Character of the subglacial drainage system in the ablation area of Dokriani glacier, India, as revealed by dye-tracer studies

Abstract

The character of the subglacial drainage system is best determined by the dye-tracer technique. Ten dye-tracer experiments were conducted at three moulins at 930, 1700 and 2300 m, respectively, from the measurement site on the Dokriani glacier, Garhwal Himalaya, India. The injections were made during July, August and September 2000. In July, the subglacial drainage appeared to be via efficient trunk channels, which resulted in dye-concentration curves with velocities between 0.37 and 0.47 m s −1. In August and September, drainage was active mainly in the inefficiently distributed system, as velocity declined and varied between 0.10 and 0.39 m s −1. Probably, the distributed system during August expanded to accommodate the increased runoff by the seasonal high discharges. Limited observations indicate that there was temporal switching between channelised and distributed drainage system.