The accurate prediction of water quality is essential for management of reservoirs used for drinking water supply. Since algae are a major source of taste and odor problems in drinking water, understanding and controlling algal growth and production is an important task. Deer Creek Reservoir supplies drinking water for over one million people in northern Utah and has been highly eutrophic in the past. Despite major reductions in external nutrient loading, including phosphorus, seasonal algal blooms in Deer Creek have not decreased to desired levels. Resuspension of sediment has been suggested as a potential source of internal nutrient loading for water bodies (including reservoirs in the Utah/Wyoming area) and may be responsible for delays in water quality improvement. I investigated sediment deposition and resuspension rates at the upper end of the reservoir and evaluated these sediments as a possible internal source of phosphorus. Sonar and GPS systems were used to make measurements of recently deposited sediment in the submerged Provo River delta of Deer Creek Reservoir during the period of May, June, July, and August 2011. ArcGIS 10 was used to interpolate survey points and calculate sediment volume changes, including areas of deposition and erosion. These data were used to develop approximate sedimentation rates for the soft sediment – which is most susceptible to resuspension during reservoir drawdown. I used previously measured field phosphorous concentrations in the sediment to estimate if these processes could affect reservoir phosphorous concentrations. The study used two survey areas, a small area near the Provo River inlet early in the year, and an extended larger area starting on June 23rd. I found that sediment volume in the smaller study area was increasing at a rate of 27-109 m3/day during the spring season. Data show that rates are slightly correlated with flow and reservoir elevation. Typically by August, Deer Creek reservoir would have been drawn down 2 to 4 m. However, due to a heavy snow pack in 2011, Deer Creek reservoir was not drawn down. When the reservoir is drawn down, the sediments in the upper region of the delta, where the survey was conducted, will be resuspended and deposited lower in the reservoir. These processes will likely result in releasing the phosphates currently bound to the sediment into the water column. Based on previous measurements of readily soluble phosphates bound to the sediment, this resuspension could release between 80 and 230 kg of phosphorus from the study area into the water column during critical times during the warm months–conditions well suited for algal growth. This amount of phosphorus, while an upper bound of what could be expected under actual field conditions, could raise phosphorus concentrations in the survey area by as much as 0.38 mg/L. The potential P (80-230 kg) release could account for 14%-42% of the TMDL. This is a potentially significant amount, especially if released during the critical late-summer period, and warrants more detailed study.

While side-scan sonar has become a valuable geophysical tool for forensic water searches, controlled research is paramount to determine the best practices for searches in aquatic environments as it provides a structured environment in which to investigate variables that influence the effectiveness of the technology and provides valuable experience for sonar operators. The purpose of this research is to conduct controlled research in order to evaluate the applicability of side-scan sonar to searches involving submerged firearms and proxy cadavers. In addition, the best practices for employing this technology in forensic searches in freshwater ponds and lakes in a humid, subtropical environment in Central Florida would be developed. Five street-level firearms were submerged in a pond, and two sets of three pig carcasses (Sus scrofa), utilized as proxies for human bodies, were staked to the bottom of a pond for this research. Transects were conducted over the firearms and the pig carcasses utilizing side-scan sonar. The first set of pig carcasses represented a child size (30-32 kg) and the second set a small adult size (51-54 kg). Results show that firearms were not detected due to the terrain and small size. However, this technology successfully located small to medium-sized proxy carcasses on a flat, sandy lake bottom when experienced operators were conducting the search. Conversely, vegetation obscured submerged bodies. While the smaller carcasses were difficult to detect throughout the data collection, medium-sized carcasses were easily discerned. Moreover, the medium-sized carcasses decomposed at the same rate as previous studies and were visible throughout each stage of decomposition. Finally, employing a 900 kHz frequency with a 20 m swath-width provided the best search parameters. Therefore, in the appropriate conditions, iv side-scan sonar is an effective tool for locating submerged bodies in freshwater lakes and ponds in a humid, subtropical environment.

Bathymetric mapping is an important tool for reservoir management, typically completed before reservoir construction. Historically, bathymetric maps were produced by interpolating between points measured at a relatively large spacing throughout a reservoir, typically on the order of a few, up to 10, meters or more depending on the size of the reservoir. These measurements were made using traditional survey methods before the reservoir was filled, or using sonar surveys after filling. Post-construction issues such as sedimentation and erosion can change a reservoir, but generating updated bathymetric maps is difficult as the areas of interest are typically in the sediment deltas and other difficult-to-access areas that are often above water or exposed for part of the year. We present a method to create complete reservoir bathymetric maps, including areas above the water line, using small unmanned aerial vehicle (sUAV) photogrammetry combined with multi-beam sonar data--both established methods for producing topographic models. This thesis presents methods to create accurate above-water shoreline models using images from sUAVs, processed using a commercial software package and a method to accurately knit sonar and Structure from Motion (SfM) data sets by matching slopes. The models generated by both approaches are point clouds, which consist of points representing the ground surface in three-dimensional space. Generating models from sUAV-captured images requires ground control points (GCPs), i.e., points with a known location, to anchor model creation. We explored issues with ground control spacing, masking water regions (or omitting water regions) in the images, using no GCPs, and incorrectly tagging a GCP. To quantify the effect these issues had on model accuracy, we computed the difference between generated clouds and a reference point cloud to determine the point cloud error. We found that the time required to place GCPs was significantly more than the time required to capture images, so optimizing GCP density is important. We found that we needed to mask water and areas related to distant regions and sky in images used for model creation. This is because water, objects in the far oblique distance, and sky confuse the algorithms that match points among images. Our sonar point clouds, while self-consistent, were not accurately georeferenced. We demonstrate a method using cross-sections of the transition between the above-water clouds and sonar clouds to geo-locate the sonar data and accurately knit the two data sets. Shore line topography models and integration of sonar and drone data is a niche area that leverages current advances in data collection and processing. Our work was applied at three different reservoirs to show that accurate post-construction reservoir bathometry maps can assist with reservoir management. A report is included that compares historical bathymetric maps with the current bathymetric maps at each of the three different reservoirs. A guide to perform the drone surveys is included in the report's appendix.

No description available.

<p> This thesis reports the results of a study that aims to develop and implement a simple, yet effective substrate identification and classification scheme for the Owen Sound and Colpoy' s Bay region of southern Georgian Bay using side scan sonar data. Documentation of substrate types in the study area is required to enhance fish rehabilitation programs conducted by the Ontario Ministry of Natural Resources. Over 500km of side scan sonar data and 1 OOkm of sub-bottom seismic data were collected in Owen Sound and Colpoy' s Bay during the summer of 2004. Analysis of the side scan images allowed identification of seven substrate types in the two bays including mud (Facies 1), sand (Facies 2), sand with ripples or dunes (Facies 3 and 4), sand with boulders (Facies 5), boulder rich lake floors (Facies 6) and bedrock (Facies 7). Patches of aquatic vegetation could also be identified on the images. Sub-bottom seismic data collected concurrently with the side scan data were used to validate interpretations of substrate type made from side scan images. This substrate identification system appears to serve as a rapid and cost-effective method of determining substrate characteristics based solely on the geophysical properties of acquired sonar and seismic data. </p> <p> Lake floor sediment distribution maps of Owen Sound and Colpoy' s Bay were subsequently created from the side scan data using both a computer-based and a more traditional hand-drawn technique. The hand-drawn mapping technique integrated interpretation of side scan images with sub-bottom seismic data and pre-existing knowledge of bathymetry, shoreline sediment types and environmental factors and appears to present the most realistic delineation of surface sediment distributions in Owen Sound and Colpoy's Bay. Substrate types within both bays can be subdivided into three distinct zones; Zone 1 is mud-rich and lies in water depths greater than 30m; Zone 2 includes sand dominated substrates and is found in water depths of between Om and 40m and Zone 3, found on exposed shoals and in shallow water areas consists of the coarsegrained gravel and bedrock substrates preferred as fish spawning grounds. </p> <p> This is the first side scan study to have been conducted in southern Georgian Bay and the results can be used to more effectively plan and design fish rehabilitation and restoration projects in the region. </p> / Thesis / Master of Science (MSc)

El objetivo de esta tesis consiste en diseñar un sistema de verificación para sónares utilizados en la actividad pesquera, los cuales están conformados por pequeños cristales piezoeléctricos que emiten pulsos acústicos que realizan el proceso de detección del cardumen. Este estudio comprende el diseño tanto de los circuitos como del programa necesario para determinar la frecuencia de estos elementos y mostrar los resultados en la pantalla del computador. La investigación se desarrolló en cuatro capítulos. En el primer capítulo nos centraremos básicamente en el marco problemático de nuestra investigación, los métodos actuales de verificación de sónares y sus complicaciones. En el segundo capítulo se detallará el estado del arte de esta investigación, las principales aplicaciones del sónar en la industria pesquera, los principales fabricantes de equipos marítimos y los conceptos necesarios para comprender el funcionamiento del sónar. En el tercer capítulo se detalla la metodología que se siguió en este estudio, así como también se muestra el diagrama de bloques del sistema de verificación del estado de los sónares que desarrollamos, a partir del cual se elaboró el diseño de los circuitos de las distintas etapas que comprende este sistema. También se presentan los diagramas de flujo del software que lo controla y por último se detalla la relación de componentes a utilizar. Finalmente, en el cuarto capítulo se hace la evaluación del diseño final del sistema, además se describen las condiciones en que se desarrollaron las pruebas preliminares y se muestran los resultados de las simulaciones tanto del software como del hardware y el costo de su implementación. Como conclusión se desarrollará un sistema eficiente para determinar la eficacia del funcionamiento de los sónares, brindando un servicio mucho más rápido y a menor costo, utilizando la tecnología disponible en el mercado.

Actualmente en el Perú, la investigación submarina está poco desarrollada y en consecuencia no existen medios suficientes para seguir una evolución constante de nuestra ciencia y tecnología en esa rama. Además el actual sistema de navegación submarina está basado en el buceo, y como es sabido está limitado ya que toda investigación depende de las máximas capacidades a los que pueda llegar un hombre totalmente preparado para llevar a cabo esta tarea. Es por eso que la investigación submarina en el Perú está supeditada a lo que puedan lograr buzos submarinos, con los límites naturales que pueda soportar una persona totalmente capacitada. Entonces el desarrollo de un control electrónico, para implementarlo en un submarino eléctrico experimental puede solucionar en gran medida los problemas existentes que impiden una mejora substancial en lo que navegación submarina se refiere. El presente trabajo contiene cuatro capítulos donde se muestra el desarrollo del sistema. El primer capítulo trata sobre la problemática que se aborda en este trabajo mostrando las dificultades actuales en investigación. El segundo muestra la fundamentación teórica que respalda este estudio. El tercer capítulo muestra el diseño de la solución que se obtiene en este desarrollo, finalmente en el cuarto capítulo se muestra los resultados de pruebas del sistema integrado. Finalmente se concluye que el desarrollo de este control electrónico brinda las herramientas necesarias para desarrollar una investigación submarina efectiva, siendo necesario continuar con el estudio de esta rama tecnológica dentro del Perú.

Active sensors, such as radar, lidar and sonar, emit a signal into the environment and gather information from its reflection. In contrast, passive sensors such as cameras and microphones rely on the signals emitted from the environment. In the current application of active sensors in multi-agent autonomous systems, agents only rely on their own active sensing and filter out any information available passively. However, fusing passive and active sensing information may improve the accuracy of the agents. Also, there is evidence that bats who use biosonar eavesdrop on a conspecific's echolocation sound, which shows a successful example of implementing active and passive sonar sensor fusion in nature. We studied the effect of such information fusion in the framework of two problems: the collective behavior in a multi-agent system using the Vicsek model and the canonical robotics problem of Simultaneous Localization And Mapping (SLAM). Collective behavior refers to emergence of a complex behavior in a group of individuals through local interaction. The Vicsek model is a well-established flocking model based on alignment of individuals with their neighbors in the presence of noise. We studied the aligned motion in a group in which the agents employ both active and passive sensing. Our study shows that the group behavior is less sensitive to measurement accuracy compared to modeling precision. Therefore, using measurement values of the noisier passive sonar can be beneficial. In addition, the group alignment is improved when the passive measurements are not dramatically noisier than active measurements. In the SLAM problem, a robot scans an unknown environment building a map and simultaneously localizing itself within that map. We studied a landmark-based SLAM problem in which the robot uses active and passive sensing strategies. The information provided passively can improve the accuracy of the active sensing measurements and compensate for its blind spot. We developed an estimation algorithm using Extended Kalman Filter and employed Monte Carlo simulation to find a parameter region in which fusing passive and active sonar information improves the performance of the robot. Our analysis shows this region is aligned within the common range of active sonar parameters. / Doctor of Philosophy / Group behavior is a fascinating phenomenon in animal groups such as bird flocks, fish schools, bee colonies and fireflies. For instance, many species of fireflies synchronize their flashing when they bio-luminesce. This synchronization pattern is a group behavior created as a result of local interaction formed by sensing individuals in the group. The research question for this dissertation is inspired by comes from group behavior in bats. Bats use echolocation to perceive the environment. They make a sound and listen to the echo of the sound coming back from objects and by analyzing the echo, they can get information about their surroundings. It has been observed that bats may also use the echo of other bats' sound to perceive their environment. In other words they use two different sensors, one is called active sonar since they actively make the sound and listen to its echoes, and the other one is called passive sonar since they just passively listen to the sound generated by other bats. If this information is useful, can we exploit that in design of engineered systems? We investigated these questions using numerical simulation to solve two test bed problems. The first problem is based on a mathematical flocking model in which the individuals in the group align through local interaction. We found out that eavesdropping improves the alignment of the group within a range of parameters in the model which are relevant to the sensing capabilities of the sonar sensors. The other problem is a canonical robotics problem known as the simultaneous localization and mapping (SLAM). In this problem, a robot searches an unknown environment and creates a map of the environment (mapping) and reports the path it takes within the map (localization). We found out that when the robot uses both passive and active sonar, depending on the accuracy of the two sensing approaches, it can improve the accuracy of both the generated map and the robot's path.

Seabed surface sediments vary with active geomorphodynamics and sediment remobilization processes. Understanding relations between geotechnical sediment properties and sediment mobilization processes can potentially improve predictions of coastal erosion and hazard mitigation. Portable free fall penetrometers have emerged as an economic and useful tool for rapid geotechnical site characterization and uppermost sediment layer investigation. Acoustic methods have been used to assess seabed layering, scour evolution, and seabed morphology. However, there still exist major limitations in using these methods for classification and characterization of seabed sediment surface layers in the context of local sediment dynamics. Therefore, the goal of this research is to advance field data collection methods and field data availability towards advancing the current understanding and prediction of nearshore sediment dynamics. Geotechnical and geophysical measurements were conducted at different sites: Delaware Bay, Delaware; Pea Island, North Carolina; York River, Virginia; Potomac River, Maryland; Guadalupe River, Brazos River, Colorado River, Texas with different soil types and properties, hydrodynamic conditions, and morphological settings. The data collected was utilized to address the research goals through: (1) combining geotechnical and acoustic measurements to get better insight on sediment dynamics and erodibility, (2) proposing a framework that utilizes PFFP data to classify soil and estimate certain sediment properties (relative density and friction angle for sand and undrained shear strength for clays), relevant for local sediment dynamics, and (3) investigating how relevant geotechnical properties are reflected in acoustic, and specifically chirp sonar measurements. The findings of this research support the capability of portable free fall penetrometer to estimate sediment properties in topmost layers for different soil types such as friction angles, with an accuracy of ± 1° and undrained shear strength values, with <10% mismatches. Geoacoustic parameters such as acoustic impedance can also be calculated from acoustic measurements and correlated to certain sediment properties such as porosity and bulk density. Combining both measurements can yield better site characterization and accurate estimation of sediment properties for a better prediction of sediment dynamics. / Doctor of Philosophy / As the impacts of climate change seem to worsen, the likelihood of extreme events increases. This includes more frequent and severe events such as erosion, storm surges, melting glaciers, and sea level rise that impacts coastlines and coastal infrastructure. The increase in water levels increases the frequency of coastal hazards and flooding. These events result in devastating consequences, economically and environmentally, and disrupt people's lives all over the world. To adapt and reduce the severity of these consequences, there is a need to capture the changes in seabed, and a better understanding of seabed properties and their erodibility. This requires a reliable site characterization and an accurate estimate of seabed properties, which remain a challenge for different marine environments. There exist different site investigation methods to estimate seabed sediment properties that fall under geotechnical or geophysical types. One of the common geotechnical methods is a Portable free fall penetrometer (PFFPs), that presents a robust and economical tool for a rapid site assessment of topmost seabed layers. Geophysical tools, and mainly acoustic methods, are also often used to complement geotechnical methods due to their ability to cover vast areas in efficient time. However, both methods still face limitations in assessing seabed layers and properties. Therefore, the objective of this research is to develop a framework that paves the way for a reliable assessment of seabed properties using geotechnical and geophysical methods. Both methods were utilized for data collection in different locations across the US: Delaware Bay, Delaware; Pea Island, North Carolina; York River, Virginia; Potomac River, Maryland. Three additional sites Guadalupe, Brazos River, and Colorado Rivers, Texas were surveyed post hurricane Harvey that resulted in extreme flooding events. The measurements are collected from different coastal environments. This better account for the diversity in seabed to achieve a more generalized and well-integrated methodology to assess seabed layers under different conditions.

In this dissertation, we seek to improve collision avoidance for autonomous underwater vehicles (AUVs). More specifically, we consider the case of a small AUV using a forward-looking sonar system with a limited number of beams. We describe a high-fidelity sonar model and simulation environment that was developed to aid in the design of the sonar system. The simulator achieves real-time visualization through ray tracing and approximation, and can be used to assess sonar design choices, such as beam pattern and beam location, and to evaluate obstacle detection algorithms. We analyze the benefit of using a few beams instead of a single beam for a low-cost obstacle avoidance sonar for small AUVs. Single-beam systems are small and low-cost, while multi-beam sonar systems are more expensive and complex, often incorporating hundreds of beams. We want to quantify the improvement in obstacle avoidance performance of adding a few beams to a single-beam system. Furthermore, we developed a collision avoidance strategy specifically designed for the novel sonar system. The collision avoidance strategy is based on posterior expected loss, and explicitly couples obstacle detection, collision avoidance, and planning. We demonstrate the strategy with field trials using the 690 AUV, built by the Center for Marine Autonomy and Robotics at Virginia Tech, with a prototype forward-looking sonar comprising of nine beams. / Doctor of Philosophy / This dissertation focuses on improving collision avoidance capabilities for small autonomous underwater vehicles (AUVs). Specifically, we are looking at the scenario of an AUV equipped with a forward-looking sonar system using only a few beams to detect obstacles in our environment. We develop a sophisticated sonar model and simulation environment to facilitate the design of the sonar system. Our simulator enables real-time visualization, offering insights into sonar design aspects. It also serves as a tool for evaluating obstacle detection algorithms. The research investigates the advantages of utilizing multiple beams compared to a single-beam system for a cost-effective obstacle avoidance solution for small AUVs. Single-beam sonar systems are small and affordable, while multi-beam sonar systems are more complex and expensive. The aim is to quantify the improvement in obstacle avoidance performance when adding additional sonar beams. Additionally, a collision avoidance strategy tailored to the novel sonar system is developed. This strategy, developed using a statistical model, integrates obstacle detection, collision avoidance, and planning. The effectiveness of the strategy is demonstrated through field trials using the 690 AUV, constructed by the Center for Marine Autonomy and Robotics at Virginia Tech, equipped with a prototype forward-looking sonar using nine beams.