Intercomparison project for TH (Thermo-Hydro) coupled heat and water transfers in permafrost regions

Page hosted by LSCE (Laboratoire des Sciences du Climat et de l'Environnement)

The results are now published and available as data file from the results page

November 2017 meeting information

July 2017 final results

July stand of the inter-comparison

Second meeting information

Kick-off meeting information

Background

Large focus was put recently on the impact of climate changes in boreal regions due to the large amplitudes expected. Large portions of these regions, corresponding to permafrost areas, are covered by water bodies (lakes, rivers) with very specific evolution and water budget. These water bodies generate major discontinuities of the ground thermal field named taliks (unfrozen zones underneath) that may play a key role in the context of climate change.

Recent studies and modeling exercises showed that a fully coupled 2D or 3D Thermo-Hydraulic (TH) approach is required to understand and model the evolution of rivers and lakes in a changing climate (e.g. Mc Kenzie et al., 2007; Bense et al., 2009; Rowland et al., 2011, Dall’Amico et al., 2011). In the recent 2012 Hydrogeology Journal special issue dealing with “Hydrogeology of cold regions”, publications confirm this trend and the review article by Painter et al. 2012 develops the need for numerical model development dealing with surface and subsurface cold region hydrological processes.

So far, 3D studies are still scarce while all numerical approaches can only be validated against analytical solutions for a purely thermic equation with phase change (e.g. Neumann, Lunardini). When it comes to the coupled TH system (coupling two highly non-linear equations), the only possible approach is to compare different codes on provided test cases and/or to have controlled experiments for validation and propel discussions to try and improve the code performances.

The INTERFROST Project

We propose here a benchmark exercise dealing with the “Subsurface thermal hydrologic processes” as presented by (Painter et al., 2012) or within the field of Cryohydrogeology (McKenzie et al. 2020) https://tc.copernicus.org/preprints/tc-2020-132/. In a first phase of the project we firstly limit our efforts to the more simple set of equations involving Darcy flow (fully saturated porous medium) coupled with heat transfer with advection and phase change. Extensions of the benchmark to Richard equations or including the air phase are considered for later phases of the project.

Phase I of the benchmark consists of some test cases inspired by existing literature (e.g. Mc Kenzie et al., 2007) as well as new ones. Some experimental cases in cold room will complement the validation approach. In view of a second phase, the benchmark project is open as well to new or alternative cases reflecting a numerical or a process oriented interest or answering a more general concern among the cold region community.

Objectives

The first objective of the project aims is to inter-compare codes and approaches for their evaluation or validation. A further purpose is to propel discussions for the optimization of codes and possibly development of new numerical approaches enabling in the end the simulation of 3D realistic systems.

How?

The idea is to start small and see whether this initiative for which some groups have already expressed their interest is more largely of interest for the cold regions hydrology scientific community. Future perspectives could include the organization of specific meetings or conference sessions in larger conferences (e.g. EGU, AGU). The organizers are grateful for the national INSU/EC2CO funding they received to initiate the project. Nevertheless, an ambitious future will require some funding solutions.

Who is concerned?

The starting point is primarilly among the cold regions hydrological/hydrogeological modeler community. Identified applications fields are impact of climate change on hydrological and hydrogeological units, waste storage applications. Very similar requirements are met in the planetology community, especially the Mars studies. Modellers from the climate community might as well be interested in the 1D part of the benchmark, considering a vertical column of soil under freezing conditions (fully saturated for the first task of the project and soon extended to non-saturated problem).

Who are we?

The INTERFROST web site is hosted by LSCE (www.lsce.ipsl.fr), the cold chamber facility is hosted by GEOPS laboratory (former IDES) (http://geops.geol.u-psud.fr/). The reader may refer to publication Grenier et al., 2012 to see our recent activity [Grenier C, Régnier D, Mouche E, Benabderrahmane H, Costard F, Davy, P (2012)]. Impact of permafrost development on underground flow patterns: a numerical study considering freezing cycles on a two dimensional vertical cut through a generic river-plain system. Hydrogeology Journal (2012), DOI 10.1007/s10040-012-0909-4).

Please consider joining the benchmark …