Regional-scale inventory of periglacial moving landforms connected to the torrential network system

Abstract

Abstract. When connected to torrential channels, periglacial moving landforms (including rock glaciers, push moraines and high-altitude landsliding masses) may constitute important active sediment sources for gravitational and torrential transfer processes such as debris flows. However, still very little is known about the location and the number of such types of sedimentary connection in given regions, as well as about the typical sediment transfer rates that can be expected. Therefore, this contribution aims at (i) describing a new methodology developed to identify and characterize moving landforms connected to the torrential network system at a regional scale and (ii) presenting the results yielded from the application of this method in a 2000 km2 region in the southwestern Swiss Alps. The developed approach is based on the analysis of simple data such as a high-resolution digital elevation model (DEM), time series of aerial images and a slope movement inventory. The approach allowed both the fast identification of moving landforms connected to torrential channels and the estimation of annual sediment transfer rates for these inventoried landforms. In the study region, results showed that such types of sedimentary connection appeared to be rather rare. Results also showed that most connected moving landforms were characterized by relatively low sediment transfer rates (<500 m3 yr−1) but several sites were identified as transferring large amounts of sediment into the torrents (>1000 m3 yr−1). As sediment transfer rates depend on the kinematical behavior of the landforms, values calculated may change in regard to the evolution of the surface velocities, which are currently generally increasing in the European Alps. When connected to torrents, periglacial moving landforms may thus represent substantial active sources of sediments for the development of debris flows and should be considered in the management of torrential catchments.

Changes in climate patterns and their association to natural hazard distribution in South Tyrol (Eastern Italian Alps)

“…In addition, between 65 and 87 rock glaciers have been mapped for the 2016-2017 and 2017-2018 periods, respectively (from the various periods in ascending MTA) among the 240 active rock glaciers that are present in the inventory www.nature.com/scientificreports www.nature.com/scientificreports/ created by Bollmann et al 36 for the entire South Tyrol. We observe more events at higher elevations and a stronger correspondence of the MTA results with (potentially dangerous) active rock glaciers 37 (Fig. 6).…”

Investigating the slope failures at the Lou rock glacier front, French Alps

“…These hypotheses are based on previous studies investigating mass movements in permafrost terrain. For instance, the local topographical setting can be conducive to the development and propagation of debris flows due to the presence of steep slopes connecting the front of the rock glacier and the main torrential channel 7,8 . Rock glacier dynamics and stability, which are also 2/31 related to local topography [9][10][11] , can further increase the susceptibility to frontal instabilities 12,13 .…”

Introduction to the special issue of <i>Geographica Helvetica</i>: “Different approaches to landform monitoring”

“…Such programs are substantially funded by governmental authorities and performed by different institutions. Fundamental research can also contribute to the monitoring of landforms on the basis of scientific projects, as we can see from the contributions in this volume or similar earlier contributions to the topic (e.g., Lane et al, 1998). Such projects often cover shorter time periods and smaller areas but still provide useful data as reference to describe environmental changes and provide in-depth understanding of geomorphological processes.…”