The magnitude and frequency of slopewash processes in a permafrost environment were examined during the summer of 1977. Small instrumented plots were set up and monitored for surface runoff at one interfluve and two valley-side locations. Subsurface water was collected at two of the sites using guttering positioned at various depths in the active layer. Snowmelt was the major source of both surface aid subsurface runoff, and summer precipitation was of little importance. Volumes of surface runoff were generally greater than those of subsurface flow, although both varied with position on the slope. Partial area contribution to streamflow was usual, the source areas being those conducive to snowbank formation. Measurement of the amounts of suspended and dissolved sediment indicated that surface wash was a more important transport agent than subsurface wash. Both processes, however, appeared to be of limited importance at the interfluve location, and only transported significant amounts of sediment at the valley-side sites where large snowbanks ablated.

Abstract not available.

This study is the first known attempt in North America to use the basal temperature of snow (BTS) method to predict the distribution of mountain permafrost. The study site, Wolf Creek Research Basin, Yukon Territory (60°30'N, 135°13'W), is a 195 km2 basin ranging in elevation from 650--2100 m with a mean annual air temperature of about -4°C at 1235 m a.s.l. A modeled BTS surface, based on 394 measured BTS values and with elevation and potential incoming solar radiation as independent variables, was created within a GIS environment with an r2 value similar to European results. The distribution of permafrost within the basin was identified from pits and boreholes. A subsequent logistic regression was used to compare modeled BTS values to the actual permafrost distribution in order to produce a map of permafrost probability in the basin. A significantly higher likelihood of permafrost, observed in a confined valley bottom, was attributed to cold air drainage. This occurrence was not predicted by the BTS model and data from the affected area were removed from later analyses. (Abstract shortened by UMI.)

Solifluction lobe process and morphology were studied on an alpine slope (1800 m a.s.l) above Kluane Lake, south-western Yukon Territory. Contemporary rates of surface movements, measured by theodolite survey, were found to be greatest in the first two weeks of spring thaw, and movements were consistently faster on lobe treads than on lobe risers. Precise monitoring of thaw-consolidation parameters on a lobe indicated that most thaw-settlement occurred when the soil was saturated to the surface. At the slope scale, surface rates increased downslope in response to gradients in soil moisture, while long-term rates of lobe advance, inferred from 14C dating of buried organic horizons, were found to be similar among 12 dated lobes. The internal stratigraphy and age distribution of these lobes together suggest periodic advance of the fronts. Observations of lobe stratigraphy with the age distribution of buried humus points towards a conceptual model of lobe development involving the slow accumulation of soliflucted material behind a rigid riser, the progressive steepening of the riser and build-up of stress, and finally the rupture of the front and its extensive collapse on to the slope. The period for this developmental cycle was estimated to be about 600 years. This internal cycle of lobe development constitutes a serious buffer to climatic influence and must be taken into account when using solifluction lobes as paleoclimate sources.

This thesis discusses the actual and modern ice margin fluctuations of valley and cirque glaciers in South Akshayuk Pass, Auyuittuq National Park (Baffin Island, NU). The fluctuation of the ice margins of the Tete de Cirque, Glacier 12, Windy Lake, Niflheim and Glacier 20A glaciers were analysed using geometrically rectified aerial photographs taken between 1948 and 1977. IKONOS and LANDSAT 7 ETM+ satellite imagery covering the 1977 to 2003 period were also used. The results indicate a mean annual ice margin retreat of 8.9 m per year during the 1948 to 2003 period. Compared to south and west-facing glaciers, the ones facing north are characterize by a smaller annual retreat rate. Ice margin fluctuations since the Little Ice Age were evaluated using lichenometric measurements of Rhizocarpon geographicum found on the moraines of the Turnweather, Tete de Cirques, Glacier 12, Windy Lake, Niflheim, Glacier 20A and Sivingavuk glaciers. Moraine ages were determined by measuring the 10 largest-diameter R. geographicum thalli in the sampling area (100 m2) and converting these measurements to ages using the regional growth curve of R. geographicum . The maximum extent of the ice margins of the valley and cirques glaciers was reached between AD 800 to 1860, mainly between 1840 and 1860 at the end of the Little Ice Age period. Size-frequency distribution, an analysis of variance, and multiple comparisons showed that some moraines were subjected to local environmental variations, which affected the growth of R. geographicum, with subsequent implications in the interpretation of the lichenometric ages of the moraines and the ice margin fluctuations.

Changes in land cover at a regional scale and the assessment of the risk of soil degradation at the scale of the basin require not only information on the physical structure of soil but also appropriate tools to evaluate these changes. In order to identify the areas subject to a high risk of degradation in a region of Northern Africa, a geomatics approach integrating the following variables was considered: state of soil degradation, slope length, aspect, presence of vegetation and the erosive potential of overland flow. In order to map the state of soil degradation, the Hue and the Coloration indices were calculated from remotely sensed imagery. The complimentary nature of these two spectral indices allows the identification of the different levels of soil degradation. A vegetation index, MSAVI(2), was used to obtain a map of vegetation. Geomorphometric data (aspect, slope length, stream power index), were derived from a DEM generated in a GIS from a topographic map at a 1:50 000 scale. These data were integrated in a GIS by means of a multicriterion model. Multicriterion evaluations were then performed to identify and map areas of potential degradation. Model results were then compared with a cartographic document (reference map) using the Kappa coefficient. Comparisons between modeled potential degradation and the reference map showed overall low levels of agreement. Subsequently, a visual comparison using photographs of the study area was also performed as a way to further evaluate the results of the proposed method. (Abstract shortened by UMI.)

This study presents surface ice motion patterns across Devon Ice Cap, with a particular focus on the Belcher Glacier drainage basin. Between summer 2007 and summer 2009, continuous differential GPS (dGPS) measurements were made to determine the motion at points along the centerline of the Belcher Glacier with ∼cm accuracy. In summer 2008, marker stakes were set out on all accessible tributaries in the Belcher basin, with each stake being surveyed with dGPS several times throughout the season. Using synthetic aperture radar (SAR) speckle tracking techniques new velocity maps were produced of seasonal changes in ice motion for the Belcher Glacier. These were validated against the field dGPS results. Ground penetrating radar (GPR) was used to determine the ice depths of each tributary basin in the Belcher Glacier study region. These ice depths are combined with velocities derived from the speckle tracking results to create flux gates which allow for estimates of total ice discharge for the Belcher basin. These volume estimates can be used to improve mass loss estimates for future modeling of Devon Ice Cap. The velocity results are compared to the work of Burgess et al (2005), who provided flow dynamics and mass loss from the Devon Ice Cap and Belcher Glacier systems using interferometry and speckle tracking of ERS 1/2 data from the mid-1990s and Radarsat-1 data from 2000. These comparisons reveal higher ice velocities on a large glacier in the southeast part of the ice cap (Southeast2 Glacier), which agrees with recent thickening of the stagnant ice into which the glacier drains.

The data from nine permafrost thermal monitoring sites at widely separated locations across northern Canada were examined individually, spatially, and temporally. Three sites are in Nunavut (Alert, Iqaluit, and Baker Lake), two in the Northwest Territories (Table Mountain and Wrigley), and four in the Yukon Territory (Wolf Creek, Sixty Mile, Alpine Burwash, and Red Creek). The sites have between one and five boreholes that are instrumented to between 3 and 60 m with records of varying durations. Most of the boreholes are co-located with weather stations recording air temperatures and snow depths. A comprehensive analysis of each site is presented assessing the relations between climate and permafrost temperatures, both in the near surface and at depth. The local characteristics at each site, and among sites, were assessed using various methods including mean annual temperatures, surface and thermal offsets, n-factors, and the apparent thermal diffusivity. Time series analyses were conducted at sites with longer air and ground temperature data records. Regional mean annual air temperatures were defined as the primary determinant of permafrost temperatures at the study sites, but this relationship is modulated by snow (depth, duration, and timing) and vegetation characteristics, the substrate material, and the moisture content, both frozen and unfrozen, within the active layer and the permafrost. Of the study sites, permafrost temperatures at Iqaluit are the most sensitive to changes in climate due to little buffering between the air and the permafrost, and permafrost temperatures at Wrigley, Table Mountain, and Wolf Creek are the least sensitive to changes in climate due to the significant latent heat effects in this isothermal permafrost associated with high amounts of ice and unfrozen moisture. Climatic cooling was observed in the earlier part of the record at Iqaluit from the late 1940's until the early 1990's, and at Alert between the early 1950's and the mid 1970's. Climatic warming was observed in mean annual and winter average temperatures at Alert, Baker Lake, Iqaluit, Table Mountain, and Wrigley in recent decades. This was reflected in warming permafrost temperatures at all of the long-term thermal monitoring sites. The greatest magnitude of ground temperature warming occurred at Iqaluit (+1.6 to +1.9°C/decade), then Alert (+0.2 to +0.6°C/decade), and Baker Lake (+0.3°C/decade). Ground temperatures at Table Mountain warmed the least (+0.1 to +0.2°C/decade), but the warming at this site is important because it represents a progressive change in unfrozen moisture in the fine-grained, ice rich permafrost.

No description available.

An experimental design was developed to evaluate the effect of active-layer detachment sliding on surface wash erosion. Specifically, the aim was to examine to what extent the disturbance of vegetation cover, changes in hydrological conditions due to topographic modification by detachment sliding and the formation of a fresh active layer affect rates of surface wash erosion. Detachment slides generally accumulated more snow than adjacent slopes and yielded greater amounts of surface runoff than vegetated slopes with similar snow covers. Surface drainage was inhibited on well-vegetated hummocky slopes where lags between radiation inputs and discharge responses were greater than at the rilled detachment slide plots. During rainfall events following snowmelt, plot response was affected by antecedent moisture conditions and the vegetation cover: surface flow was generated only in detachment slide scars and at the mixed plots but not on vegetated undisturbed slopes or on the bare undisturbed slope. Suspended sediment concentrations at the fresh detachment slide scars are two orders of magnitude greater than on vegetated slopes. Greater amounts of surface runoff production at fresh scars and the removal of vegetation result in high rates of surface erosion and high sediment yields (1560 g/m$\sp2)$ at fresh detachment slide scars. (Abstract shortened by UMI.)