Hydrology of a morainic landscape near St. Denis, Saskatchewan, in relation to the genesis, classification and distribution of soils
Date
1983-09
Authors
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ORCID
Type
Degree Level
Masters
Abstract
The purpose of this study was to ascertain the relationship
between groundwater flow, soil moisture regimes, and soil genesis and
distribution in a hummocky morainal landscape. In addition, the color
criteria used to classify soils affected by saturation and reduction
were examined on soils that were monitored for soil moisture and redox
potential.
The results of this study indicate that the genesis of soils in
a given landscape position can be related to certain groundwater flow
conditions, as based on piezometers and observation wells. Non-saline
and non-carbonated soils in upland depressions can be attributed to
"depression-focused" recharge by snow and snowmelt runoff in the
spring, as evidenced by groundwater mounds and strong recharge
conditions. The upper surface of the water table in the spring
resembles a "mirror-image" of the ground surface and extensive
leaching occurs under the upland sloughs. Non-saline and carbonated
soils around upland depressional fringes, on lower slope positions,
are found to be associated with local discharge in the spring via the
adjacent groundwater mound, as well as upward flow in the summer when
phreatophytic consumption by willows created a water table depression
around the slough fringes. Normally, a shallow water table would be
expected to dominate these soils in the spring, as evident by
carbonates at the soil surface. However, the two dry years of this
study resulted in a much deeper water table in the spring. Saline and
carbonated soils at low elevations in the study area can be associated
with a shallow and rather stable water table, and local discharge fran
surrounding higher elevations. The relatively short length of the local flow systems and high salinity of the soil extracts in this
area, indicates that the soluble salt content of the glacial till is a
factor in increasing soil salinity at discharge ends of local flow
systems. Generally, carbonated or non-carbonated, and non-saline
soils on mid and upper slope positions can be related to a deep water
table with mainly recharge or lateral flow occurring in the saturated zone. Highly permeable gravel and sand lenses in the till deposits
channel flow laterally, and determine to a large extent flow
direction, within the less permeable glacial till. Upland soil types
are more dependent on slope position and infiltration than the depth
to water table or groundwater flow.
Electrical conductivity and soluble salt distribution of soil
extracts reveal that upland depression infiltration of surface runoff
water is the dominant factor in influencing distribution of soluble
salts in this hummocky landscape. Low quantities of soluble salts
under the upland depressions and higher values in adjacent upslope
soils suggest lateral flow is not a major water redistribution
process. The dominance of magnesium sulphate salts throughout the
area indicates that relatively short local flow systems prevailed in
this area. Soils in a given landscape position exhibit similar
chemical characteristics as evident by dithionite-, oxalate- and
pyrophosphate-extractable iron, electrical conductivity values,
Mg++/Ca++ ratios of water-soluble soil extracts, and the presence or
absence of Mg-bearing calcites in the upper Ck or Cca horizons.
Humic Luvic Gleysols exhibit the greatest reduction as
exemplified by matrix chromas of 1 or less. Other Gleysols are less
strongly gleyed, having moderately low matrix chramas and mottles.Mottle contrast may be too specific at the present time to correctly
classify soils affected by saturation and reduction. Most Cca
horizons near the soil surface in Gleysolic soils have rusty mottles,
indicating that these horizons were once reduced.
Four soils in upland depressions and three soils on lower
slopes were monitored for extent of saturation and redox potential.
The two soils occupying the middle of the sloughs, which had the
wettest moisture regime in the spring, exhibit reducing conditions.
It is doubtful whether soil moisture and redox conditions recorded
were representative of actual conditions during soil development, due
to the two abnormally dry years of this study. Color criteria fail to
satisfactorily identify some gleyed intergrades and well-drained soils
on mid and upper slope positions.
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Citation
Degree
Master of Science (M.Sc.)
Department
Soil Science
Program
Soil Science