ALPINE SUBGLACIAL HYDROLOGY

The size and shape of subglacial flow pathways exert a strong influenc e over the pressure and speed at which meltwaters are routed through g laciers. These characteristics, in turn, influence glacier sliding vel ocity and the quantity and quality of bulk meltwaters discharging from glaciers. In this paper we summarise four empirical research approach es that have been developed to improve our understanding of the subgla cial hydrology of predominantly temperate-based, alpine glaciers: inve stigations of bulk meltwater discharge and chemistry; tracer studies; proglacial bedrock investigations, and borehole investigations. As a r esult of linking these studies to conceptual or numerical models, thre e arborescent and four non-arborescent, or distributed, subglacial dra inage configurations are described. These drainage networks may be nei ther spatially nor temporally persistent, but may compete with, and re place, each other on a seasonal basis. A qualitative model of the temp oral and spatial evolution of a typical alpine subglacial drainage sys tem is advanced on the basis of research conducted at Haut Glacier d'A rolla, Switzerland. Copyright (C) 1998 Elsevier Science Ltd.