MELTWATER DRAINAGE AND SEDIMENT TRANSPORT IN A SMALL GLACIARIZED BASIN, WANDA GLACIER, KING GEORGE ISLAND, ANTARCTICA

Resumo

Basal sediment transport by efficient subglacial drainage systems is widely assumed to dominate the sediment budget of most temperate glaciers in glacimarine environments. Hydrological characteristics of the drainage system and mechanisms of basal sediment transport in Wanda Glacier, King George Island, were examined by the analyses of temporal variations of discharge and sediment load in the proglacial channels. In the investigation about the variability of sediment load transfer to Admiralty Bay, we analyzed the control of the drainage system, thermal conditions, ice flow velocity, topography and meteorological conditions in the period. Data collected on January 2010 and 2011 show the control of the subglacial drainage configuration on rates of basal sediment evacuation and delivery by subglacial meltwater to glacimarine environment. Thus, such data demonstrate a strong relation between suspended sediment load, water discharge and air temperature, radiation and precipitation rate. High sediment concentrations recorded in proglacial channels are related to efficient rates of basal sediment transport, thus, indicate sediment yield availability to Martel Inlet glacimarine environment. Direct measurements of sediment in proglacial channels allowed the estimation of the actual sedimentary contribution of 19.49 kg s-3 to the glacimarine environment. Sediment load is an indicator of erosion and sediment yield processes beneath the glacier. These processes are interconnected with the high summer temperatures presented, responsible for the relatively high rates of meltwater production and the sediment supply to glacimarine environment and with consequences for the sediment dynamics of the study area.