A study of suspended sediment transport dynamics was undertaken in the West River at Cape Bounty, Melville Island, Nunavut. Hydrometerological conditions and sediment transport were measured over three seasons in order to characterize suspended sediment transport and grain size characteristics in relation to catchment and channel snowpack. Catchment snow water equivalence was measured at the beginning of the season, and discharge, suspended sediment concentration (SSC) and grain size were measured at high temporal resolution through the runoff period to evaluate diurnal-, event- and seasonal-scale discharge-suspended sediment and grain size hysteresis. In addition, two models of a time-integrated suspended sediment trap, modified from Philips et al. (2000), were deployed in both streams to assess the representativeness of the captured sediment. The West stream discharge was dominated by the snowmelt peak in all three seasons. From 54-96% of suspended sediment was transported during this short period, although hysteresis relationships indicate that delivery of sediment and water were not synchronous and interannual relationships suggest disproportionate increases in sediment discharge with increased catchment snowpack. Clockwise and counter-clockwise suspended sediment hysteresis relationships were apparent and associated with lesser and greater snowpack, respectively. Additionally, grain size hysteresis suggested variable sediment sources during the season. Assessment of the time-integrated suspended sediment trap in the East and West streams illustrated that the captured material was not representative of the ambient stream conditions. Captured mass was typically two orders of magnitude less than expected iii capture rates (<1%) and that the captured sediment was significantly coarser than the ambient stream suspended sediment load. Investigations of suspended sediment transfer in this small, High Arctic catchment reveal that sediment transport increased with increased catchment snowpack, but delivery of water and sediment were not synchronous during the nival discharge event suggesting changing sediment accessibility during the season. An attempt to collect a time-integrated suspended sediment sample that would incorporate variability in the character and magnitude of sediment delivery provided an unrepresentative sample, but results indicate that a detailed examination of hydraulic relationships between the trap and ambient conditions could ultimately lead to the development of a more representative trap. / Thesis (Master, Geography) -- Queen's University, 2007-09-16 10:03:25.925

Suspended sediment delivery dynamics in two watersheds at Cape Bounty, Melville Island, Nunavut, Canada were studied to characterize the hydroclimate conditions in which laminated sediments formed. Process work over three years determined snow-water equivalence was the primary factor that controlled sediment yield in both catchments. Cool springs (2003, 2004) enhanced runoff potential and intensity because channelized meltwater was delayed as it tunneled through the snowpack and reached the river channel (sediment supply) within 1-2 days. In warm springs (2005), meltwater channelized on the snowpack and did not immediately reach the river bed (7-10 days). Sediment transport was reduced because flow competence was lower and sediment supplies limited. Sediment deposition in the West Lake depended on surface runoff intensity. Short-lived, intense episodes of turbid inflow generated underflow activity which delivered the majority of seasonal sediment. In 2005, runoff was less intense and few underflows were detected compared to the cooler, underflow dominated 2004 runoff season. As well, grain-size analysis of trapped sediment indicated that deposition rates and maximum grain-size were decoupled, indicative of varied sediment supplies and delivery within the fluvial system. These decoupled conditions have important implications for paleohydrological interpretations from downstream sedimentary records. Two similar 600-year varve records were constructed from the lakes at Cape Bounty. Although these series were highly correlated throughout, time-dependent correlation analysis identified divergence in the early 19th century. Because the varve records were from adjacent watersheds and subject to the same hydroclimatic conditions, the divergence suggests watershed-level changes, such as increased local active layer detachments. The varve record from West Lake was highly correlated with lagged autumn snowfall and spring temperature. Similar relationships between these variables and East Lake were not as strong or significant. Long-term climatic interpretations should be carefully assessed. A single record from either of these lakes might lead to autumn snowfall and/or spring-melt intensity reconstructions, given the process work and weather record correlations. The recent divergence reveals potential changes likely to occur as warming increases variability within the Arctic System. Multidisciplinary monitoring and observations should continue in order to quantify future variability and evaluate the impact on these systems. / Thesis (Ph.D, Geography) -- Queen's University, 2008-09-02 12:11:53.483

Using a sediment budget approach, suspended sediment transport dynamics were studied over the 2010 summer runoff season in the 8 km2 West River catchment at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island, Nunavut. Research was carried out in an effort to determine the longer term impacts and response of recent (2007-8) active layer detachments (ALD) on the river system. In 2010, measured ALD inflows contributed 4.7% of the measured sediment yield, a decrease of 13.3% from 2007 when they initially formed. This indicates that while they continue to supply sediment to the main river, the impact they have on sediment fluxes, and hence the sediment budget has diminished, with time. Results from the sediment budget indicate that connectivity and the sediment delivery ratio within the system have also decreased with time. Sediment budget analysis shows that in response to this additional sediment, the West River progressively stores more sediment throughout the season, storing as much as 85% of sediment inflows during baseflow. Sediment was preferentially deposited within the channel, with coarser material deposited in the upper reaches, and finer material deposited in the lower reaches. Similarly, the transported and stored sediment became progressively finer with time, indicating the importance that river competence and wetted perimeter have on sediment transport as the larger sediment was entrained earlier in the season under higher flow conditions when the sediment was accessible, and finer sediment transported later in the season due to decreased competence and reduced accessibility of sediment. This sediment storage is expected to replenish sediment in the channel that is eroded during peak discharge in spring, and also dampens the effects that disturbances have on the sediment budget through storage. Sediment stored in the channel towards the end of the season does not contribute to sediment yield and may prove to be an important source of sediment in future years under late summer rainfall events. / Thesis (Master, Geography) -- Queen's University, 2011-12-08 16:31:48.633

No description available.

Peatlands store 30% of global terrestrial organic carbon. At the Mer Bleue research site in southern Canada (45.40° N, 75.50° W), it has been shown that changes in water storage affect carbon fluxes in and out of the peatland. Mer Bleue has a distinct hummock – hollow surface topography. The micro-topographical features affect the temporal and spatial variations in water table. Sampling the temporal and spatial variations on two separate plots with varying degrees of micro-topographic relief took place during the 2010 field season. Each plot has 100 manual observation wells in a 2 x 2 metre grid that have been sampled every 2-3 weeks and several transects of 4-7 automatic capacitance data loggers, continuously recording water levels every 15 minutes. The continuous water table measurements were situated to maximize the difference in elevation between adjacent hummocks and hollows. Our results indicate that the spatial pattern of the water table at any given time is a subdued reflection of the surface topography – i.e. greater depth under hummocks than hollows. The continuous water table measurements show that the variations in water table are synchronized, despite differences in surface micro-topography. When combined with the surface elevation the patterns in time and space can be used to provide a tempo-spatial ecologically meaningful measure of water storage, explain the feedbacks between moisture and peat accumulation, and suggest a basis for scaling point measurements to account for topographic variations. / Les tourbières contiennent 30% du carbone organique terrestre au monde. Au site de recherche Mer Bleue à Ottawa (45.40° N, 75.50° W), on a montré que les flux de carbone sont contrôlés par des fluctuations de stockage total du tourbières. La nappe phréatique indique la rétention d'humidité. La tourbière à Mer Bleue a une microtopographie distincte de buttes et creux. Les caractéristiques des micro-topographique affectent les variations temporelles et spatiales de la nappe phréatique. L'échantillonnage a eu lieu entre Juin et Décembre 2010, en deux parcelles à des degrés divers de l'allégement de micro-topographiques. Chaque parcelle dispose de 100 puits d'observation dans un manuel de 2 x 2 mètres de grille qui ont été échantillonnés tous les 2-3 semaines et plusieurs transects de 4-7 automatique des enregistreurs de données capacitive, enregistrement en continu des niveaux d'eau toutes les 15 minutes. Les mesures en continu de la nappe phréatique se trouvaient à maximiser la différence d'altitude entre les buttes et les creux adjacents. Les résultats indiquent que la répartition spatiale de la nappe phréatique à un moment donné est un reflet modéré de la topographie de surface. Les mesures en continu de la nappe phréatique montrent que les variations de la nappe phréatique sont synchronisés, malgré les différences de surface micro-topographie. Lorsqu'il est combiné avec l'élévation de la surface des modèles dans le temps et l'espace peut être utilisé pour fournir une mesure tempo-spatiale écologiquement significatives de stockage de l'eau, expliquent les rétroactions entre l'accumulation d'humidité et de la tourbe, et de proposer une base pour l'extension des mesures ponctuelles pour tenir compte des variations topographiques.

Watershed models can play an important role in regional planning. Their ability to consider large, spatially diverse regions and assess the impact of different land use scenarios on water resources can lead to better, more informed decision making. Recent legislation in Ontario has led to the adoption of watershed models as part of drinking water source protection planning processes. In this study, the ability of the SWAT model to simulate the hydrology of the Raisin River watershed, an area of 556km2 located in eastern Ontario, is examined. The model was calibrated using data from 1985 to 1994 and validated using data from 1995 to 2004. Weekly average flow rates were used to evaluate the model, producing a Nash Sutcliffe coefficient of 0.798 for the period of calibration and 0.788 for the validation period. Model error is most significant during the annual snowmelt period, suggesting deficiencies in the way snowmelt is modeled. Baseflow predictions are correct on an annual basis but exhibit more volatility than the observed flow. The Nash Sutcliffe coefficient is a common measure of hydrologic model performance but suffers from being strongly biased to certain times of the year. Specifically, it is insensitive to periods of low flow which are important for source protection planning. The possibility of transforming the observed and predicted flow rates to compensate is discussed. The methodology presented takes advantage of readily available standardised data, permitting a similar modeling exercise to be easily undertaken for a different region. Results and analysis as presented could be used directly in the development of source protection plans. Spatial and temporal variation of water budget components (runoff, recharge and evapotranspiration) throughout the watershed is discussed. The impact of land use and soil type on the water budget is also highlighted. / Les modèles de bassin d'eau peuvent jouer un rôle important dans la planification régionale. Leur capacité de considérer de grandes régions, diverses en espace et évaluer l'impact de scénarios d'utilisation de différentes terres sur des ressources en eau peut mener à des prises de décisions meilleures et plus informées. La récente législation en Ontario a mené à l'adoption de modèles de bassin d'eau faisant partie de processus de planification de protection de source d'eau potable. Dans cette étude, la capacité du modèle SWAT (Outil d'évaluation du sol et de l'eau) pour simuler l'hydrologie du bassin de la Rivière Raisin, un secteur de 556km2 situé à l'est de l'Ontario, est examiné. Le modèle a été calibré au cours de la période de 1985 à 1994 et validé au cours de la période de 1995 à 2004. Des débits hebdomadaires moyens ont été utilisés pour évaluer le modèle, produisant un coefficient Nash Sutcliffe de 0.798 pendant la période de calibrage et 0.788 pendant la période de validation. L'erreur modèle est la plus significative pendant la période de fonte de neige annuelle, suggérant des manques dans la manière que la fonte de neige est modelée. Les prédictions du débit de base sont correctes sur une base annuelle, mais exposent plus de volatilité que le flux observé. Le coefficient Nash Sutcliffe est une mesure commune de performance du modèle hydrologique, mais souffre en étant fortement influencé par certains temps de l'année. Spécifiquement, il est insensible aux périodes de bas débit qui sont importantes pour la planification de la protection de source. La possibilité de transformer les débits observés et prévus pour indemniser est discutée. La méthodologie présentée profite de données standardisées aisément disponibles, permettant à un exercice de modélisation semblable d'être facilement entrepris pour une région différente. Les résultats et l'analyse tel que présentés pourraient$

A visco-elastic analytical model is presented for the simulation of large scale groundwater flow and land subsidence. Groundwater flow is simulated by a two-dimensional flow model. Land subsidence is modeled vertically by using the Taylor-Merchant one dimensional consolidation theory. In application, multiple aquifers are generalized by using a field approach based on a few 'bulk parameters', which allows the direct use of records obtainable in situ. / The visco-elastic model is applied to analyze and predict the land subsidence in Bangkok, Thailand. The results demonstrate that the visco-elastic model can yield a satisfactory prediction of consolidation that is better than that obtained with the classical Theis-Jacob approach. / Predictions of the piezometric head and subsidence for the 20 years from 1981-2000 were made based on the following three scenarios: (1) a constant withdrawal at 1980's rate, (2) a cessation of all pumping wells, and (3) simultaneous pumping and injection, with injection exceeding 1980's pumping rate by 50%.

No description available.

Although snow's behaviour is well known in rural contexts through a long standing and widespread network of measurement and recording, the specificity of existing urban datasets to where they were measured limits their applicability to other cities. In this study, snow measurements were performed in urban and suburban Montreal, Québec, Canada over the course of the winter of 2007-2008. Observations of density, depth and albedo showed general trends similar to those expected from rural snow but with density values closer to those measured in other urban studies. Snow properties were scaled up to the convective footprint of an eddy covariance flux tower. Convective fluxes showed little to no relationship with observed snow conditions. Snow evolution data was used in the validation of an offline version of the snow subroutine that is part of the ISBA land surface model. Best results were found for locations subjected to little or no disturbance. Worst results were found for highly disturbed locations. / Malgré que le comportement de la neige soit bien documenté en milieu rural grâce à des réseaux de mesure en place depuis longtemps, la complexité des milieux urbains fait en sorte que le transfert de données acquises dans une ville à une autre n'est pas justifiable. Dans le but de la recherche présentée dans cette thèse, des mesures de la couverture neigeuse ont été effectuées dans un quartier résidentiel de la ville de Montréal, Québec, Canada et dans une de ses banlieues au cours de la saison hivernale 2007-2008. Les tendances générales se comportent similairement à celles observées en milieu rural à l'exception que les valeurs de densité se rapprochaient plus de valeurs observées au cours d'autres études urbaines. Les propriétés de la neige ont alors été mises à l'échelle de la zone source convective d'équipements de mesure de flux énergétiques. Les flux convectifs n'ont pas montrés de signe d'une dépendance aux conditions de neige. La base de données de l'évolution des propriétés de la neige a également servi dans la validation d'une version autonome du modéle de neige faisant partie du modéle d'échange de surface ISBA. Les meilleurs résultats ont étés obtenus pour des endroits subissant le minimum de perturbations humaines. Les pires résultats découlent de la simulation d'endroits très dérangés.

Peatlands are significant soil carbon and freshwater reservoirs at the global scale, and thus play a key role in the global carbon and water cycles. Peatland inception and development are intrinsically related to optimal environmental conditions, including an adequate hydro-morphological setting that promotes the occurrence of waterlogged soils and low topographic gradients. This thesis investigates the hydrology of 0.2 km2 northern peatland complex, located in the region of Schefferville, Québec, Canada, in which a significant area has developed over a relatively steep topographic gradient. The objective of this thesis is to quantify and characterize the spatiotemporal flux of regional groundwater to the peatland local flow system in an attempt to evaluate the relative importance of this flux compared with other water inputs. A three-dimensional groundwater flow model, the finite-difference U.S. Geological Survey MODFLOW code, is used to simulate the peatland and characterize the groundwater flow system. The model is parameterized with data measured from June 17th to September 4th, 2009, including continuous meteorological measurements from an automatic weather station, 14 observation wells, and two 90° V-notch weirs gauging stream discharge. This study establishes that, over the measuring period, the regional groundwater influx accounted for 27% ± 0.4% of the total water inputs, the remainder 73% ± 0.4% consisting of precipitation (54% ± 0.4%), surface water inflow (14% ± 0.4%), and change in storage (5% ± 0.4%). Consequently, it is the main conclusion of this work that regional groundwater inflows were, volumetrically, the second most important source of water to the peatland local flow system. / Les tourbières représentent d'importants réservoirs naturels riches en carbone et en eau douce à l'échelle globale. Ils jouent par conséquent un rôle majeur à la fois dans le cycle du carbone et le cycle hydrologique. L'origine et le développement des tourbières sont liés à l'existence de circonstances environnementales optimales. Il s'agit essentiellement d'un contexte hydro-morphologique adéquat favorisant l'occurrence de sols saturés en eau sur des terrains relativement plats. Ce document présente les résultats d'une étude scientifique conduite dans un complexe tourbier nordique, situé dans la région de Schefferville, Québec, Canada. Ce terrain représente un cas particulier peu observé dans la nature : une large partie de l'accumulation de matière organique a eu lieu sur un gradient topographique prononcé. L'objectif de cette étude est de quantifier et caractériser le flux spatiotemporel du système de circulation de l'eau souterraine régional à la nappe d'aquifère du système tourbier local. Un modèle numérique de circulation de l'eau souterraine est utilisé afin de simuler le système tourbier et caractériser son régime hydraulique. Basé sur le code informatique du modèle MODFLOW, développé par le Service de Géologie des Etats Unis (McDonald and Harbaugh 1988), le modèle tridimensionnel est utilisé afin de simuler la circulation des eaux sou terraine. Le modèle incorpore une série de données météorologiques et hydrométriques en tant que paramètres d'entrée. Mesurées entre le 17 juin et le 4 septembre 2009, ces données proviennent d'une station météo installée pour les besoins de l'étude sur le terrain même, ainsi que 14 puits d'observations et 2 barrages pour mesure le débit. Cette étude établit que, sur l'ensemble de la période d'étude, le flux de l eau souterraine du système régional a représenté 27% des entrées en eau. Les 73% restant se divisent entre 54% pour la précipitation, 14% pour l influx de surface et 5% pour le changement de stockage hydraulique. En conséquence, la conclusion majeure de cette étude est que le flux régional d'eau souterraine est, d'un point de vue volumétrique, le deuxième flux le plus important dans le system tourbier nordique.