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...
Published in: | Geoscientific Model Development |
---|---|
Main Authors: | , |
Format: | Text |
Language: | English |
Published: |
2019
|
Subjects: | |
Online Access: | https://doi.org/10.5194/gmd-11-3497-2018 https://gmd.copernicus.org/articles/11/3497/2018/ |
id |
ftcopernicus:oai:publications.copernicus.org:gmd63008 |
---|---|
record_format |
openpolar |
spelling |
ftcopernicus:oai:publications.copernicus.org:gmd63008 2023-05-15T16:40:11+02:00 BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application Kavanagh, Mark Tarasov, Lev 2019-01-16 application/pdf https://doi.org/10.5194/gmd-11-3497-2018 https://gmd.copernicus.org/articles/11/3497/2018/ eng eng doi:10.5194/gmd-11-3497-2018 https://gmd.copernicus.org/articles/11/3497/2018/ eISSN: 1991-9603 Text 2019 ftcopernicus https://doi.org/10.5194/gmd-11-3497-2018 2020-07-20T16:23:08Z 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. The model is validated with a synthetic ice sheet geometry and different bed topographies to test basic water flow properties and mass conservation. Synthetic ice sheet tests show that the model behaves as expected with water flowing down gradient, forming lakes in a potential well or reaching a terminus and exiting the ice sheet. Channel formation occurs periodically over different sections of the ice sheet and, when extensive, displays the arborescent configuration expected of Röthlisberger channels. The model is also shown to be stable under high-frequency oscillatory meltwater inputs. Text Ice Sheet Copernicus Publications: E-Journals Geoscientific Model Development 11 8 3497 3513 |
institution |
Open Polar |
collection |
Copernicus Publications: E-Journals |
op_collection_id |
ftcopernicus |
language |
English |
description |
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. The model is validated with a synthetic ice sheet geometry and different bed topographies to test basic water flow properties and mass conservation. Synthetic ice sheet tests show that the model behaves as expected with water flowing down gradient, forming lakes in a potential well or reaching a terminus and exiting the ice sheet. Channel formation occurs periodically over different sections of the ice sheet and, when extensive, displays the arborescent configuration expected of Röthlisberger channels. The model is also shown to be stable under high-frequency oscillatory meltwater inputs. |
format |
Text |
author |
Kavanagh, Mark Tarasov, Lev |
spellingShingle |
Kavanagh, Mark Tarasov, Lev BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application |
author_facet |
Kavanagh, Mark Tarasov, Lev |
author_sort |
Kavanagh, Mark |
title |
BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application |
title_short |
BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application |
title_full |
BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application |
title_fullStr |
BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application |
title_full_unstemmed |
BrAHMs V1.0: a fast, physically based subglacial hydrology model for continental-scale application |
title_sort |
brahms v1.0: a fast, physically based subglacial hydrology model for continental-scale application |
publishDate |
2019 |
url |
https://doi.org/10.5194/gmd-11-3497-2018 https://gmd.copernicus.org/articles/11/3497/2018/ |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
eISSN: 1991-9603 |
op_relation |
doi:10.5194/gmd-11-3497-2018 https://gmd.copernicus.org/articles/11/3497/2018/ |
op_doi |
https://doi.org/10.5194/gmd-11-3497-2018 |
container_title |
Geoscientific Model Development |
container_volume |
11 |
container_issue |
8 |
container_start_page |
3497 |
op_container_end_page |
3513 |
_version_ |
1766030568998305792 |