Changes in sediment connectivity following glacial debuttressing in an Alpine valley system

摘要: Abstract Increasing air temperature and declining winter snowfalls are resulting in rapid glacier recession the expansion of proglacial margins Alpine regions. Such include substantial debris accumulations (e.g. frontal/lateral moraine ridges; till-covered steep valley sidewalls) which may be unstable due to glacial debuttressing. Rainfall, snowmelt ice melt out then cause mass movements. Here, we quantify decadal-scale erosion deposition patterns changes connectivity for two sidewall geomorphological systems following retreat Glacier d'Otemma, Switzerland. We apply archival digital photogrammetric methods period 1964 2009 determine high resolution elevation models. These were differenced calculate evolution sediment connectivity. found that gully headward (rates between ca. −10.6 mm/year −1002.1 mm/year) was main process during thinning but increasing depositional rates downslope gullies (ca. +21.3 +298.5 mm/year) recorded years associated with significant alluvial fan growth at slope base. While gullying enhanced by removing glacially conditioned transfer buffers, so connecting side-slopes upstream sinks (the upslope contributing area increased +73.8% +195.1% each subsystem), fans reduced rapidly enlarging forefields. The detail these responses is three generic processes: (1) wider geomorphic setting – here, presence a bastion as primary part cascade strongly influenced morphology likely length paraglacial length; (2) thickness left retreating controlled influence bedrock topographic buffers on connectivity; (3) extent diffusive drainage develop response hillslope base, tend disconnect flux. Post-glacially, development has self-limiting effect while increases connectivity, eroded leads plain reduces