport mechanism, and c) sediment being delivered sub-glacially rather than supra-glacially, further enhancing connectivity.

中文翻译：

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冰川初露期间和刚刚发生后沉积物斜坡的冰缘调整

摘要 新西兰福克斯冰川/Te Moeka o Tuawe 山谷冰川退缩期间和之后，每日时间推移图像和像素跟踪用于监测和跟踪沉积物覆盖的山坡的空间和时间变化。2014 年至 2018 年对福克斯冰川及周边山坡的观测表明，山坡崩塌主要与冰川退缩相一致，并由冰川退缩和降雨加速山坡运动引发。在冰川退缩期间，山坡的破坏主要是由于沉积物滑动、沉积物内部变形以及偶尔的地表碎屑掉落、流动和雪崩，在研究期间将大约 9.2 M m3 的沉积物直接输送到冰川底部，每天最大主要沉积物质量每天平均移动 0.4 m。在出土后，山坡破坏主要是由局部降雨引起的泥石流引起的，这些泥石流引发了沉积物覆盖的斜坡的沟壑。来自福克斯河的脚尖侵蚀和融化的死冰维持了斜坡的持续不稳定性和相关运动，而局部泥石流促进了持续的快速破坏。对冰川退缩过程中沉积物覆盖的山坡时空变化的跟踪表明，在降雨或冰川退缩加速的几天内，尤其是在夏季，广泛的山坡响应会迅速发生。碎屑流，通常被认为是冰河环境中的主要侵蚀过程，仅在完全初出应力后发生并且供应有限，仅在沉积物滑动发生后发生。与许多其他案例研究不同，由于缺乏储存空间和大量降雨导致大规模运动，冰川退缩后沉积物的连通性很高，有效地将山坡沉积物输送到冰川前河道。量化从冰河系系统转移的沉积物量的尝试可能被低估了，因为 a) 缺乏对初露的早期和后期阶段的关注 b) 依赖泥石流作为主要的运输机制，以及 c) 沉积物被输送到亚冰川而不是超冰川，进一步增强了连通性。