Hydraulics of Channelized Flow in Ice‐Supersaturated Debris: 1. Rock Glacier Hydrology in Alpine Glacial‐Periglacial Systems

• Published in: Water resources research Vol. 61; no. 2
• Main Authors: Seelig, Magdalena, Seelig, Simon, Krainer, Karl, Winkler, Gerfried
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 01.02.2025
• Subjects: alpine aquifer; Aquifers; Austrian Alps; channel network; Channels; energy; Energy dissipation; Energy exchange; Energy losses; Feedback loops; Flow distribution; Flow pattern; Flow system; Fluid flow; fluid mechanics; Fluorescence; Friction resistance; Glacial drift; Glacier hydrology; Glaciers; Groundwater; Groundwater flow; Heat transfer; Hydraulic properties; Hydraulics; hydrograph; Hydrology; ice; lakes; landscapes; Moraines; Permafrost; Permafrost thaws; Porous media; Rock; rock glacier; Rock glaciers; Rocks; sediments; Slope stability; Soil degradation; Solute transport; Solutes; Spatial distribution; spring; talus; tracer test; Tracers; water; Water springs
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2024WR037235

Frozen sediment accumulations, including rock glaciers, talus, and moraines, constitute complex aquifers in permafrost‐affected terrain. The spatial distribution of permafrost ice largely governs the flow of water through the subsurface, which exhibits a spectrum of flow patterns, ranging from diffuse flow through a porous matrix to concentrated flow along discrete channels. This study characterizes the groundwater flow system within three active rock glaciers drained by springs in the Austrian Alps. We study the alteration of recharge pulses traveling through the rock glaciers to decipher the dominant flow pattern. Key hydraulic properties are explored through a combined evaluation of spring hydrographs and fluorescence tracer tests. Water predominantly flows through a network of channels within the frozen subsurface. This flow is rapid and highly turbulent, implying high energy dissipation and effective heat transfer. Although the channels exhibit large hydraulic diameters, their irregular structure contributes to exceptionally high frictional resistance. These high energy losses accelerate the melting process and promote flow‐melt feedback loops, driving permafrost degradation and facilitating flow concentration. Ultimately, the hydraulic properties of these channel networks influence permafrost thaw, solute transport, lake outburst hazards, and slope stability. Key Points Water flowing through active rock glaciers is concentrated along a network of channels on top and within their frozen core Flow along the channels is rapid, turbulent, and subject to substantial frictional resistance Effective heat transfer along the channels drives the expansion of channel networks and amplifies their hydrologic connectivity