Spring water characteristics in the marginal permafrost region of the Southern Carpathians

Permafrost is defined as the ground (including soil or rock) that remains at or below 0°C for a minimum of two consecutive years (Harris et al., 1988). Due to permafrost`s sensitivity to climate change, it is essential to study the hydrology of rock glaciers to predict and mitigate the impacts of climate-induced changes, including permafrost thaw.

Physico-chemical analyses along with temperature monitoring of springs seeping from the base of the rock glacier fronts were conducted over two consecutive years (2022 and 2023) in various glacial valleys in the central part of the Retezat Mountains.

The measurement of spring water temperature during late summer (SWTS) is employed to discern permafrost distribution in alpine regions. According to previous studies (Frauenfelder et al., 1998; Scapozza, 2009), a water temperature above 2°C indicates the absence of permafrost, while a temperature between 1 and 2°C indicates the possible presence of permafrost, and a temperature below 1°C indicates that permafrost is likely.

In this study physico-chemical and isotopic analyses along with temperature measurements were conducted on springs not originating from rock glaciers, serving as a comparative approach.

The springs associated to rock glaciers draw water from four sources: groundwater, rain, snow and permafrost (Krainer et al., 2007). Among these, snow and permafrost are the primary sources that regulate the low spring temperatures. The cooling effect of a persistent snow layer in mountainous regions such as the Retezat Mountains can have significant influence on spring water temperatures even in the summer months. After snow melts, the presence of permafrost mainly governs the low temperatures of the springs. Only four springs exhibited temperatures below 2°C during the warm season, while many others showed temperatures close to 2-3°C. Given the patchy occurrence of permafrost in the Southern Carpathians and the fact that the frozen materials are located a few hundred meters away from the rock glacier front we hypothesize that permafrost may also be present in rock glaciers characterized by spring temperatures above 2°C. Based solely on the results of physico-chemical analysis, it is impossible to differentiate whether the spring water originates from ice or snow.

KEYWORDS: permafrost, spring water, rock glaciers, SWTS

REFERENCES

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Harris, S.A., French, H.M., Heginbottom, J.A., Johnston, G.H., Ladanyi, B., Sego, D.C., van Everdingen, R.O., 1988, Glossary of Permafrost and Related Ground-Ice Terms, National Research Council of Canada, Ottawa, 156 p.

Krainer, K., Mostler, W. & Spötl, C. (2007). Discharge from active rock glaciers, Austrian Alps: a stable isotope approach. Austrian Journal of Earth Sciences 100: 102–112.

Scapozza, C. (2009). Contributo dei metodi termici alla prospezione del permafrost montano: esempi dal massiccio della Cima di Gana Bianca (Val Blenio, Svizzera). Bollettino della Società Ticinese di Scienze Naturali 97: 55–66.