Visando garantir a disponibilidade hídrica em seus diferentes usos são construídos reservatórios, estes sempre associados a problemas de perda de volume de armazenamento devido ao processo de assoreamento. A atualização destes dados, bem como a quantificação do assoreamento geralmente é feita através de Levantamento Batimétrico. Apesar da grande importância do tema não é observado na literatura um método padronizado para a realização de estudos batimétricos, autores e organizações apresentam métodos dispares quanto à quantidade e disposição dos dados. Deste modo, a presente pesquisa buscou elencar os métodos apresentados na literatura e analisá-los quanto a precisão obtida no cálculo de volume do reservatório, utilizando como estudo de caso o reservatório da UHE Três Irmãos (SP). Observou-se que os MDTs gerados pelos métodos não representavam com fidelidade trechos estreitos do reservatório (braços) bem como o talvegue. Foi então proposto um método para a determinação do espaçamento entre seções bem como uma rotina para geração de MDT considerando características do talvegue. O método proposto para determinação do espaçamento entre seções se mostrou capaz de representar com relativa boa precisão trechos dos braços (diferença máxima encontrada de 5,01%) e apresentou tempo de coleta de dados de 60% do método mais preciso apresentado na literatura. A rotina de geração de MDT proporcionou em média melhora de aproximadamente 30% na qualidade dos dados de volume calculados. Por meio da aplicação dos métodos desenvolvidos na UHE Chavantes foi calculado um assoreamento de 3,91%, de acordo com os resultados, sem a utilização das rotina de geração de MDT desenvolvida cálculo do volume do reservatório seria subestimado em 1,61%, superestimando o cálculo do assoreamento. / Water reservoirs are built with the main purpose of guaranteeing water supply, however, their volume always decreases due the sedimentation processes. Bathymetric surveys can be deployed to assess the current volumetric capacity of a given reservoir and to estimate and quantify the sedimentation process. Although Bathymetric surveys are considered to be a key factor when analyzing and assessing properties of a given reservoir, a standard method for its deployment is yet to be defined. Authors and research groups presents different methods about the sampling rate as well as the choice of adequate spots for data collection. The overall goal of this research was to identify and analyze the different methods deployed in previous published literature analyzing the accuracy of the volume data provided by these different methods. Três Irmãos reservoir (São Paulo) was used as a case study where methods were compared. It was pointed out that the DEMs obtained were unable to accurately represent narrower reservoirs areas (tributaries) and the thalweg. Therefore was proposed a new method for determining the distance among survey sections as well as a routine for DEM generation takes into account the thalweg characteristics. Results revealed that the data pulled out was able to represent with accuracy the tributary areas (maximum difference was 5.01%). In addition, a reduced data collection time was observed (60%) when compared against the most accurate method found in published literature. The proposed technique for DEM generation indicated approximately 30% of quality improvement in the data calculated for the reservoir volume. The developed method was applied on a bathymetric survey conducted on the Chavantes reservoir (São Paulo). The loss of reservoir capacity assessed was 3.19%. According to results, a bathymetric survey which does not deploy the new method proposed would underestimate the reservoir\'s volume by 1.61% and overestimate the sedimentation process.

Internal waves are generated in a fluid if the density increases continuously with depth. The variation in density with depth, or stratification, defines the natural frequency of the fluid N. Two common examples of stratified fluids are the ocean and atmosphere; internal waves are generated continuously in both mediums. Although there are many internal wave generation mechanisms, one common and frequently studied method is tidal flow over oceanic bathymetry. If the local natural frequency of the water near the topography is greater than the tidal frequencyω, internal waves will be generated by the tidal flow over the topography. If N=ω, only evanescent waves will be formed. Unlike internal waves, evanescent waves decay rapidly as they move vertically away from their generation site. As evanescent waves pass from an evanescent region (N=ω),through a turning depth (N=ω) and into a propagating region (N=ω), they become propagating internal waves. Because internal waves can propagate energy across large distances, they play an important role in oceanic mixing and the overall energy budget of the ocean. Knowing where these waves are formed from evanescent waves and their corresponding energy improves understanding of the impact on their surrounding area.Kinetic energy density of evanescent and internal waves formed from oscillatory flow over topography in evanescent regions is first estimated using synthetic schlieren experiments and a novel linear theory model. Experiments were performed with two Gaussian topographies in an exponential density profile. The linear theory model, which uses a set of equations that links the evanescent and propagating regions with the Airy function to overcome the discontinuity inherent with a turning depth, was compared to the experiments. Both methods showed that increasing Fr1,the strength of the evanescent region relative to the excitation frequency, causes the propagating kinetic energy to decrease. In addition, kinetic energy decreased with increasing distance between the topography and the turning depth. Because the model does not account for non-linearities such as turbulence generation, it regularly overestimates propagating kinetic energy relative to the experiments. After comparing the model with synthetic schlieren experiments, it was used to estimate that 25% of the evanescent wave energy generated by an oceanic topography located at 15◦N, 130◦E can become propagating wave energy.The influence of topography shape and fluid density profile on kinetic energy density was also explored through a combination of experiments, a linear theory model, and numerical simulations. From numerical simulations, kinetic energy can be directly calculated with the velocity pro-file and indirectly with the density perturbation field, in the same manner as the synthetic schlieren experiments. Average propagating internal wave kinetic energy (KE∗ 2) as a function of Fr1D/H,which combines Fr1 with the relative distance between the topography and the turning depth D/H,was compared for all methods. KE∗ 2 decreases with increasing Fr1D/H for all methods. Also, far from the turning depth, the direct and indirect simulations indicate similar kinetic energy when in the propagating region, where a distance from the turning depth can be quantified based on N and ω. This work was expanded to include a medium Gaussian, steep Gaussian, sinusoidal, and complex topography with two layer linear, parabolic, cubic, and exponential density profiles to investigate the validity of assuming an average natural frequency in the evanescent region and the impact of the topographic slope on KE∗ 2. A comparison of the density profiles indicated that using a two layer linear density profile has similar results compared to the other density profiles for estimating KE∗ 2 as a function of Fr1D/H. Also, KE∗ 2 is non-negligible for Fr1D/H<4. Increasing the maximum slope of a topography shape decreases the kinetic energy of the generated internal waves, though it was found that the energy is dependent upon the actual shape of the topography as well.Particle image velocimetry (PIV) experiments were performed and compared to synthetic schlieren (SS). While SS experiments generally resulted in an overestimate of kinetic energy relative to the PIV results, the trends from each experimental method matched well. It is recommended that SS be used in regions away from turning depths, but that either are valid in the evanescent and propagating regions. PIV methods should be used when results near the turning depth or the topography are desired.

Philosophiae Doctor - PhD / Enhancing our understanding of wetland properties and the ecosystem services provided by wetlands within a dynamic landscape, is fundamental to ensuring appropriate management strategies for enhanced biodiversity and ecosystem benefits. With increased anthropogenic activities and the impacts of climatic variability, a better understanding of the factors influencing the water balance dynamics of wetlands can provide insight into how wetlands respond to change. The main aim of the research was to improve the understanding of the spatial and temporal availability of water and storage of a depression wetland in a semi-arid climate, and to relate these to ecosystem functions. As ecosystems are intricately connected to society, a secondary aim of the research was to gain insight to how wetland ecosystems, within a changing climate and landscape, provide benefits to society, and add value to human-wellbeing. Soetendalsvlei, a shallow freshwater depression, and one of the few coastal freshwater lakes of South Africa, was the focus of the research.

Accurate prediction of tsunami waves requires complete boundary and initial condition data, coupled with the appropriate mathematical model. However, necessary data is often missing or inaccurate, and may not have sufficient resolution to capture the dynamics of such nonlinear waves accurately. In this thesis we demonstrate that variational data assimilation for the continuous shallow water equations (SWE) is a feasible approach for recovering both initial conditions and bathymetry data from sparse observations. Using a Sadourny finite-difference finite volume discretisation for our numerical implementation, we show that convergence to true initial conditions can be achieved for sparse observations arranged in multiple configurations, for both isotropic and anisotropic initial conditions, and with realistic bathymetry data in two dimensions. We demonstrate that for the 1-D SWE, convergence to exact bathymetry is improved by including a low-pass filter in the data assimilation algorithm designed to remove scale-scale noise, and with a larger number of observations. A necessary condition for a relative L2 error less than 10% in bathymetry reconstruction is that the amplitude of the initial conditions be less than 1% of the bathymetry height. We perform Second Order Adjoint Sensitivity Analysis and Global Sensitivity Analysis to comprehensively assess the sensitivity of the surface wave to errors in the bathymetry and perturbations in the observations. By demonstrating low sensitivity of the surface wave to the reconstruction error, we found that reconstructing the bathymetry with a relative error of about 10% is sufficiently accurate for surface wave modelling in most cases. These idealised results with simplified 2-D and 1-D geometry are intended to be a first step towards more physically realistic settings, and can be used in tsunami modelling to (i) maximise accuracy of tsunami prediction through sufficiently accurate reconstruction of the necessary data, (ii) attain a priori knowledge of how different bathymetry and initial conditions can affect the surface wave error, and (iii) provide insight on how these can be mitigated through optimal configuration of the observations. / Thesis / Candidate in Philosophy

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Vattendrag och stränder graderades under 1700-1800-talet mycket lågt (impediment) då marken inte var odlingsbar. Samma mark är idag eftertraktad av människor för fritids- eller permanentboende i en lugn miljö. Problem kan idag uppstå vid gränssättningen av strandfastigheter som nybildas. Problemen är vanligen kopplade till var gränserna verkligen är belägna och var fastighetsägarna anser att gränserna borde vara belägna. För att bestämma var gränserna går måste lantmätaren gå tillbaka till ursprungshandlingarna för stamfastigheten och utföra en grundlig arkivforskning. Syftet är att undersöka hur gränssättningen utförs idag. Frågor som besvaras i studien är: Hur bestäms gränserna för strandfastigheter juridiskt? Hur ser noggrannheten ut för gränserna i vattenområden och har djupkurvans osäkerhet någon inverkan på gränssättningen? På vilket sätt kan batymetrisk laserskanning, jämfört med nuvarande metoder, vara en lämplig metod för att bestämma strandfastigheters gränser? Metoden som valdes var kvalitativa intervjuer. Intervjuerna utfördes med utvalda personer på Lantmäteriet samt företaget Airborne Hydrography AB. Teorin bakom undersökningen uppdelades i tre delar. Första delen behandlar Lantmäteriets arbetssätt vid gränssättning av strandfastigheter. Den andra delen behandlar strandfastigheter och lagarna som ska följas för att bilda dem. Den tredje delen behandlar batymetrisk laserskanning och den tekniska noggrannheten instrumenten är kapabla att leverera. Resultatet visar att noggrannheten på gränserna i vattenområdet är svårbedömda då redovisning av gränserna ofta saknas och ursprungliga strandlinjen är svår att lokalisera. Laserbatymetri kan i vissa fall inverka positivt på gränssättningen i strandfastigheters vattenområden och underlätta lantmätarens arbete med gränssättningen. Slutsatsen är att lantmätarna är tvungna att utföra omfattande arkivforskning för att kunna bestämma strandlinjen och att handlingarna i en förrättning blir svårare att tolka ju äldre stamfastigheterna är. Genom att undersöka nuvarande tillvägagångssätt vid strandfastigheters gränssättning och föra ihop resultatet med den laserbatymetriska mätmetoden fann författarna en möjlig lösning för de osäkra gränserna i vattenområden. Strandlinjen, 300 meters gränslinjen samt var 3 meters djupkurvan är belägen / Water areas and beaches were during the 18- and 19 century's very low graded (waste land) because it was not possible to grow any crops on the grounds. The same properties are today highly regarded real-estate. People buy beach front properties as summer homes or as permanent living, in a low stress environment. Because of this, the establishment of the estates boundaries can create problems when new beach front properties are created. The problems are usually linked to where the land boundaries really are located and where the property-owners consider it to be. To establish where the boundaries really are located the surveyor must perform a thorough archival research on the original property. The purpose of this study was to investigate how the establishments of the estates boundaries are performed today. Questions to answer are: How are the boundaries' established legally? How accurate are the boundaries in water areas, and have the uncertainty of the 3 meter depth curve any influence on the boundaries? Can the bathymetric laserscanner, compared with the current method, be a suitable method to establish the boundaries of beach front properties? The method selected in this study was qualitative interviews. The interviews were performed with experienced people from the Swedish "Lantmäteriet" and the company Airborne Hydrography AB. The theory was divided in three parts. Part one addresses "Lantmäteriets" role and workings with creating beach front property. Part two addresses the laws involved in creating beach front property. Part three addresses bathymetric laserscanning and the technical accuracy the instrument are capable of. The result shows that the accuracy of the boundaries in water areas are difficult to assess due to lack of references that often are missing and the shoreline is hard to locate. Laserbatymetri can in certain cases have a positive effect on beach front properties boundaries border setting in water areas and help the surveyor. The conclusion is that the surveyor must undertake an extensive archival research to find the shoreline and it is more difficult the older the original properties are. By examining the current method of establishing these boundaries and mix the result with the bathymetric laserscanning method the authors found a possible solution for the uncertain boundaries of water areas. The shoreline, 300meters boundary line and where the 3 meters depth curve is located

The use of iceberg-keel ploughmarks as proxy indicators of past and present iceberg morphology, keel depth and drift direction has seldom been approached in the southern hemisphere. Using high-resolution multi-beam swath bathymetry of the mid-shelf Pine Island Trough and outermost Weddell Sea shelf regions of Antarctica, detailed analysis of >13,000 iceberg-keel ploughmarks was undertaken. By considering the draft of icebergs calved from Antarctica today, calculated from detailed satellite altimetric datasets by this work, almost all observed ploughmarks were interpreted to be relict features. In Pine Island Trough, ploughmark planform parameters and cross-sections imply calving of a large number of non-tabular icebergs with v-shaped keels from the palaeo-Pine Island-Thwaites ice stream. Geological evidence of ploughmark form and modern water depth distribution indicates calving-margin thicknesses (949 m) and subaerial ice cliff elevations (102 m) equivalent to the theoretical threshold predicted to trigger ice-cliff structural collapse and calving by marine ice-cliff instability (MICI) processes. Thus, ploughmarks provide the first observational evidence of rapid retreat of the palaeo-Pine Island-Thwaites ice stream, driven by MICI processes commencing ~12.3 cal ka BP. On the Weddell Sea shelf, ploughmark morphologies imply considerable variation in palaeo-iceberg shape and size, most likely reflecting calving from multiple source margins. In turn, an absence of grounded ice on the Weddell Sea shelf and a palaeo-oceanographic regime comparable to today are implied at the time of formation. Analysis of a 3D seismic cube of the Sea Lion Field area of the North Falkland Basin reveals iceberg-keel ploughmarks incised into the modern- and palaeo-seafloor, formed by icebergs of varying shape and size that most-likely calved from the Antarctic Ice Sheet during three past glacial periods (estimated ages ~18 - 26.5 ka BP, ~246 ka BP, ~9.8 Ma BP). Despite illustrating the possibility of iceberg drift into the North Falkland Basin today, the relict ploughmark age implies little risk to any seafloor structures in the area, which might be required for hydrocarbon production. By these analyses, the significance of iceberg-keel ploughmarks as indicators of palaeo-glaciology and palaeo-oceanography at the time of formation is emphasised.

Pliocene to Pleistocene glacial-marine deposits adjacent to the Fairweather Ground basement in the Gulf of Alaska are the focus for seismic interpretation using public domain seismic reflection data. The late Tertiary and early Quaternary sections of the Yakataga Formation record a glacial/ interglacial climate change sequence with increasing rates of sedimentation (175 meters per million years to 4000 meters per million years). The foreland basin sediment load is deposited onto the Yakutat block, a microplate that takes up the strike-slip to convergent movement with respect to North America and Pacific plates. Tectonic activity during the last 5 million years has resulted in Eocene rock exposed at the sea floor. High resolution bathymetry data adjacent to the Yakutat microplate is utilized to 1) observe the results of deformation from Pacific plate loading on the Yakutat microplate and 2) interpret the Transition fault as an active thrust to oblique thrust fault.

Le contrôle de la qualité de l'eau est fondé naturellement et traditionnellement sur des mesures et des prélèvements in situ. Des images satellites étalonnées à partir des données mesurées in situ fournissent une information quantitative et continue sur le milieu aquatique et peuvent être employées pour estimer, avec une approximation raisonnable, les facteurs affectant la qualité de l’eau L’objectif de ce travail consiste à modéliser les propriétés optiques de l’eau de mer et les paramètres physico-chimiques qui caractérisent les eaux côtières. L'application est basée sur le développement d’un Système d’Information Marin caractérisant un système de gestion de base de données géoréférencié POlGIS dédié à la gestion de l'information marine dans le cas de contrôle, suivi et surveillance de la pollution. Nous présentons des modèles exprimant les variables indicatrices de la qualité des eaux du littoral Algérois et la réflectance calculée de chaque pixel à partir d’un modèle physique de correction radiométrique. Les mesures in- situ sont effectuées pour des zones de différentes qualités d’eaux et leurs réflectances sont calculées à partir des images satellites SPOT, Landsat TM, MSS, IRS1C et Seawifs Finalement, des modèles sont établies avec les réflectances permettent d’obtenir des images satellites indicatrices de la pollution et de la bathymétrie des zones côtières à partir du logiciel de traitement d’image PCSATWIN développé afin d’estimer pour chaque pixel le degré de pollution du milieu. / In order to protect the natural medium and to control the pollution caused by such rejects, it is necessary to achieve a continuous survey of the reject zones. The goal of this study is a developed a methodology for modelling pollution and bathymetry from the digital satellite images.Indeed, our objective consists of the development of a software POLGIS intended for the management of the marine databases for the control and the monitoring of the pollution Satellite imagery can be used to estimate, with a reasonable accuracy, the factors affecting the water quality .It has a great importance to achieve the necessary continuous monitoring of the relevant area with an overall analysis of its pollution. A modelling analysis between the pollution contents and the reflectance calculated by the satellite images allow us to transform rough images into images treated and combined using a software of satellite image processing PCSATWIN developed in this study. This complex phenomena us developed an analytic model of radiatif transfer simulation in water coupled to an atmospheric model in order to simulate measure by satellite. This direct model permits to follow the solar radiance in his trajectory Sun-Atmosphere - Sea - Depth of sea- sensor. The goal of this simulation is to show for every satellite of observation (Spot, Landsat MSS, TM) possibilities that can offer in domain of bathymetry.The reflectance coefficient is calculated from satellite image, the detection and the possible determination of the zones contaminated by pollution using the space techniques constitute an effective means to intervene in order to ensure the monitoring of the Algerian coasts. The analysis shows us that each sensor offers useful information and that the combination between these various informations makes it possible to propose a procedure of maps establishment that can be interpreted as pollution maps.