Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: An antenna for ground level deployed Ground Penetrating Radar applications is presented. The antenna is matched to the ground via a low impedance dielectric matching section improving the radiation pattern and input impedance characteristics. A bowtie antenna was used for the design with the edges rounded to stabilize the resonant frequency. The radiation pattern was focused to the one side of the antenna for ground penetration using a non-absorptive metallic cylindrical air filled cavity. Edge reflections from the antenna were reduced by means of discrete resistor terminations between the antenna and the cavity. A wire equivalent of the solid metallic antenna was investigated giving similar characteristics to that of the solid antenna. The radiation pattern deformation arising from transmitting a wave from an antenna in air into the ground due to the impedance mismatch was investigated. This was overcome with the use of a polypropylene dielectric slab inserted between the antenna and the ground. Together with improving the radiation pattern the antenna was less sensitive to ground parameter variations and to an air gap introduced between the slab and the ground. This was implemented as a wheel mounted system with adjustable height settings depending on the terrain. A pair of mounted antennas was constructed to be tested on an existing bistatic Stepped Frequency Continuous Wave radar operating in the 50-400 MHz band developed by the University of Cape Town. This antenna is seen as providing a solution to the problem of coupling an antenna to a low wave impedance medium such as ground. / AFRIKAANSE OPSOMMING: 'n Antenne word vir Grond Penetrerende Radar toepassings voorgestel. Dit is spesifiek ontwikkel vir oppervlak ontplooide stelsels ontwerp. Die antenne is aangepas tot die grond deur middel van 'n diëlektriese aanpassingseksie wat die starlingspatroon en intree-impedansie karakteristieke verbeter. Die antenne is tot die grond toe aangepas deur middel van 'n diëlektriese aanpassingseksie wat die starlingspatroon en intree-impedansie karakteristieke verbeter. 'n Strikdas antenne was gebruik vir die ontwerp, met die kante gerond om die resonante freqwensie te stabiliseer. Om die stralingspatroon van die antenne na een kant toe te fokus was 'n nie-absorbeerede metaleiese, luggevulde, silindriese holte daaragter geplaas om die energie vorentoe te weerkaats. Weerkaatsings van die rand van die antenne word onderdruk met behulp van koppelende weerstande tussen die antenne en die holte. A draad ekwivalent van die antenne was ook ondersoek met goeie ooreenstemming met die soliede strikdas. Die impedansie wanaanpassing wat ontstaan as 'n antenne wat in lug is, in die grond in straal veroorsaak dat die stralingspatroon van die antenne vervorm word. Dit was gevind dat deur 'n aanpassings blad van 'n diëlektriese materiaal, naamlik polipropileen, gebruik te maak tussen die antenne en die grond dat dit die probleem oplos. Saam met dit was gevind dat die antenne minder sensitief was vir veranderings in grondparameters en ook vir 'n lug gaping tussen die blad en die grond. Die het gemaak dat die antenne op wiele gemonteer kon word met verstelbare hoogte afhangend van die terrein. 'n Stel geskaleerde antennes was gemaak om op 'n beskikbare bistatiese Trap Frekwensie Kontinue Golf radar te werk. Dit werk oor die 50-400 MHz band en was ontwikkel deur die Universitiet van Kaapstad. Die antenne word gesien as 'n oplossing vir antenne koppelingsprobleme ondervind by laë golf impedansie materiale.

[pt] O método GPR Ground Penetrating Radar foi empregado nesta pesquisa visando estimar suas potencialidades como uma metodologia viável para os estudos geológicos, geotécnicos e ambientais em condições brasileiras.Para o alcance deste objetivo foram realizados ensaios em campo procurando avaliar a capacidade deste método na detecção das alterações provenientes da ação intempérica na formação do solo residual, ou seja, estimar a profundidade e espessura dos horizontes pedológicos, e o topo rochoso em um perfil geotécnio. Foram também realizados ensaios em laboratório onde fez-se o monitoramento do efeito da contaminação por hidrocarbonetos em blocos indeformados de solo residual, tanto em condições não saturadas, quanto na zona de saturação, procurando avaliar a aplicabilidade do método GPR na detecção deste tipo de contaminante.Os resultados obtidos permitiram imagear com boa resolução os contrastes bruscos, como o topo da rocha sã e blocos inclusos no solo, mas não a detecção nítida dos horizontes no perfil; e pela análise do monitoramento da contaminação, ainda é recente afirmar que o método GPR possa ser empregado com grande eficiência na detecção de contaminantes orgânicos em solo residual. / [en] The GPR method Ground Penetration Radar was used in this work, aiming at estimating its potentialities as a viable methodology to geological, geotechnical and environmental studies of Brazilian soil-rock conditions.In order to reach this objective, in situ tests have been carried out to evaluate the capability of the method in the detection of characteristics of weathering profiles in residual soils. In this case, the aim was to estimate the depth and width of pedological horizons and the bedrock in a geotechnical profile. Laboratory tests were also carried out in blocks of undisturbed residual soil of gnaissic origin. In these blocks, the effects of contamination by petroleum hydrocarbons were monitored. Both the unsaturated and the vadose zones have been monitored. The main objective in relation to the GPR was to evaluate the applicability of the method in the detection of such contaminants.The results obtained allowed to image gross contacts with good resolution such as soil-intact bedrock contacts and blocks inside soils. However, the clear detection of profile horizons were not well imaged. Regarding the contamination monitoring, it is early to affirm that the GPR method might be employed efficiently in the detection of organic contaminants in residual soils.

Across a large part of the UK highways network the carriageway and pavement foundations are drained by Highway Filter Drains (HFDs). A HFD is a linear trench constructed either at the pavement edge or central reserve, fitted with a porous carrier pipe at the base and backfilled with an initially highly porous aggregate material. This arrangement enables the swift removal of surface runoff and subsurface water from the pavement system minimising road user hazards and eliminating risk of structural damage to the pavement sub-base. The highly porous backfill filters throughout its operational life fines washed from the pavement wearing course or adjacent land. HFDs have been found to be prone to collecting near the basal sections (pipe) or surface layers contaminants or detritus that causes the filter media to gradually block. The process has been defined as HFD clogging and it has been found to lead to reduced drainage capacity and potentially severe drop of serviceability. O&M contractual agreements for DBFO projects usually propose in-service and handback requirements for all assets included in the concession portfolio. Different performance thresholds are thus prescribed for pavements, structures, ancillary assets or street lighting. Similar definitions can be retrieved for drainage assets in such agreements, and these include HFDs. Performance metrics are defined though in a generic language and residual life (a key indicator for major assets that usually drives long-term maintenance planning) is prescribed without indicative means to evaluate such a parameter. Most of pavement maintenance is carried out nowadays using proactive management thinking and engineered assessment of benefits and costs of alternative strategies (what-if scenarios). Such a proactive regime is founded upon data driven processes and asset specific ageing / renewal understanding. Within the spectrum of road management, maintenance Life Cycle Costs are usually generated and updated on an annual basis using inventory and condition data linked to a Decision Support Tool (DST). This enables the assessment and optimisation of investment requirements and projection of deterioration and of treatment impacts aligned to continuous monitoring of asset performance. Following this paradigm shift in infrastructure management, a similar structured methodology to optimise HFD maintenance planning is desired and is introduced in this thesis. The work presented enables the identification of proactive maintenance drivers and potential routes in applying a systemised HFD appraisal and monitoring system. An evaluation of Asset Management prerequisites is thus discussed linked to an overview of strategic requirements to establish such a proactive approach. The thesis identifies condition assessment protocols and focuses on developing the means to evaluate deteriorated characteristics of in service drains using destructive and non-destructive techniques. A probabilistic HFD ageing / renewal model is also proposed using Markov chains. This builds upon existing deterioration understanding and links back to current treatment options and impacts. A filter drain decision support toolkit is lastly developed to support maintenance planning and strategy generation.

No registro estratigráfico da Planície Costeira do Rio Grande do Sul estão presentes quatro sequências deposicionais de alta frequência, correspondentes a quatro sistemas do tipo laguna-barreira (I a IV). Estas sequências possuem idades pleistocênicas e holocênica e se desenvolveram em resposta a ciclos glacioeustáticos da ordem de 100 ka. O sistema costeiro holocênico, relacionado à sequência mais jovem (IV), possui setores contemporâneos com padrões de empilhamento opostos. Partindo desta observação duas hipóteses foram formuladas e investigadas. A primeira hipótese refere-se à existência de padrões de empilhamento opostos também nas sequências deposicionais mais antigas (I, II e III) e a segunda é a de que estes padrões estejam expressos na morfologia das barreiras costeiras. Uma análise geomorfológica e estratigráfica foi realizada através das geotecnologias, com o emprego do sensoriamento remoto, do geoprocessamento, de sistemas de posicionamento e do método geofísico do georradar. Os dados foram obtidos em diferentes setores da planície costeira, com enfoque na região sul, entre a fronteira com o Uruguai (Chuí) e a desembocadura da Lagoa dos Patos (Rio Grande). Nesta região, estão presentes os sistemas laguna-barreira II, III e IV, portanto estes contaram com um maior detalhamento. As interpretações realizadas permitiram estabelecer um arcabouço estratigráfico, com a definição das principais superfícies chave e tratos de sistemas, além de um modelo de evolução paleogeográfica para a região sul. A existência dos padrões de empilhamento retrogradacional, progradacional e degradacional foi constatada nas sequências deposicionais mais antigas. Ainda que estas não tenham sido datadas foi possível inferir que comportamentos distintos tenham ocorrido simultaneamente ao longo das linhas de costa relacionadas a estas sequências deposicionais. A variabilidade do comportamento dos sistemas costeiros foi verificada também através das suas características morfológicas, as quais possuem grande influência em seu potencial de preservação. Contudo, alterações posteriores, de origem erosiva e/ou deposicional, modificaram significativamente as feições originais. A aplicação das geotecnologias referidas acima, através da perspectiva da estratigrafia moderna, permitiu ampliar o conhecimento acerca dos sistemas deposicionais costeiros, especialmente das sequências relacionadas aos sistemas laguna-barreira II e III. / The stratigraphic record of Rio Grande do Sul Coastal Plain embraces four high-frequency depositional sequences corresponding to four barrier-lagoon systems (I to IV). These sequences have been developed during the Pleistocene and Holocene, in response to glacioeustatic cycles of 100 ka. The Holocene coastal system, related to the younger sequence (IV), exhibits contemporaneous sectors with opposites stacking patterns. From this observation, two hypotheses were formulated and investigated. The first hypothesis was that the opposite stacking patterns also exist in the older depositional sequences (I, II and III), and the second was that these patterns are expressed, today, in the morphology of the coastal barriers. A geomorphologic and stratigraphic analysis was performed applying various geotechnologies, like remote sensing, geoprocessing, positioning systems and the geophysical method of ground penetrating radar (GPR). The data were obtained in different sectors of the coastal plain, with a focus on the southern region between the border with Uruguay (Chui) and the inlet of Lagoa dos Patos lagoon (Rio Grande). In this region the barrier-lagoon systems II, III and IV were identified and studied in greater detail. The interpretations allowed establishing a stratigraphic framework, setting out the main key surfaces and systems tracts, and a paleogeographic model of the evolution of the southern coastal plain. The existence of retrogradational, progradational and degradacional stacking patterns was found in the older sequences. Although the absolute age of these units has not been determined, it was possible to infer that different behaviors have occurred simultaneously along the shorelines related to these depositional sequences. The variability on the behavior of the coastal systems was also verified by their morphological characteristics, which have great influence on their preservation potential. However, subsequent changes due to erosive and/or depositional events may have significantly modified the original features. The application of geotechnologies from the perspective of modern stratigraphy improved the knowledge of coastal depositional systems, especially of the sequences related to barrier-lagoon systems II and III.

O presente trabalho tem como objetivo a reconstrução da história evolutiva ao longo do Holoceno da planície costeira de cordões litorâneos estabelecidos sobre o vale fluvial do Rio Itabapoana/ES. A partir desse objetivo, foram realizadas as seguintes etapas metodológicas: Sensoriamento Remoto, Topografia, Geofísica e Geocronologia. Através da análise da imagem de satélite RapidEye, na composição colorida R5-G3-B1, foram discriminadas classes de cobertura vegetal. A relação entre a vegetação e o solo exposto proporcionou a identificação de três padrões distintos na planície costeira de cordões litorâneos. A obtenção de dados contínuos de altimetria através de um sistema global de navegação por satélite (GNSS), concentrado no caminhamento perpendicular à linha de costa, permitiu a elaboração e análise do perfil altimétrico dos cordões litorâneos, identificando-se três principais características: 1) nos primeiros 600 m tem-se um acréscimo na elevação; 2) em seguida, uma longa faixa “estável”, de pouca mudança na elevação; 3) por fim, o decréscimo da elevação nos últimos 500 m. Para caracterizar a arquitetura deposicional em subsuperfície dos cordões litorâneos, utilizou-se um Radar de Penetração no Solo (GPR) O registro obtido com GPR possibilitou a identificação de três padrões, representados pelas unidades retrogradacional e progradacional, onde o padrão de empilhamento compõe uma sequência de barreira regressiva ou progradante. Para a obtenção de uma relação cronoestratigráfica, seis amostras de sedimentos da fração arenosa de deposição eólica foram coletadas para a obtenção de idades absolutas a partir de Luminescência Opticamente Estimulada (LOE). Os cordões datados apresentaram idades holocênicas, com idades inferiores a 5.261 ± 396 anos. A integração dos resultados obtidos através dos métodos aplicados permitiu o reconhecimento de três padrões que levaram à interpretação de três fases decorrentes das variações do nível relativo do mar e do aporte sedimentar na evolução da planície. Essas fases representam os períodos de transgressão, regressão normal e regressão forçada. / The aim of this study is the reconstruction of the evolutionary history along the Holocene of the of beach ridges coastal plain established on the fluvial valley of Itabapoana River/ES. From this objective, the following methodological steps were performed: Remote Sensing, Topography, Geophysics and Geochronology. Through the analysis of the RapidEye satellite image, in the color composition R5-G3-B1, classes of vegetal cover were discriminated. The relationship between vegetation and exposed soil provided the identification of three distinct patterns of the beach ridges coastal plain. Obtaining continuous data of altimetry with a GNSS system, concentrated in the path perpendicular to the coastline, allowed the elaboration and analysis of the altimetric profile of the beach ridges. It was identified three main characteristics: 1) in the first 600 m there is an increase in elevation; 2) then along “stable” stretch, with little change in elevation; 3) lastly, the decrease of the elevation in the last 500 m. A Ground Penetrating Radar (GPR) was used to characterize the depositional architecture in the subsurface of the beach ridges The GPR record allowed the identification of three patterns, represented by the retrogradational and progradational units, in which the stacking pattern consists of a regressive or progradational barrier sequence. Six sediment samples of the sandy fraction of wind deposition were collected to obtain absolute ages from Optically Stimulated Luminescence (OSL). The dated ridges presented Holocene ages, with ages lower than 5,261 ± 396 years. The integration of the results obtained allowed the recognition of three patterns that led to the interpretation of three phases due to the variations of the relative sea level and the sedimentary budget in the evolution of the plain. These phases represent periods of transgression, normal regression and forced regression.

Ground-Penetrating Radar (GPR) is a popular non-destructive geophysical technique with a wide range of diverse applications. Civil engineering, hydrogeophysics, forensic, glacier geology, human detection and borehole geology are some of the fields in which GPR has been applied with successful or promising results. One of the most mainstream applications of GPR is landmine detection. A lot of methods have been suggested over the years to assist the landmine detection issue. Metal detectors, trained rats or dogs, chemical methods and electrical resistivity tomography are –amongst others– some of the suggested techniques. The non-destructive nature of GPR makes it an attractive choice for a problem such as demining in which contact to the ground is not allowed. The main advantage of GPR is its ability to detect both metallic and non-metallic targets. Furthermore, GPR can provide an insight regarding the nature of the target (e.g. size, burial depth, type). From the above, it is evident that GPR can potentially reduce the false alarms emerging from small metallic objects (e.g. bullets, wires, etc.) usually encountered in battle-fields and industrialised areas. Combining the robustness of the metal detector with the resolution of GPR results in a reliable and efficient detection framework which has been successfully applied in Cambodia and Afghanistan. Despite the promising, and in some cases impressive results, aspects of GPR can be further improved in an effort to optimise GPR’s performance and decrease its limitations. The validation of a GPR system is usually achieved through the so called Receiver Operation Characteristics (ROC) which depicts the probability of detection with respect to the false alarm rate. ROC is a highly nonlinear function which is sensitive to the environment as well as to the antenna unit. Landmines are typically small objects, often less than 10 cm diameter, which are shallow buried, usually in less than 10 cm depth, and sometimes almost exposed. In order for the landmines to be resolved, high frequency antennas are essential. The latter are sensitive to soil’s inhomogeneities, rough surface, water puddles, vegetation and so on. Apart from that, the near field nature of the problem makes the antenna unit part of the medium which contributes to the unwanted clutter. The above, outlines the multi-parametric nature of the problem for which no straightforward approach has yet to be proposed. Numerical modelling is a practical and solid approach to understand the physical behaviour of a system. In the case of GPR for landmine detection, numerical modelling can be a practical tool for designing and optimising antennas in synthetic but nonetheless realistic conditions. Apart from that, evaluation of a processing method only to a specific environment is not a robust approach and does not provide any evidence for its wider inclusivity and limitations. However, evaluation in different conditions can become costly and unpractical. Numerical modelling can tackle this problem by providing data for a wide range of scenarios. An extensive database of simulated responses, apart from being a practical testbed, can be also employed as a training set for machine learning. A multi-variable problem like demining, in order to be addressed using machine learning, requires a large amount of data. These must equally include all possible different scenarios i.e. different landmines, in different media with stochastically varied properties and topography. Additionally, different heights of the antenna and different depths of the landmines must also be examined. Numerical modelling seems to be a practical approach to achieve an equally distributed and coherent dataset like the one briefly described above. Numerical modelling of GPR for landmine detection has been applied in the past using generic antennas in simplified and clinical scenarios. This approach can be used in an educational context just to provide a rough estimation of GPR’s performance. In the present thesis a realistic numerical scheme is suggested in which, simplifications are kept to a minimum. The numerical solver, employed in the suggested numerical scheme, is the Finite- Difference Time-Domain (FDTD) method. Both the dispersive properties and the Absorbing Boundary Condition (ABC) are implemented through novel and accurate techniques. In particular, a novel method which implements an inclusive susceptibility function is suggested and it is shown that surpasses the performance of the previous approaches while retaining their computational efficiency. Furthermore, Perfectly Matched Layer (PML) and more specifically Convolutional Perfectly Matched Layer (CPML) is implemented through a novel time-synchronised scheme which it is proven to be more accurate compared to the traditional CPML with no additional computational requirements. An accurate numerical solver, although essential, is not the only requirement for a realistic numerical framework. Accurate implementation of the geometry and the dielectric properties of the simulated model is highly important, especially when it comes to high-frequency near-field scenarios such as GPR for landmine detection. In the suggested numerical scheme, both the soil’s properties as well as the rough surface are simulated using fractal correlated noise. It is shown, that fractals can sufficiently represent Earth’s topography and give rise to semi-variograms often encountered in real soils. Regarding the dielectric properties of the soils, a semi-analytic function is employed which relates soil’s dielectric properties to its sand fraction, clay fraction, sand density, bulk density and water volumetric fraction. Subsequently, the semi-analytic function is approximated using a Debye function that can be easily implemented to FDTD. Vegetation is also implemented to the model using a novel method which simulates the geometry of vegetation through a stochastic process. The experimentally-derived dielectric properties of vegetation are approximated –similarly to soil’s dielectric properties– with a Debye expansion. The antenna units tested in the numerical scheme are two bow-tie antennas based on commercially available transducers. Regarding the targets, three landmines are chosen, namely, PMN, PMA-1 and TS-50. Dummy landmines are used in order to obtain their geometrical characteristics and comparison between measured and numerically evaluated traces are used to tune the dielectric properties of the modelled landmines. Lastly, water puddles are realistically implemented in the model in an effort to realistically simulate high-saturated scenarios. The proposed numerical scheme has been employed in order to test and evaluate widely used post-processing methods. The results clearly illustrate that post-processing methods are sensitive to the antenna unit as well as the medium. This highlights the importance of an accurate numerical scheme as a testbed for evaluating different GPR systems and post-processing approaches in wide range of scenarios. Using an equivalent 2D numerical scheme –restricted to 2D due to computational constrains– preliminary results are given regarding the effectiveness of Artificial Neural Network (ANN) subject to an adequate and equally distributed database. The results are promising, showing that ANN can be successfully employed for detection as well as classification using only a single trace as input. A basic requirement to do so is a representative training set. This can be synthetically generated using a realistic numerical framework. The above, provide solid arguments for further expanding the proposed machine learning scheme to the more computationally demanding 3D case.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Esta pesquisa investigou a formação de depósitos arenosos localizados na planície costeira da Baixada de Sepetiba, em Itaguaí, estado do Rio de Janeiro. A deposição sedimentar e a evolução desta área, na Baixada de Sepetiba tem sido estudada nas três últimas décadas, principalmente, porque é um ambiente de depósitos arenosos antigo de idade Holocênica a Pleistocênica que corresponde a uma linha de praia, originada com eventos transgressivos e/ou regressivos que tiveram seu ápice durante o Quaternário. A metodologia de Radar de Penetração no Solo (GPR) é usada, principalmente nos casos de trabalho em que se estuda um ambiente costeiro arenoso. Este campo da Geofísica tem sido usado para examinar características, tais como: a espessura de depósitos arenosos, a profundidade de um aqüífero, a detecção de uma rocha ou um aqüífero, e determina a direção de progradação. Esta pesquisa usa técnicas de radar de penetração no solo (GPR) para analisar as estruturas, em subsuperfície desde que o ambiente estudado seja definido como linha de costa, as margens de uma lagoa mixohalina, chamada Baía de Sepetiba. Neste trabalho realizamos um total de 11 perfis, que foram processados pelo software ReflexWin. Durante o processamento do dado aplicamos alguns filtros, tais como: subtract-mean (dewow), bandpassfrequency e ganhos. E as melhores imagens dos perfis foram realizadas usando-se uma antena de 200 MHz (canal 1) e outra antena de 80 MHz. Neste caso, obtivemos imagens de alta resolução a uma profundidade de até 25 metros. / This research investigated the formation of sandstones located in the coastal plain region of Sepetiba, in Itaguaí, Rio de Janeiro State. The deposition sedimentary and the evolution of the coastal plain Sepetiba has been studied in the last three decades, mainly because it is an ancient environment of sandy deposits formed during the Holocene. In addition, diverse authors define the sediments as deposited at beaches originated with transgressive and/or regressive that peaked during the Quaternary. The methodology of Ground Penetrating Radar (GPR) was here used to study the coastal sandy environment. This geophysical technique has been used to examine characteristics such as: thickness of the sand deposits, the detection of the bedrock and to determinate the direction of progradation. This research also used the technique of ground penetrating radar to analyze the structures in the subsurface since the environment studied can be defined as the shoreline, the margins of lagoon, called Sepetiba Bay. In this work we realized a total of eleven (11) profiles, which have been processed with the software Reflex win. During data processing apply some filters, such as: subtract mean (dewow), bandpassfrequency and gains. And the much better images of radargramas have been realized using a 200 MHz antenna (channel 1) and an antenna 80 MHz In this case, obtained images of radargramas with high resolution to 25 meters depth. The results were used to build sections and their interpretations allowed to conclude that the studied sedimentary sequence was deposited in delta and shorelines Quaternary environments.

No registro estratigráfico da Planície Costeira do Rio Grande do Sul estão presentes quatro sequências deposicionais de alta frequência, correspondentes a quatro sistemas do tipo laguna-barreira (I a IV). Estas sequências possuem idades pleistocênicas e holocênica e se desenvolveram em resposta a ciclos glacioeustáticos da ordem de 100 ka. O sistema costeiro holocênico, relacionado à sequência mais jovem (IV), possui setores contemporâneos com padrões de empilhamento opostos. Partindo desta observação duas hipóteses foram formuladas e investigadas. A primeira hipótese refere-se à existência de padrões de empilhamento opostos também nas sequências deposicionais mais antigas (I, II e III) e a segunda é a de que estes padrões estejam expressos na morfologia das barreiras costeiras. Uma análise geomorfológica e estratigráfica foi realizada através das geotecnologias, com o emprego do sensoriamento remoto, do geoprocessamento, de sistemas de posicionamento e do método geofísico do georradar. Os dados foram obtidos em diferentes setores da planície costeira, com enfoque na região sul, entre a fronteira com o Uruguai (Chuí) e a desembocadura da Lagoa dos Patos (Rio Grande). Nesta região, estão presentes os sistemas laguna-barreira II, III e IV, portanto estes contaram com um maior detalhamento. As interpretações realizadas permitiram estabelecer um arcabouço estratigráfico, com a definição das principais superfícies chave e tratos de sistemas, além de um modelo de evolução paleogeográfica para a região sul. A existência dos padrões de empilhamento retrogradacional, progradacional e degradacional foi constatada nas sequências deposicionais mais antigas. Ainda que estas não tenham sido datadas foi possível inferir que comportamentos distintos tenham ocorrido simultaneamente ao longo das linhas de costa relacionadas a estas sequências deposicionais. A variabilidade do comportamento dos sistemas costeiros foi verificada também através das suas características morfológicas, as quais possuem grande influência em seu potencial de preservação. Contudo, alterações posteriores, de origem erosiva e/ou deposicional, modificaram significativamente as feições originais. A aplicação das geotecnologias referidas acima, através da perspectiva da estratigrafia moderna, permitiu ampliar o conhecimento acerca dos sistemas deposicionais costeiros, especialmente das sequências relacionadas aos sistemas laguna-barreira II e III. / The stratigraphic record of Rio Grande do Sul Coastal Plain embraces four high-frequency depositional sequences corresponding to four barrier-lagoon systems (I to IV). These sequences have been developed during the Pleistocene and Holocene, in response to glacioeustatic cycles of 100 ka. The Holocene coastal system, related to the younger sequence (IV), exhibits contemporaneous sectors with opposites stacking patterns. From this observation, two hypotheses were formulated and investigated. The first hypothesis was that the opposite stacking patterns also exist in the older depositional sequences (I, II and III), and the second was that these patterns are expressed, today, in the morphology of the coastal barriers. A geomorphologic and stratigraphic analysis was performed applying various geotechnologies, like remote sensing, geoprocessing, positioning systems and the geophysical method of ground penetrating radar (GPR). The data were obtained in different sectors of the coastal plain, with a focus on the southern region between the border with Uruguay (Chui) and the inlet of Lagoa dos Patos lagoon (Rio Grande). In this region the barrier-lagoon systems II, III and IV were identified and studied in greater detail. The interpretations allowed establishing a stratigraphic framework, setting out the main key surfaces and systems tracts, and a paleogeographic model of the evolution of the southern coastal plain. The existence of retrogradational, progradational and degradacional stacking patterns was found in the older sequences. Although the absolute age of these units has not been determined, it was possible to infer that different behaviors have occurred simultaneously along the shorelines related to these depositional sequences. The variability on the behavior of the coastal systems was also verified by their morphological characteristics, which have great influence on their preservation potential. However, subsequent changes due to erosive and/or depositional events may have significantly modified the original features. The application of geotechnologies from the perspective of modern stratigraphy improved the knowledge of coastal depositional systems, especially of the sequences related to barrier-lagoon systems II and III.

O presente trabalho tem como objetivo a reconstrução da história evolutiva ao longo do Holoceno da planície costeira de cordões litorâneos estabelecidos sobre o vale fluvial do Rio Itabapoana/ES. A partir desse objetivo, foram realizadas as seguintes etapas metodológicas: Sensoriamento Remoto, Topografia, Geofísica e Geocronologia. Através da análise da imagem de satélite RapidEye, na composição colorida R5-G3-B1, foram discriminadas classes de cobertura vegetal. A relação entre a vegetação e o solo exposto proporcionou a identificação de três padrões distintos na planície costeira de cordões litorâneos. A obtenção de dados contínuos de altimetria através de um sistema global de navegação por satélite (GNSS), concentrado no caminhamento perpendicular à linha de costa, permitiu a elaboração e análise do perfil altimétrico dos cordões litorâneos, identificando-se três principais características: 1) nos primeiros 600 m tem-se um acréscimo na elevação; 2) em seguida, uma longa faixa “estável”, de pouca mudança na elevação; 3) por fim, o decréscimo da elevação nos últimos 500 m. Para caracterizar a arquitetura deposicional em subsuperfície dos cordões litorâneos, utilizou-se um Radar de Penetração no Solo (GPR) O registro obtido com GPR possibilitou a identificação de três padrões, representados pelas unidades retrogradacional e progradacional, onde o padrão de empilhamento compõe uma sequência de barreira regressiva ou progradante. Para a obtenção de uma relação cronoestratigráfica, seis amostras de sedimentos da fração arenosa de deposição eólica foram coletadas para a obtenção de idades absolutas a partir de Luminescência Opticamente Estimulada (LOE). Os cordões datados apresentaram idades holocênicas, com idades inferiores a 5.261 ± 396 anos. A integração dos resultados obtidos através dos métodos aplicados permitiu o reconhecimento de três padrões que levaram à interpretação de três fases decorrentes das variações do nível relativo do mar e do aporte sedimentar na evolução da planície. Essas fases representam os períodos de transgressão, regressão normal e regressão forçada. / The aim of this study is the reconstruction of the evolutionary history along the Holocene of the of beach ridges coastal plain established on the fluvial valley of Itabapoana River/ES. From this objective, the following methodological steps were performed: Remote Sensing, Topography, Geophysics and Geochronology. Through the analysis of the RapidEye satellite image, in the color composition R5-G3-B1, classes of vegetal cover were discriminated. The relationship between vegetation and exposed soil provided the identification of three distinct patterns of the beach ridges coastal plain. Obtaining continuous data of altimetry with a GNSS system, concentrated in the path perpendicular to the coastline, allowed the elaboration and analysis of the altimetric profile of the beach ridges. It was identified three main characteristics: 1) in the first 600 m there is an increase in elevation; 2) then along “stable” stretch, with little change in elevation; 3) lastly, the decrease of the elevation in the last 500 m. A Ground Penetrating Radar (GPR) was used to characterize the depositional architecture in the subsurface of the beach ridges The GPR record allowed the identification of three patterns, represented by the retrogradational and progradational units, in which the stacking pattern consists of a regressive or progradational barrier sequence. Six sediment samples of the sandy fraction of wind deposition were collected to obtain absolute ages from Optically Stimulated Luminescence (OSL). The dated ridges presented Holocene ages, with ages lower than 5,261 ± 396 years. The integration of the results obtained allowed the recognition of three patterns that led to the interpretation of three phases due to the variations of the relative sea level and the sedimentary budget in the evolution of the plain. These phases represent periods of transgression, normal regression and forced regression.

Interception av snö eller regn på trädkronor är en viktig del av det hydrologiska kretsloppet. Upp till en tredjedel av all snö som faller över skogsområden når aldrig marken på grund av stora avdunstningsförluster av interceptionsförrådet, vilket minskar vårflöden i älvar. Goda prognoser av dessa flöden är viktiga för vattenkraftsindustrin. För att kunna förbättra modeller, i vilka interceptions-avdunstningsprocessen ingår, krävs lämpliga mätmetoder för interceptionförrådet av snö. Syftet med detta arbete var att undersöka om impulsradarutrustning kan användas för att mäta interceptionsförrådet av snö på barrträd. Metoden bygger på att mäta hastigheten och utsläckningen hos en elektromagnetisk impulsvåg, vilken skickas från en sändarantenn genom ett avsnitt skog till en mottagarantenn. Både utsläckningen och hastigheten påverkas av snö och vatten på trädens kronor, och kan med så kallade blandningsformler relateras till mängd vatten. Blandningsformler beskriver de elektromagnetiska egenskaperna hos heterogena material. Laboratorietester visade att interception av flytande vatten på små trädkronor gav upphov till förändringar av impulsvågens hastighet och utsläckning mätbara med radarutrustningen. Uppskattningar av mängden intercepterat vatten från radarmätningarna gav en överskattning jämfört med oberoende referensmätningar, däremot stämde relativa variationer väl överens mellan mätningarna. Tydliga samband mellan impulsvågens utsläckning och mängden intercepterat vatten kunde inte bestämmas från experimenten. Utsläckningsresultaten var svårtolkade och lämpliga blandningsformler hittades inte i litteraturen. Metoden testades även en vecka i fält i norra Sverige. Trots att installationen inte var den bästa visade resultaten ändå god överensstämmelse mellan uppskattade förändringar av interceptionsförrådet från radarmätningarna, och observerade väderförändringar samt oberoende referensmätningar med en trädvågsanordning. Resultaten tyder på att metoden kan ge goda uppskattningar av interceptionsförrådet, då en väl fungerande installation av utrustningen används och efter att vidare kalibreringsförsök genomförts. / Interception of rain or snow in forest canopies is an important component of the hydrological cycle. Up to one third of the total winter precipitation never reaches the ground in forest areas due to evaporation losses of intercepted snow, which reduces spring-time water flow in rivers. Accurate spring flow predictions are important for the hydro-power industry. Appropriate measurement methods of intercepted snow are needed in order to improve models involving the interception evaporation process. The aim of this study was to explore the possibilities of an impulse radar system to measure the snow interception storage on coniferous trees. The method is based on measurements of the velocity and attenuation of an electromagnetic impulse wave, generated in a transmitting antenna and sent through a forest section and detected by a receiving antenna. The attenuation and velocity is affected by ice and water in the canopy air space, and can be related to amounts of water using so-called mixing formulas that describe the average electromagnetic properties of heterogeneous materials. Controlled laboratory measurements on small canopies showed that interception of liquid water was well above the detectable limits of the radar system, with respect to both attenuation and velocity changes. Estimations of the mass of intercepted water based on velocity changes overestimated the reference measurements, but relative variations were well captured. No clear relation could be found between amount of water on canopies and impulse wave attenuation from the experiments. The attenuation results were difficult to interpret, and appropriate mixing formulas were not found in the literature. The method was further tested for one week under field conditions in northern Sweden. In spite of a non-optimal equipment installation results of estimated changes of the interception storage showed a good agreement with observed weather variations and reference measurements using a tree weighing device. The method can have good conditions to give correct estimations of the snow interception storage, using appropriate installation and further calibration measurements.