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

INTRODUCTION

Channels of supraglacial streams develop like as those of alluvial or rock streams, but the impact of some system variables varies widely with each of these morphogenetically different environments (Knighton 1981, Leopold, Wolman 1960, Marston 1983, Park 1981). What they have in common is the formation in a homogeneous ice environment which can vary as to some properties of the ice, like its crystallographic lattice, density, thermal conductivity, cracking, and rock detritus content.

Supraglacial streams are usually devoid of sedimentary material and clastic bank material. Their development is not controlled by any vegetation. Water discharge is characterised by high velocities (up to several m s-1), is usually restricted to the ablation season, and as a rule displays a regular diurnal rhythm. Variations in the discharge produce either low- or high-energy streamflows, both at a short (diurnal) and a longer (seasonal or annual) time scale.

These features of supraglacial streams make them excellent objects for the study of channel hydraulics on the one hand, and the relief of the glacier surface in the context of ablation processes on the other. The aim of the present work is to elucidate selected mechanisms of glacier ablation as reflected in the morphological and hydraulic conditions of a supraglacial stream.