Impact of relict rock glaciers on spring and stream flow of alpine watersheds: Examples of the Niedere Tauern Range, Eastern Alps (Austria)

In crystalline mountain regions, relict rock glaciers are apparent sediment accumulations that likely influence the runoff in alpine watersheds as a result of their discharge behavior. However, little is known about their impact on the streamflow further downstream. More than 560 mostly relict rock glacier-related landforms have been identified in the Styrian part of the Niedere Tauern Range (Austria). The catchment of a single relict rock glacier (Schoneben Rock Glacier, SRG), and two catchments with relict rock glaciers in their headwaters were investigated with a simple lumped-parameter rainfall-runoff model. The model parameters of the SRG catchment are in agreement with the existing conceptual understanding of the discharge dynamics and provide the parameter configuration to simulate the runoff of ungauged relict rock glacier catchments in the area. In addition, a semi-distributed approach-was applied to quantify the impact of relict rock glacier-influenced headwaters on the downstream runoff. The results suggest that the contribution ranges from about a quarter to more than four times its areal share. The highest impact is observed during the late snow melt period and in the late summer. This highlights the relevance of these sediment accumulations in relation to water management issues, in particular concerning altering meteorological conditions due to climate change.