Digital elevation model provides information about the Aufey field in the Trans-Himalayan region

A team of geographers from Heidelberg University’s South Asia Institute studied the thickness and volume of the previously unexplored Aufey field in the trans-Himalayan region of Ladakh, India.

The team, led by Professor Marcus Nusser, used high-resolution remote sensing data and digital terrain models from ground imagery to compare the volumes of naturally occurring and artificially created ice reservoirs. Differences between winter and summer topographic models provide information about the nature of seasonal ice deposits and their underlying hydrogeological conditions.

Ophei is a hydrological phenomenon that occurs especially in cold, dry and permafrost regions. It is caused by continuous freezing of spring water or along small rivers during the winter. The ice layer can reach a thickness of several meters and contributes significantly to local water supplies, especially in spring.

In the Trans-Himalayan region of Ladakh, aufei accumulation can increase in ice reservoirs. Previous studies had already established that aufei are widely distributed in parts of Ladakh and the Tibetan Plateau.

With the aim of gaining new insights into the composition of these seasonal ice accumulations, Professor Nusser’s team investigated two natural Aufei fields and two artificially created ice reservoirs in Ladakh. The thickness and volume were investigated.

During field visits in fall 2022 and spring 2023, researchers took thousands of photos of both ice reservoirs and combined them with images from all four Pleiades satellites during the site visit. The team then generated a digital elevation model and calculated a total Aufei volume of up to 302,000 cubic meters.

Natural aufei fields were found to be larger in area and thicker than ice accumulated in artificial reservoirs, with ice thickness exceeding 3 meters in isolated cases.

Current findings indicate that large amounts of groundwater reach the surface during the winter. Since water overflows occur at the same location every year, the formation of Aufei fields could provide information about the hydrogeological properties of near-surface aquifers, says Dr. Dagmar Blombierstaudl. explains.

“Our study shows that the Aufei field is not isolated, but widely distributed and holds large amounts of water. Nevertheless, this phenomenon is not observed in hydrological models. It has not been taken into account yet,” Professor Nusser emphasizes.

High-resolution satellite imagery has proven particularly valuable for analysis of the Aufei field. “Images allow us to study even remote and inaccessible locations. This allows us to draw deep conclusions about the formation and composition of the Aufey field, resulting in a better understanding of the Aufey phenomenon. “We will be able to deepen our understanding of climate change and determine the impact of climate change.” A scientist who serves as the head of the geography department at the South Asia Institute at Heidelberg University.

This research work was carried out as part of a project on the importance of aufei and ice reservoirs in climate change adaptation in the Trans-Himalayan region of Ladakh. The research results were published in the journal Science of the Total Environment.