THE STUDY OF KINEMATIC GNSS SURVEYING FOR BIM GEOREFERENCING

Sub-annual glacier surface velocity derived from remote sensing images are receiving increasing attention. In the meantime, systematic seasonal errors (i.e. biases) have been reported in time series derived from optical images on various landforms, such as landslides or dunes. The extent to which such biases affect glacier velocity maps remains poorly investigated. Here, we propose characterizing the amplitude and spatial distribution of these seasonal biases.

Changes in water reaching the base of glaciers strongly affect their sliding speed by altering water pressure beneath the ice. High water pressure is often thought to develop during summer melt, enlarging cavities at the glacier base and increasing sliding speed. Our observations show instead that the cavities mainly grow during winter, when water pressure builds up in isolated cavities. As the cavities become connected during the melt season, water pressure decreases and the glacier slows down.

The flow of glaciers and ice sheets results from ice deformation and basal sliding driven by gravitational forces. Quantifying the rate at which ice deforms under its own weight is critical for assessing glacier evolution. This study uses borehole instrumentation in an Alpine glacier to quantify ice deformation and constrain ice viscosity in a natural setting. Our results show that the viscosity of ice at 0 °C is largely influenced by interstitial liquid water, which enhances ice deformation.