Modeling Suspended Sediment Discharge in a Glaciated Arctic
Catchment--Lake Peters, Northeast Brooks Range, Alaska
Abstract
Seasonal suspended sediment transfer in glaciated catchments is
responsive to meteorological, geomorphological, and glacio-fluvial
conditions, and thus is a useful indicator of environmental system
dynamics. Knowledge of multifaceted fluvial sediment-transfer processes
is limited in the Arctic–a region sensitive to contemporary
environmental change. For two glaciated sub-catchments at Lake Peters,
northeast Brooks Range, Alaska, we conducted a two-year endeavor to
monitor the hydrology and meteorology, and used the data to derive
multiple-regression models of suspended sediment load. Statistical
selection of the best models shows that incorporating meteorological or
temporal explanatory variables improves performances of turbidity- and
discharge-based sediment models. The resulting modeled specific
suspended sediment yields to Lake Peters are: 33 (20-60) Mg
km-2 yr-1 in 2015, and 79 (50-140)
Mg km-2 yr-1 in 2016 (95%
confidence band estimates). In contrast to previous studies in Arctic
Alaska, fluvial suspended sediment transfer to Lake Peters was primarily
influenced by rainfall, and secondarily influenced by temperature-driven
melt processes associated with clockwise diurnal hysteresis. Despite
different sub-catchment glacier coverage, specific yields were the same
order of magnitude from the two primary inflows to Lake Peters, which
are Carnivore Creek (128 km2; 10% glacier coverage)
and Chamberlin Creek (8 km2; 23% glacier coverage).
Seasonal to longer term sediment exhaustion and/or contrasting glacier
dynamics may explain the lower than expected relative specific sediment
yield from the more heavily glacierized Chamberlin Creek catchment.
Absolute suspended sediment yield (Mg yr-1) from
Carnivore Creek to Lake Peters was 28 times greater than from Chamberlin
Creek, which we attribute to catchment size and sediment supply
differences. Our results are useful for predicting changes in fluvial
sediment transport in glaciated Arctic catchments.