DGPS LEVELLING AND MONUMENT STABILITY AT 70 ° NORTH

• Main Authors: Sheng Li Matthew Tait, Elizabeth Cannon
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Arctic; Canada; Mackenzie Delta; Global warming; Ice; International Polar Year; permafrost
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.575.1373; http://plan.geomatics.ucalgary.ca/papers/Li Tait et al_Geomatica_2007.pdf

The International Polar Year and the proposed development of the Mackenzie Delta gas reserves will focus attention on Arctic observation in the coming years. Methods of geodetic observation will be used alongside other scientific experiments to determine the effects of man-made and global warming changes to the environment, which will have impacts on civil infrastructure, and geological and ecological conditions. Changes in elevation are indicative of subsidence due to gas extraction, deepening of the permafrost active layer, the thawing of ground ice, and changes in the eco-system. The challenges of measuring elevation change in such a remote area, where there are few naturally stable areas or artificial benchmarks such as tide gauges, and where observations utilising conventional methods are hampered by the complex hydrol-ogy in the Mackenzie Delta, ensure the pre-eminence of global positioning in this area. Differential GPS (DGPS) levelling has its own unique challenges at 70º North, such as degraded satellite geometry and increased ionospheric effects. In addition, the full error budget of a DGPS method includes the signal of the survey monument in the permafrost environment, which is subject to seasonal heave and settlement. This paper reports on two studies that, combined, indicate the accuracy that can be expected using DGPS levelling onto survey monuments in permafrost at this latitude. The Arctic regions of Canada will be subject to intense study in the coming years due to the planned production of gas in the Mackenzie Delta