The seasonal fields of aufeis (icing) are an important resource for the water supply of the local population in the upper Indus basin. However, little research has been done on them so far. Geographers at the South Asian Institute at Heidelberg University have now examined the spread of aufeis and, for the first time, have created a comprehensive inventory of these fields of aufeis. The more than 3,700 accumulations of stratified ice are important for these high mountain regions located between South Asia and Central Asia, particularly with regard to hydrology and climatology.
In the semi-arid regions of the Himalayas of India and Pakistan, water from snowmelt and glaciers plays an essential role for irrigation in local agriculture and hydropower generation. In this context, aufeis has received little attention. It is in the form of thin layers of sheet-shaped ice that are formed by successive freezing of water and can reach several meters in thickness. This phenomenon occurs on a seasonal basis under watersheds, along streams or streams under conditions of frequent freeze-thaw cycles. “In some cases, this process is deliberately promoted by the construction of stone walls. These artificial reservoirs are used in some valleys of the tributaries of the Haut-Indus as water harvesting measures to fill the seasonal water shortage in the spring. However, the amount of ice, size and number of natural fields of aufeis has so far been unknown, ”emphasizes Professor Dr Marcus Nüsser of the South Asian Institute at the University of Heidelberg.
The geographers of Heidelberg have now drawn up an inventory of these fields for the entire Haut-Indus basin and, in this context, also analyzed the role of topographical parameters such as altitude and slope. The basis was several field campaigns carried out in the region as well as the evaluation of nearly 8,300 Landsat satellite images taken between 2010 and 2020. With this imagery, scientists were able to record the characteristic seasonal formation of aufeis and map the bodies of recurring ice every year. . They detected more than 3,700 aufeis fields, covering a total area of around 300 square kilometers. The majority of aufeis fields are found in the Trans-Himalayas of Ladakh and on the Tibetan plateau. On the other hand, they hardly occur at all in the western part of the Haut-Indus region, explains Marcus Nüsser.
The study is part of a project funded by the German Foundation for Research into the importance of aufeis and ice reservoirs for people and agriculture in the Indian region of Ladakh. Participating scientists are studying the effectiveness of different types of ice reservoirs and whether they operate efficiently on a seasonal basis. “Climate change is altering both the rate of melt and the annual runoff schedule, leading to increasing uncertainties for irrigated agriculture,” says Professor Nüsser. “Our findings can help identify suitable locations for ice reservoirs that can improve seasonal water availability for local agriculture. In addition, we will investigate to what extent aufeis bodies can serve as appropriate indicators of climate change.
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