A Consistent Framework for Coupling Basal Friction With Subglacial Hydrology on Hard-Bedded Glaciers

Area of Science:

• Glaciology
• Geophysics
• Environmental Science

Background:

• Subglacial drainage and basal friction in glaciers are controlled by basal cavities.
• Existing hydro-mechanical models treat cavity-driven friction and hydraulic transmissivity separately, leading to inconsistencies.
• A unified approach is needed to accurately model glacier basal processes.

Purpose of the Study:

• To develop a novel coupled hydro-mechanical model for glacier basal processes.
• To ensure a consistent description of cavity evolution governing both friction and drainage.
• To validate the model against observational data of glacier sliding speed.

Main Methods:

• Developed a common cavity-evolution description for transient friction and hydraulic transmissivity.
• Coupled hydro-mechanical model incorporating unified cavity dynamics.
• Validation using a unique observational record of glacier sliding speed from the French Alps.

Main Results:

• The new coupling approach resolves inconsistencies found in previous models.
• The model successfully explains observed glacier sliding speeds.
• Sliding speed is directly related to basal shear stress and water discharge on multi-day to multi-decadal timescales.

Conclusions:

• A unified cavity-evolution model provides a more physically consistent representation of glacier basal processes.
• The model advances our understanding of glacier sliding dynamics and subglacial hydrology.
• Water pressure is a dependent variable adjusting to maintain necessary cavitation ratios.