<p> With more than half of the world's population living in urban areas, it is important that the relationships between the urban environment and climate are better understood. The current research aims to continue the effort in assessing and understanding the urban environment through the use of a global climate model (GCM). Given the relative newness of the presence of an urban land type and model in a GCM, there are many more facets of the urban-climate relationship to be investigated. By comparing thirty-year ensembles of CAM4 coupled with CLM4 both with (U) and without (U_n) the inclusion of the urban land type, the sensitivity of the atmospheric model to urban land cover is assessed. As expected, largest differences tend to be in the Northern Hemisphere due to the location of most of the globe's densest and expansive cities. Significant differences in the basic climate variables of temperature and precipitation are present at annual, seasonal, and monthly scales in some regions. Seasonality to the urban influence also exists with the transition months of Spring and Fall having the largest difference in temperatures. Of the eleven regions defined by Oleson (2012), three were most impacted by the presence of urban land cover in the model&mdash;Europe, Central Asia, and East Asia. </p><p> Since urban attributes can vary greatly within one world continent, the sensitivity of regional climates to the urban type parameters is also explored. By setting all urban land cover to only one urban density type, the importance of city composition on climate, even within the same city, is highlighted. While preserving the distinct urban regional characteristics and the geographical distribution of urbanized areas, the model is run with homogeneous urban types: high density and tall building district. As with the default urban and excluded urban runs, a strong seasonality to the differences between the solo-high-density simulation and default urban (U_HD &ndash; U) and solo-tall-building-district-density simulation and default urban (U_TBD &ndash; U) exists. Overall, the transition and winter months are most sensitive to changes in urban density type.</p>

Shifts in vegetation from a moss-shrub peatland to one more dominated by shrubs will influence the microclimate. I analyzed the seasonal effect of increasing shrub cover in response to two NPK treatments (5NPK and 20NPK, with addition rates of 3.2 g N m-2 y-1 and 6.4 g N m-2 y-1, respectively) compared to the control (0NPK) in triplicate 3 x 3 m plots in an ombrotrophic bog located in Ottawa, Ontario. Half-hour measurements of light, soil temperature and moisture were measured in each plot. During the growing season, increases in LAI resulted in a decrease in soil temperature by 0.3 to 1.5 oC in the top 2 cm. Differences in the average soil moisture amongst treatments were small, and it ranged between 0.20 to 0.33 m3 m-3. Variations in temperature between the plots decreased with increasing depth. During the winter, soils under the fertilized plots were warmer, where temperatures were above 0 oC for 2 ± 1 day(s) longer in the 20NPK plots. An increase in LAI was negatively correlated with light transmission through the canopy, decreasing PAR transmission in the 20NPK plots by up to 66 %. A factorial lab study of the effect of changes in temperature, moisture and light on the CO2 exchange in S. capillifolium showed that there was a significant interaction between moisture and temperature, and its effect on CO2 exchange. The absence of moss in the 20NPK plots is in part the result of changes in the shrub canopy leading to decreases in light to the surface layers. Due to the sensitivity of Sphagnum to a changing microclimate, alterations to the competitive balance between the shrub and moss layer could lead to changes in C storage in these ecosystems. / Les changements dans la végétation d'une tourbière de mousse-arbuste à une tourbière dominée uniquement par les arbustes influenceront le microclimat. J'ai analysé l'effet saisonnier de l'augmentation de la couverture arbustive en réponse à deux traitements NPK (5NPK et 20NPK avec taux additionnels de 3.2 g N m-2 y-1 et 6.4 g N m-2 y-1, respectivement) par rapport au contrôle (0NPK) en triple exemplaires de lots de 3 m x 3 m dans une tourbière ombrotrophe située à Ottawa, en Ontario. Des mesures prises aux demi-heures évaluant la lumière, la température du sol et l'humidité ont été enregistrées. Au cours de la saison de croissance, l'augmentation de LAI a entraîné une diminution de la température du sol de 0.3 à 1.5 °C dans les deux premiers centimètres de la tourbe. Les différences dans l'humidité du sol moyenne entre les traitements étaient minimes, variant de 0.20 à 0.33 m3 m-3. Les variations de température entre les parcelles diminuent avec la profondeur. Pendant l'hiver, les sols dans les parcelles fertilisées ont gardés plus de chaleur, les températures étaient supérieures à 0 °C pendant 2 ± 1 jour (s) de plus dans le 20NPK. Une augmentation de la LAI était corrélée négativement avec transmission de la lumière à travers le couvert arbustif, diminuant la transmission du PAR dans les parcelles 20NPK jusqu'à 66%. Une analyse factorielle de laboratoire de l'effet des variations de température, d'humidité et de la lumière sur les échanges de CO2 sur S. capillifolium a montré qu'il y avait une interaction significative entre l'humidité et la température et ses effets sur les échanges de CO2. L'absence de mousse dans les parcelles 20NPK est en parti la résultat des changement à la couvert arbustif qui fait en sort que il y a moin de lumiere à le niveau de la surface. En raison de la sensibilité des Sphagnes à un microclimat changeant, les modifications de l'équilibre concurrentiel entre les arbustes et la couche de mousse pourrait conduire à des changements dans le stockage de C dans ces écosystèmes.

Numerical simulation of forming processes has been an important means for material selection, tool design, and process optimization. A critical component of simulation, however, is an accurate material constitutive model, describing the response of the material under possible modes of deformation. The accuracy, in turn, is linked to the tests and techniques applied for identification of constitutive models: the more elaborate the identification, the more reliable the material parameters. For textile composites, uncontrollable factors such as contact friction, misalignment, slip, variations in local fiber volume, and tow compaction are sources that generate considerable scatter in the response of fabrics. Accordingly, characterization methods occasionally suffer from non-repeatability of test data even under similar testing conditions. Furthermore, it is typical that different deformation modes result in different sets of material parameters. If variance of material response within the replication of tests and deformation modes is neglected, then the identification of model parameters can be far from the true material behavior. In order to confront the above shortcomings, this work is an attempt to elaborate on the characterization of textile composites using a new inverse method by means of a signal-to-noise weighting scheme, and two constitutive models by means of a phenomenological invariant-based approach. A full identification of the developed constitutive models for a typical woven fabric is applied using the introduced inverse method and a set of data from standard testing methods, with close attention to the behavior of the composite constituents in a macro level. Particularly, the effects of fiber-resin interactions and fiber misalignment are introduced. A novel modified picture frame test is also studied and used for validating the models. From the results of this work, it is expected that the use of a number of test methods simultaneously and the inclu / La simulation numérique pour les procédés de formation est un instrument important pour le choix des matériaux, la conception d'outils et l'optimisation des procédés. Un des composants critiques de la simulation reste cependant un modèle constitutif de matériaux précis, pouvant décrire la réponse du matériau sous des modes de déformation possibles. Par ailleurs, l'exactitude est liée aux essais et aux techniques appliqués pour l'identification des modèles constitutifs: plus l'identification est raffinée, plus les paramètres du matériau sont fiables. Pour des composés textiles, des facteurs incontrôlables tels que le frottement de contact, la déviation d'alignement, le glissement, les variations de volume local des fibres, et le tassement des fibres sont des sources qui produisent un éparpillement considérable dans la réponse des tissus. Par conséquent, les méthodes de caractérisation souffrent occasionnellement de la non-répétabilité des données des essais même lorsque les conditions d'essais sont semblables. De plus, il est typique que différents ensembles de paramètres du matériau soient obtenus à partir des différents modes de déformation. Si la variance de la réponse du matériau dans les répliques d’essais et les modes de déformation est négligée, l'identification des paramètres du modèle peut alors être loin du véritable comportement du matériau. Afin de confronter les imperfections mentionnées ci-dessus, la présente étude est une tentative d'élaboration de la caractérisation des composés textiles en utilisant une nouvelle méthode inverse basée sur un schéma pondéré signal/bruit et deux modèles constitutifs par le biais d’une approche basée sur l’invariance des phénomènes. Une identification complète des modèles constitutifs développés est appliquée à un tissu typique en utilisant la méthode inverse proposée et un ensemble de données obtenus à partir des méthodes d'essais stand

A model for ecological resilience of Amazonian ecosystems was developed integrating processes such as atmosphere-biosphere coupling with disturbance factors such as fire and climate change. The focus of the study was on the status of ecosystems in the state of Mato Grosso and the possibility of forest to savannah transition was examined using remote sensing data. There was a consistent reduction in EVI during the dry season in Mato Grosso – May through August of each year. The 2005 drought demonstrated a greater dry-season reduction in EVI than normal and there was also a higher frequency of fires (48, 682) than in 2006 (28, 466). There was an increase in fires with distance from the major highways – which is contrary to the results of previous studies. It was estimated that there was a reduction in the amount of forest ecosystems from 2001 to 2006. / Un modèle de résilience écologique de l'écosystème amazonien a été développé, intégrant des processus tels que le couplage atmosphère-biosphère avec des facteurs de perturbation tels que le feu et les changements climatiques. L'objectif de cette étude était d'évaluer l'état des écosystèmes dans l'état du Mato Grosso. Une possible transition de la forêt à la savane a été examinée en utilisant des données de télédétection. Il y a eu une réduction de l'EVI pendant la saison sèche dans le Mato Grosso, de mai à août pour chaque année d'étude. La sécheresse de 2005 a provoqué une réduction de l'EVI plus importante que la normale, en plus d'augmenter la fréquence des feux (48, 682) par rapport à 2006 (28, 466). Il y a eu une augmentation des incendies avec la distance par rapport aux principales autoroutes, ce qui est contraire aux résultats des études précédentes. Il a été estimé qu'il y a eu une réduction du nombre d'écosystèmes forestiers entre 2001 et 2006.

Large-scale civil engineering works, planning and land-management in areas known to have a landslide problem require regional landslide susceptibility evaluation. The Matrix Assessment Approach (MAP) is introduced as a technique for establishing an index of slope stability over large areas. The method allows the relative landslide susceptibility to be computed over large areas using a discrete combination of geological/geomorphological parameters. MAP was applied to a region in the Peak District, Derbyshire. The model identified key geological/geomorphological parameters involved in deep-seated failures, provided an effective means of classifying the stability of slopes over a large area and successfully indicated sites of previously unmapped landslides. The resultant regional landslide susceptibility index provides useful preliminary information for use at the pre-site/reconnaissance stages, of large-scale civil engineering works such as highway construction. Unlike deep-seated failures, shallow translational slides usually do not prevent the use of areas above and below the failure, however, they can cause considerable inconvenience and expense When remedial engineering works are necessary. An investigation was undertaken in order to establish the precise critical state of geomorphological factors involved in shallow translational landsliding in the Peak District. Back calculations based on the Infinite Slope Stability Model showed how the factor of safety against shallow translational sliding changed as one geomorphological parameter varied. The value of the factor of safety was very sensitive to changes in the values of effective cohesion and piezometric height, moderately sensitive to changes in the values of regolith depth and the angle of slope inclination and insensitive to changes in the values of angle of friction with respect to effective stresses and soil unit weight. The recognition of such meso/micro geomorphological thresholds is not only important for geomorphologists concerned with landform evolution, it is also fundamental to successful and safe engineering practices.

In the past three decades, peatlands all over the world such as upland bogs, tropical fens, have been undergoing significant and rapid degradations. These degradations cause carbon loss and CO2 emissions, and also fuel climate change. In this research, I present three case studies on how space geodetic tools, especially Radar Interferometry (InSAR), can be used to monitor and to advance our understanding of the long-term surface changes in peatlands. First, I investigate the eroding extent and severity of upland UK peatlands using InSAR. Both short wavelength C-band and long wavelength L-band data are explored in this study. I detect a long-term peat subsidence rate of about 0.3 cm/yr, and 2 cm of decrease in peat height between 2002 and 2010. I also examine the coherence performance of C- and L-band over upland bogs. I find L-band data provides better coherence than C-band in upland bogs. Second, I use InSAR time series generated by L-band images to map the spatial and temporal subsidence of drained tropical peatlands in Sumatra, Indonesia. And based on InSAR-derived subsidence rate data, I estimate carbon loss or CO2 emission. Third, I assess the effectiveness of peatland restoration work in in Central Kalimantan, Indonesia using InSAR (L-band images). Restoration effects and impact factors are investigated by the spatial and temporal changes of peat height, which also provide useful information for guiding future restoration activities in this region. Overall, this research suggests that InSAR time series is feasible to monitor long-term peat height change in peatlands, provides new insights into the dynamic surface changes in peatlands, and helps to study the carbon loss and CO2 emissions from peatlands, and understand restoration effects.

<p> This project assesses the elevation of several vegetation zones of the Los Cerritos Wetlands in Southern California to determine the possible effects of sea level rise on the salt marsh vegetation, the foundation of coastal salt marsh ecology. Steamshovel Sough in the Los Cerritos Wetland contains ideal habitat for the project. This coastal salt marsh is unique in that it abuts artificial elevation gradients of urban development on all sides. The confined nature of the wetland restricts its ability to adjust to future sea levels, a process known as coastal squeeze, which calls the sustainability of this scarce ecosystem into question. In-situ surveying of indicator species Parrish's Glasswort and Pacific Cordgrass (<i>Arthrocnemum subterminale </i> and <i>Spartina foliosa</i>) revealed the habitat elevations above sea level. Modelling various sea level rise scenarios using the habitat ranges determined through in-site surveying reveal expected future habitat zones. Los Cerritos Wetland has a notable susceptibility to sea level rise because of topographic convolutions created by local urban development. One and two foot sea level rise scenarios project substantial zone shifts resulting in pronounced winners and losers. The results here highlight the delicacy of the marsh and its intimate relationship to sea level, and hold a powerful utility to restoration project managers seeking to create a salt marsh that reflects the natural distribution of various habitats and which possesses longevity in the face of the changing environment.</p>

Integrated Catchment Management (ICM), defined as the design of intervention strategies encompassing and integrating the fields of hydrology, environmental, social and economic science, is vital in order to reach sustainable solutions on a catchment basis. Modelling lies at the core of the ICM process as it supports baseline studies and enables analysis of proposed intervention measures both for present day conditions and under future scenarios. Its core role in ICM leads to the need to develop modelling into a more comprehensive activity within which the design of a modelling approach, selection of tools and need for linkages can be thoughtfully matched to the requirements of ICM. Initial research revealed a gap in this area, leading to development of a Framework for Catchment Modelling Studies (FCMS) intended to create a staged and systematic approach that could be used as a template for development of modelling exercises that strike the right balance between ICM needs, project costs and the availability of human and technical resources. To demonstrate the utility of the FCMS and populate it with application guidance, practical techniques and examples, technical research was focused on analysis of groundwater-surface water interaction in the Rio Salado Basin. This flatland of 175,000km2, is located in the Buenos Aires Province of Argentina and features widespread groundwater-surface water interaction as the key driver of the flooding in vast areas of the basin. This flooding currently limits the potential for agricultural and livestock development of what is, economically, most important region of the country. Research revealed that use of uncoupled groundwater-surface water models was inadequate to simulate observed flooding in a test area of the Rio Salado Basin, and a new program - iSISMOD - was developed by coupling MODFLOW (McDonald and Harbaugh, 1988) with ISIS (HR Wallingford and Halcrow, 1995) to permit dynamic coupling of both systems and support improved flood probability mapping. The research concludes that adoption of an FCMS approach would provide scientists and engineers with a systematic basis from which to think through technical issues involved in the modelling cycle, and would facilitate improved decision making on key issues, such as when uncoupled models must be replaced by coupled models. This systematic approach is not only resource-effective, it is more importantly essential to support development of integrated catchment management plans that are sustainable.

This thesis utilised the River Frome, Dorset, as a study catchment within which to examine the seasonal effects of large aquatic plants, or 'macrophytes', on hydraulic roughness, water velocity, river stage and fine sediment distribution. The thesis formed part of LOCAR, a NERC thematic research programme, and was motivated by the need to provide empirical data to improve river management and to help achieve a compromise between vegetation management for flood control and for maintaining and maximising biodiversity. The thesis employed a hierarchical research design with linked data collection at macro-, meso-, and microscales. (i) Macroscale research employed archival River Habitat Survey data and primary river surveys to place the more detailed meso- and microscale work in context. The analyses revealed the existence of a distinct chalk river group and examined the place of the River Frome within this. This provided contextual information to aid extrapolation of the current findings and facilitates comparisons with previous and future research. (ii) Mesoscale research focused upon stage and discharge measurements, and grid-based measurements of hydraulic variables. The analyses showed that macrophytes can have demonstrable and quantifiable effects on hydraulic roughness and sediment storage, which causes seasonal change in the stage/discharge relationship. However, this effect varies according to channel morphology and riparian land use and is subject to the attainment of a critical biomass. (iii) Microscale analyses employed high-frequency turbidity probes to investigate sediment processes within macrophyte beds. Each vegetation patch acted as a unique sediment filter, the characteristics of which changed over the growing season, and varied with distance along the patch. The results also suggested that retention of fine sediment is size selective and varies according to plant architecture and in-channel location. The thesis findings imply that vegetation management must be approached with greater sensitivity to reach scale and sub-reach characteristics.

This thesis is a collection of three essays on the economics of transboundary river management (contained in chapters 2-4) the contents of which is outlined below: Chapter 2 examines the equity-efficiency trade-off on a transboundary river where an upstream and a downstream riparian withdraw irrigation water. Equity is defined as ‘equal sharing of waters’ - a notion consistent with egalitarianism and equality of opportunity. Property rights are undefined, a priori, but riparians can enter an equal quota cooperative agreement (with side payments and restricted trade in water quotas). We find that the equity-efficiency trade-off is relatively insignificant, in prevalence as well as magnitude, and limited to special cases where the upstream riparian has a substantial relative cost advantage and/or water is very scarce. Chapter 3 examines a transboundary river conflict arising when upstream hydropower water releases do not coincide with the seasonal irrigation needs of a downstream riparian. We consider and rank the qualitative impact of a range of infrastructure investments, potentially initiated and co-financed by multilateral development banks (MDBs). Basinwide social efficiency and regional stability can, under certain conditions, be improved through Pareto-improving investments, including enhancement of upstream hydropower efficiency and expansion of downstream reservoir capacity. The findings are used to analyse proposed infrastructure projects in the Syr Darya Basin shared by Kyrgyzstan, Uzbekistan and Kazakhstan. Chapter 4 examines riparian cooperative behaviour on the Syr Darya river. To resolve their conflict of interest, riparian states have resorted to annual cooperative agreements. This arrangement, however, has largely failed due to lack of trust between the parties. Striving for self-sufficiency in irrigation water, Uzbekistan has initiated new reservoir construction. The chapter examines their economic impact. We report a laboratory experiment modelling the Syr Darya river scenario as a multi-round three-player trust game with non-binding contracts. Payoff schemes are estimated using real-life data. While basinwide efficiency maximisation requires regional cooperation, our results demonstrate that cooperation in the laboratory is hard to achieve. Uzbek reservoirs improve the likelihood of cooperation only weakly and their positive economic impact is limited to low-water years.