SEASONAL AND DIURNAL FLUCTUATIONS IN SUSPENDED SEDIMENT CONCENTRATIONS IN GLACIAL MELTWATER ON MOUNT RAINIER, WASHINGTON

Mount Rainier is the most glaciated peak in the conterminous United States, offering a valuable laboratory for studying glacial processes. This study examines the sensitivity of suspended sediment concentrations (SSC) in glacial meltwater to meteorological conditions. We collected meltwater from Emmons and Nisqually Glaciers, as close to the glacier termini as possible, and filtered these samples to find the concentration of sediment per liter of water. Meltwater discharge was estimated in order to determine the relationship between discharge and suspended sediment transport. Our measurements suggest that the diurnal minimum of SSC is in the morning, while peak concentrations are in the evening, following the warmest part of the day. Our data also show a delayed or prolonged SSC minimum on cloudy mornings; SSCs in meltwater from Nisqually Glacier decreases over two days from 3,170 mg/L to 750 mg/L, as conditions changed from sunny to cloudy with rain. SSCs in glacial meltwater also decrease as the ablation season progresses; previous studies suggest that this change occurs due to a decrease in available sediment beneath the glacier. Analysis of meltwater from Nisqually Glacier in October reveals the opening of and evacuation of sediment from the subglacial environment in response to a rain event.

Session No. 158--Booth# 125

T184. Geologic Research at Mount Rainier and Other Cascade Volcanoes: Ideal Natural Laboratories for Cutting-Edge Research with Implications to Life Safety and Infrastructure Protection in the Pacific Northwest (Posters)

Monday, 23 October 2017: 9:00 AM-6:30 PM

Halls 4EF (Washington State Convention Center)

Geological Society of America Abstracts with Programs. Vol. 49, No. 6
doi: 10.1130/abs/2017AM-308075

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