BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application

We present BrAHMs (BAsal Hydrology Model): a physically based basal hydrology model which represents water flow using Darcian flow in the distributed drainage regime and a fast down-gradient solver in the channelized regime. Switching from distributed to channelized drainage occurs when appropriate...

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Bibliographic Details
Published in:Geoscientific Model Development 2018-08, Vol.11 (8), p.3497-3513
Main Authors: Kavanagh, Mark, Tarasov, Lev
Format: Article
Language:English
Subjects:
Analysis
Computer simulation
Drainage
Fluxes
Geophysical research
Glaciation
Hydraulic conductivity
Hydraulic flow
Hydrogeology
Hydrologic models
Hydrology
Hydrostatic pressure
Ice
Ice formation
Ice sheets
Lakes
Mathematical models
Meltwater
Numerical schemes
Numerical stability
Robustness (mathematics)
Water conservation
Water flow
Water pressure
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Summary:We present BrAHMs (BAsal Hydrology Model): a physically based basal hydrology model which represents water flow using Darcian flow in the distributed drainage regime and a fast down-gradient solver in the channelized regime. Switching from distributed to channelized drainage occurs when appropriate flow conditions are met. The model is designed for long-term integrations of continental ice sheets. The Darcian flow is simulated with a robust combination of the Heun and leapfrog-trapezoidal predictor-corrector schemes. These numerical schemes are applied to a set of flux-conserving equations cast over a staggered grid with water thickness at the centres and fluxes defined at the interface. Basal conditions (e.g., till thickness, hydraulic conductivity) are parameterized so the model is adaptable to a variety of ice sheets. Given the intended scales, basal water pressure is limited to ice overburden pressure, and dynamic time stepping is used to ensure that the Courant-Friedrichs-Lewy (CFL) condition is met for numerical stability.
ISSN:1991-9603
1991-959X
1991-962X
1991-9603
1991-962X
DOI:10.5194/gmd-11-3497-2018