E l e c t r o n i c   r e p r i n t


HYDRAULIC GEOMETRY
OF A SUPRAGLACIAL STREAM,

RAGNARBREEN, SPITSBERGEN

Andrzej Kostrzewski and Zbigniew Zwolinski

CATCHMENTS OF SUPRAGLACIAL STREAMS

In their classifications of the Spitsbergen catchments, neither Pulina (1986) nor Leszkiewicz (1987) consider those of glacial streams. They both treat them as subcatchments within larger drainage systems of glaciated areas. By the classification criteria adopted by Leszkiewicz (1987), that is, the kind of alimentation and drainage as well as the degree of terrain glaciation, the catchments of supraglacial streams are extremely diversified in the polar geomorphic environment of Spitsbergen, and not only there. Their main features include: on the one hand, supply by meltwater (a nival regime), ablation water (a glacial regime), and to a lesser degree rainwater (a pluvial regime), the flow of water on a glacier substratum, and short-term variations (seasonal fluctuations) in the intensity of water circulation; on the other hand, a long-term recovery (recurrence every few years) of the circulation routes of the waters, their free and artesian flows, and the likelihood of the Stenborg's effect (cf. also Baranowski 1977, Clayton 1964, Dozier 1976, Ewing 1970, Ferguson 1973, Knighton 1985, Leszkiewicz (1987), Marston 1983, Rozkowski 1980). In this situation it seems justified distinguishing a type of glacier stream catchments which can be further divided into 3 subtypes: catchments of supraglacial, englacial and subglacial streams.

Glacier streams flowing on the surface of a glacier, inside, or under it, greatly influence its ablation relief. The role of supraglacial streams is especially prominent here. Moreover, their development affects the complexity of englacial and subglacial systems. The supraglacial stream network is relatively easily accessible, and hence available for measurements of various kinds. This does not mean, however, that it is possible to define e.g. the boundaries of their catchments or their water balance with any precision. Still, the study of some channel parameters of supraglacial streams provides an insight into the mechanisms of their development, and hence into relief formation on a glacier surface.