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Immediate report of Victoria University of Wellington Antarctic Expedition 1989-90: VUWAE 34

Abstract

Abstract

This project involved the second year of a hydrological, glaciological, and sediment transport monitoring programme in the Miers Valley. Information required to study and quantify the energy and mass balances of the glacier-river-bake system have been collected.

Data with significant implications to our understanding of the controls of stream flow in the Antarctic were collected. Evidence that direct solar radiation rather than temperature controls the stream flow has considerable importance to the current discussion of global warming and conflicts with many of the "popular" theories being advanced.

Fluvial sediment transport appears to be highly variable both through time and in space. Movement is of sand-sized particles (and smaller) and commences at very low flows and velocities. Coarser material forms a "lag" deposit on the bed and appears to be essentially immobile except under high flow regimes.

Once stream flow begins for the season there is usually sufficient energy available to mobilise any available sand-sized sediment. The fact that sediment is not continuously in motion suggests that the system is supply constrained. The sand is supplied from erosion of the stream banks and importantly from material present in water drained from the glaciers.

The different surficial materials throughout the valley reflect different proportions of the incoming solar radiation. As expected the "lighter" surfaces reflect a greater proportion than the darker surfaces. Data collected, but still to be analysed, should allow the absolute amounts of incoming radiation and the proportion reflected from each surface type to be quantified.

The change in albedo affects the temperature profiles under the various pavements, the depth to permafrost, the thickness of the active layer, and consequently the degree of development of the "patterns".

Resurvey of the three rows of five ablation poles on the Adams and Miers glaciers indicates, from the observed angles only, a movement of the upper portions of the glaciers of the order of 1 m.

No changes were evident in the appearance of the aprons or glacier snouts between seasons. Some spalling of material had obviously occurred but even the close spacing of survey points of 10 m made it difficult to detect any changes with "simple" survey techniques.

Over 100 photographs, carefully controlled for position and orientation, were taken to provide a stereoscopic coverage of the glacier snouts. These will allow a terrestrial photogrammetric survey of both the Miers and Adams glacier fronts. This should allow relatively small changes to be detected and quantified.