Fluvial suspended sediment yields over hours to millennia in the High Arctic at proglacial Lake Linnévatnet, Svalbard

• Main Authors: Schiefer, Erik, Kaufman, Darrell, McKay, Nicholas, Retelle, Michael, Werner, Al, Roof, Steven R.
• Format: Text
• Language: unknown
• Published: SCARAB 2018
• Subjects: fluvial monitoring; Linnévatnet; sediment traps; sediment yield; varves; Arctic; Svalbard; glacier
• Online Access: https://scarab.bates.edu/faculty_publications/73

Sediment yield can be a sensitive indicator of catchment dynamics and environmental change. For a glacierized catchment in the High Arctic, we compiled and analyzed diverse sediment transfer data, spanning a wide range of temporal scales, to quantify catchment yields and explore landscape response to past and ongoing hydroclimatic variability. The dataset integrates rates of lake sedimentation from correlated varve records and repeated annual and seasonal sediment traps, augmented by multi-year lake and fluvial monitoring. Consistent spatial patterns of deposition enabled reconstruction of catchment yields from varve- and trap-based fluxes. We used hydroclimatic data and multivariate modeling to examine annual controls of sediment delivery over almost a century, and to examine shorter-term controls of sediment transfer during peak glacier melt. Particle-size analyses, especially for annual sediment traps, were used to further infer sediment transfer mechanisms and timing. Through the Medieval Warm Period and Little Ice Age, there were no apparent multi-century trends in lake sedimentation rates, which were over three times greater than those during the mid-Holocene when glaciers were diminished. Twentieth-century sedimentation rates were greater than those of previous millennia, with a mid-century step increase in mean yield from 240 to 425 Mg km−2 yr−1. Annual yields through the twentieth century showed significant positive relations with spring/summer temperature, rainfall, and peak discharge conditions. This finding is significant for the future of sediment transfer at Linnévatnet, and perhaps more broadly in the Arctic, where continued increases in temperature and rainfall are projected. For 2004–2010, annual yields ranged from 294 to 1330 Mg km−2 yr−1. Sediment trap volumes and particle-size variations indicate that recent annual yields were largely dominated by spring to early summer transfer of relatively coarse-grained sediment. Fluvial monitoring showed daily to hourly sediment transfer to be related to current and prior discharge, diurnal hysteresis, air temperature, and precipitation.