Topographic primacy in rock glacier distribution revealed by GAMs and their water storage: Insights from a new polygonised inventory of the southeastern Tibetan Plateau

Rock glaciers constitute essential freshwater reservoirs in high-mountain regions. Despite their hydrological and ecological importance, few studies have been conducted in the southeastern Tibetan Plateau. Existing research exploring their drivers and predicting their distribution has been limited due to historically restricted datasets and the application of a limited number of drivers. We mapped 9543 rock glaciers and comprehensively analysed their spatial distribution against an extensive suite of environmental variables by leveraging emerging global and regional datasets. The rock glaciers in this area have distinct morphometric characteristics (mean length = 601 m; area = 0.1 km²; elevation = 4558 m a.s.l.; slope = 20.8°) and show predominant N-NW aspect orientation. They present on certain climatic conditions (mean annual temperature = −3.2 °C; annual precipitation = 769 mm; mean annual ground temperature = 0.9 °C; annual snow duration = 227 days; snow index = 22.1). Generalized additive modelling combining factors from multiple environmental categories demonstrated superior performance, indicating complex controls on rock glacier formation. Our analyses reveal that while climatic and cryospheric factors exhibit strong correlations, topographic variables, particularly relief, serve as more robust predictors of rock glacier distribution. Hydrologically, these features store 0.3–0.8 times the water equivalent of modern glaciers, highlighting their importance for regional water storage and downstream supply. Observed vegetation expansion at lower elevations suggests ongoing periglacial stabilization, a process projected to intensify with climate warming. These findings emphasize the critical need for systematic monitoring of rock glaciers as both climate-sensitive indicators and vital components of mountain water cycles.