RGIK guidelines for compiling consistent rock glacier inventories

Rock glaciers are characteristic and ubiquitous periglacial landforms. They contain key information for understanding the past and present evolution of the mountain cryosphere, as well as for addressing a range of more applied concerns such as water supply/quality and geohazard assessment, especially in relation to ongoing climate change. Their spatial distribution and characterization, including their state of activity, has long been documented by means of rock glacier inventories (RoGIs). However, owing to the inherent morphological complexity of these landforms, contrasting definitions, and limited international cooperation, most RoGIs compiled around the globe exhibit a high degree of heterogeneity. This is a critical shortcoming that hampers our ability to combine RoGIs across regions towards the compilation of a global inventory. To address this limitation, the International Permafrost Association (IPA) Action Group (2018–2023) on Rock Glacier Inventories and Kinematics (RGIK) has fostered and coordinated international collaborative work to develop widely accepted guidelines for inventorying rock glaciers, including the characterization of kinematic behavior (RGIK, 2023a). Accordingly, a technical definition of rock glaciers and a methodological workflow for inventorying these landforms are provided. This RGIK definition relies on three morphological criteria: the mandatory evidence of a rock glacier front and adjoining lateral margins, and optionally, ridge-and-furrow topography. Deliberately, the definition does not address the questions of formative mechanism(s) and ice origin. To account for landform complexity, a hierarchical classification scheme of rock glacier units (RGUs) and systems (RGSs) is also introduced. The methodological workflow is composed of four steps: (i) detection, which consists of rock glacier identification according to the relevant morphological criteria; (ii) location, which involves assigning a georeferenced primary marker to each RGU and RGS; (iii) characterization, which among a set of optional attributes, entails assigning a geomorphological type of upslope connection and a degree of activity to each RGU; and (iv) delineation, in which the rock glacier outline is mapped and relevant degree of uncertainty is documented. Primarily, this workflow is based on a geomorphological approach, which may be supported with a kinematic approach, when reliable kinematic data is available. The coordination of ongoing testing, training, and prospective developments is entrusted to the IPA Standing Committee on RGIK, which was established in 2024. • A technical definition of rock glaciers (RGs) based on morphological criteria is provided. • A methodological workflow to reduce inventorying heterogeneity is presented. • The workflow consists of RG detection, location, characterization, and delineation. • The workflow incorporates RG kinematic information when reliable data is available. • RGIK delineation rules afford significant reduction in mapping heterogeneity.