Bench-top modelling of ice dynamics
Project Goals: Analogue models have been used extensively in the Earth sciences to improve understanding of natural processes. Here we apply these techniques to simulate water flow under ice sheets and glaciers. Ice deformation is represented with polydimethyl-siloxane (PDMS) – a liquid polymer used extensively in the tectonics-related deformation experiments. PDMS is a transparent, non-toxic material with a specific weight similar to that of ice and a strain-rate dependent viscosity making it well-suited to ice flow studies. The polymer is loaded into a 4’x 6’ plastic box coated with a water-based lubricant across 80% of the box width to reduce friction at the interface between the polymer and the base of the box. Water is injected at this interface via a set of tubes that distribute the incoming water supply across the upstream end at a constant discharge. We measure horizontal surface displacement by tracking several bright stickers placed on the surface of the polymer through a sequence of images that make up each experimental run. Coincident water discharge and channel pattern measurements are made to correlate changes in discharge to changes in channel geometry and surface motion. Of particular interest is the response of the channel system to discharge pulses. To observe this we change discharge into the flume from ~70 cm3/s to 550 cm3/s which reflects an ~8-fold increase in discharge and represents a typical diurnal discharge fluctuation observed on alpine glaciers.