This thesis research consists of two separate studies. The first study presents the assessment and representation of the effects of soil macropores on the soil hydraulic properties in land surface models for more accurate simulations of soil moisture and surface hydrology. Hydraulic properties determine the soil water content and its transport in the soil. They are provided in most current climate models as empirical formulas by functions of the soil texture. Such is not realistic if the soil contains a substantial amount of macropores. A two-mode soil pore size distribution is incorporated into a land surface model and tested using an observational dataset at a tropical forest site with aggregated soils. The result showed that the existence of macropores greatly affects the estimation of hydraulic properties. Their influence can be included in land models by adding a second function to the pore-size distribution. A practical hydraulic scheme with macropore considerations was proposed given that the existing schemes are not applicable for large-scale simulations. The developed scheme was based on the physical attributes of the water in soil capillary pores and the statistics of several global soil databases. The preliminary test showed that it captures part of soil macropore hydraulic features without sacrificing the estimation accuracy of hydraulic properties of water in soil matrix. The second study presents the development of an integrated land/ecosystem model by combining the advanced features of a biophysically based land model, the Community Land Model, and an ecosystem biochemical model. The results from tests of the integrated model at four forest sites showed that the model reasonably captures the seasonal and interannual dynamics of leaf area index and leaf nitrogen control on carbon assimilation across different environments. With being coupled to an atmospheric general circulation model (AGCM), the integrated model showed a strong ability to simulate terrestrial ecosystem carbon fluxes together with heat and water fluxes. Its simulated land surface physical variables are reasonable in both geographic distribution and temporal variation with considering the interactive vegetation parameters.

No description available.

L'évolution des versants est le résultat de l'action combinée des processus d'altération et de transport sédimentaire. Même si il est généralement admis que l'efficacité de ces processus varie en fonction du climat, la quantification de l'influence climatique sur l'érosion des versants reste encore peu développée aujourd'hui. S'inscrivant dans cette problématique, notre étude est consacrée au développement d'un nouveau modèle numérique d'érosion des versants, ayant pour objectif de mieux représenter, à différentes échelles de temps, les multiples aspects du contrôle climatique sur les processus de transport de sol. Ce modèle numérique permet de simuler l'évolution de l'épaisseur de sol et du relief à l'échelle d'un versant; il repose sur une paramétrisation simple de la production de sol couplée à une paramétrisation multi-processus du transport de sol, qui comprend plusieurs variables en étroite relation avec le climat (débit de ruissellement, épaisseur de couche active). Le calcul de ces variables est réalisé sur base de séries temporelles de précipitation et de température avec l'aide d'un modèle de transfert de chaleur et d'un modèle de bilan hydrologique. Le comportement du modèle a été étudié au travers de quelques exemples génériques et d'analyses de sensibilité. Les résultats obtenus montrent des différences significatives dans la façon dont se comporte chaque processus de transport sous conditions climatiques variables, et également dans la manière dont chaque processus affecte l'érosion globale des versants. Ces résultats mettent ainsi en lumière l'importance de la paramétrisation multi-processus du transport de sol dans la modélisation de la réponse des versants aux changements climatiques. Nous avons également développé une méthode associant le modèle d'érosion de versant à un algorithme d'inversion (Neighbourhood Algorithm). Cette méthode a permis de caractériser de manière quantitative l'évolution des versants ardennais (NE Belgique) lors du dernier cycle glaciaire-interglaciaire, sur base d'un scénario climatique simple et de nombreuses données topographiques et d'épaisseurs de sol. Les résultats de l'inversion produisent des prédictions en accord avec certaines observations sur la morphologie des versants ardennais ainsi qu'avec des taux d'érosion estimés indépendamment sur base de concentrations en isotopes cosmogéniques, même si on montre que la distribution actuelle des épaisseurs de sol ne renferme pas assez d'information pour déterminer entièrement les taux de production et de transport de sol lors des périodes froides et tempérées du dernier cycle climatique. Les résultats de l'inversion suggèrent des taux de transport de sol bien plus élevés lors de la période froide que lors de la période tempérée, produisant une succession de systèmes limités par la production de sol d'une part (période froide), et par le transport de sol d'autre part (période tempérée). Un pic de transport de sol est prédit lors des transitions entre ces périodes. Les résultats laissent également suggérer qu'un équilibre dynamique en terme d'épaisseur de sol a été récemment atteint dans les parties convexes des versants, alors que des sols peu épais observés dans les parties concaves pourraient correspondre à des traces de la distribution des épaisseurs de sol qui prévalait lors de la dernière glaciation. / Hillslope evolution results from the combined action of weathering and sediment transport processes, which are thought to be both influenced by climate. Yet, the strength and nature of the connection between climate and hillslope erosion remain poorly understood at a quantitative level. In this study, we present a new numerical model of soil production and transport, which aims to better represent, at different time scales, the climate control on soil transport. The numerical model operates at the scale of a single hill and predicts the rates of soil thickness and elevation change, by using a simple parametrization of soil production and a multi-process parametrization of soil transport which includes climate-dependent variables (overland flow discharge and active-layer depth). Simple ground heat transfer and water balance models are used for calculating these variables from time-series of precipitation and temperature. The behaviour of the model has been studied through a few simulation examples and sensitivity analysis. The results highlight the importance of considering multi-process parameterization of soil transport when modelling the response of the hillslope system to climate variations, as these results display significant differences on how each transport process behaves under various climatic conditions and on how each process affect the evolution of the system. Our numerical model has also been combined with an inversion scheme (Neighbourhood Algorithm) to extract quantitative information on the evolution of hillslopes in the Ardenne (Belgium, NW Europe) during the Last Glacial-Interglacial Cycle, using a simple climatic scenario and a unique set of topographic and soil thickness data. Model predictions based on inversion results are consistent with independent observations on hillslope morphology and cosmogenic nuclide-derived erosion rates, although the inversion results show that soil production and transport rates under both the cold and warm phases of the last climatic cycle cannot be fully constrained by the present-day soil thickness distribution. The inversion results suggest that soil transport is by far more efficient during the cold climatic phase than during the warm phase, resulting in the succession of weathering-limited (cold phase) and transport-limited (warm phase) systems. Maximum soil transport rates are predicted during the transitions between the cold-warm phases. The results also suggest that a soil thickness dynamic equilibrium has been recently reached on convex regions of the hillslopes, while shallow soils found in convergent areas may be the relics of the soil thickness distribution that formed during the cold phase.

abstract: For this dissertation, three separate papers explore the study areas of the western Grand Canyon, the Grand Staircase (as related to Grand Canyon) and Desolation Canyon on the Green River in Utah. In western Grand Canyon, I use comparative geomorphology between the Grand Canyon and the Grand Wash Cliffs (GWC). We propose the onset of erosion of the GWC is caused by slip on the Grand Wash Fault that formed between 18 and 12 million years ago. Hillslope angle and channel steepness are higher in Grand Canyon than along the Grand Wash Cliffs despite similar rock types, climate and base level fall magnitude. These experimental controls allow inference that the Grand Canyon is younger and eroding at a faster rate than the Grand Wash Cliffs. The Grand Staircase is the headwaters of some of the streams that flow into Grand Canyon. A space-for-time substitution of erosion rates, supported by landscape simulations, implies that the Grand Canyon is the result of an increase in base level fall rate, with the older, slower base level fall rate preserved in the Grand Staircase. Our data and analyses also support a younger, ~6-million-year estimate of the age of Grand Canyon that is likely related to the integration of the Colorado River from the Colorado Plateau to the Basin and Range. Complicated cliff-band erosion and its effect on cosmogenic erosion rates are also explored, guiding interpretation of isotopic data in landscapes with stratigraphic variation in quartz and rock strength. Several hypotheses for the erosion of Desolation Canyon are tested and refuted, leaving one plausible conclusion. I infer that the Uinta Basin north of Desolation Canyon is eroding slowly and that its form represents a slow, stable base level fall rate. Downstream of Desolation Canyon, the Colorado River is inferred to have established itself in the exhumed region of Canyonlands and to have incised to near modern depths prior to the integration of the Green River and the production of relief in Desolation Canyon. Analysis of incision and erosion rates in the region suggests integration is relatively recent. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2016

The Cenozoic evolution of the Pyrenean-Cantabrian mountain belt was driven by both internal andexternal processes, such as tectonics, erosion and deposition. This alpine belt is made up by thePyrenees and the Cantabrian Mountains, and is characterized by significant lateral variations intotal shortening, structural styles and topography. This thesis aims to better constrain the controlson exhumation and topography development during syn- to post-orogenic times, from the Eoceneto the Pliocene, by focusing on two characteristic parts of the belt: the Southern Central Pyreneesand the Central Cantabrian Mountains. To this purpose, a multi-disciplinary approach isdeveloped, combining low-temperature thermochronology with different numerical modelingtools. To better understand lateral variations in exhumation of the belt, a new low-temperaturethermochronology dataset is presented for the Cantabrian domain. The first part of this thesispresents new apatite fission-track data and (U-Th)/He analysis on zircons, constraining the timingand amount of exhumation along the central Cantabrian cross-section. In particular, the Eocene toOligocene ages obtained from the different thermochronometers allow us to infer a more importantamount of burial and, consequently, a thicker Mesozoic sedimentary section than previouslyconsidered, thereby also refining the structural style of the section at the upper crustal scale.The extensive thermochronological dataset existing in the central Pyrenees is then used toreconstruct the late-stage evolution of the South Central Axial Zone by thermo-kinematic inversemodeling. The model predicts rapid exhumation of the area during late Eocene (late syn-orogenic)times, followed by a post-orogenic evolution that is strongly controlled by base-level changes. Asa consequence of the establishment of endorheic conditions in the adjacent Ebro foreland basin,together with the strong erosion of the Axial Zone, the southern foreland area was infilled by animportant amount of erosional deposits in late Eocene to early Oligocene times. The models allowus to constrain the level of infilling at ~2.6 km and to date the excavation of these sediments at~10 Ma, following opening of the Ebro basin toward the Mediterranean Sea. The thickness ofsediments draping the foreland fold-and thrust belt was verified using fission-track analysis and(U-Th)/He measurements on apatites from foreland sediments. Thermal modeling of the dataprovides an estimate of 2 to 3 km of sediments on top of the foreland and confirms its incision inLate Miocene times. The effect of syn-orogenic deposition on the building and late evolution ofthe southern Pyrenean fold-and-thrust belt has been modeled in the last chapter of this thesis usinga 2D thermo-mechanical numerical modeling approach. The models highlight the potential effectof syn-tectonic sedimentation on thrust kinematics at several stages of wedge building. Ourmodeling also shows that the addition of an Oligocene sediment blanket perturbs the thrustingsequence by stabilizing the central part of the external wedge and enhancing both frontal andinternal accretion; a pattern that reproduces the observed deformation in the Southern CentralPyrenees. / The Cenozoic evolution of the Pyrenean-Cantabrian mountain belt was driven by both internal andexternal processes, such as tectonics, erosion and deposition. This alpine belt is made up by thePyrenees and the Cantabrian Mountains, and is characterized by significant lateral variations intotal shortening, structural styles and topography. This thesis aims to better constrain the controlson exhumation and topography development during syn- to post-orogenic times, from the Eoceneto the Pliocene, by focusing on two characteristic parts of the belt: the Southern Central Pyreneesand the Central Cantabrian Mountains. To this purpose, a multi-disciplinary approach isdeveloped, combining low-temperature thermochronology with different numerical modelingtools. To better understand lateral variations in exhumation of the belt, a new low-temperaturethermochronology dataset is presented for the Cantabrian domain. The first part of this thesispresents new apatite fission-track data and (U-Th)/He analysis on zircons, constraining the timingand amount of exhumation along the central Cantabrian cross-section. In particular, the Eocene toOligocene ages obtained from the different thermochronometers allow us to infer a more importantamount of burial and, consequently, a thicker Mesozoic sedimentary section than previouslyconsidered, thereby also refining the structural style of the section at the upper crustal scale.The extensive thermochronological dataset existing in the central Pyrenees is then used toreconstruct the late-stage evolution of the South Central Axial Zone by thermo-kinematic inversemodeling. The model predicts rapid exhumation of the area during late Eocene (late syn-orogenic)times, followed by a post-orogenic evolution that is strongly controlled by base-level changes. Asa consequence of the establishment of endorheic conditions in the adjacent Ebro foreland basin,together with the strong erosion of the Axial Zone, the southern foreland area was infilled by animportant amount of erosional deposits in late Eocene to early Oligocene times. The models allowus to constrain the level of infilling at ~2.6 km and to date the excavation of these sediments at~10 Ma, following opening of the Ebro basin toward the Mediterranean Sea. The thickness ofsediments draping the foreland fold-and thrust belt was verified using fission-track analysis and(U-Th)/He measurements on apatites from foreland sediments. Thermal modeling of the dataprovides an estimate of 2 to 3 km of sediments on top of the foreland and confirms its incision inLate Miocene times. The effect of syn-orogenic deposition on the building and late evolution ofthe southern Pyrenean fold-and-thrust belt has been modeled in the last chapter of this thesis usinga 2D thermo-mechanical numerical modeling approach. The models highlight the potential effectof syn-tectonic sedimentation on thrust kinematics at several stages of wedge building. Ourmodeling also shows that the addition of an Oligocene sediment blanket perturbs the thrustingsequence by stabilizing the central part of the external wedge and enhancing both frontal andinternal accretion; a pattern that reproduces the observed deformation in the Southern CentralPyrenees.

O principal objetivo deste trabalho é prever a evolução de margens divergentes desde o início da extensão litosférica, levando-se em consideração a interação entre processos superficiais e tectônicos. Para isto, foi desenvolvido um modelo numérico que acopla isostasia flexural, efeitos térmicos, estiramento litosférico e processos superficiais. A isostasia flexural é simulada através de uma placa elástica fina sobre um fluido invíscido, representando o comportamento flexural da litosfera flutuando sobre a astenosfera. Durante a simulação, a estrutura térmica da litosfera evolui como um resultado da advecção e difusão do calor no interior da Terra. Considera-se que o estiramento da litosfera é acomodado por falhas planas na crosta superior e deformação dúctil na crosta inferior e manto. O modelo de processos superficiais descreve como a paisagem é erodida e como os sedimentos são transportados e depositados nas bacias sedimentares. Através desse modelo numérico, é mostrado que o estiramento litosférico tem uma profunda influência na evolução da migração de escarpas em margens divergentes. Os resultados sugerem que escarpas limitadas por falhas criadas em flancos de rifts por descarregamento mecânico e resposta flexural têm pouca chance de \"sobreviver\" através de recuo erosivo se a crosta inferior sob o flanco do rift foi substancialmente estirada. Nessa configuração, o divisor de drenagem que persiste através do tempo é criado em direção ao continente em uma posição que depende da rigidez flexural da crosta superior. Esse cenário ocorre quando a topografia pré-rift mergulha para o continente, caso contrário a evolução da escarpa é guiada pelo divisor de águas interior pré-existente. Esses conceitos são aplicados no estudo das margens do sudeste da Australia e do sudeste do Brasil, onde o cenário de retração de escarpas através de recuo erosivo mostrou-se improvável. O mesmo modelo numérico foi utilizado para estudar como a passagem de uma anomalia térmica sob a litosfera pode afetar a evolução pós-rift de bacias sedimentares em margens divergentes. Os resultados numéricos mostram que a velocidade da litosfera em relação à anomalia térmica e a rigidez flexural da litosfera oceânica e continental afetam a evolução de bacias sedimentares devido ao soerguimento da superfície relacionado com a expansão térmica da litosfera. Como exemplo, é estudada a possível influência de uma anomalia térmica (Pluma de Trindade?) na evolução das bacias de Campos e Espírito Santo, na margem sudeste brasileira. / The purpose of this work is to predict the evolution of divergent margins since the onset of lithospheric extension, taking into account the interaction between surface and tectonic processes. For this, a numerical model was developed to study the coupling of flexural isostasy, thermal effects, stretching of the lithosphere and surface processes. The flexural isostasy is simulated through a thin elastic plate overlying an inviscid fluid, representing the flexural behavior of the lithosphere floating on the asthenosphere. During the simulation, the thermal structure of the lithosphere evolves as a result of advection and diffusion of heat in the Earths interior. The stretching of the lithosphere is assumed to be accommodated by planar faults in the upper crust and ductile flow in the lower crust and mantle. The surface processes model describes how the landscape is eroded and how the sediments are transported and deposited in the sedimentary basins. The results from this numerical model show that the amount of lithospheric stretching has a profound influence on the evolution of escarpment migration in divergent margins. These results suggest that fault-bounded escarpments created at rift flanks by mechanical unloading and flexural rebound have little potential to survive as retreating escarpments if the lower crust under the rift flank is substantially stretched. In this configuration, a drainage divide that persists through time is created landward in a position that depends on the flexural rigidity of the upper crust. This scenario occurs when the pre-rift topography dips landward, otherwise the evolution of the escarpment is guided by the pre-existing inland drainage divide. These concepts are applied to study the margins of Southeastern Australia and Southeastern Brazil, where the retreating escarpment scenario showed to be unlikely. The same numerical model is used to study how the passage of a thermal anomaly under the lithosphere can affect the post-rift evolution of sedimentary basins in divergent margins. The numerical results show that the velocity of the lithosphere relative to the thermal anomaly and the flexural rigidity of the continental and oceanic lithospheres affect the evolution of sedimentary basins due to surface uplift related to thermal expansion of the lithosphere. As an example, the model is applied to assess the possible influence of a thermal anomaly (Trindade Plume?) on the evolution of the Campos and Esp rito Santo Basins, in Southeastern Brazilian margin.

This master's thesis deals with the study of the reactions of the ozone and oxygen with various construction materials. Ozone as an unstable gas tends to decompose spontaneously and this process can be accelerated by reaction with other substances. The aim of this work is to determine the course of ozone's formation and its depletion in after the contact with various substances. Ozone is widely used mainly due to its disinfecting effects. Therefore, the monitoring of these reactions is beneficial for the choosing of ozonizer's material or its accessories. The theoretical part of this work describes the important properties of the ozone, the possibilities of using this gas, various methods of its generation, the influence of gas admixtures and a temperature on its generation and decomposition, the methods of determining the concentration and surface reaction. The dependence of ozone's formation on the size of the reaction space was monitored for either the silicone and Teflon material in the experimental part of the thesis. The length of the hoses was 20-50 cm and the diameter of the inner space was 6 mm for Teflon and 7,99 mm for a silicone. Furthermore, other experiments were performed for the silicone material, where the formation of the ozone was monitored while the oxygen and argon were being used as working gases. The formation and the depletion of the ozone depending on the changes of reaction time were investigated in the third series of experiments. We worked with a ceramic material with two different inner diameters and also with a brass and a stainless steel material in this experiment. The materials were constructed as the tubes of the same length of 54 cm. The ozone generated from the oxygen was enclosed into the reaction tube and the depletion was monitored. The last experiment was focused on the monitoring of the course of ozone's formation in a quartz cuvette influenced by the reaction time and the composition of the working gas. The amount of generated ozone was determined by absorption spectrometry in the all studied cases. The ozone flowing through the system was adsorbed by the surface of the material during the discharge. A mixture of gases (the adsorbed ozone, the oxygen and the argon in various ratios) was present in the sealed reaction space. The Ozone was formed on the surface of the material. The adsorbed ozone decomposed into a molecular and an atomic oxygen. The atomic oxygen reacted with the oxygen molecule occurring in the reaction space. The reaction time leading to the biggest obtained concentration of generated ozone was determined by the experimental data. For most of the materials, the reaction time was about 6 minutes.

<p>Rivers are constantly undergoing change due to erosion and sedimentation along their banks. Although these processes generally occur gradually, flood events can significantly accelerate river migration, creating a risk for human life and infrastructure. As a result, it is important to identify river reaches that are prone to channel migration and determine the extent of migration. However, detailed information about river migration across entire river networks is not readily available. This study seeks to develop a Python-based tool that can generate river migration rasters across large watersheds using Landsat imagery. The methodology involves extracting the centerlines of river features in Landsat imagery using the Modified Normalized Difference Water Index (MNDWI) and the Skeletonize function available in the scikit-image library, followed by the application of the Particle Image Velocimetry (PIV) algorithm to compute the river channel migration. The PIV algorithm generates a set of migration rasters that are analyzed to extract the long-term migration of each of the reaches. The tool also creates intermediate outputs, such as the MNDWI raster, binary land-water raster, and skeletonized river centerlines, which can be further analyzed to gain insights into the river's behavior. The methodology is implemented in the Wabash and Lower Mississippi River Basins, and the tool's effectiveness is validated against manual measurements of the river migration available for the Wabash Basin. In addition, this study analyzes the correlation between long-term migration and various factors, such as reach sinuosity, drainage area, geology, and streamflow. The results of the analysis show that drainage area is highly correlated with river migration. The correlation results are compared with the prior literature, thereby serving to validate the developed framework. This framework has the potential to aid decision-makers and policymakers in identifying the long-term patterns of river channel migration, facilitating their efforts to plan for infrastructure resilience. By utilizing this methodology, river managers and other stakeholders can gain insights into river migration across large watersheds and identify areas that require further monitoring and management.</p>

<p>In vapour phase deposition, the knowledge and control of homogeneous and heterogeneous reactions in connection to precursor design may lead to the deposition of the desired material; structure or phase. This thesis is a document attempting to increase the knowledge of film growth in the B-N system.</p><p>In the present work, surface processes like adsorption, abstraction, migration and nucleation have been modelled on an atomic scale using density functional theory (DFT). The systems studied are mainly cubic and hexagonal boron nitride surfaces ((c-BN) vs. (h-BN)), but also the α-boron (001) surface.</p><p>It has been shown that DFT and a cluster approach is a reliable tool in modelling boron nitride surfaces and surface processes, provided that certain functionals, basis sets and geometrical constraints are used.</p><p>By using surface stabilisers such as H species in an electron- or radical-rich environment, it has been shown that <i>i)</i> the structure of cubic boron nitride surfaces can be sustained, and <i>ii)</i> c-BN may nucleate on the h-BN (001) basal plane. Furthermore, the nucleation of c-BN from arbitrary and experimental growth species is energetically preferable over a continuous growth of h-BN on the h-BN (001) edges.</p><p>An atomic layer deposition (ALD) process for boron nitride was developed. It resulted in turbostratic (t-BN), transparent, well-adherent and almost atomically smooth BN films. However, with the cubic phase of boron nitride absent in the ALD films, more effort needs to be put into both the theoretical and the experimental branches of this field of science.</p>

In vapour phase deposition, the knowledge and control of homogeneous and heterogeneous reactions in connection to precursor design may lead to the deposition of the desired material; structure or phase. This thesis is a document attempting to increase the knowledge of film growth in the B-N system. In the present work, surface processes like adsorption, abstraction, migration and nucleation have been modelled on an atomic scale using density functional theory (DFT). The systems studied are mainly cubic and hexagonal boron nitride surfaces ((c-BN) vs. (h-BN)), but also the α-boron (001) surface. It has been shown that DFT and a cluster approach is a reliable tool in modelling boron nitride surfaces and surface processes, provided that certain functionals, basis sets and geometrical constraints are used. By using surface stabilisers such as H species in an electron- or radical-rich environment, it has been shown that i) the structure of cubic boron nitride surfaces can be sustained, and ii) c-BN may nucleate on the h-BN (001) basal plane. Furthermore, the nucleation of c-BN from arbitrary and experimental growth species is energetically preferable over a continuous growth of h-BN on the h-BN (001) edges. An atomic layer deposition (ALD) process for boron nitride was developed. It resulted in turbostratic (t-BN), transparent, well-adherent and almost atomically smooth BN films. However, with the cubic phase of boron nitride absent in the ALD films, more effort needs to be put into both the theoretical and the experimental branches of this field of science.