The first consistent inventory of rock glaciers and their hydrological catchments of the Austrian Alps

Abstract

A first consistent and homogenized polygon-based inventory of rock glaciers of the Austrian Alps is presented. Compiling previous inventories and updating them by using digital elevation models (1 m grid resolution) derived from airborne laser scanning yield a dataset of 5769 rock glaciers in a ca. 48400 km2 large area. A consistent methodological approach for assigning attributes, stored in a detailed attribute table, was developed and applied here to improve comparability and reproducibility. The majority (60 %) of the studied landforms is considered to be relict (no permafrost); the remaining 40 % may still contain permafrost ice and are thus classified as intact. Rock glaciers range in elevation from 476 to 3312 m a.s.l. and cover a total area of 303 km2. The distribution of rock glaciers is mainly related to the topography of the Austrian Alps and related effects such as past glaciation history.In addition, a comprehensive analysis of the hydrological catchment areas of all individual rock glaciers was carried out. A hydrological catchment analysis in rock glacier areas is of great interest for sustainable water management issues in alpine catchments as these landforms represent shallow aquifer systems with a relatively high storage and thus buffer capability, especially in crystalline bedrock areas. A total area of almost 1280 km2 is drained through rock glaciers.The presented rock glacier and rock glacier catchment inventories provide an important basis for further research, particularly for a better understanding of the hydrogeology and geomorphology of alpine catchments and their potential alteration in the light of climate change, but also in terms of paleoglaciation and deglaciation in the Alpine Lateglacial to Holocene period. As such, the inventories are seen as an important base to stimulate further research.

Rock Glacier Kinematics in the Kaunertal, Ötztal Alps, Austria

“…[47]), where rugged bedrock topography and unconsolidated sediments in the form of talus slopes, moraines and rock glaciers dominate the landscape [48]. [49]. Rock glaciers are shown as colour-coded dots scaled to the planimetric size of individual landforms.…”

“…Environmental Motion Tracking (EMT) is a feature tracking software developed by Schwalbe [56] that uses a least squares matching approach (LSM) to track image features over monoscopic image sequences. LSM matches the location of image patches, i.e., rectangular windows, by [49]. Rock glaciers are shown as colour-coded dots scaled to the planimetric size of individual landforms.…”

“…A recently updated inventory comprises 129 rock glaciers [49], covering a total surface area of 8.25 km 2 equivalent to 3.6% of the total catchment size. The distribution of intact rock glaciers in the valley suggests permafrost occurrence reaches down to around 2270 m a.s.l.…”

“…The creation of a standardized rock glacier inventory of Austria is still in progress, but many regional inventories are available [20,38,54,55]. We utilize a subset from an inventory of rock glacier polygons in Tyrol, as updated and compiled by Wagner et al (in press) [49] from the results of previous studies. For this inventory, rock glaciers were delineated by identification of creep-related morphological characteristics in shaded high-resolution digital elevation models (DEMs) and aerial images.…”

Glacial geomorphology of the Ahuriri River valley, central Southern Alps, New Zealand

“…Morphological evidence for rock glacier identification includes ridges and furrows, lateral slopes and steep front, collapse structures, flow structures and distinct changes of the slope in the rooting zone (Schmid et al, 2015). For digitisation of the individual rock glacier boundaries we also followed the most recent polygon-based rock glacier inventory by Wagner et al (2020). The distribution of rock glaciers in the Ahuriri River valley is mainly related to the local topography and climate of the Southern Alps and related effects such as Quaternary glaciation history.…”