Impact of mountain permafrost on flow path and runoff response in a high alpine catchment

Abstract

Permafrost in high alpine catchments is expected to disappear in future warmer climates, but the hydrological impact of such changes is poorly understood. This paper investigates the flow paths and the hydrological response in a 5 km2 high alpine catchment in the Ötztal Alps, Austria, and their changes resulting from a loss of permafrost. Spatial permafrost distribution, depth to the permafrost table, and depth to the bedrock were mapped by geophysical methods. Catchment runoff and meteorological variables were monitored from June 2008 to December 2011. These data were used along with field experience to infer conceptual schemes of the dominant flow paths in four types of hillslopes that differ in terms of their unconsolidated sediment characteristics and the presence of permafrost. The four types are: talus fans, rock glaciers, Little Ice Age (LIA) till, and pre‐LIA till. Permafrost tends to occur in the first three types, but is absent from pre‐LIA till. Based on these flow path concepts, runoff was simulated for present conditions and for future conditions when permafrost has completely disappeared. The simulations indicate that complete disappearance of permafrost will reduce flood peaks by up to 17% and increase runoff during recession by up to 19%. It is argued that change modeling needs to account for flow path types and their changes based on geophysical surveys and field investigations.

After the peak water: the increasing influence of rock glaciers on alpine river systems

“…Due to their cold waters, rock glacial streams were found to decrease summer water temperature in tributaries along the river continuum, thus extending refuge areas for cold‐adapted species (Harrington, Hayashi, & Kurylyk, ). In general, rock glaciers (including fossil forms, i.e., those without ice) and other landscape features including talus bodies, moraines, and tills represent important groundwater sources (Clow et al, ; Harrington, Mozil, Hayashi, & Bentley, ; Rogger et al, ; Wagner, Pauritsch, & Winkler, ; Winkler et al, ) that are able to influence the quantity and quality of running waters in alpine catchments (Engel et al, ; Liu, Williams, & Caine, ; Weekes, Torgersen, Montgomery, Woodward, & Bolton, ). However, most research to date has focused on the hydrology of single landforms (e.g., for talus bodies, see Muir, Hayashi, & McClymont, ; for moraines, Roy, & Hayashi, ; for rock glaciers, Harrington et al, ; Winkler et al, ), and we are not aware of any study attempting a longitudinal characterization of stream conditions under their combined influence at the catchment scale.…”

Hydrological impacts of near‐surface soil warming on the Tibetan Plateau

“…In cold regions, runoff regimes are subject to strong permafrost conditions, because the presence of permafrost layer acts as a barrier to constrain soil water to recharge deeper layers 4,5 . Induced by a warmer climate, widespread degradation has occurred in soil freeze/thaw (F/T) processes on the TP, including an increase in active layer thickness and decrease in permafrost extent 6–8 .…”

Improved characterization of alpine permafrost through structurally constrained inversion of refraction seismic data

“…Methods sensitive to electrical properties are the most popular for permafrost investigations due to the contrasting electrical resistivity corresponding to lithological media (commonly related to moderate values), water (highly conductive) and ice (which is assumed to be an electrical insulator). Hence, electrical resistivity tomography (ERT) and ground penetrating radar (GPR) are widely used in permafrost studies (Hinkel et al, 25 2001;Berthling et al, 2008;Hilbich et al, 2008;Krautblatter et al, 2010;Schöner et al, 2012a;Kneisel et al, 2014;Supper et al, 2014;Kellerer-Pirklbauer and Kaufmann, 2017;Rogger et al, 2017). The main limitation in ERT refers to the necessity of the electrodes to have a good galvanic contact with the ground (Hauck, 2013;Supper et al, 2014), as required to inject high current densities and warrant an adequate signal strength.…”

“…Several studies have investigated the applicability of the refraction seismic tomography (RST) method to monitor permafrost processes such as seasonal variations in the thickness of the active layer (e.g., Hilbich, 2010;Rogger et al, 2017) and to overcome the limitations of ERT (Hilbich, 2010;Hauck et al, 2011;Draebing and 5 Krautblatter, 2012). For a detailed review of the application of refraction seismic in permafrost studies, we refer to Draebing (2016).…”