Glacial erosion and sediment transport in the Mittivakkat Glacier catchment, Ammassalik Island, southeast Greenland, 2005

摘要

A station for monitoring suspended sediment concentration with high time resolution was developed and located near the outlet from the Mittivakkat Glacier in order to monitor "true" glacial erosion. Sediment transport at 10 minute intervals for a 64-day period of the 2005 melt season was determined for the Mittivakkat Glacier catchment, southeast Greenland The total transport for the whole period was 17 800 t based on measurements with an OBS3 (optical backscatter) sensor and 17 300 t with a Partech IR500 (infrared transmissometer), with maximum transport values of 25 and 24110-min"1, respectively. The results confirm earlier measurements of specific transport of more than 1000 t km"2 year"1 from the Mittivakkat Glacier. Comparison with concentrations obtained from manual suspended sediment samples from a station near the outlet to the sea, confirm results based on earlier Caesium-1.3 7 inventories indicating that sediment is trapped in the proglacial valley between the glacier and the sea. The material produced from glacial erosion is mainly released in late July-August when the glacier drainage system is fully developed and enough melt water is available for transport.