This research conducts a spatial and temporal analysis of the distribution of fecal coliform throughout the Capital Regional District (CRD) of southern Vancouver Island. The research is based on 17 years of historical data of stormwater samplings from 1995 to 2011 in the nearshore region. ArcGIS is used to map the fecal coliform data collected within and adjacent to nearshore areas to identify peaks above a regulated threshold. Heavily polluted areas are in Victoria downtown, Esquimalt and the southeastern shore of Oak Bay. Land-use data and drainage patterns are used to determine relationships between fecal coliform levels and land-use by considering relevant, temporally dependent factors. Temperature is positively correlated with FC level and precipitation is negatively correlated. The residential land use is identified as the main source of bacterial contamination. This analysis leads to a regression model that indicates two peaks (July and October) of FC level occur in a 12-month period and positively related to minimum temperature and cloud cover ratio. / Graduate

Forest fires occur frequently in the boreal forest of North America and greatly affect vegetation dynamics, biogeochemical cycles and resident human populations. Estimates of the frequency of boreal forest fires would be useful for understanding boreal ecosystems and managing the affects of fires on human populations. The objectives of this work were to investigate relations between fire frequency and climate change, vegetation)n type and waterbreaks in Wood Buffalo National Park (WBNP), located in northern Alberta. To address these objectives, four hypotheses were tested: 1) tree ring-width records from the boreal forest can provide a proxy climate record; 2) annual area burned in the boreal forest varies in response to climate changes; 3) boreal fores: fire frequency varies with differences in forest type and the proximity to waterbreaks and 4) fossil pollen and macroscopic charcoal records from massive lake sediments can provide meaningful estimates of local fire frequency. The first hypothesis was tested by constructing tree ring chronologies from 3 white spruce and two jack pine sites in WBNP. All five chronologies were significantly positively correlated with June precipitation in the growth year or the previous year, and were significantly negatively correlated with historical records of fire weather and annual area burned. The second hypothesis was tested by analyzing historical records of annual area burned and climate. and tree ring records of fire history and climate. Annual area burned was significantly negatively correlated with seasonal means of fire weather indices. The time since last fire was estimated using tree ring records from 166 sites located throughout WBNP. These records exhibited decadal and centennial scale variations in fire frequency. Comparisons with tree ring other proxy climate records suggest that the~e variations are related to climatic changes. The third hypothesis was tested using survival analysis of the time since last fire records, disaggregated by dominant vegetation and the mean distance to waterbreaks. Sites dominated by jack pine (Pinus banksiana) and aspen (Populus tremuloides) exhibited significantly higher fire frequencies than did sites dominated by black spruce (Picea mariana) or white spruce (Picea glauca). Fire frequency increased with increased mean distance to waterbreaks. The fourth hypothesis was tested by analyzing fossil pollen and charcoal records from two lakes at -5 year resolution for 600 years. I compared their fire history records with local tree ring records of fire, and their mean fire intervals with regional fire frequency estimates for sites with similar vegetation and mean distances to waterbreaks. One lake exhibited a meaningful fire frequency estimate and the other lake did not. The poor fire frequency estimate was related to high sediment mixing and the lack of homogenous vegetation around the lake. The results indicate that: 1) area burned and fire frequency in the boreal forest of northern Alberta varies temporally at the annual, decadal and centennial scales; 2) fire frequency varies spatially in relation to vegetation type and mean waterbreak distance; and 3) lakes with massive sediments can provide meaningful estimates of local fire frequency. / Thesis / Doctor of Philosophy (PhD)

Variations in Leaf Area Index (LAI) can greatly alter output values and patterns of various models that deal with energy flux exchange between the land surface and the atmosphere. Customarily, such models are initiated by LAI estimated from satellite-level Vegetation Indices (VIs) including routinely produced Normalized Difference Vegetation Index (NDVI) products. However, the accuracy from LAI-VI relationships greatly varies due to many factors, including temporal and spatial variations in LAI and a selected VI. In addition, NDVI products derived from various sensors have demonstrated variations in a certain degree on describing temporal and spatial variations in LAI, especially in semi-arid areas. This thesis therefore has three objectives: 1) determine a suitable VI for quantifying LAI temporal variation; 2) improve LAI estimation by considering both temporal and spatial variations in LAI; and 3) evaluate routinely produced NDVI products on monitoring temporal and spatial variations in LAI.<p> The study site was set up in conserved semi-arid mixed grassland in St. Denis, Saskatchewan, Canada. One 600 m - long sampling transect was set up across the rolling typography, and six plots with a size of 40 × 40 m each were randomly designed and each was in a relatively homogenous area. Plant Area Index (PAI, which was validated to obtain LAI), ground hyperspectral reflectance, ground covers (grasses, forbs, standing dead, litter, and bare soil), and soil moisture data were collected over the sampling transect and plots from May through September, 2008. Satellite data used are SPOT 4/5 images and 16-day Moderate Resolution Imaging Spectroradiometer (MODIS) 250m, 1km as well as 10-day SPOT-vegetation (SPOT-VGT) NDVI products from May to October, 2007 and 2008. The results show that NDVI is the most suitable VI for quantifying temporal variation of LAI. LAI estimation is much improved by considering both temporal and spatial variations. Based on the ground reflectance data, the r2 value is increased by 0.05, 0.31, and 0.23 and an averaged relative error is decreased by 1.57, 1.62, and 0.67 in the early, maximum, and late growing season, respectively. MODIS 250m NDVI products are the most useful datasets and MODIS 1km NDVI products are superior to SPOT-VGT 1km composites for monitoring intra-annual spatiotemporal variations in LAI. The proposed LAI estimation approach can be used in other studies to obtain more accurate LAI, and thus this research will be beneficial for grassland modeling.

Variations in Leaf Area Index (LAI) can greatly alter output values and patterns of various models that deal with energy flux exchange between the land surface and the atmosphere. Customarily, such models are initiated by LAI estimated from satellite-level Vegetation Indices (VIs) including routinely produced Normalized Difference Vegetation Index (NDVI) products. However, the accuracy from LAI-VI relationships greatly varies due to many factors, including temporal and spatial variations in LAI and a selected VI. In addition, NDVI products derived from various sensors have demonstrated variations in a certain degree on describing temporal and spatial variations in LAI, especially in semi-arid areas. This thesis therefore has three objectives: 1) determine a suitable VI for quantifying LAI temporal variation; 2) improve LAI estimation by considering both temporal and spatial variations in LAI; and 3) evaluate routinely produced NDVI products on monitoring temporal and spatial variations in LAI.<p> The study site was set up in conserved semi-arid mixed grassland in St. Denis, Saskatchewan, Canada. One 600 m - long sampling transect was set up across the rolling typography, and six plots with a size of 40 × 40 m each were randomly designed and each was in a relatively homogenous area. Plant Area Index (PAI, which was validated to obtain LAI), ground hyperspectral reflectance, ground covers (grasses, forbs, standing dead, litter, and bare soil), and soil moisture data were collected over the sampling transect and plots from May through September, 2008. Satellite data used are SPOT 4/5 images and 16-day Moderate Resolution Imaging Spectroradiometer (MODIS) 250m, 1km as well as 10-day SPOT-vegetation (SPOT-VGT) NDVI products from May to October, 2007 and 2008. The results show that NDVI is the most suitable VI for quantifying temporal variation of LAI. LAI estimation is much improved by considering both temporal and spatial variations. Based on the ground reflectance data, the r2 value is increased by 0.05, 0.31, and 0.23 and an averaged relative error is decreased by 1.57, 1.62, and 0.67 in the early, maximum, and late growing season, respectively. MODIS 250m NDVI products are the most useful datasets and MODIS 1km NDVI products are superior to SPOT-VGT 1km composites for monitoring intra-annual spatiotemporal variations in LAI. The proposed LAI estimation approach can be used in other studies to obtain more accurate LAI, and thus this research will be beneficial for grassland modeling.

Recent advancements in the development of high-efficiency multijunction solar cells have led to a renewed interest in the design and implementation of high concentration photovoltaic systems. With the emergence of novel materials and design structures, understanding the operation of multijunction solar cells has become a challenging task. Modeling and simulation hence play an important role in the analysis of such devices. In this dissertation, techniques for accurate optoelectrical modeling of concentrating photovoltaic systems, based on multijunction solar cells, are proposed. A 2-dimensional, distributed circuit model is proposed, parametrized to values obtained by numerical modeling of three multijunction cell designs, namely: a three-junction, lattice matched design, a three-junction lattice-mismatched, inverted metamorphic design, and a four-junction,lattice matched design. Cell performance for all the three designs is evaluated under both uniform and nonuniform illumination profiles at high concentrations and efficiency enhancement by optimizing finger spacing is proposed. The effect of luminescent coupling from higher bandgap subcells is also determined.Fresnel-lens based, refractive concentrating optical systems are modeled and optimized using an optical ray-tracing simulator at two different concentrations, with and without a secondary optical element. The corresponding optical efficiency, acceptance angle, and the degree of nonuniformity are determined for each optical system. An integrated approach,combining optical design with electrical modeling is proposed for optimizing the multijunction solar cell in tandem with the corresponding concentrating optics. The approach is validated by on-sun, acceptance angle measurements, using a three-junction,lattice-matched cell. Also, temperature effects are modeled and are experimentally validated for a three-junction, lattice-matched design. Experimental results with a single-junction, dilute-nitride cell, targeted for four-junction operation, are presented as well. A modified distributed circuit model is used for analysis of temperature effects in a four-junction solar cell, and the results under both uniform and nonuniform temperature profiles are presented. When implemented, the designs and their corresponding analyses, may result in new insights into the development of CPV systems, thereby enabling enhanced efficiencies at higher concentrations.

Made available in DSpace on 2017-07-10T14:38:19Z (GMT). No. of bitstreams: 1 jislaine.pdf: 1680477 bytes, checksum: fd1ff3624e2ae8e46f1e311b5237e545 (MD5) Previous issue date: 2013-08-05 / Variations in spatial and temporal scale in the provision of food resources play a central role in changing patterns of food utilization by fish species. Thus, the aim of this study was to evaluate the spatial and temporal variations in the use of food resources for species of small fish in the Verde River, the Upper Paraná River basin, Mato Grosso do Sul. Samples were collected during the rainy season and dry from November 2010 to August 2012, using trawls, cast nets and gillnets. Nine sampling sites were grouped into three biotopes: upstream and downstream of the Branca Waterfall and tributarie. The stomach contents of 3,263 individuals belonging to 12 species of small size were analyzed according to the volumetric method. Altogether 31 food items were recorded. For all biotopes analyzed the consumption of seeds was higher in the rainy season, and plant (leaves) in the dry season. Hymenoptera was an important item in the diet of fish species, but the proportions were different in consumption between periods and biotopes. The consumption of Coleoptera and Isoptera was significant only in the downstream Branca Waterfall in the rainy season and aquatic plant was consumed more in tributarie in the dry season. The Principal Coordinate Analysis (PCoA) and indicate spatial and temporal segregation of species in the diet, showed the interaction between these two factors. Significant differences were observed in the composition of the diet among biotopes, rainy and dry seasons and interaction. Resources allochthonous origin was clearly the most consumed by the species in all biotopes in both hydrological periods. The dietary overlap between species, even with significant seasonal and spatial differences, was considered low (< 0.4 ) for about 60 % of species pairs . Thus, we conclude that spatial and seasonal changes occurred in the use of food resources for species of small fish and these variations were related to differences physiographic channel and environment that contributed to seasonal changes in the diet were significant, reflecting also the low overlap feed between species / Variações em escala espacial e temporal na oferta dos recursos alimentares desempenham um papel central nas alterações dos padrões de utilização dos alimentos pelas espécies de peixes. Dessa forma, o objetivo deste estudo foi avaliar as variações espaciais e temporais no uso dos recursos alimentares pelas espécies de peixes de pequeno porte no rio Verde, Bacia do Alto rio Paraná, Mato Grosso do Sul. As coletas foram realizadas no período chuvoso e seco, de novembro de 2010 a agosto de 2012, utilizando arrastos, tarrafas e redes de espera. Foram nove locais de amostragem, agrupados em três biótopos: montante e jusante da Cachoeira Branca e tributário. Os conteúdos estomacais de 3.263 indivíduos pertencentes a 12 espécies de pequeno porte foram analisados de acordo com o método volumétrico. Ao todo foram registrados 31 itens alimentares. Para todos os biótopos analisados, o consumo de sementes foi maior no período chuvoso, e vegetal (folhas) no período seco. Hymenoptera foi um item importante na dieta das espécies de peixes, porém as proporções no consumo foram distintas entre os biótopos e períodos. O consumo de Coleoptera e Isoptera foi expressivo apenas na jusante da cachoeira branca no período chuvoso e vegetal aquático foi mais consumido no tributário na estação seca. A análise de coordenadas principais (PCoA) além de indicar segregação espacial e temporal na dieta das espécies, evidenciou a interação entre estes dois fatores. Diferenças significativas foram verificadas quanto à composição da dieta entre os biótopos, períodos chuvoso e seco e para a interação. Recursos de origem alóctone foram nitidamente os mais consumidos pelas espécies em todos os biótopos em ambos os períodos hidrológicos. A sobreposição alimentar entre as espécies, mesmo apresentando diferenças espaciais e sazonais significativas, foi considerada baixa (<0,4) para cerca de 60% dos pares de espécies. Assim, podemos concluir que ocorreram mudanças espaciais e sazonais no uso dos recursos alimentares pelas espécies de peixes de pequeno porte e essas variações estiveram relacionadas às diferenças fisiográficas do canal e entorno que contribuíram para que mudanças sazonais na dieta fossem significativas, refletindo também na baixa sobreposição alimentar entre as espécies

Dans l’ensemble de la thèse, nous avons appliqué des techniques de ‘mesure des variations spatiales’ pour l'étude des variations géographiques de taux d'hospitalisation en France. La thèse est composée de 4 études :Étude 1 : « Variation géographique des recours aux procédures chirurgicales en France en 2008-2010 et comparaison avec les États-Unis et la Grande-Bretagne ».Étude 2 : « Variation géographique des admissions pour les prothèses du genou, de la hanche et la fracture de la hanche en France : existence d’une demande induite dans le secteur des hôpitaux à but lucratif et dans les hôpitaux public et privés à but non-lucratif »Étude 3 : « Caractéristiques et tendances des admissions non urgentes à but lucratif et sans but lucratif hôpitaux en France en 2009 et 2010 ». Étude 4 : « Taux d'admission pour des ’hospitalisations évitables par le système ambulatoire’ (ACSC) en France en 2009-2010 : tendances, variation géographique, coûts et comparaison internationale ». / For all of this work, we applied ‘small-area variation’ techniques to the study of geographic variations in hospitalization rates in France. We conducted four studies:Study 1: Geographic variation in rates of common surgical procedures in France in 2008-2010 and comparison to the US and BritainStudy 2: Geographic variation in admissions for knee replacement, hip replacement, and hip fracture in France: evidence of supplier-induced demand in for-profit and not-for profit hospitalsStudy 3: Characteristics and patterns of elective admissions to for-profit and not-for-profit hospitals in France in 2009 and 2010Study 4: Rates of admission for ambulatory care sensitive conditions in France in 2009-2010: trends, geographic variation, costs, and an international comparison

We designed an experiment to evaluate change in students' spatial skills as a result of specific interventions. Our test subjects included high school students in earth science classes, college level non-science majors enrolled in large enrollment introductory geoscience courses and introductory level geoscience students. All students completed spatial tests to measure their ability to mentally rotate three-dimensional objects and to construct a three-dimensional object from a two-dimensional representation. Results show a steady improvement in spatial skills for all groups. They also indicate that students choosing science majors typically have much higher spatial skills as they enter college. Specific interventions to improve spatial skills included having a subgroup of the non-science majors and high school students complete a suite of Geographic Information System (GIS) activities. The intervention at the high school level was more extensive and resulted in significant improvements in both categories of spatial ability. At the college level, the non-science majors that received the intervention showed no significant difference from those that did not, probably because the time spent on the intervention was too short. The geoscience majors had nearly three times the improvement of non-science majors in both categories of spatial ability attributed to hands-on weekly laboratory experiences. These results reveal a wide range of abilities among all groups of students, and suggest that we evaluate teaching strategies in all courses to ensure that students can interpret and understand the visual imagery used in lectures.

The microbial communities found in soils are inherently heterogeneous and often exhibit spatial variations on a small scale. Becker et al. (2006) investigate this phenomenon and present statistical analyses to support their findings. In this project, alternative statistical methods and models are considered and employed in a re-analysis of the data from Becker. First, parametric nested random effects models are considered as an alternative to the nonparametric semivariogram models and kriging methods employed by Becker to analyze patterns of spatial variation. Second, multiple logistic regression models are employed to investigate factors influencing microbial community structure as an alternative to the simple logistic models used by Becker. Additionally, the microbial community profile data of Becker were unobservable at several points in the spatial grid. The Becker analysis assumes that the data are missing completely at random and as such have relatively little impact on inference. In this re-analysis, this assumption is investigated and it is shown that the pattern of missingness is correlated with both metabolic potential and spatial coordinates and thus provides useful information that was previously ignored by Becker. Multiple imputation methods are employed to incorporate the information present in the missing data pattern and results are compared with those of Becker.

With an intensification of heavy rain events in a changing climate and a rapid urbanization the risk for pluvial flooding is increasing in our societies. Pluvial flooding, which is formed when the rainfall rate exceeds the infiltration or drainage rate, can occur rapidly and cause great damages, large economic losses and possibly risk human lives. This kind of flooding is difficult to predict since it is caused by short-term and often local processes, but preventive measures and more robust infrastructure developed over the last decades have decreased the risk of the most severe damages. One way to prevent damage is to map risk areas and take measures by performing a cloudburst modelling, which can be done as a 2D hydraulic modelling. Common practice in cloudburst modelling today is to use a uniform design storm, often the Chicago Design Storm (CDS), with the same hyetograph applied evenly over the whole model area. Even though rain is not spatially uniform this assumption might be valid for more stratiform frontal rain. Intense rain events however have a higher spatial variation in rain intensity, and an assumption like this might significantly affect the results. This study aimed to investigate the effect of the spatial variation in rain intensity on the modelled hydraulic response from an intense rain event. It was performed through a case study of the cloudburst in Gävle, Sweden, in August 2021. A 2D hydraulic model of the city was prepared in the software MIKE 21 Flow Model FM and the cloudburst event was simulated with a spatially varied rainfall input, based on radar data from the event with a 2x2 km resolution, and with spatially uniform rainfall input both with the temporal variation in rain intensity from the event and with a Chicago Design Storm, all with the same total volume. The scenarios were evaluated in terms of proportion of the model area being flooded, the average maximum flooding depth and by mapping the difference in flooding depth over the whole area. The results showed that the spatial variation of rainfall input had a significant effect on the hydraulic response in the city and that assuming a uniform rainfall might lead to an underestimation of the flooding depths in parts of the model area compared to a varied one. The average flooding depth was only a few percent higher for the spatially varied rain compared to the uniform rain with a similar time variation, but in large central areas of the city the model with the uniform rain underestimated the maximum flooding depth by 5-35%. The uniform CDS rain was seen to both over- and underestimate the flooding depth, but in the central and flooded parts of the city underestimation dominated. This points out a risk of using uniform design storms in cloudburst modelling, since a spatially varied rain of the same volume could give more severe effects than the simulated response and that using a uniform design storm potentially introduces an uncertainty in the modelled results that could be important to point out and further quantify. / Med en intensifiering av häftiga regnväder i ett förändrat klimat och en allt snabbare urbanisering ökar risken för pluviala översvämningar i våra samhällen. Pluviala översvämningar, som skapas av att regnintensiteten är högre än infiltrations- eller dräneringshastigheten, kan uppstå plötsligt och orsaka stora skador, ekonomiska förluster och även i värsta fall riskera människoliv. Denna typ av översvämning är svår att förutse eftersom den orsakas av snabba och ofta lokala processer, men förebyggande åtgärder och mer robust infrastruktur som har utvecklats de senaste decennierna har minskat risken för de allvarligaste skadorna. Ett sätt att förebygga skador är att kartera riskområden genom skyfallsmodellering, till exempel med en tvådimensionell hydraulisk modell. Praxis idag är att använda spatialt uniforma typregn vid skyfallsmodellering, där samma hyetograf appliceras jämnt över hela modellområdet. Detta antagande kan ge giltiga resultat för mer stratiforma frontregn, men intensiva regn, skyfall, har generellt sett en hög spatial variation i intensiteten vilket gör att antagandet skulle kunna påverka resultatet signifikant. Denna studie syftade till att undersöka effekten av den spatiala variationen i regnintensitet på den simulerade hydrauliska responsen från ett intensivt regn och den utfördes som en fallstudie av skyfallet i Gävle 17-18 augusti 2021. En 2D hydraulisk modell av Gävle förbereddes i programmet MIKE 21 Flow Model FM och simuleringar utfördes med en spatialt varierad regnindata, baserad på radardata från tillfället med en 2x2 km upplösning, och med spatialt uniforma regnindata både med den verkliga tidsvariationen och med en Chicago Design Storm (CDS), alla med samma totala volym. Skillnaden mellan scenarierna utvärderades genom att jämföra andel översvämmat modellområde, medel av maximala översvämningsdjupet och en kartering av skillnaden i översvämningsdjup över hela modellområdet. Resultaten visade att den spatiala variationen i regnindatan hade en signifikant effekt på den simulerade hydrauliska responsen i staden och att antagande om uniform regnintensitet kan leda till en underskattning av översvämningsdjupen i modellområdet jämfört med ett varierat regn. Medelvärdet av översvämningsdjupet var endast några procent högre  för det spatialt varierade regnet, men i stora centrala områden underskattade modellen med det uniforma regnet det maximala översvämningsdjupet med 5-35 %. Det uniforma CDS-regnet både under- och överskattade översvämningsdjupet, men i centrala och översvämmade områden var det större delar som underskattades. Detta visar på en risk med att använda uniforma typregn i skyfallsmodellering, då ett spatialt varierat regn med samma volym skulle kunna ge betydligt allvarligare effekter än de som modellen har visat och att användandet av uniforma testregn potentiellt inför en osäkerhet i resultaten som är viktig att poängtera och även att vidare undersöka och kvantifiera.