Underwater static targets are objects under the water that can¡¦t move autonomously. Apparatus feasible for detecting underwater static targets includes: optics, acoustics and geophysical instruments. The purpose of this research is discussing the efficiency of applying side-scan sonar, magnetometer, sub-bottom profiler and echo sounder simultaneously to search, detect, identify and locate underwater static targets. Procedures of this research include: 1. Discussing the capabilities of instruments and identification principles on target. 2. Using a real case to groundtruth target identification principles. 3. Assessing the superiority of the methodology. According to the characteristics of these apparatus, the water depth, collected by echo sounder, is capable of expressing the relief of the seabed. Seabed sonographs, recorded by side-scan sonar, show that it is feasible to detect, identify and locate targets on the seabed. Sub-bottom profiler provides the sub-surface sedimentary information which can be used to detect buried targets. Magnetometer can detect environmental magnetic intensities, which can locate and determine the size of ferrous targets. Analysis of the data collected at Hai-Köu Wan, Ping-Dong County yields following conclusions: 1. The water depth data, recorded per 15 meters by the echo sounder, is capable of detecting large targets and concentrated artificial reefs only. 2. Sonographs obtained by side-scan sonar show target¡¦s characteristics and location on seabed. It can be utilized to identifying targets and mapping targets distributions. 3. Sub-bottom profile graphs show the composition and thickness of sub-surface sediments. 4. Magnetic anomalies show that there are evident variations around the battle-ship reef or concentrated electric-pole reefs on the research area. It represents that the magnetometer is capable in detecting underwater ferrous targets. 5. Targets detecting rate and identifying accuracy can be increased by the mutual comparison of various information. By applying the technique established in this research and the survey results at Hai-Köu Wan, targets at the survey site can be identified and located precisely. There are about 1100 units of 2-m concrete reefs, 670 units of electric-pole reefs and a battle-ship reef at Hai-Köu Wan. It can be concluded that, applying echo-sounder, side-scan sonar system, sub-bottom profiler and magnetometer simultaneously can search, detect, identify and locate underwater static targets more effective than applying a single instrument such as side-scan sonar system.

Multi-beamecho sounder systemhas been around nowfor some 40 years and their use in shallow waters for the last 14 years. With modern shallow water systems running at up to 9,600 soundings/second, data collection at the rate of approximately 250 million soundings/day system is possible. Processing of Multibeam Echo sounder (MBES) data is a challenging task from both hydrographic and technological perspectives. We recognize that a completely automatic system is improbable, but propose that significant benefits can still be had if we can automatically process good quality data, and highlight areas that probably need further attention. We propose an algorithm that takes uncleaned MBES data and attempts to pick out outliers as possible as we can. The traditionalmethod that is still in use today by numerous software applications is based on a line-by-line processing approach. Automatically filtering for a depth window, by beam number, slope between points, quality flags and recently by whether the beam¡¦s error is outside the IHO order for the survey are a number of ways in which the line-by-line approach has been speeded up. The fundamental differences between our method and the previous methods are that our algorithm does not actually delete any soundings at all and transform original one dimension information into two dimensions. Finally, we use Hierarchical Clustering to classifyMBES data into outliers and normal. We develop the user interface formulti-beamecho sounder quality control. It provides almost the necessary tools and modules to perform a survey. Standard modules are Survey planning (track guidance lines, waypoints), channel design and 3D modeling, data acquisition, data QC and data processing/flagged. However, it will visualize the soundings to aid the decisionmaking process.

Hydroakustiska mätningar har gjorts i nästan två hundra år. Det kan liknas med topografiska mätningar på land och visar hur sjö- eller havsbottnar ser ut. Idag används ekolod vilket är en teknik som skickar ut ljudvågor i vattnet för att mäta hur lång tid det tar för ljudet att studsa på bottnen och sedan komma upp till instrumentet igen. Därefter går det att räkna ut djupet med hjälp av ljudhastighetsberäkningar. Vid inmätning av enkelstråligt ekolod rekommenderas användande av tvärsektioner som kontroll av data. Flerstråligt ekolod behöver däremot inte tvärsektioner då övertäckning mellan stråken används som kontroll. I denna studie undersöks hur antalet tvärsektioner påverkar djupkartor skapade av Seafloor HydroLite TM enkelstråligt ekolod. Detta är även en undersökning av hur djupkartor producerade av SeaFloor HydroLite TM enkelstråligt ekolod skiljer sig mot djupkartor producerade av Kongsberg EM 2040 MK11 flerstråligt ekolod. Studieområdet är 1820 m2 och är beläget vid Forsbackas hamn i Storsjön, Gävle kommun. Vid inmätning av flerstråligt ekolod användes en övertäckning av lägst 50 %. Fem huvudstråk och sju tvärsektioner mättes med enkelstråligt ekolod för området. Djupkartor med olika antal tvärsektioner gjordes i Surfer 10 från enkelstråligt ekolod. Därefter jämfördes djupkartor av enkelstråligt ekolod mot kartor gjorda av data från flerstråligt ekolod för att se hur djupkartorna skiljer sig och för att se hur djupkartorna av enkelstråligt ekolod påverkas av olika antal tvärsektioner. Med användande av flerstråligt ekolod som referens mot djupkartor gjorda av enkelstråligt ekolod blev resultaten att RMS och standardosäkerhet minskar med 1 cm i RMS-värde och med 2 cm i standardosäkerhet. Jämförelse mellan ekolods systemen visar att skillnaden av djupvärderna är runt 10 cm. Slutsatserna från denna studie är att tvärsektioner endast förbättrar kvalitén på djupkartor marginellt vid jämn och enhetlig bottentopografi, men fyller en viktig funktion genom att kontrollera kvalitén av inmätningsdatat. Samt att SeaFloor HydroLite TM klarar av order 1b vid ett djup omkring en till fyra meter om ej kravet på full bottentäckning beaktas. Seafloor HydroLite TM skapar en översiktlig djupkarta medan djupmodellerna från Kongsberg EM 2040 MKII ser mera detaljer. / Hydroacoustic measurements have been conducted for almost two hundred years. It can be compared to topographic measurements on land and shows the appearance of lake or ocean floors. Today, echosounders are used, which is a technique that sends out sound waves into the water to measure the time it takes for the sound to bounce off the bottom and return to the instrument. Sound velocity calculations can then be used to calculate the depth. The use of cross-sections is recommended as a data control of single beam echosounder. However, multi beam echosounders only use overlap as control. This study examines how the number of cross-sections affects depth maps created by Seafloor HydroLite TM single beam echosounder. It also investigates the differences between depth maps produced by the SeaFloor HydroLite TM single beam echosounder and the Kongsberg EM 2040 MK11 multi beam echosounder. The study area covers 1820 m2 and is located at Forsbackas Harbor in Storsjön, Gävle municipality. A minimum overlap of 50% was used for the surveying with the multi beam echosounder. Five main lines and seven cross-sections were measured using the single beam echosounder. Depth maps with different numbers of cross-sections were created using data from the single beam echosounder. The maps from the single beam echosounder were compared to maps created from the data obtained by the multi beam echosounder to assess the differences and the impact of varying numbers of cross-sections on the depth maps from the single beam echosounder. By using the multi beam echosounder as a reference for the depth maps created by the single beam echosounder, the results showed a decrease of 1 cm in RMS value and 2 cm in standard deviation. The comparison between the echosounder systems revealed a difference of around 10 cm in depth values. The conclusions from this study are that cross-sections only marginally improve the quality of depth maps in cases of even and uniform bottom topography but serve an important function in validating the quality of the survey data. Additionally, the SeaFloor HydroLite TM is capable of meeting Order 1b at depths ranging from one to four meters if the requirement for full bottom coverage is not considered. The Seafloor HydroLite TM creates a general overview of the depth map, while the depth models from the Kongsberg EM 2040 MKII provide more detailed information.

This research experimentally shows the effect of sediment roughness characteristics on the acoustic reflection coefficient. This information is useful when trying to classify various types of sediment over an area. This research was conducted in an indoor laboratory tank at Applied Research Laboratories (ARL) at the University of Texas at Austin. A single beam echo-sounder (SBES) system was developed to project and receive a wideband (3 kHz to 30 kHz) acoustic pulse. A method was developed using the system transfer function to create a custom pulse that would minimize the dynamic range over the wide frequency band. A matched filtering and data processing algorithm was developed to analyze data over the full frequency bandwidth and over smaller frequency bands. Analysis over the smaller frequency bands showed the effect of the roughness on the reflection coefficient with respect to frequency. It was found that the reflection coefficient is significantly lower at the higher frequencies (above 20 kHz) than at the lower frequenices [sic] due to off specular scattering. It was also found that the variability of the reflection coefficient was significantly higher for the rough sediment than for the smooth sediment. / text

Single-beam echosounders are an inexpensive, practical and non-invasive means of remote sensing the seabed. Ideally, the common single-beam echosounder should be able to tell fishers, navigators, engineers and scientists what the seabed consists of in addition to water depth. Low-frequency underwater acoustic systems (<10 kHz) can do this in some circumstances, but are expensive, offer limited resolution and potentially hazardous to marine mammals. High-frequency systems, such as single and multibeam echosounders, are very effective at mapping bathymetry, but do not characterize the seabed directly. Instead, these systems divide the seabed into self-similar segments or classes, and then rely on ground-truth data (usually sediment grab samples) to assign seabed-type labels such as sand, etc., to the classes. However, inadequate and inaccurate ground-truth is a major problem. Single-beam seabed classification methods also suffer from a lack of discriminatory power and from artefacts such as water depth and seabed slope. The cause of these problems is that the methods lack a basis in physics and are mainly statistical. Then, the central objective in this dissertation is to develop physics-based methods to improve classification and to address the problem of ground-truth by inferring seabed characteristics directly from the acoustics. An overview of current methods is presented along with case studies of single-beam surveys to introduce the current seabed classification method called QTC VIEW™ and to identify specific problems. A physical basis is established in scattering and geometrical theories and observations of field and model data. This leads to new classification and characterization methods that overcome the shortcomings of current seabed classification methods. Advancements also include new physical models of echosounding. The new methods are presented, implemented and evaluated. Highlights of experimental results include a new testbed located in Patricia Bay, British Columbia. The testbed consists of exhaustive ground-truth, surveys and novel controlled experiments with various single-beam echosounders, ranging in frequency from 12 to 200 kHz. Simulated echo time series data from the numerical BORIS model and a new analytic model are used to augment the testbed. Evaluation of experimental results shows the new physics-based methodology improves seabed classification significantly and enables seabed characterization by an uncalibrated single-beam echosounder. / Graduate

Traditionellt har större fartyg bestyckade med ekolod använts för att utföra batymetriska mätningar av sjö- och havsbottnar. Att utföra mätningar i grunda vatten har varit problematiskt eftersom större fartyg inte kan nå dessa grunda vatten. För att tackla det problemet har mindre obemannade ytfarkoster (USV) utvecklats för att mäta grunda vatten. Dessa USVs hjälper även till vid områden nära stenar som inte har fått uppdaterade djupvärden. Den här undersökningens syfte är att utvärdera hur en Seafloor HydroLite TM enkelstrålsekolod monterad på en USV skiljer sig från insamlingsmetoderna GNSS och med måttband. Den syftar även till att utvärdera vilken interpolationsteknik som är mest lämpad för skapande av djupmodeller med enkelstrålsekolodsdata. Det kommer också studeras hur tvärsektioner påverkar djupmodellerna skapade med enkelstrålsekolod. De experimentella mätningarna med GNSS, måttband och enkelstrålsekolod utfördes i sjön Öjaren som ligger utanför Sandviken. I undersökningen inmättes totalt 91 punkter med GNSS och måttband samt 8 mätstråk och 9 tvärsektioner med enkelstrålsekolod monterad på en USV. Djupmodellerna skapades i Surfer 10 med interpolationsteknikerna kriging, natural neighbor och triangulation with linear interpolation. Alla beräkningar genomfördes i Microsoft Excel och data insamlat med måttband ansågs vara det sanna värdet vid jämförelsen mellan insamlingsmetoderna. Resultaten visade att djupmodellerna skapade med GNSS-data är snarlika till djupmodellerna skapade med måttbandsdata samt att djupmodellerna med GNSS-data visar på den minsta skillnaden mot djupmodellerna skapade med enkelstrålsekolodsdata. Resultatet från jämförelsen mellan interpolationsteknikerna visar på att användandet av de olika interpolationsteknikerna inte har en signifikant påverkan på djupmodellen. Våra slutsatser av undersökningen blev att användande av ett enkelstrålsekolod kan bidra till att skapa en mer detaljerad djupmodell än om enbart GNSS eller måttbandsdata används. Det är också en mer kostnadseffektiv metod eftersom mer data kan samlas in på kortare tid. Det kan dock uppstå felmätningar vid insamlade av data med enkelstrålsekolod som kan vara svåra att upptäcka. Tilläggande av tvärsektioner kan bidra till att skapa en ännu mer detaljerad djupmodell och kan användas som kontrollpunkter vid kontroll av enkelstrålsekolodsdata. / Traditionally, large vessels armed with echo sounders have been used to conduct bathymetric surveys of the seas and oceans. Conducting surveys of shallow water have been troublesome since larger vessels cannot reach and survey shallow waters. To tackle that problem smaller unmanned surface vessels (USV) have been developed to survey shallow waters. It also helps in the areas closest to rocks that do not have updated depth measurements. This study aims to assess how a Seafloor HydroLite TM single-beam echo sounder mounted on a USV differs from other surveying methods. It also aims to evaluate which interpolation methods is most suitable for creating depth models by utilizing single-beam echo sounder data. It will also be studied how cross section lines affect the created depth using the USV. The experimental surveys with GNSS, measuring tape and single-beam echo sounder were used in the lake Öjaren that is located outside of Sandviken. In this study a total of 91 points were collected with GNSS and measuring tape and 8 sounding lines and 9 cross sections lines were collected using echo sounder mounted on the USV. The depth models were created in Surfer 10 using different interpolation methods i.e. kriging, natural neighbor and triangulation with linear interpolation. All calculation were performed in Microsoft Excel and the measurements collected with measuring tape were assumed as a “true” value to evaluate the different surveying techniques. The results showed that the depth model obtained using GNSS data is close to the depth model created using measuring tape data and shows lowest difference in comparison to the USV technique. The results from the comparison between interpolation methods showed that the use of different interpolation methods not have a significant impact on the depth model. The study concludes that the use of a single-beam echo sounder can help to create a more detailed depth model than using GNSS or measuring tape. It is also a cost effective method that helps collect more data in a short time. Though, some errors can appear in the data collected using the single-beam echo sounder that can be hard to detect. The cross section lines can contribute to a more detailed depth model and can be used as control points.

Made available in DSpace on 2015-03-26T13:28:36Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1715165 bytes, checksum: ba96ef5c3249cefde8551b95cd57d667 (MD5) Previous issue date: 2014-11-25 / With developments in recent years, methods for bathymetric surveys using acoustic sensors (echo sounders) and signals transmitted by satellite navigation receivers, it becomes possible to describe the submerged same level of detail which is embossed with the surface relief describes terrestrial. A graphical representation of the underwater relief occurs from Digital Elevation Models (DEMs) generated by interpolating seeking, from measurements, predict the depth at unsampled locations. The geometrical information taken from bathymetric surveys, the volume of liquid water or mud present, for example in a reservoir, is the most relevant. This study sought to determine the products generated by single beam bathymetric survey, as well as the methods of kriging interpolation and Topo to Raster. The study areas were a box of decanting of the water treatment plant and a dam lake of Furnas, where surveys were conducted, with total station and bathymetric surveys, with a single beam echo sounder which operates at frequencies 33 kHz and 210 kHz . In the settling box, first bathymetric survey was conducted (Lbat 1). Then be emptied and cleaned the box and before filling it again, surveying, (Ltop) was performed with total station. Immediately after filling, without water and mud decanted, another bathymetric survey (Lbat 2) was performed. To survey the dam lake of Furnas, held automated bathymetric survey, ie, using the GNSS technology for positioning. First, the data from the survey, we evaluated the methods of kriging interpolation and Topo to Raster in the DEM generation of the settling box. The conclusion was that the interpolator Top to Raster conditioning showed remarkable deformations at the edges and in the center of the study area and should be discarded. The next stage of this work was to evaluate the accuracy of DEMs generated by applying kriging on data from single beam bathymetric survey, Lbat 2, using the frequencies of 33 kHz and 210 kHz. Possession of DEMs were calculated discrepancies between information from them and points of surveying. The results showed an accuracy of about 5 cm in mean depths of 3.21 m, and that as the surveys were conducted after cleaning the box, with clean water, there was no significant difference in the accuracy of DEMs generated with depths raised to the frequencies 33 kHz and 210 kHz. Then the DEMs were generated by kriging for the first bathymetric survey, Lbat 1, when solid waste resulting from the settling process still existed. Volumes were calculated and compared to evaluate the frequency of 33 kHz echo sounder to determine the volume of mud in the box. After analyzing the results, it was found that using only the first bathymetric survey, with the frequencies 33 kHz and 210 kHz, there was detected 186 m3 of sludge, in a total volume of 799 m3 of water and mud which, with the clean water the volume is determined by accurate bathymetry, showing discrepancy of 0.63% for the frequency of 210 kHz and 0.12% for the frequency of 33 kHz. To survey the lake of Furnas DEMs were generated by kriging interpolation method and the Top to Raster, varying the spacing between the regular survey lines using horizontal scan lines to the regular survey lines. Through statistical analysis of the discrepancies between estimated by interpolating depths and depths observed in the scan lines of the bathymetric survey, the kriging showed better results for spacings of 40 and 80 meters. Considering the isobatimétricas between different DEMs created, it is observed that for larger spacings the interpolator to Top Raster presented smoother features when compared to the DEMs generated by kriging. / Com a evolução, nos últimos anos, dos métodos de levantamentos batimétricos utilizando sensores acústicos (ecobatímetros) e receptores de sinais transmitidos por satélites de navegação, torna-se possível descrever o relevo submerso com mesmo nível de detalhe com que se descreve o relevo da superfície terrestre. A representação gráfica do relevo submerso se dá a partir de Modelos Digitais de Elevação (MDEs) gerados por interpoladores que buscam, a partir das medidas realizadas, predizer a profundidade em locais não amostrados. Das informações geométricas extraídas de levantamentos batimétricos, o volume de água ou lama líquida presente, por exemplo em um reservatório, é a mais relevante. Este trabalho busca avaliar produtos gerados pelo levantamento batimétrico monofeixe, assim como os métodos de interpolação krigagem e Topo to Raster. As áreas de estudo foram uma caixa de decantação de estação de tratamento de água e um lago da represa de furnas, onde foram realizados levantamentos topográficos, com estação total e levantamentos batimétricos, com ecobatímetro monofeixe que opera nas frequências 33 kHz e 210 kHz. Na caixa de decantação, primeiramente foi realizado levantamento batimétrico (Lbat 1). Em seguida, esvaziou-se e limpou-se a caixa e, antes de enchê-la novamente, foi realizado um levantamento topográfico, (Ltop), com estação total. Logo após o enchimento, com água e sem lama decantada, foi realizado outro levantamento batimétrico (Lbat 2). Para o levantamento no lago da represa de furnas, realizou-se levantamento batimétrico automatizado, ou seja, empregando a tecnologia GNSS para o posicionamento. Primeiramente, com os dados do levantamento topográfico, se avaliou os métodos de interpolação krigagem e Topo to Raster na geração do MDE da caixa de decantação. A conclusão foi que o interpolador Topo to Raster condicionado apresentou notáveis deformações nas bordas e no centro da área de estudo, devendo ser descartado. A próxima etapa do trabalho foi avaliar a acurácia dos MDEs gerados aplicando krigagem nos dados do levantamento batimétrico monofeixe, Lbat 2, utilizando as frequências de 33 kHz e 210 kHz. De posse dos MDEs foram calculadas as discrepâncias entre informações extraídas deles e os pontos do levantamento topográfico. Os resultados apresentaram uma acurácia em torno de 5 cm, em profundidades médias de 3,21 m, e que, como os levantamentos foram realizados após a limpeza da caixa, com água limpa, não se verificou diferença significativa na acurácia dos MDEs gerados com as profundidades levantadas com as frequências 33 kHz e 210 kHz. Em seguida foram gerados os MDEs pela krigagem para o primeiro levantamento batimétrico, Lbat 1, quando ainda existiam resíduos sólidos resultantes do processo de decantação. Os volumes foram calculados e comparados a fim de avaliar a frequência de 33 kHz do ecobatímetro para determinar o volume de lama na caixa. Após analisar os resultados verificou-se que usando somente o primeiro levantamento batimétrico, com as frequências 33 kHz e 210 kHz, não se detectou 186 m3 de lama, num volume total de 799 m3 de água e lama, e que, com a água limpa, o volume determinado pela batimetria é acurado, apresentando discrepância de 0,63% para a frequência de 210 khz e 0,12% para a frequência de 33 khz. Para o levantamento do lago de furnas foram gerados MDEs pelo método de krigagem e pelo Topo to Raster, variando o espaçamento entre as linhas regulares de sondagem, utilizando linhas de verificação transversais às linhas regulares de sondagem. Através da análise estatística das discrepâncias entre as profundidades estimadas pelos interpoladores e as profundidades observadas nas linhas de verificação do levantamento batimétrico, a krigagem apresentou melhores resultados para espaçamentos de 20 a 80 metros. A diferença entre os volumes determinados para os espaçamentos de 20 a 40 metros foi menor que 2%,. Considerando as isobatimétricas entre os diversos MDEs criados, observa-se que para espaçamentos maiores o interpolador Topo to Raster apresentou feições mais suavizadas quando comparado com os MDEs gerados pela krigagem.

Orientador: Nilton Nobuhiro Imai / Banca: Maria de Lourdes Bueno Trindade Galo / Banca: Júlia Celia Mercedes Strauch / Resumo: Este trabalho relata um estudo de caso, no qual se procedeu a um levantamento ecobatimétrico para se obter dados de profundidade do corpo de água e da altura da vegetação aquática submersa, realizado num trecho do Rio Uberaba, que faz parte do Reservatório de Porto Colômbia, abrangendo uma área de aproximadamente 360 mil m². Os dados foram processados e avaliados com o objetivo principal de desenvolver uma abordagem de inferência espacial no mapeamento de macrófitas submersas presentes na região pesquisada. Para isso, verificou-se a viabilidade do uso de interpoladores convencionais para mapear as variáveis coletadas pelo ecobatímetro, avaliou-se o potencial de imagem multiespectral de alta resolução espacial (QuickBird) na detecção da vegetação estudada, realizou-se uma análise espacial para avaliar tendência para esse tipo de ocorrência e, finalmente, estudou-se a possibilidade de se utilizar técnica de geoestatística na inferência da altura de macrófitas submersas da área de estudo. As interpolações convencionais não se mostraram satisfatoriamente adequadas para mapear a variável altura da vegetação submersa, porém, a utilização da interpolação linear por triangulação foi suficiente para representar adequadamente o relevo submerso. A imagem multiespectral se mostrou capaz de detectar aproximadamente 21% de macrófitas submersas. Com relação à análise espacial, os resultados indicaram que a dependência espacial é uma tendência que deve ser levada em consideração, daí ter sido utilizada a geoestatística na abordagem de inferência espacial da vegetação. A análise dos semivariogramas forneceu conhecimento relacionado aos métodos de levantamentos ecobatimétricos. A inferência espacial por krigagem apresentou resultado satisfatório, comparado às interpolações convencionais mencionadas anteriormente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In this work was accomplished a case study in which an echo sounder survey was conducted to obtain data of water body depth and submerged aquatic vegetation height. The study was realized specifically on a region of Uberaba River with approximately 360.000 m². This river is part of the Porto Colombia reservoir. The data was processed and evaluated with main objective to develop an approach of spatial inference for map submersed macrophyte in the region studied. For this, it was verified the availability of using conventional interpolation to map the variables collected by the echo sounder, it was evaluated the potential of multispectral image with high spatial resolution (QuickBird) to detect the vegetation, it was done a spatial analysis and finally it was verified the possibility of using geostatistic technique to infer the submerged macrophytes height in the study area. The use of linear interpolation by triangulation was enough to represent rightly the underwater topography; however, the conventional interpolations were not satisfactorily to map the submerged vegetation height. The multispectral image was able to detect approximately 21% of submerged macrophytes. About spatial analysis, the results indicated that the spatial dependence must be considered, therefore, it was used the geostatistic in the spatial inference of submerged vegetation. Semivariograms analysis provided important knowledge about methods of echo sounder survey. The spatial inference by kriging showed satisfactory results if compared with conventional interpolations mentioned above. Finally, the approach used to mapping submerged macrophytes height can be applied in other regions and this can help the reservoirs management, allowing improve the knowledge about the local ecosystem and therewith developing an action strategy to contain the spread of submerged aquatic vegetation / Mestre

Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2001-02-25Bitstream added on 2014-06-13T20:48:52Z : No. of bitstreams: 1 rotta_lhs_me_prud.pdf: 9845813 bytes, checksum: 8afe01cd2ab27aa9636ee65187b34e5d (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho relata um estudo de caso, no qual se procedeu a um levantamento ecobatimétrico para se obter dados de profundidade do corpo de água e da altura da vegetação aquática submersa, realizado num trecho do Rio Uberaba, que faz parte do Reservatório de Porto Colômbia, abrangendo uma área de aproximadamente 360 mil m². Os dados foram processados e avaliados com o objetivo principal de desenvolver uma abordagem de inferência espacial no mapeamento de macrófitas submersas presentes na região pesquisada. Para isso, verificou-se a viabilidade do uso de interpoladores convencionais para mapear as variáveis coletadas pelo ecobatímetro, avaliou-se o potencial de imagem multiespectral de alta resolução espacial (QuickBird) na detecção da vegetação estudada, realizou-se uma análise espacial para avaliar tendência para esse tipo de ocorrência e, finalmente, estudou-se a possibilidade de se utilizar técnica de geoestatística na inferência da altura de macrófitas submersas da área de estudo. As interpolações convencionais não se mostraram satisfatoriamente adequadas para mapear a variável altura da vegetação submersa, porém, a utilização da interpolação linear por triangulação foi suficiente para representar adequadamente o relevo submerso. A imagem multiespectral se mostrou capaz de detectar aproximadamente 21% de macrófitas submersas. Com relação à análise espacial, os resultados indicaram que a dependência espacial é uma tendência que deve ser levada em consideração, daí ter sido utilizada a geoestatística na abordagem de inferência espacial da vegetação. A análise dos semivariogramas forneceu conhecimento relacionado aos métodos de levantamentos ecobatimétricos. A inferência espacial por krigagem apresentou resultado satisfatório, comparado às interpolações convencionais mencionadas anteriormente... / In this work was accomplished a case study in which an echo sounder survey was conducted to obtain data of water body depth and submerged aquatic vegetation height. The study was realized specifically on a region of Uberaba River with approximately 360.000 m². This river is part of the Porto Colombia reservoir. The data was processed and evaluated with main objective to develop an approach of spatial inference for map submersed macrophyte in the region studied. For this, it was verified the availability of using conventional interpolation to map the variables collected by the echo sounder, it was evaluated the potential of multispectral image with high spatial resolution (QuickBird) to detect the vegetation, it was done a spatial analysis and finally it was verified the possibility of using geostatistic technique to infer the submerged macrophytes height in the study area. The use of linear interpolation by triangulation was enough to represent rightly the underwater topography; however, the conventional interpolations were not satisfactorily to map the submerged vegetation height. The multispectral image was able to detect approximately 21% of submerged macrophytes. About spatial analysis, the results indicated that the spatial dependence must be considered, therefore, it was used the geostatistic in the spatial inference of submerged vegetation. Semivariograms analysis provided important knowledge about methods of echo sounder survey. The spatial inference by kriging showed satisfactory results if compared with conventional interpolations mentioned above. Finally, the approach used to mapping submerged macrophytes height can be applied in other regions and this can help the reservoirs management, allowing improve the knowledge about the local ecosystem and therewith developing an action strategy to contain the spread of submerged aquatic vegetation