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.