Thesis (M.S.) in Zoology--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 97-110).

No description available.

Dissertation (Ph. D. in Physical Oceanography) Naval Postgraduate School, December 1994. / "December 1994." Dissertation supervisor(s): R.L. Haney. Includes bibliographical references (p. 75-79). Also available online.

Hydrological connectivity is crucial for understanding and managing water resources, ecological processes, and landscape dynamics. High-Resolution Digital Elevation Models (HRDEMs) derived from Light Detection and Ranging (LiDAR) data offer unprecedented detail and accuracy in representing terrain features, making them invaluable for mapping hydrological networks and analyzing landscape connectivity. However, challenges persist in accurately delineating flow networks, identifying flow barriers, and optimizing computational efficiency, particularly in large-scale applications and complex terrain conditions. This dissertation addresses these challenges through a comprehensive exploration of advanced techniques in deep learning, spatial analysis, and parallel computing. A common practice is to breach the elevation of roads near drainage crossing locations to remove flow barriers, which, however, are often unavailable or with variable quality. Thus, developing a reliable drainage crossing dataset is essential to improve the HRDEMs for hydrographic delineation. Deep learning models were developed for classifying images that contain the locations of flow barriers. Based on HRDEMs and aerial orthophotos, different Convolutional Neural Network (CNN) models were trained and compared to assess their effectiveness in image classification in four different watersheds across the U.S. Midwest. The results show that most deep learning models can consistently achieve over 90% accuracies. The CNN model with a batch size of 16, a learning rate of 0.01, an epoch of 100, and the HRDEM as the sole input feature exhibits the best performance with 93% accuracy. The addition of aerial orthophotos and their derived spectral indices is insignificant to or even worsens the model’s accuracy. Transferability assessments across geographic regions show promising potential of best-fit model for broader applications, albeit with varying accuracies influenced by hydrography complexity. Based on identified drainage crossing locations, Drainage Barrier Processing (DBP), such as HRDEM excavation, is employed to remove the flow barriers. However, there's a gap in quantitatively assessing the impact of DBP on HRDEM-derived flowlines, especially at finer scales. HRDEM-derived flowlines generated with different flow direction algorithms were evaluated by developing a framework to measure the effects of flow barrier removal. The results show that the primary factor influencing flowline quality is the presence of flow accumulation artifacts. Quality issues also stem from differences between natural and artificial flow paths, unrealistic flowlines in flat areas, complex canal networks, and ephemeral drainageways. Notably, the improvement achieved by DBP is demonstrated to be more than 6%, showcasing its efficacy in reducing the impact of flow barriers on hydrologic connectivity. To overcome the computational intensity and speed up data processing, the efficiency of parallel computing techniques for GeoAI and hydrological modeling was evaluated. The performance of CPU parallel processing on High-Performance Computing (HPC) systems was compared with serial processing on desktop computers and GPU processing using Graphics Processing Units (GPUs). Results demonstrated substantial performance enhancements with GPU processing, particularly in accelerating computationally intensive tasks such as deep learning-based feature detection and hydrological modeling. However, efficiency trends exhibit nonlinear patterns influenced by factors such as communication overhead, task distribution, and resource contention. In summary, this dissertation presents a GeoAI-Hydro framework that significantly advances the quality of hydrological connectivity modeling. By integrating deep learning for accurate flow barrier identification, employing DBP to enhance flowline quality, and utilizing parallel computing to address computational demands, the framework offers a robust solution for high-quality hydrological network mapping and analysis. It paves the way for contributions to more effective water resource management, ecological conservation, and landscape planning.

This is a study of the publications and publishing practices of Alexander Dalrymple (1737-1808). Dalrymple was cumulatively a private publisher of nautical charts and plans (from 1767), the ''examiner of ships' journals'' and chart publisher for the East India Company (from 1779), and Hydrographer to the Admiralty (from 1795). The core of the study is a catalogue of the known publications of Alexander Dalrymple, defining and establishing his oeuvre. The catalogue is in two parts, Catalogue A for the letterpress publications, numbering 257, and Catalogue B for the engraved charts, plans of ports, views of land, and other Illustrations, numbering 1116. The entries in each part of the catalogue are arranged chronologically by date of publication, with full bibliographical and technical descriptions, and notes of attribution, dating and inter-relationships. The introduction gives a short account of Dalrymple's life, focussing on his publishing activity, and introducing his geographical and political pamphlet publishing. Four phases of activity in his nautical publication are identified: the decision to publish charts and memoirs from his own voyages in the Eastern Archipelago (1769-1772); the private publication of charts and plans with grants or subscriptions from the East India Company (1772-1779); the annual series of charts, plans, views and memoirs issued from 1779 onwards for the East India Company; and the organisation and output of the Admiralty Hydrographic Office which he ran in parallel with his East India Company work after 1795. This is supplemented by a discussion of the continuing use made of Dalrymple's charts after his death in 1808. An investigation of Dalrymple's engraving and publishing practices follows, with a brief survey of his technical leaflets and manuals on nautical surveying and chronometer use, and an account of Oriental Repertory, his chief non-nautical publication. The study emphasises the close personal control Dalrymple exercised over his publications, and the consequent problems in the Admiralty and East India Company in developing arrangements to continue publishing charts after his death.

One challenge for Autonomous Underwater Vehicle (AUV) multibeam surveying is the limited ability to assess internal vertical agreement rapidly and reliably. Applying an external ellipsoid reference to AUV multibeam data would allow for field comparisons. A method is established to merge ellipsoid height (EH) data collected by a surface vessel in close proximity to the AUV. The method is demonstrated over multiple collection missions in two separate areas. Virtual tide corrector values are derived using EH data collected by a boat and a measured ellipsoid to chart datum separation distance. Those values are compared to measurements by a traditional tide gauge installed nearby. Results from the method had a mean difference of 6 centimeters with respect to conventional data and had a mean total propagated uncertainty of 15 centimeters at the 95% confidence interval. Methodologies are examined to characterize their accuracies and uncertainty contribution to overall vertical correction.

Using the hydrographic data collected by the ACONA from June 1961 to May 1963, the Oregon coastal front has been examined. Representative sigma-t surfaces were chosen to delineate the front, and changes in position of these surfaces with time were used to obtain zonal flow rates for the frontal and surface layers. From May to early October upwelling resulted in offshore flow. Onshore flow was indicated from late October to January, and indeterminate zonal flow occurred during the remainder of the year. Flow within the front agreed with these surface flows in ten of the fourteen observational periods. / Graduation date: 1964

Airborne lidar bathymetry (ALB) is a method used to survey and map coastal and littoral zones. Along with extracting seafloor depth and reflectance in the surveyed area, a fundamental requirement of these surveys is to detect underwater targets, hazards, or obstructions. The ability to detect underwater targets depends on a target's dimensions and reflectance, the depth and turbidity of the water, system and survey configuration, data processing capabilities, and algorithmic sophistication. Understanding the effects of each of these factors on the performance of underwater target detection is essential in determining the target detection capabilities of a proposed ALB system. After detailing the development of a simulation environment to model received ALB system waveforms, this work explores the theoretical target detection capabilities of an ALB system.

Abstract The Penghu Channel (PHC), situated in the southeastern Taiwan Strait (TS), is the major conduit for the South China Sea water (SCSW) and Kuroshio subsurface water flowing into the TS. However, the previous studies in this area were largely focused on the aspects of physical oceanography, with scant attention to the chemical hydrography is poorly studied, and therefore little understood. In order to better understand the seasonal variations of chemical hydrography in the southern PHC, we conducted a systematic survey of chemical hydrography aboard R/V Ocean Research III during cruises in January, March, July and October 2001 as well as March 2002. The water above 200m in the southern PHC is characteristic of salinity and temperature between those of SCSW and Kuroshio water (KW), suggesting it is mixing between these two waters. Nonetheless, the salinity and temperature below 200m are dominated by the SCSW. The relative amount of SCSW and KW flowing into the PHC has varied seasonally and annually. During the transition period of monsoon, KW was more than SCSW, but SCSW had a larger quantity during the northeast and southwest monsoon. The slope of the regression line between the d13CDIC and PO4-3 (0-100m, -0.55; below 100m, -0.30) indicates that the distributions of d13CDIC and PO4-3 in the study area may be controlled by the effect of air-sea exchange or the mixing of different water masses or both. In addition, to evaluate the overall error in d13CDIC analysis, we have checked carefully whether the different storage bottles, the various duration of storage, and different amount of saturated HgCl2 solution added in the water samples would produce uncertainty on the d13CDIC analysis. Our results show no significant discrepancy among these the different treatments, suggesting that the water samples can be stored without measurable d13CDIC change at least for 3 months.

Discharge hydrographs computed from the theory of linear flow through topologically random channel networks are compared to observed hydrographs on nine arid-region watersheds, with drainage areas ranging from 0.33 hectares to 1363 hectares, at the Walnut Gulch Experimental Watershed in southeast Arizona. Over 90 rainfall-runoff events are tested, with extremes ranging from 12.5 mm to 71 5 mm for rainfall depth, 0.4 mm to 50 mm for runoff volume, and 0.031 ems to 73.5 ems for peak discharge. Topologic Instantaneous Unit Hydrographs (TIUH's) are estimated from topologic and link-length parameters, and a scaling parameter. The topologic information is parameterized as the number of first-order links (magnitude) and the link-length distribution is parameterized by the mean. Both can be measured in the field or from topographic mapping and aerial photography. The scaling parameter is the "effective" kinematic celerity, which is a single-valued estimate of the kinematic celerity of the flow through the channel network for the duration of the event. The TIUH's lead to unit hydrographs, which are convolved with temporally distributed rainfall excess patterns computed using both the 0 index and the curve number, to give composite watershed hydrographs. Effective kinematic celerities are varied until the composite hydrographs match the observed hydrographs in terms of peak discharge and hydrograph efficiency. Results indicate that the TIUH approximately reproduces observed hydrographs, with calibrated effective kinematic celerities that fall within a reasonable range of magnitudes. Agreement between simulated and observed hydrographs is improved by introducing a lag to account for overland travel times to the channel network. The magnitude of the calibrated effective kinematic celerity is significantly related to watershed characteristics, including area, length, and slope. Regression equations are developed and the resulting predicted celerities are combined with map measured topologic and link-length parameters to give simulated hydrographs that approximately match the observed. Magnitude and link-length combine into a single parameter that is consistent across map scales and has the potential to be a watershed descriptor. Calibrated values of effective kinematic celerity vary little across map scales, suggesting that adequate results are obtained without additional expense for highly detailed mapping.