DENDRITIC SUBGLACIAL DRAINAGE SYSTEMS IN COLD GLACIERS FORMED BY CUT-AND-CLOSURE PROCESSES

Dendritic subglacial drainage systems in cold glaciers formed by cut-and-closure processes. Geografiska Annaler: Series A, Physical Geography, 96, 591–608. doi:10.1111/ geoa.12059 ABSTRACT. The routing and storage of meltwater and the configuration of drainage systems in glaciers exert a profound influence on glacier behaviour. However, little is known about the hydrological systems of cold glaciers, which form a significant proportion of the total glacier population in the climate sensitive region of the High Arctic. Using glacio-speleological techniques, we obtained direct access to explore and survey three conduit systems and one moulin within the tongue area of Tellbreen, a small cold-based valley glacier in central Spitsbergen. More than 600 m of conduits were sur-veyed and mapped in plan, profile and cross-section view to analyse the configuration of the drainage system. The inves-tigations revealed that cold-based glaciers can exhibit a den-dritic drainage network with supra-, en- and subglacial components formed most likely by cut-and-closure processes as well as surface-to-bed drainage via moulins. Furthermore, we observed that water is stored within the glacier and released gradually via subglacial conduits during the winter months, forming a large and active icing in the proglacial area. The presence of supra-, en- and subglacial components, the surface-to-bed moulin and the dendritic subglacial drainage network suggest that existing models and understanding of the hydrology of cold glaciers needs to be re-evaluated, mostly concerning the different possible pathways and pro-cesses that form the hydrological system. Key words: cold glaciers, englacial/subglacial conduit, glacier hydrology, glacio-speleology, icings, Svalbar