Forschungsprojekt ::

SEHAG subproject 3 - Spatial and temporal changes in the geomorphic process dynamics on slopes in the Central Alps since the Little Ice Age

Dieses Projekt ist Teil des Forschungsprojektes Research Unit SEHAG - Sensitivity of high Alpine geosystems to climate change since 1850 (SEHAG)

Projektbeschreibung

High mountain geosystems react very sensitively to global warming and corresponding changes in precipitation conditions. This includes a rapid retreat of glaciers, changes in permafrost distri-bution and changes in the alpine vegetation, which, in turn, influence the discharge regime of mountain streams and have a strong impact on sediment supply from the slopes (by e.g. fluvial erosion or debris flows). However, the reaction of geosystems to changing climatic forcing is very complex and varies strongly in both, space and time due to the heterogeneity in the natural conditions. Changes in forcing (e.g. temperature, precipitation) lead to changes in the associated geosystems, which directly affect for example the availability of sediments due to retreating glaciers or melting permafrost. As a consequence the reworking of sediment deposits may lead to an increase of sediment supply to the channels. On the other hand, changes in the alpine alti-tudinal zones (e.g. rise of the tree line) can lead to a stabilization of former unstable sediment deposits by vegetation with a following decrease in the sediment supply. But changing geo-morphic activity on slopes (or the reaction of system compartments) is not only a consequence of changes in the geosystems by climate forcing. As geomorphic processes on slopes interact in complex cascading systems, the changes in the geomorphic dynamics can also be affected by system internal changes as a consequence of e.g. extreme events.

Thus the research unit SEHAG (Sensitivity of high Alpine geosystems to climate change since 1850) wants to increase the knowledge of the reactions of geosystems as well as of the geo-morphic process dynamics on climate change and will establish its investigation in three differ-ently glaciated catchments in the central Alps, situated in the north and the south of the alpine main divide. Within the research unit the subproject 3 will focus on geomorphic processes on slopes (fluvial erosion, ground avalanches, landslides and debris flows). By using historical pho-tographs (from archives), existing LiDAR observations and by present day measurements (Li-DAR, SfM), the historical and present day surface changes by geomorphic processes will be derived for several time steps since the LIA (1850AD). Additional investigations will be per-formed regarding the determination of geomorphic processes with high magnitude and low fre-quency (e.g. mapping of debris flows, dating by lichenometry, investigating lake sediments). Combining the results of all these investigations with the results of the other subprojects of the research unit (e.g. information about the climate forcing, the changes in the geosystems), the expected changes in the geomorphic process dynamics can be investigated in the context of changes in the climate forcing (due to climate change) and in the context of changes in the ge-osystems (e.g. changes in permafrost distribution, change in the vegetation). As there will be results available for all three catchments, it can be analysed if there exist differences regarding the system reactions between different areas within the Central Eastern Alps. All these results of the first funding period should make it possible to model the future system reactions (till 2050), which will be the main part of the second project period.