Hydrology of Active Rock Glaciers: Examples from the Austrian Alps

Abstract

Hydrological investigations of three active rock glaciers in the Austrian Alps (Reichenkar rock glacier in the western Stubai Alps, Kaiserberg rock glacier in the western Ötztal Alps, and Gößnitz rock glacier in the Schobergruppe) demonstrate that discharge is mainly controlled by the local weather conditions, the thermal properties of the debris layer, and the physical mechanisms that control the flow of meltwater through the rock glacier. Discharge of active rock glaciers is characterized by strong seasonal and diurnal variations. Water derived from snowmelt and summer thunderstorms is quickly released causing floods. Fair weather periods with intense melting of snow and ice cause pronounced diurnal variations in discharge. Water temperature of active rock glacier springs is constantly below 1°C during the whole melt season. Electrical conductivity of the water is low during high discharges due to high amounts of meltwater derived from snow/icemelt and/or precipitation, and high during cold weather periods and in autumn when discharge is very low and consists mainly of groundwater. The discharge pattern of active rock glaciers is similar to that of glaciers due to similar meltwater sources and flow paths. However, the average yearly mean specific discharge from active rock glaciers is significantly lower than that of glaciers.