Modeling supraglacial lake drainage and its effects on the seasonal evolution of the subglacial drainage system in a tributary setting

Abstract:

A numerical scheme (GlaDS) is used to model both channelized and distributed drainage systems to see which dominates after the draining of a supraglacial lake on a synthetic glacier that is made up of an outline that features a main branch and a tributary. The geometry is based on the surge-type Black Rapids Glacier in Alaska, where a lake develops in the higher ablation zone, and drains rapidly early in the melt season. It has also been observed that this lake drainage causes a twofold or threefold speed-up of the main branch, with some acceleration of the lower-lying Lokket tributary. This speed-up can be considered a surrogate for a surge, which also initiates in the main branch, while, during times of quiescence, the ice flow on the tributary is dominant. We investigate the effects of varying timing and volume of lake drainage volume inputs with a particular emphasis on the effects of the lake drainage on the evolution of the subglacial system in the tributary.