UID:
kobvindex_GFZ23787041X
Format:
Getrennte Zählung
,
Illustrationen
ISBN:
9157655049
,
91-576-5504-9
ISSN:
1401-6249
Series Statement:
Acta Universitatis Agriculturae Sueciae. Agraria 72
Content:
Water flow in frozen soils is closely linked to the heat dynamics in the soil-snowatmosphere
system. Therefore, a detailed understanding of both thermal and hydraulic
processes, as well as the way they are linked is required to quantify and predict the fluxes
during freezing and snowmelt. This thesis focuses on different key processes with regard
to water dynamics in frozen soils: (a) the heat exchange at the snow surface, (b) the
snowmelt infiltration, (c) the freezing characteristic curve, and (d) the frost-induced
solute redistribution. Experimental studies were conducted both in the laboratory, using
small soil columns and in the field, on soil plots of 4 m2 Oysimeters) and on an arable
field of 6 ha. A one-dimensional numerical SV AT-model (SOIL) with a new two-domain
concept for water flow in partly frozen soils was applied to these experiments.
Measurements of soil water content (total and liquid), soil temperature, groundwater
level and solute concentration as continuous time-series provided valuable information
about the physical dynamics in the soil during cycles of freezing and thawing. For a
shallow or patchy snowcover the simulation of soil frost was very sensitive to the surface
energy balance and the snow depth and required accurate precipitation and radiation
measurements. The two-domain infiltration model reproduced the field observations
better than a single-domain model and gave more flexibility when simulating different
field conditions. However, it also increased the model sensitivity. Major sources of
uncertainty were the frost-induced water redistribution, the hydraulic conductivity of the
initially air-filled pores and the freezing rate of the infiltrating water in the frozen soil.
Accurate measurements of soil hydraulic properties were essential for calibrating the
model for new soils.
Further development of the model will have to include a more sophisticated description
of the snow processes and the solute transport in order to be able to address key
environmental problems.
Note:
Zugleich: Dissertation, Sveriges Lantbruksuniversitet, Uppsala, 1997
,
Contents
Frozen soil hydrology
Review and practical relevance
The complex frozen soil environment
Objectives
Heat exchange above and within frozen soils
Heat exchange at the snow surface
Heat transfer through the snow pack
Soil freezing characteristic curve
Frost-induced solute redistribution
Water infiltration and redistribution in frozen soil
Experimental work
Modelling
Model versus measurements
Conclusions
Ongoing and future work
Improved description of the processes at the pore scale
Improved description of the snow pack
Link to larger-scale models
References
Acknowledgments
,
Englisch
Language:
English
Keywords:
Hochschulschrift
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