What governs ice melting by turbulent water flow is one of the biggest questions in glaciology. The dynamics of glaciers and ice sheets is tightly linked to how water flows at their bed. If there is a sufficient water input, the water starts melting channels in the ice and can drain more readily out of the glacier bed. Melting at the interface between glaciers and oceans is a major source of ice loss in Greenland and Antarctica and could trigger ice flow instabilities accelerating sea-level rise.

The image (right) shows the flutes and incipient channels forming during the experiment.

However, there is dearth of data on the physical controls of ice melting by subglacial water flow, so we designed a physical experiment to explore the problem.

Preliminary results

(Twitter has the most up-to-date developments and some videos)

Poster describing the experiment presented at the SoCal Geomorphology Symposium at Scripps on May 4th 2019

(pdf poster file here)

Background and description

The flow of water at the surface, inside and under glaciers is pivotal to understand their evolution, and thus their past and future behavior. Since Röthlisberger first introduced a model of water flow through glaciers about 40 years ago Röthlisberger (1972), fundamental issue seem to stand between theoretical formulations and field observations (Walder, 2010). Field observation of channelized water flow are particularly challenging, and, in general, heat exchange between turbulent water flow and ice remains enigmatic.

In the Earth Surface Dynamics Lab at Caltech, we are designing an experiment to help answer these questions. The experiment is designed to reproduce and explore how pressurized water flow melts an ice body. The ice making for such an experiment is very specific, yet inspiration from the track building from events such as the RedBull Crashed Ice, and thanks to the help of Bietak Production, we were able to acquire ‘ice mats’ that we hooked to a chiller and start producing ice.

Making a glacier in the lab. The chiller cools an ethylene glycol solution that is recirculated through the ‘ice mats’ (seen on the right of the picture) at a temperature of -15˚C to build an ice block that is 3 m long and 30 x 30 cm in cross section. To the left, one can see temperature sensors that will be be frozen into the ice when the ice block has reached its full size.

With this experiment we are hoping to explore the importance of water temperature and wall roughness on the heat exchange between flowing water and ice. Improving our understanding of such heat exchange will have broad implications for glaciology.

I will update this page as the experiment building is moving forward and with the preliminary data.


Röthlisberger, H. (1972). Water pressure in intra‐ and subglacial channels. Journal of Glaciology, 11(62), 177–203.

Walder, J. S. (2010). Röthlisberger channel theory: its origins and consequences. Journal of Glaciology, 56(200), 1079–1086.