RD&D-Programme 2004 - SKB

Shoreline displacement has an isostatic and a eustatic component. The process must be studied
globally, which can be done with GIA (Global Isostatic Adjustment) models /21-7, 21-8/.
A project in which GIA modelling is a central part and whose purpose is to understand and
quantify shoreline displacement, given different ice sheet scenarios and earth models, is planned
to start in 2004. The descriptions of ice extent and thickness during the Weichselian that have
been formulated within the project “Basal conditions and hydrology of continental ice sheets”
are important as input data for the modelling. The review of shoreline displacement since the
Late Weichselian /21-3/ will also be used in the project.
A compilation of northern European climate archives, which cover periods longer than
10,000 years, has been initiated and is planned to be completed in 2004. Data will be compared
with the climate input data used in modelling of the extent of the ice sheet during the
Weichselian. In combination with ice extent and shoreline data, they will also serve as a basis
for planned permafrost studies, see further section 21.2.
The evolution of the climate in Scandinavia during an interglacial period and the past
2,000 years will be studied in special projects. They are described in greater detail in
section 21.3.
Climate and climate-related questions are also dealt with in section 20.8.
21.1 Glacial domain
An overview of the processes studied within the glacial domain is shown in Figure 21-3. The
figure shows the margin of a warm-based ice sheet. The basal conditions and hydrology of the
ice are of great importance for the thermal, hydrological, mechanical and chemical conditions
both on the surface and in the bedrock and the repository.
Questions of special interest are:
• Possible depth of subglacial permafrost.
• Water pressures and water flows.
• Possible infiltration of glacial meltwater and up-coming of deep saline groundwaters.
• Changes in rock stresses and tendency towards rock movements.
• Couplings between hydrological and mechanical processes.
Conclusions in RD&D 2001 and its review
Besides the general conclusions presented above, SKI points out that SKB should clarify what
importance the meltwater production at the base of a continental ice sheet has for hydrology and
groundwater composition. SKB concurs with this and also intends to clarify the importance of
these basal conditions and meltwater production for thermal and mechanical conditions.
Newfound knowledge since RD&D 2001
Extensive geological information intended to be used as calibration and validation data in ice
sheet modelling has been compiled as a subproject within the aforementioned project “Basal
conditions and hydrology of continental ice sheets”. Examples of such data are ice margin positions
during the Weichselian, occurrence of weathered bedrock, block fields, Veiki moraines,
till-covered eskers and soil depth or bare rock /21-9/. The compilation also includes a qualitative
evaluation of the information, as well as alternative interpretations in the literature. The purpose
of the compilation is to identify and evaluate ice margin positions in order to use the results to
calibrate the ice sheet model, as well as to identify areas where periods of glaciation have been
dominated by either cold-based or warm-based ice conditions, information that will be used for
validation of output data from the model.
294 RD&D-Programme 2004