Hydrology
An initial examination of the hydrologic and climatic data is tending to confirm the findings of last season. These are:
| 1. | Stream flow is directly controlled by the amount, and intensity, of solar radiation striking the glaciers. Such is the level of this control that clouds passing in front of the sun can be identified in the hydrographs. |
| 2. | Temperature has only a minor affect on stream flow, determining to a slight degree the "baseflow" when there is no direct sunlight. |
| 3. | There is a maximum amount of melt able to be generated, if there is no cloud when the sun is at a particular azimuth. This is indicated by "flat" peaks on the hydrographs. |
| 4. | The maximum amount of melt possible on any day during the season (if there is no cloud) is cyclic and increases as the angle of the sun gets higher. Essentially maximum stream flows are cyclic around the "longest day".page 15.gif) |
| 5. | Periods with several "clear days in a row had higher flows as a result of gradually increasing "baseflows". |
Fluvial sediment Transport
An intensive fluvial sediment sampling programme has shown that sediment transport is characterised by:
| 1. | High spatial and temporal variability as found in other studies. |
| 2. | Movement of sand sized and smaller particles. Particles larger than this appear to form a "pavement" or lag deposit" on the bed. These larger particles tended to roll only when the sand around them was removed under high flow regimes. |
| 3. | Movement tends to be via migrating ripples although movement commences at very low flows and very low velocities. This ease of movement appears to be a result of particle shape (predominately spherical) and the generally smooth and regular bed. |
| 4. | The fluvial transport system appears to be supply constrained. That is, there always appears to be sufficient energy available to shift any sand sized particles present. On occasion, however, both temporally and spatially these particle sizes are absent. |
Albedo Studies
Distinctive differences were found between the albedo (reflective) properties of the various surficial deposits in the valley.
| 1. | The glaciers had the highest reflective properties (except when covered with silt) followed by lake ice, marble dominated pavement, granite pavement, and lastly volcanic dominated pavement. |
| 2. | The change in albedo affects the temperature profiles under the pavement, the depth to permafrost, the thickness of the active layer, and consequently the degree of development of the "patterns". |
| 3. | The degree of development of the patterns appears to be related to the availability of moisture and the cryergic activity at the site. Variation in the rate of this activity in the valley is largely controlled by the albedo of the different surfaces. |
Ground Survey and Photogrammetry
Considerable survey work was again undertaken during the past season. Tying into the various benchmarks established in 1988-89 and completion of the survey network during the past season allowed the following work to be undertaken.
| 1. | A resurvey of the three rows of five ablation poles on the Adams and Miers glaciers. The observed angles suggest movement of the upper portions of the glaciers to be of the order of 1 m. |
| 2. | A resurvey of the glacier snouts and their associated aprons. No changes are evident in the preliminary calculations of the measurements of the aprons or glacier snouts between the two 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. |
Ablation of the "fallen" ice also makes it difficult to establish amounts of ice lost from the system. To precisely measure the stability or shift of the glacier fronts and to assess the glacier ice lost from the snout, a terrestrial photogrammetric survey of both the Miers and Adams Glaciers was undertaken this season. Approximately 100 photographs were taken to provide a stereoscopic coverage of the glacier snouts. Each photograph position was accurately set up with respect to a known geometry. Foreground and background survey marks were established using "terrier bolts" which were flagged with coloured discs mounted on special fittings for
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photography. With this "height" control it is intended to map the glacier fronts using the floating mark of the photogrammetric plotter. This will result in very accurate profiling and contouring which will allow minor changes in the morphology and volume of the glacier snouts to De quantified very accurately.
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photography. With this "height" control it is intended to map the glacier fronts using the floating mark of the photogrammetric plotter. This will result in very accurate profiling and contouring which will allow minor changes in the morphology and volume of the glacier snouts to De quantified very accurately.