Bedload transport and sediment yield in the Onyx River, Antarctica

Abstract

AbstractBedload transport measurements were made in a braided reach of the Onyx River, Wright Valley, Antarctica, during summer 1984/85. Transport was predominantly of sand in the form of dunes, which moved in a band down the centre of the channels, the perimeters of which were composed of a gravel pavement created during short duration high flows in earlier years. Transport rates at‐a‐point and past‐a‐cross‐section were highly variable in space and time, even under conditions of constant discharge, and it was inferred that many factors other than hydraulic conditions—particularly sediment supply—control transport rates.An empirical power function relationship between sediment discharge and water discharge was used to predict an average annual total sediment discharge of 3400 t y−1 past the study reach. This gives a specific sediment yield of 5.9 t km−2 · y−1, which is two orders of magnitude less than values for Arctic and Alpine proglacial rivers, and confirms earlier conclusions that sedimentation rates on Antarctic sandur are much lower than in the arctic.