Abstract ID: 28.7490 | Accepted as Talk | Talk | 2025-02-27 17:00 - 17:15 | Ágnes‐Heller‐Haus/Small Lecture Room

Aufeis is an important yet one of the least studied components of the mountain cryosphere in the Trans-Himalaya. These seasonal laminated sheet-like ice masses form in winter by successive freezing of overflowing water that seeps from the ground, a spring or emerges from below river ice. In the Trans-Himalaya of Ladakh, water stored in aufeis fields serves as an important water source for irrigation and pastoral communities. In some villages, aufeis accumulation is enhanced in ice reservoirs (commonly known as “artificial glaciers”) since decades to store the winter baseflow for irrigation during the water scare period in spring. Despite this importance, research on aufeis in the region is still at the beginning.
In previous studies we have already revealed the widespread occurrence of aufeis across the Trans-Himalaya in an elevation between 4000 and 5500 m a.s.l. The largest aufeis field covers an area of 14 km², which is almost triple the size of the largest high-altitude glaciers in Central Ladakh. While mapping the spatial extent of aufeis can be effectively mapped with well-established remote sensing methods, aufeis thickness estimations are more challenging but an essential first step towards an improved understanding of the mountain water cycle.

For this study we have selected four case study sites: two ice reservoirs (Phuktse & Igoo) and two catchments (Gya and Sasoma) with natural aufeis occurrence. We demonstrate the unexplored potential of differencing digital elevation models (DEM) calculated from very high-resolution stereo Pléiades satellite data and terrestrial photographs for aufeis studies.

DEM differencing revealed substantial amounts of aufeis volumes across the four study sites ranging from 44,969m³ in Phuktse up to 105,790m³ in Sasoma. Ice thickness in both ice reservoirs reaches up to 2.8 m, while natural aufeis fields occasionally even exceed thickness over 3 m. Very high-resolution stereo satellite imagery represents promising datasets for aufeis studies on large spatial scales. They can fill an observation gap that is induced by the inaccessibility and remoteness of many aufeis-prone area and large sizes of individual aufeis fields. Point clouds and DEMs from terrestrial photographs revealed a high level of detail that is especially useful for in-depth studies of aufeis morphology and seasonal dynamics. In the context of ice reservoirs, the usage of terrestrial images obtained through, e.g. trail cameras, could help to closely monitor aufeis development and to develop sustainable water management strategies.

Our study does not only provide the first quantification of aufeis volumes in the Trans-Himalaya. It also contributes to ongoing efforts to implement and validate existing remote sensing methods for aufeis studies on regional scales. It highlights the need to study lesser-known cryospheric components to enhance our understanding of the mountain hydrology. This might help to shed light on key factors that play a significant role in aufeis formation, such as groundwater distribution that is still unknown for most parts of the Trans-Himalaya.