2272
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
elements for impact assessment (see Andersson-Sköld et al,
2011).
4.3
Data processing and databases
Information, data and results from different studies must be
organized in an orderly manner to allow for quick access to all
materials. For this purpose, a GIS database was built up to
simplify data processing and to enable work with the large
amount of information acquired during the project.
5
R&D IN CURRENT INVESTIGATION
The investigation included a comprehensive risk analysis to be
performed in a rather large area with many factors to be taken
into account. The methodology chosen for the investigation
using a risk matrix was developed and used in previous
landslide analysis.
The commission stipulates that the investigation is expected
to result in a complete risk analysis along the Göta river
together with a general increase of knowledge regarding
landslide analysis and risk mapping. A number of working
studies were therefore initiated to study and improve different
methods used in this kind of analysis. The Research and
Development efforts have mainly been concentrated on
mapping of input parameters, understanding of the erosion
process, the estimation of probability of landslide and new
routines for assessment and presentation of impact of landslides
in different areas.
The assignment, which in addition to studying the current
situation should also take into account increased flow and
runoff conditions in the river valley, asked for a study of the
climate changes at a regional level.
The research and development linked to the commission
was mainly needs-driven and provided direct assistance in the
investigation. Research on mapping and handling of quick clay
is an example of efforts which provided valuable knowledge for
the investigation. A method based on field measurements has
been improved and implemented in the project for classification
and mapping of sensitive and quick clays.
Efforts have also been made to try to understand and predict
the impact of climate changes on prevailing groundwater
conditions. These changes are expected to affect both the mean
value of the groundwater level and its variations in time.
Even though it has been the object of a number of earlier
analysis and studies, the ongoing erosion in the Göta river
valley is still incompletely known. Better knowledge has been
acquired and improved models have been developed for both
the bottom erosion and erosion of the slopes at the waterline.
Analysis and measurements of erosion and sediment transport
coordinated with the determination of bathymetric and
topographic conditions have been performed in this project. The
R&D-work has also included studies of boat related erosion and
the use of advanced numerical models.
6 RESULTS AND REPORTING
The results of the project are presented in two different forms:
-
a series of 34 reports in which the results from the different
R&D groups are presented including study of groundwater,
erosion, methodology of probability analysis, methodology
for estimation of consequences, mapping of quick clay, etc.
-
a final report in three parts including general discussions
and recommendations, a complete presentation of the
methods used in the investigation and finally risk maps
covering the whole valley, see Swedish Geotechnical
Institute (2012) or SGI’s website:
As expected, the investigation shows that climate changes
will increase the risk of landslides in the Göta river valley.
However, it also shows that high level of risk is already
estimated in many areas which can be affected even in today’s
climate. Both the risk for landslide in the present climate
conditions and the effect of the climate change in form of new
estimation of risk in the future are presented in the final report.
The investigation also leads to a general presentation of
protective and preventive measures which could be taken in
different parts of the valley. Examples of practical measures
that have to be considered are excavations, backfills, soil
reinforcement and erosion protection. Besides a rough
estimation of the costs of protective measures, the report also
includes recommendations regarding different monitoring
activities which should be regularly performed along the river.
7 REFERENCES
Alén, C., Bengtsson, P.-E., Berggren, B., Johansson, L. &
Johansson, Å. (2000). Skredriskanalys i Göta älvdalen –
Metodbeskrivning. (In Swedish). Swedish Geotechnical Institute,
Report 58, Linköping.
Andersson-Sköld, Y. (2011). Metod för inventering och värdering
av konsekvenser till följd av skred i Göta älvdalen samt Metodik
konsekvensbedömning - Känslighetsanalys, klassindelning och
applicering av metodik i hela utredningsområdet. (In Swedish). Swedish
Geotechnical Institute, Göta älvutredningen delrapport 12 & 13,
Linköping.
Bergström, S., Andreasson, J., Losjö, K., Stensen, B. & Wern, L.
(2011) Hydrologiska och meteorologiska förhållanden i Göta älvdalen.
(In Swedish). Swedish Geotechnical Institute, Göta älvutredningen
delrapport 27, Linköping.
Blied, L. och Persson, H. (2011). Bedömd förändring av maximala
grundvattennivåer i Göta älvdalen till följd av förändrat klimat. (In
Swedish). Swedish Geotechnical Institute, Göta älvutredningen
delrapport 9, Linköping.
Hultén, C., Andersson-Sköld, Y., Ottosson, E., Edstam, T. &
Johansson, Å. (2007). Case studies of landslide risk due to climate
change in Sweden, International geotechnical conference on climate
change and landslides, Ventnor, Isle of Wight. Proceedings 2007, pp
149-157.
Hultén, C., Edstam, T., Arvidsson, O. & Nilsson, G. (2006).
Geotechnical conditions for increased drainage from Lake Vänern to
River Göta. (In Swedish). Swedish Geotechnical Institute, SGI Varia
565, Linköping.
Rydell, B., Persson, H., Blied, L. & Rankka, W. (2011).
Erosionsförhållanden i Göta älv. (In Swedish). Swedish Geotechnical
Institute, Göta älvutredningen delrapport 1, Linköping.
Swedish Geotechnical Institute (2012). Landslide risk in the Göta
river valley in a changing climate. Final Report Part 1-3, Swedish
Geotechnical Institute, Linköping.
