ABSTRACT

Within Alpine catchments, glacial landforms are subject to post-depositional reworking during and following deglaciation. Ice-marginal moraines are thought to rapidly stabilise within ~200 years in this topographic context, although ice-proximal slopes are particularly prone to alteration by debris flows and solifluction. This study investigates landform transformation, documenting geomorphological change at the Bas Glacier d’Arolla, Switzerland. Gully development on a moraine slope was assessed using archive image sets obtained in 1977, 1988 and 2009 to derive historical elevation models. Raster differencing suggests that the mean rate of surface lowering on the upper moraine slope was 7.15 ± 1.83 m (± minimum level of detection) over the observation period (1977–2009), a rate of 0.22 m yr⁻¹. The erosion of the landform resulted in an incontiguous moraine crestline. Whilst some landforms may undergo limited transformation upon deglaciation, selected sites are subject to rapid geomorphologic change, involving crestline retreat via the initial dissection by gullies, followed by the removal of inter-gully slopes.

摘要

在阿尔卑斯流域内，冰川地貌在冰消期间和之后会受到沉积后的改造。在这种地形背景下，冰缘冰碛被认为会在约 200 年内迅速稳定，尽管近冰坡特别容易因泥石流和泥流而发生改变。这项研究调查了地貌转变，记录了瑞士巴斯冰川达罗拉的地貌变化。使用 1977 年、1988 年和 2009 年获得的档案图像集评估了冰碛斜坡上的沟壑发育，以得出历史高程模型。栅格差分表明，在观测期间（1977-2009），上冰碛坡地表下降的平均速率为 7.15 ± 1.83 m（± 最低检测水平），速率为 0.22 m yr ^-1。地貌的侵蚀导致了不连续的冰碛顶线。虽然一些地貌在冰川消融时可能会经历有限的转变，但选定的地点会经历快速的地貌变化，包括通过最初的沟壑分割而导致山顶线后退，然后去除沟壑间的斜坡。