The estimation or modeling of biophysical variables such as surface roughness, vegetation phytomass, and soil moisture in the Arctic is an important step towards understanding arctic energy fluxes, effects of changing climate, and hydrological patterns. This research uses Synthetic Aperture Radar (SAR) data, along with ancillary optical and environmental data, to create models that estimate these biophysical variables across different High Arctic landscapes, with the goal of applying the models across even larger areas. Field work was conducted at two High Arctic locations on Melville Island, Nunavut, Canada. At each location, surface roughness values were measured at a number of randomized plot locations using a pin meter. Soil moisture values were measured using a time domain reflectometry (TDR) instrument within six hours of multiple overpasses of the RADARSAT-2 SAR sensor. Surface roughness models were generated with multi-incidence angle and fully polarimetric SAR data, with resulting R2 values ranging between 0.39 and 0.66, and normalized root mean squared error (N_RMSE) values of 14% - 22%. The output from the final surface roughness model was used as an input to the soil moisture models. Vegetation phytomass was modeled with multi-angular SAR data, using a soil adjusted vegetation index (SAVI) derived from optical data across the study area as a measure of verification. The resulting model had a significant (p <0.05) relationship to the SAVI values, with an R2 of 0.60. This model was then compared to field-collected above-ground phytomass values, and a model was derived that related SAR data directly to phytomass. This model again showed a strong relationship, with an R2 value of 0.87. The final biophysical variable that was modeled, soil moisture, showed moderate agreement to field-measured soil moisture values (R2 = 0.46, N_RMSE = 0.15%), but much stronger relationships were found for relative moisture values at fine scales across the landscape. These models, when taken together, demonstrate that SAR data is capable of modeling biophysical variables across high latitude environments. These models will help address larger questions, such as how SAR can be used to better understand moisture and energy exchanges over regional areas in high arctic environments. / Thesis (Ph.D, Geography) -- Queen's University, 2014-02-03 16:52:26.856

Stephens Lake, Manitoba is an example of a peatland reservoir that has undergone physical changes related to mineral erosion and peatland disintegration processes since its initial impoundment. In this thesis I focused on the processes of peatland upheaval, transport, and disintegration as the primary drivers of dynamic change within the reservoir. The changes related to these processes are most frequent after initial reservoir impoundment and decline over time. They continue to occur over 35 years after initial flooding. I developed a remote sensing approach that employs both optical and microwave sensors for discriminating land (i.e. floating peatlands, forested land, and barren land) from open water within the reservoir. High spatial resolution visible and near-infrared (VNIR) optical data obtained from the QuickBird satellite, and synthetic aperture radar (SAR) microwave data obtained from the RADARSAT-1 satellite were implemented. The approach was facilitated with a Geographic Information System (GIS) based validation map for the extraction of optical and SAR pixel data. Each sensor’s extracted data set was first analyzed separately using univariate and multivariate statistical methods to determine the discriminant ability of each sensor. The initial analyses were followed by an integrated sensor approach; the development of an image classification model; and a change detection analysis. Results showed excellent (> 95%) classification accuracy using QuickBird satellite image data. Discrimination and classification of studied land cover classes using SAR image texture data resulted in lower overall classification accuracies (~ 60%). SAR data classification accuracy improved to > 90% when classifying only land and water, demonstrating SAR’s utility as a land and water mapping tool. An integrated sensor data approach showed no considerable improvement over the use of optical satellite image data alone. An image classification model was developed that could be used to map both detailed land cover classes and the land and water interface within the reservoir. Change detection analysis over a seven year period indicated that physical changes related to mineral erosion, peatland upheaval, transport, and disintegration, and operational water level variation continue to take place in the reservoir some 35 years after initial flooding. This thesis demonstrates the ability of optical and SAR satellite image remote sensing data sets to be used in an operational context for the routine discrimination of the land and water boundaries within a dynamic peatland reservoir. Future monitoring programs would benefit most from a complementary image acquisition program in which SAR images, known for their acquisition reliability under cloud cover, are acquired along with optical images given their ability to discriminate land cover classes in greater detail.

Wetlands are recognized as valuable landscapes for their contribution to biodiversity, ecosystem services and population livelihoods. However, current global wetland inventories do not spatially represent wetland extent at a spatial and temporal resolution appropriate for conservation and management purposes. Among the best existing global inventories, the Global Lakes & Wetlands Database (GLWD; Lehner & Döll, 2004) is a static database assembled from various existing data sources that unfortunately suffers from the inconsistency among its data sources. Another, the Global Surface Water Extent Dataset (GSWED; Prigent et al. 2007; Papa et al. 2010) produced from a multi-satellite method is capable of monthly measurements but possesses a coarse spatial resolution incapable of discriminating distinct surface water bodies. Faced with the limitations of current global inventories, a new methodological approach is required to provide the improved wetland inventory needed by the research and conservation communities.This thesis investigates a methodology capable of producing a high-resolution (~ 500 m) surface water extent map by spatially downscaling the coarse resolution (~27 km) inundated area estimates of GSWED. The methodology inspired by Bwangoy et al. (2010) has a pragmatic and straight-forward design to ensure and ease its global application. The work of this thesis consists of an initial implementation and validation of the methodology across the African continent. The downscaling approach relies on the topographic and hydrographic information from the globally available HydroSHEDS data (Lehner et al., 2008) to distribute inundated area at the finer resolution to the most topographically inundation prone areas. Thirteen hydro-topographic variables were computed from HydroSHEDS and then consolidated into a single inundation probability map with the use of decision tree learners. The decision trees were trained on regional inundation maps and subsequently employed to generate a topographic probability of inundation map at high-resolution for the entire continent. The probability map is turned into an inundated/non-inundated map by splitting the probability distribution into two (inundated/non-inundated) with a defined threshold value. A threshold value is chosen for each GSWED cell to produce an inundation map replicating the inundated area estimates of GSWED within the cell at the finer resolution. To represent the maximum wetland extent at different timescales, two sets of inundated areas estimates were downscaled as high-resolution inundation maps with this MWT downscaling procedure: 1) the mean annual maximum (MAMax) estimates were calculated for each cell from the monthly estimates of GSWED between 1993 and 2004; 2) the fusion maximum (MaxFusion) was generated from a fusion of the time-series maximum (TSMax) also calculated from GSWED, with the wetland area from GLWD. The MaxFusion estimates were produced to correct some data gaps of GSWED, as well as to offer a more complete and reliable maximum wetland extent map. The MAMax and MaxFusion estimates respectively totalled 1339 and 2779 thousand km2 of wetland area across the continent; higher than most previous estimates for Africa.Validation of the spatial distribution of inundation at the finer resolution exhibited high levels of agreement against reference regional maps (Overall Accuracy ~ 92%; KIA ~ 80%). Over selected wetland study sites, comparisons of the MaxFusion downscaled map with the global land cover GLC2000 (Mayaux et al. 2004) and wetland database GLWD indicated that the downscaled map possessed slightly lower but more consistent agreement with GLC2000 than GLWD did. Regardless, the level accuracy of the tested methodology is considered satisfactory to pursue production of a first version global inundation map. Possible follow-up applications making use of the downscaled inundation maps such as a global hydro-geomorphic wetland classification. / Bien que l'importance des milieux humides pour la biodiversité et les services écosystémiques soit reconnue, les bases de données actuellement disponibles ne sont pas en mesure de décrire globalement les charactéristiques biophysiques des milieux humides de façon utile à des fins de gestion et de conservation. Parmi les inventaires globaux de milieux humides disponibles, la Global Lake & Wetland Database (GLWD) (Lehner & Döll, 2004), , est une représentation statique constituée de plusieurs sources qui est cependant spatiallement inconsistente. Un autre inventaire, le Global Surface Water Extent Dataset (GSWED) (Prigent et al. 2007; Papa et al. 2010) produite à partir d'une méthode multi-satellitaire, possède une faible résolution spatiale incapable de différencier des plans d'eau distincts. Compte tenue des limites des actuels inventaires, une nouvelle approche est nécessaire pour générer le nouvel et amélioré inventaire que demande diverses communautés de chercheurs.Cette thèse examine la possibilité de produire une représentation spatiale d'inondation et de milieux humides globale à haute résolution (~ 500 m) à partir d'une réduction d'échelle des estimés surfaces inondées de faible résolution (~27 km) du GSWED. La méthode inspirée par Bwangoy et al. (2010) a été développée de façon pragmatique et simple afin d'assurer son application globale sans heurt. Cette thèse est une application initiale de la méthodologie à des fins de validations sur le continent africain. La méthode de réduction de résolution repose sur de l'information topographiques et hydrographiques globales provenant des données HydroSHEDS (Lehner et al. 2008) pour distribuer la surface inondée de GSWED à la plus fine résolution aux endroits les plus prompt à l'inondation. Treize variables hydro-topographiques furent calculées à partir d'HydroSHEDS et ensuite consolidée dans une probabilité d'inondation calculée pour chaque pixel de haute résolution d'HydorSHED,S grâce à un arbre de décision. L'arbre de décision fut entraîné et validé avec des images satellitaires régionales d'inondation et fut utilisé par la suite pour générer des probabilités d'inondation sur l'ensemble du continent. La carte de probabilités d'inondation résultante est ensuite transformée en carte d'inondation en utilisant une valeur seuil divisant la distribution de probabilités en deux. Une valeur seuil est choisie pour la surface de chaque cellule de GSWED pour répliquer la surface inondée de GSWED.En tant qu'estimé de surface provenant de GSWED, les valeurs mensuelles entre 1993 et 2004 furent agrégée pour produire des estimés du maximum annuel moyen (MAMax) ainsi que le maximum historique (TSMax). Pour produire des estimées fiables représentant la surface maximale inondée et pour corriger pour certaines des lacunes des estimés de GSWED, les estimés du TSMax furent fusionnés à celles de GLWD, générant les estimées maximales de fusion (MaxFusion). La surface totale estimée pour l'ensemble du continent africain pour MAMax et MaxFusion est estimées respectivement à 1339 et 2779 milliers de km2, plus élevée que la plupart des estimés précédents.La validation de la distribution spatiale de l'inondation à la plus fine résolution a démontré un bon accord (Précision globale ~ 92%; KIA ~ 80%) lorsque comparée à des cartes régionales d'inondations ou de milieux humides. De plus, la comparaison du résultat cartographique avec le GLC2000 et le GLWD sur quelques sites particuliers a indiqué une concordance avec GLC2000 consistante, malgré qu'inférieure à celle de GLWD. Malgré les défauts du produit, le niveau de précision de la méthodologie testée peut être considérée suffisant pour poursuivre son développement et son application globale. D'autre projets de recherches découlant de celui-ci et faisant usage d'une carte d'inondation global à haute-résolution peuvent avoir faire à un classification hydro-géomorphique de milieux humides.

No description available.

<p> Three-dimensional mapping and modeling can contribute to knowledge about the real world. Techniques are largely driven by available technology and typically involve expensive equipment and expert skill. Recent advances have led to low-cost remotely sensed data collection and generation of 3D terrain models using Uninhabited Aerial Vehicles (UAV) and Structure from Motion (SfM) processing software. This research presents a low-cost alternative to 3D mapping by pairing UAV collection methods with three SfM processing techniques. Surface models are generated from the same image set captured from a low-cost UAV coupled with a digital camera. Accuracy of resulting models identifies strengths and weaknesses of each technique. Analysis of different slope ranges investigates the divide at which surfaces generated become less reliable. This research provides a deeper understanding of the strengths and limitations of emerging technologies used together in a fresh approach to photogrammetry.</p>

The detection of clandestine graves is an emerging tool in hyperspectral remote sensing. Though previous studies have demonstrated that it is possible to use hyperspectral remote sensing techniques in detection of mass graves, there is a lack of studies demonstrating the feasibility to utilize this same technology for the detection of individual burial sites. This thesis summarizes the first year of a multi-year study to ascertain the detectable changes to vegetation and soil spectra caused by the chemicals released from a single decomposing body. Eighteen pig (Sus scrofa) carcasses were buried in a temperate environment in Ottawa, ON. Three scenarios were examined; surface body deposition, 30 cm, and 90 cm soil cover. A Twin Otter aircraft with hyperspectral sensors covering the visible to shortwave infrared range was used to collect the imagery. In addition to the airborne sensor, a portable spectroradiometer was used to collect plant and soil spectra in the lab (the soil and plant samples were collected coincidentally with the airborne imagery). Through chemical analysis of the soil collected both before site set up and coincidentally with the airborne imagery, I was able to determine the changes in chemistry and spectra caused by decomposing cadavers rather than just soil disturbance. Statistical analysis of the Chlorophyll and Carotenoids extraction demonstrates separability of vegetation into three categories: 1) background, 2) disturbed soil, shallow and deep graves, and 3) surface burials. Statistical analysis of the vegetation spectra corresponded to the chemical analysis in differentiating between background, disturbed soil, shallow and deep graves, and surface burials, as well analysis of the soil spectra allowed for separation into disturbed soil, shallow and deep graves, and surface burials. / La détection des fosses clandestines (tombes) est un domain d'étude récent (un nouvel outil) dans la télédétection hyperspectrale. Bien que des études antérieures ont démontrés qu'il est possible d'utiliser des techniques de télédétection hyperspectrale pour la localisation des fosses communes, il y a un manque d'études démontrant la faisabilité d'utiliser cette même technologie pour la détection des tombes individuelles. Cette thèse se porte sur la première année d'une étude a long terme, elle constate que des changements sont détectables au niveau de la réponse spectrale de la végétation et de du sol. Ces changements sont causés par les produits chimiques libérées par un corps en décomposition. Dix-huit carcasses de porc (Sus scrofa) ont été enterrées dans un environnement tempéré à Ottawa, ON. Trois scénarios ont été examinés: la décomposition d'un corps déposé en surface, un corps enterré à 30 cm dans le sol, et un corps enterré à 90 cm dans le sol. Un avion Twin Otter avec des capteurs hyperspectrales couvrant les ondes visible à l'infrarouge du spectre électromagnétique ont été utilisés pour recueillir des images aériennes du site. En plus, un spectroradiomètre portable a été utilisé pour recueillir des signatures spectrales des plantes et du sol en laboratoire (les échantillons ont été collectés en même temps que l'imagerie aérienne). Grâce à l'analyse chimique du sol faite avant et après l'établissement du site, ainsi qu'en même temps que l'imagerie aérienne, j'ai déterminer que certains changements chimiques ainsi que des changements dans la réflectance sont causés par la décomposition des cadavres plutôt que par la perturbation du sol. L'analyse statistique des niveaux de chlorophylle et des caroténoïdes démontre une séparabilité de la végétation en trois catégories: 1) le fond, 2) les sols perturbés, les tombes peu profondes et les tombes profondes, et 3) les corps déposé en surface. L'analyse statistique des signatures spectrales de la végétation confirme à l'analyse chimique pour différencier entre le fond, le sol perturbé, les tombes peu profondes et profondes, et les corps décomposant en surface. L'analyse des signatures spectres de sol a aussi permis de séparer entre un sol perturbé, une tombe peu profonde ou profonde, ou un « enterrement » de surface.

Sphagnum's strong water-holding capacities, its dominance in bogs, and the overall importance of water in regulating photosynthesis make it a key ecosystem engineer. Though its effectiveness in this context has rarely been tested, Spectral Vegetation Indices (SVIs) derived from hyperspectral data allow for efficient modeling of Sphagnum gravimetric water content over large scales. This study tests whether a linear model relating a SVI to Sphagnum gravimetric water content (i.e. S. capillifolium, S. magellanicum, S. angustifolium/S. fallax, or all Sphagnum species pooled together) can be applied to the landscape level using airborne hyperspectral imagery taken over Mer Bleue Bog, near Ottawa, Ontario, Canada. The depth of a Sphagnum species sample contributing to the reflectance and the vertical distribution of water across a species sample was also analyzed to test the accuracy of water content measurements. Additionally, image SVI data were compared to field SVI data to test the effectiveness of image spectra. Results indicate that light penetrated 1.5 cm in S. capillifolium samples, 1.0 cm in S. magellanicum samples, and 2.5 cm in S. angustifolium/S. fallax samples. Water variability was highest in samples with elevated water contents for every Sphagnum species analyzed. The Normalized Difference Water Index (NDWI) (dimensionless) was the most effective in estimating Sphagnum gravimetric water content of all SVIs (Root Mean Square Error=161.34%, P= 0.000). Image NDWI values mimicked field NDWI values (Root Mean Square Error= 0.000740, P= 0.0000). The application of the NDWI to areas identified as being favorable for Sphagnum growth in an image resulted in a map of Sphagnum gravimetric water content for a given day in a bog. / Le contenu d'eau des sphaignes est important pour le fonctionnement des tourbières ombrotrophes, suite aux fortes capacités de rétention d'eau dans ces espèces, la domination de ses espèces dans les tourbières ombrotrophes, et l'importance d'eau dans la régulation de la photosynthèse. L'efficacité des "Spectral Vegetation Indices" (SVIs) dérivée des données hyperspectrales permet une modélisation efficace du contenu d'eau gravimétrique des sphaignes sur de grands échelons. Cependant, l'efficacité des SVIs dans ce contexte a été rarement examinée. Cette étude examine si un modèle linéaire reliant un SVI au contenu d'eau gravimétrique des sphaignes (i.e. S. capillifolium, S. magellanicum, S. angustifolium/S. fallax, ou tous les espèces Sphagnum jumelées ensemble) peut être appliqué au niveau paysagier en utilisant l'imagerie hyperspectrale aérienne prise au-dessus de la tourbière ombrotrophe Mer Bleue, située à proximité d'Ottawa, en Ontario, au Canada. La profondeur d'un échantillon d'une espèce de Sphagnum qui contribue à la réflectance et la distribution verticale d'eau à travers un échantillon a aussi été analysée pour tester l'exactitude des mesures du contenu d'eau. De plus, les données de SVI générées par les images ont été comparées aux données SVI générées par les mesures prises sur le terrain pour examiner l'efficacité des spectres générées par les images. Les résultats indiquent que la lumière a pénétré à une profondeur de 1.5 cm dans les échantillons de S. capillifolium, 1.0 cm dans les échantillons de S. magellanicum, et 2.5 cm dans les échantillons de S. angustifolium/S. fallax. La variabilité d'eau a été le plus prononcée dans les échantillons avec des contenus d'eaux gravimétriques élevées pour chaque espèce de Sphagnum analysée. La "Normalized Difference Water Index" (NDWI) (sans dimension) a été la plus efficace dans l'estimation du contenu d'eau gravimétrique des espèces de tous les SVIs ("Root Mean Square Error"=161.34%, P= 0.000). Les valeurs de NDWI dérivées du terrain ont été semblabes à celles collectionnées sur le terrain (“Root Mean Square Error”= 0.000740, P= 0.0000). L'application du NDWI aux régions identifiées comme étant favorables pour la croissance des sphaignes dans une image a donné, comme résultat, une carte du contenu d'eau gravimétrique des sphaignes pour une journée dans une tourbière ombrotrophe.

<p> Abstract not available.</p>

<p> This study investigates the potential for hydrothermal alteration and circulation in lava domes using combined analytical, remote sensing and numerical modeling approaches. This has been accomplished in three parts: <i>1) </i> A comprehensive field, geochemical and remote sensing investigation was undertaken of the hydrothermal system in the Santiaguito lava dome complex in Guatemala. The Santiaguito domes were found to contain mainly hydrous silica alteration, which is unlikely to weaken dome rock, but the summit of Santa Maria was found to contain pervasive argillic alteration (clay minerals), which do pose more of a collapse-related hazard. These results were confirmed by hot spring geochemistry which indicated that water in the domes was responsible for some rock dissolution but had a residence time too short to allow for secondary mineralization. <i>2)</i> A finite element numerical modeling approach was developed which was designed to simulate the percolation of meteoric water in two dome geometries (crater-confined and 'perched'), and the results were compared to the surface expression of hydrothermal systems on existing lava domes. In both cases, we concluded that simulated domes which lacked a high-temperature (magmatic) heat source could not develop a convecting hydrothermal system and were dominated by gravitational water flow. In these low-temperature simulations, warm springs (warmer high fluid fluxes) were produced at the base of the dome talus and cool springs were dispersed lower down the slope/substrate; fumaroles (high vapor fluxes) were confined to the dome summits. Comparison with existing dome cross sections indicates that the simulations were accurate in predicting fumarole locations and somewhat accurate at predicting spring locations, suggesting that springs may be subject to permeability contrasts created by more complicated structural features than were simulated in this study. <i>3)</i> The results of the numerical modeling were used to calculate alteration potential in the simulated domes, indicating the most likely areas where alteration processes might either reduce the strength of a dome or reduce permeability that could contribute to internal pressurization. Rock alteration potential in low-temperature lava domes was found to be controlled by material permeability and the presence or absence of a sustained heat source driving hydrothermal circulation. High RAI values were preserved longer in low-permeability domes, but were more strongly developed in domes with higher permeabilities. Potential for mineral dissolution was highest at the base of the dome core, while the potential for mineral precipitation is highest at the dome core-talus interface. If precipitated minerals are impermeable, the dome core/talus interface would be a likely location for accumulation of gases and initiation of gas-pressurization-related collapse; if alteration is depositing weak (i.e. clay) minerals in this area, the dome core/talus interface might be a candidate for collapses occurring as the result of alteration processes. </p><p> The results of this study are all geared toward answering two broad questions: <i> Where are hydrothermal alteration processes likely to occur or be focused within lava domes?</i> and <i>What effect could these processes have on dome stability?</i> In the specific case of the Santiaguito dome complex, the combination of a quickly-recharged, low-temperature hydrothermal system in the inactive domes actually indicated a low possibility of collapse related to alteration minerals. This result was reinforced by the results of the numerical modeling, which indicated that domes are unlikely to develop sustained hydrothermal convection without the presence of a significant (magmatic) heat source and&mdash;in the case of Santiaguito&mdash;are likely to produce more hydrous silica alteration minerals when they also lack a source of acidic gases. Models of alteration potential do detail, however, that both shallow and deep dome collapses are still a possibility with a low-temperature hydrothermal system, given either a) a source of acidic gases to drive the formation of clay minerals (which are most likely to be deposited at the core/talus interface of a dome, or b) enough deposition of silica minerals in pore spaces to lower permeability in dome rock and promote internal gas pressurization. The results of this study are not limited to lava domes, as the volcanic edifices on which they rest are composed of the same materials that comprise lava domes and are therefore susceptible to the same hydrothermal processes. Further simulations of both lava domes and their associated edifices, including mineral species models, could help constrain under what conditions a lava dome or volcano is likely to develop areas of weak mineral precipitates (such as clay minerals) which could provide sites for collapse, or develop an impermeable cap of silicate minerals which could trap rising vapor and contribute to the pressurization of the edifice in question (which can in turn lead to collapse).</p>

Stephens Lake, Manitoba is an example of a peatland reservoir that has undergone physical changes related to mineral erosion and peatland disintegration processes since its initial impoundment. In this thesis I focused on the processes of peatland upheaval, transport, and disintegration as the primary drivers of dynamic change within the reservoir. The changes related to these processes are most frequent after initial reservoir impoundment and decline over time. They continue to occur over 35 years after initial flooding. I developed a remote sensing approach that employs both optical and microwave sensors for discriminating land (i.e. floating peatlands, forested land, and barren land) from open water within the reservoir. High spatial resolution visible and near-infrared (VNIR) optical data obtained from the QuickBird satellite, and synthetic aperture radar (SAR) microwave data obtained from the RADARSAT-1 satellite were implemented. The approach was facilitated with a Geographic Information System (GIS) based validation map for the extraction of optical and SAR pixel data. Each sensor’s extracted data set was first analyzed separately using univariate and multivariate statistical methods to determine the discriminant ability of each sensor. The initial analyses were followed by an integrated sensor approach; the development of an image classification model; and a change detection analysis. Results showed excellent (> 95%) classification accuracy using QuickBird satellite image data. Discrimination and classification of studied land cover classes using SAR image texture data resulted in lower overall classification accuracies (~ 60%). SAR data classification accuracy improved to > 90% when classifying only land and water, demonstrating SAR’s utility as a land and water mapping tool. An integrated sensor data approach showed no considerable improvement over the use of optical satellite image data alone. An image classification model was developed that could be used to map both detailed land cover classes and the land and water interface within the reservoir. Change detection analysis over a seven year period indicated that physical changes related to mineral erosion, peatland upheaval, transport, and disintegration, and operational water level variation continue to take place in the reservoir some 35 years after initial flooding. This thesis demonstrates the ability of optical and SAR satellite image remote sensing data sets to be used in an operational context for the routine discrimination of the land and water boundaries within a dynamic peatland reservoir. Future monitoring programs would benefit most from a complementary image acquisition program in which SAR images, known for their acquisition reliability under cloud cover, are acquired along with optical images given their ability to discriminate land cover classes in greater detail.