Exploratory calculations concerning the influence of glaciation and permafrost on the groundwater flow system, and an initial study of permafrost influences at the Finnsjoen site - an SKB 91 study.

摘要

The present report describes some exploratory calculations concerning the potential groundwater flow during the recession phase of a future glaciation. The exercise forms part of the SKB 91 performance assessment project, and aims at qualitatively illustrating the prevailing hydrological phenomena under extreme glacier conditions, and at quantitatively indicating the order of magnitudes for the groundwater flows that can be expected during the withdrawal of an ice-sheet. The interest has been focussed on the deglaciation phase, since it can be expected that large amounts of water are available for infiltration at this time. Conditions assuming either intact or melted away permafrost were considered within the project. Apart from the exploratory calculations mentioned above, an initial attempt at modelling a permafrost situation at the Finnsjoen site was carried out. This part of the study did not include the presence of melting-water, but was focussed on the potential occurrence of permafrost and its impact on the groundwater flow as a potential barrier. These calculations are reported separately in an Appendix. Neither part of the project addressed the conceptual uncertainties like potential crustal downwarping, thermal buoyancy effects by the heat evolution from the repository, fracture zone conductivities being affected by the overburden from the ice-shelf, etc, etc. The project made use of the finite element code NAMMU for solving the equation system, while the program package HYPAC was used for pre- and postprocessing purposes. (au). (Atomindex citation 23:078593)