Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 139-142).

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 139-142).

Thesis (Ph. D. - Civil Engineering)--University of Arizona. / Includes bibliographical references (leaves 98-102).

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): MacMahan, Jamie. "September 2009." Description based on title screen as viewed on 5 November 2009. Author(s) subject terms: Overtopping, run-up, barrier, natural beach, Carmel River Beach Includes bibliographical references (p. 41-44). Also available in print.

Tropical habitats have high taxonomic and ecological diversity, but they are currently subject to high rates of extinction. Amphibian populations are declining globally and while we have some understanding of the causes of these declines, it is unclear how these losses will influence ecosystem structure and function. Secondary production and trophic basis of production analyses link consumers to energy flow and reflect the relative importance of various energy sources and energy flow pathways in food webs. These techniques can yield valuable information on the roles of individual consumers in ecosystem function, and thus the ecological consequences of extinction and extirpation events. I estimated the trophic basis of production in a Panamanian headwater stream to identify major sources of energy, measure energy flow through consumers, and characterize interactions among trophic levels and functional feeding groups. I examined gut contents of 19 dominant macroinvertebrate and two dominant tadpole taxa collected during dry and wet seasons before an amphibian decline. I used previously published estimates of secondary production, assimilation efficiencies, and net production efficiencies, along with gut content data, to quantify food web structure and energy flow pathways. Overall consumption of allochthonous materials was greater than autochthonous (p < 0.001), and the dominant food sources were non-algal biofilm and vascular plant detritus. Autochthonous materials were consumed at higher rates during the dry season (p = 0.012). Total consumption rates varied within and among shredders (0.85 - 12.10 g/m2/yr), scrapers (0.46 - 0.91 g/m2/yr), filterers (1.20 - 4.67 g/m2/yr), gatherers (0.43 - 2.44 g/m2/yr) and predators (0.05 - 0.95 g/m2/yr). Overall consumption rates in pool habitats were higher compared to riffles. The degree of omnivory in the food web was much higher than has been observed in similar temperate streams. Omnivory was prevalent across all functional feeding groups, but more pronounced in predators, especially Anacroneuria (55% animal and 45% plant materials in guts). There was also an ontogenetic shift among most dominant macroinvertebrates from smaller, energy rich food sources (e.g., non-algal biofilm) to larger, less nutritious materials (e.g., vascular plant material) with increase in size. My research is the first to provide quantitative estimates of energy flow through a neotropical headwater stream food web. Information from this study is central to understanding and conserving tropical headwater streams. Further, my results, along with post-amphibian decline analyses from the same stream, will allow for a comprehensive assessment of the ecological consequences of amphibian declines.

Rapid field-based assessment methods for classifying stream permanence in headwater streams are needed to accurately inform regulatory decisions regarding which streams are protected under the Clean Water Act. In North Carolina, a rapid field-based assessment method for identification of intermittent and perennial streams has been developed. The North Carolina Method (NC method) uses 26 attributes divided into three categories geomorphology, hydrology, and biology to assess a particular study reach's flow permanence. In this method, the attribute scores for a given study reach are totaled and the sum of the score is used to rank the reach as ephemeral, intermittent, or perennial. The study objective were to (1) evaluate the NC method's ability to classify the flow permanence of agricultural, low order, study reaches in Southern Illinois and (2) create empirical models that predict flow permanence at a given stream location. The results of the study show the NC method successfully differentiated ephemeral from intermittent and perennial study reaches 100% of the time. However, there was lower fidelity in differentiating between intermittent and perennial study reaches and correctly determined flow permanence 82% of the time. In two of the cases where the NC method categorized the streams incorrectly, the score was on the threshold between intermittent and ephemeral. If these study reaches were categorized during a drier period they may have scored correctly. These results suggest the NC method would be a strong foundation for the development of a rapid field-based assessment protocol method for Illinois. Regression models were developed to predict NC method scores using a variety of hydrologic, geomorphic, and land-cover metrics. Two statistically significant models (>95% confidence interval) for estimating NC method stream permanence scores were developed using these physical parameters. One of the significant regression models developed used watershed area alone as a predictor of the NC method stream permanence scores. The second significant regression model employed bankfull width, upslope surface-water area, and upslope area of grass lands. These models explained 61% and 69% of the variance in the NC method stream-permanence scores, respectively. While the regression models develop here are not capable of explicitly modeling stream-permanence class with a high degree of accuracy, they are useful for guiding stream-permanence study-site selection.

No description available.

This study presents a geochemical characterization of stream waters draining the sedimentary exhalative (SEDEX) Tom and Jason Pb-Zn deposits and surroundings in the MacMillan Pass, Yukon. Streams sampled have wide ranging pH values of 3 to 8.2. Dissolved metal concentrations vary widely with water source and pH. Of note, streams draining the Tom and Jason deposits are acidic and neutral respectively, which greatly affects metal solubility. The Tom Deposit drainage is extremely high in dissolved and fine sediment fraction lead, as well as dissolved zinc. Neutral streams draining the Jason deposit have less dramatic metal concentrations, but do show elevated dissolved zinc and fine sediment fraction lead concentrations. Modelling using the thermodynamic equilibrium program PHREEQC and XRD analysis indicate that ferricrete hardpans underlying acidic drainages are formed where drainage water is saturated with respect to schwertmannite. Ferrihydrite is formed where the rapid mixing of waters increases the pH rapidly. An aluminium oxy-hydroxide, likely gibbsite, precipitates where pH levels exceed 4.5, however it appears to dissolve with decreasing pH. This study looks at dissolved, suspended and fine fraction sediments to provide a more complete view of metal movement under various conditions which may be useful to both exploration and environmental fields.

The correlator is a key component of the digital backend of a modern radio telescope array. The 64 antenna MeerKAT telescope has an FX architecture correlator consisting of 64 F-Engines and 256 X-Engines. These F- and X-Engines are all hosted on 128 custom designed FPGA processing boards. This custom board is known as a SKARAB. One SKARAB X-Engine board hosts four logical X-Engines. This SKARAB ingests data at 27.2 Gbps over a 40 GbE connection. It correlates this data in real time. GPU technology has improved significantly since SKARAB was designed. GPUs are now becoming viable alternatives to FPGAs in high performance streaming applications. The objective of this dissertation is to investigate how to build a GPU drop-in replacement X-Engine for MeerKAT and to compare this implementation to a SKARAB X-Engine. This includes the construction and analysis of a prototype GPU X-Engine. The 40 GbE ingest, GPU correlation algorithm and the software pipeline framework that links these two together were identified as the three main sub-systems to focus on in this dissertation. A number of different tools implementing these sub-systems were examined with the most suitable ones being chosen for the prototype. A prototype dual socket system was built that could process the equivalent of two SKARABs worth of X-Engine data. This prototype has two 40 GbE Mellanox NICS running the SPEAD2 library and a single Nvidia GeForce 1080Ti GPU running the xGPU library. A custom pipeline framework built on top of the Intel Threaded Building Blocks (TBB) library was designed to facilitate the ow of data between these sub-systems. The prototype system was compared to two SKARABs. For an equivalent amount of processing, the GPU X-Engine cost R143 000 while the two SKARABs cost R490 000. The power consumption of the GPU X-Engine was more than twice that of the SKARABs (400W compared 180W), while only requiring half as much rack space. GPUs as X-Engines were found to be more suitable than FPGAs when cost and density are the main priorities. When power consumption is the priority, then FPGAs should be used. When running eight logical X-Engines, 85% of the prototype's CPU cores were used while only 75% of the GPU's compute capacity was utilised. The main bottleneck on the GPU X-Engine was on the CPU side of the server. This report suggests that the next iteration of the system should offload some CPU side processing to the GPU and double the number of 40 GbE ports. This could potentially double the system throughput. When considering methods to improve this system, an FPGA/GPU hybrid X-Engine concept was developed that would combine the power saving advantage of FPGAs and the low cost to compute ratio of GPUs.