Streamflow monitoring of the Onyx River in the Wright Valley and various other glacier melt streams in the Dry Valleys
Monitoring of the stream flow of glacial streams in the Dry Valleys was monitored from the 1969/1970 summer until the 1990/1991 season. The data was used to contribute to the understanding of the mass balance of the glacier-river-lake systems in the Dry Valleys because these fluctuations are indicators of climate change in this part of Antarctica. Most of the work was concentrated on a study of the Onyx River system in the Wright Valley. This river is of particular interest because it is the largest of the very few streams that occur in Antarctica, and because it is the only river that has been studied where the stream flow is derived entirely from glacier melt and melting permafrost. Stream flow monitoring was conducted at two sites on the Onyx River in the Wright Valley, one near where the river flows into Lake Vanda (constructed in the 1969/70 field season) and the other 2km downstream from the lake at the terminal of the Lower Wright Glacier (constructed in the 1972/73 field season). The second site needed to be above the confluence of the meltwater stream from the Clarke Glacier to monitor the flow contribution of the Lower Wright and Greenwood Glaciers to the Onyx River, the source of the Onyx River. Other glacier meltwater streams which might contribute to the Onyx River flow, including the meltwater streams from the Clarke, Goodspeed, Hart, Meserve and the Bartley Glaciers were monitored later in the programme during various years (Streams observed in the 1979/80-1982/83 field seasons when a flow monitor was erected on the Clarke Glacier stream and then another installed on each of the Meserve and Bartley Glacier streams in the 1983/84 seasons). In the 1988/89 season, a project was undertaken to extend the spatial scale of the study and stream flow monitoring stations were erected near the outlet of the Upper Victoria Lake in Victoria Valley, downstream from the Garwood Glacier Lake in the Garwood Valley and at three sites on the Adams and Miers streams in the Miers Valley. Water flow was generally monitored continuously from the time the water first went over the monitoring station until the flow ceased or the party had to leave the field. Yearly maintenance and often rebuilding was required on each weir/monitoring station due to destruction during the winter months or water flow damage. When water flow was higher than the weirs, stream gauging was conducted to gain accurate flow discharge rates. Water samples were collected at some sites and analysed for suspended sediment particles. Water temperature was recorded on the Onyx River where a thermistor was installed in the river downstream of the weir and water temperature readings were taken every six hours for the duration of the monitoring sessions. These were to be compared with the Vanda ground and air temperature as a help towards understanding the valleys heat budget. In the 1980/81 season, a hydraulic geometry survey of the Onyx River at ten selected sites along its course, from Lake Brownworth to Lake Vanda was surveyed. At each site a cross section and long section was surveyed. Flow measurements, details of channel structure and channel material types were obtained. The survey was repeated in the following season.
The data was collected at the time by the New Zealand Ministry of Works and Development, a part of the Division of Science and Industrial Research (DSIR). The DSIR was disbanded and several new organisations were formed. At this time, the investigator was concerned about the survival of the large amount of data generated by this project. In the late 1990s while working with the National Institute of Water and Atmospheric Research (NIWA), he collated all of the hydrological data, had it checked for quality and then permanently filed in the NIWA electronic archives. A copy was also supplied to the University of New Hampshire, USA, who at the time had continued some work on the Onyx River. The investigator still holds the files of the programmes, correspondence etc. for the period that the Ministry of Works ran the programme. All of the reports were also submitted to Antarctica New Zealand as their Science Reports and copies of these are retained in their archives. Please contact either the investigator or Antarctica New Zealand for more information.