Rock glacier outflows: a distinct alpine stream type?

Alpine glaciers are predicted to significantly decrease their water contribution to European Alps ecohydrology, while rock glaciers may become increasingly important due to their slower ice loss. Different alpine stream habitat types can be distinguished according to water source. However, despite the large amount of literature available for glacier-, groundwater- and snowmelt/precipitation-fed habitats, very little is known on rockglacier-fed streams. We describe the habitat parameters of two rockglacier outflows during summer 2017, compared to streams with different water origin (two groundwater-fed, two glacier-fed, one mixed origin) in the upper Solda Valley (Eastern Italian Alps). The Solda rockglacier stream is characterized by high channel stability, low turbidity, high electrical conductivities and high Ca, Mg, PO4, Sr, As and Ba concentrations. The water chemistry of the Zay rock-glacial stream resembles the stream of mixed origin. Results suggest a potential hydroecological role of rockglacier-fed streams in the context of Alpine deglaciation.