Sediment Concentration in Melt Waters as an Indicator of Erosion Processes Beneath an Alpine Glacier

Abstract

Suspended-sediment concentrations in melt waters from the Gornera, Gornergletscher, Switzerland, were determined at hourly intervals for periods during the ablation seasons of 1974 and 1975. Rapid erratic fluctuations of suspended-sediment concentration produced peaks which occurred both before and after highest daily flows. Clockwise daily hysteresis rating loops between sediment concentration and discharge included many involutions. Suspended-sediment-concentration-discharge rating curves were different for rising and falling limbs of individual diurnal hydrographs and varied from day to day. Close-interval measurements of sediment concentration and discharge records allow interpretation of the nature of ice–water–sediment interactions at the bed of an Alpine glacier. At Gornergletscher, subglacial sediment is delivered to melt waters flowing in the smaller basal conduits, which often change course suddenly, entraining unworked sediment stored at the bed. During diurnal discharge maxima, sediment concentration in the Gornera is reduced because the rate of increase of water volume outstrips the rate of supply of sediment. The drainage of the ice-dammed lake Gornersee, producing exceptionally high flows, extended the drainage network over large areas of the glacier bed, and evacuated much sediment.

Composite suspended sediment particles and flocculation in glacial meltwaters: preliminary evidence from Alpine and Himalayan basins

“…In addition, monitoring the downstream passage of a glacially sourced suspended sediment pulse may provide further insights into freshwater flocculation processes (including electrochemical mechanisms), since both the proportion of organic matter and bacterial activity are likely to increase downstream; see Petticrew, (1996) and Droppo et al (1997). Equally, information on the mineralogy, structure and abundance of source-derived aggregated suspended particles may provide insights into the nature of the sub-glacial drainage system and sediment sources; see Eyles (1978), Collins (1979Collins ( , 1989, and Foster et al (2000). Droppo et al (1998) have shown that suspended sediment transport to and within the Mackenzie River Delta in the subarctic zone of Northern Canada is dominated by composite particles (flocs).…”

Energy Dissipation During Subglacial Abrasion at Nisqually Glacier, Washington, U.S.A.

“…Integration of daily mass-flux measurements through time, when observations are lacking, can be a serious error if extraordinary, short-term releases of water and sediment are overlooked (0strem, [CI97SJ;Collins, 1979).…”

Hydrology, erosion and sediment production in a surging glacier: Variegated Glacier, Alaska, 1982–83

“…The characteristics of streams draining from a glacier can be used to infer the properties of the drainage system in the glacier (Collins, 1978(Collins, , 1979Tranter and Raiswell, 1991;Fountain, 1992 ) and coupling between the drainage system and glacier motion (Humphrey and others, 1986). In order to provide information about the evolution of the drainage system of Variegated Glacier, Alaska, U.S.A., as it changed between surging and nonsurging states, its outlet streams were observed from 1980 to 1985.…”