Variability of net soil erosion and it's association with topography in Canadian Prairie agricultural landscapes
Date
1986
Authors
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Journal ISSN
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Publisher
ORCID
Type
Degree Level
Doctoral
Abstract
In this thesis, the central hypothesis is that net soil erosion varies systematically
with landscape topography. To test this hypothesis, two small (84 and 180 ha)
agricultural drainage basins In central Saskatchewan were studied. The
concentration of 137Cs in the soil was used to estimate net erosion, integrated over
the past 20 to 25 years, at nearly 300 sites in the two study basins. The
topography of each study area was represented by a digital terrain model.
Computer programs were used to calculate topographic variables for each element
of the digital terrain models. These variables expressed the three-dimensional
surface shape and relative position of each element within the landscape.
Representative samples drawn from each basin showed only weak correlations
between topographic variables and net erosion. A seven unit landform model of
the association between net erosion and topography was proposed. The model
units were main channel, tributary channels, swales, midslopes, crest slopes, level
upland, and depressions. An analysis of variance showed these landform units to
have significantly different net erosion ranks. While the model was applicable to
both study basins, the mean net erosion for some units differed markedly between
basins. Correlations between net erosion and topographic variables within the
landform units were generally stronger than for the basins as a whole. The
correlations suggested different processes dominate soil redistribution in different
parts of the basins. An algorithm was introduced to objectively group net erosion
estimates into topographically defined subsets. The classification results supported
the seven unit landform model.
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Degree
Doctor of Philosophy (Ph.D.)
Department
Geography
Program
Geography