Browsing by Author "Hugenholtz, Chris H."

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    3D Geologic Mapping and Characterization Using Digital Outcrop Models Generated from Uninhabited Aerial Vehicles and Structure-from-Motion Photogrammetry
    (2020-07-17) Nesbit, Paul Ryan; Hugenholtz, Chris H.; Hubbard, Stephen M.; Sjogren, Darren Boyd
    Outcrops are a primary source of geologic information and key in developing knowledge for teaching, training, and research. Observations from outcrop exposures provide opportunities to directly characterize detailed sedimentological composition, architectural characteristics, and link observations across various scales. Conventional field mapping techniques have remained largely unchanged for the past two centuries and are commonly limited in their ability to quantitatively constrain measurements, extend observations laterally, and document features at multiple scales. Recently, technological advances in uninhabited/unmanned aerial vehicles (UAVs) have prompted wide use in various geoscience disciplines to supplement field data with quantifiable digital information. However, application of UAVs to geologic mapping has been limited, due to unique challenges in data collection, processing, analysis, and visualization predominantly associated with intricate 3D exposures in complex topographic settings. This dissertation is focused on detailed investigation of 3D mapping, analysis, and dissemination from UAV-derived digital outcrop models (DOMs) that can potentially provide multi-scale perspectives and quantitative measurements that were previously difficult, or impossible to achieve with conventional field methods alone.
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    Aeolian Controlled Landscape Evolution at a Martian Analogue Site in Northwestern Argentina
    (2020-03-05) Favaro, Elena Angelica; Hugenholtz, Chris H.; Sjogren, Darren Boyd; Martin, Yvonne E.
    Aeolian processes are the most pervasive agent of surficial change in the solar system. Encompassing sediment entrainment, transport, deposition, deflation, and abrasion, aeolian-driven landscape modification can affect planetary surfaces over a range of spatial and temporal scales. On Earth, aeolian processes shape the landscape across all seven continents. In our solar system, Mars is the only other planet known to have active aeolian processes. As the main geological agent of change over the past 4 billion years, wind has sculpted the Martian surface into patterns we recognize from studies of arid landscapes on Earth. Of interest to scientists is constraining the paleo- and contemporary wind regime of Mars to better understand its geologic, climatic, and erosional histories. Terrestrial aeolian research in Martian analogue environments has become an integral research practice to achieve these objectives. This thesis investigates process-form linkages between the aeolian environment and landscape on the Puna Plateau, Northwestern Argentina. A well-known Martian analogue, the Puna Plateau is ideal for conducting aeolian analogue research owing to its high altitude, low atmospheric pressure, aridity, wind regime, pyroclastic and basaltic geology, and the presence of a number of enigmatic bedrock landforms and granular bedforms known to exist on Mars, including, yardangs, periodic bedrock ridges, megaripples, and wind streaks. This research applies a diverse suite of in situ, laboratory, modelling, and remote sensing methodologies and analysis techniques to characterize sediment transport, the wind regime, abrasion dynamics, and distribution of landforms in the study area. Results from each study were used to refine and inform subsequent research questions. Among the findings of these works, we (i) identify a new abrasion feature, propose an evolutionary cycle, and highlight the diagnostic utility of this and other bedrock abraded features; (ii) identify variability of wind direction in the study area using wind re-analysis models, demonstrate the range of densities of mobilized grains using in situ sediment traps, and highlight the challenges of constraining sediment flux and abrasion rates in multimodal density environments; and (iii) use a high-resolution digital elevation model to statistically analyze yardang distribution, put forth hypotheses about initiation mechanisms, and relate the distribution of yardangs in the study area to those found elsewhere on Earth and Mars. The research in this thesis demonstrates the utility and necessity of using multiple methodologies to holistically define complex aeolian systems.
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    Evaluating Technologies and Methods for Measuring Methane Emissions from the Upstream Oil and Gas Sector
    (2020-10-13) Fox, Thomas Arcadius Oram; Hugenholtz, Chris H.; Else, Brent G. T.; Du, Ke
    Methane, a potent greenhouse gas, is commonly emitted during the production, processing, transmission, and storage of oil and natural gas (O&G). The O&G industry is the leading source of anthropogenic methane in Canada and the US, but methane measurement and mitigation strategies remain underdeveloped. In recent years, an increasing number of O&G producing jurisdictions have introduced regulations mandating methane leak detection and repair (LDAR) programs in order to reduce fugitive emissions. Meanwhile, innovation in methane measurement has exploded, with companies emerging that promise to reduce methane emissions using drones, aircraft, satellites, fixed installations, handheld instruments, and other vehicle systems. These new solutions are not well understood, and how they might contribute to reducing methane emissions is unclear. This thesis seeks to improve understanding of emerging methane-sensing technology performance and participation in the O&G industry. Specifically, it seeks to reveal whether current and emerging technologies are technically capable of reducing emissions, can meet regulatory requirements for approval, and offer cost savings relative to established methods. This thesis presents four chapters of research with the following main results: (1) Screening is a way for mobile technologies to rapidly search for large leaks. Most emerging technologies and methods use screening and can detect methane in some capacity, but much more testing is needed to understand performance metrics, precise limitations, how to direct follow-up, and mitigation potential; (2) Policies are evolving to enable adoption of new systems, but careful work will be required to properly evaluate suitability through controlled testing, simulation modeling, and piloting; (3) LDAR-Sim and similar tools can support the development of LDAR programs with new technologies but modeling results are highly sensitive to technology performance assumptions, empirical inputs, and environmental conditions; (4) Screening technologies that require follow up may struggle to be cost-effective due to high quantification errors and the confounding presence of vented and combustion emissions at most facilities. Impressive progress has been made in developing, enabling, and implementing new LDAR technologies, but regulators, industry, and researchers should continue to work together to ensure credible and defensive emissions reductions are achieved through implementation.
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    Megaripple Stripes
    (2019-04-25) Gough, Tyler Robert; Hugenholtz, Chris H.; Wolfe, Stephen Andrew; Martin, Yvonne Elizabeth
    This thesis incorporates field measurements, satellite imagery, and numerical modelling to explain the formation and evolution of a poorly-understood and relatively undocumented longitudinal aeolian bedform pattern. The pattern consists of alternating streamwise corridors of megaripples separated by corridors containing smaller bedforms. This pattern, referred to herein as megaripple stripes, is observed at sites on Earth and Mars. Measurements from satellite imagery indicate a strong positive relation between the crosswind and downwind wavelengths of megaripple corridors. Field measurements of stripe morphology and grain size indicate a consistent pattern whereby the surface texture of the megaripple corridors is coarser than the intervening corridors of smaller bedforms. The amplitude and wavelength of features in the megaripple corridors are larger than the features in the smaller bedform corridors. The three-dimensional morphology and sediment sorting pattern of megaripple stripes was reproduced in a numerical model that incorporated two aeolian transport species: saltons and reptons. Simulations suggest striped pattern development is a self-organizing process resulting from grain size and topographic feedbacks that are sensitive to the bulk concentration and erosion probability of reptons. In the simulations, regular megaripples emerge from a high bulk concentration of reptons and impact ripples develop from a very low bulk concentration of reptons. Megaripple stripes emerge when the bulk concentration is intermediate between megaripple and impact ripple formation. Therefore, it is hypothesized that megaripple stripes develop in unimodal transport environments with supply-limited reptons. The nature and dynamics of reptons are largely determined by the wind regime, the grain size distribution, and by the grain density distribution in some environments. Repton behaviour, spanwise transport, and other relevant aeolian processes are discussed in relation to megaripple stripes.
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    Modelling and Mapping Fine-Scale Vegetation Biomass in Banff National Park Using Remotely Sensed Data Collected by Unmanned Aerial Systems
    (2020-05-12) Poley, Lucy Gem; McDermid, Gregory J.; Bender, Darren J.; Hugenholtz, Chris H.
    Ecological investigations and long-term monitoring programs in grassland ecosystems often require detailed information on vegetation parameters across an area of interest. However, characterization of grassland vegetation is challenging using ground-based measurements or satellite imagery due to the fine-scale heterogeneity present in grasslands. Unmanned Aerial Systems (UASs) provide a way to characterize vegetation at a high spatial resolution, bridging the gap between ground-based measurements and satellite imagery. Motivated by the need for long-term monitoring of fine-scale vegetation parameters following the reintroduction of plains bison (Bison bison bison) to Banff National Park, Canada, this research explored how UAS-derived data could be used to estimate the aboveground biomass of vegetation at remote grassland sites in Banff’s bison reintroduction zone. I assessed the factors affecting quality of UAS-based vegetation estimation in previous research to design a series of analytical experiments. I conducted UAS surveys at study sites in July 2018 using visible-light and multispectral sensors. Concurrent to the aerial surveys, I collected ground-based data on shrub and herbaceous vegetation biomass. I derived spectral and textural variables using one or more wavelengths of light from the UAS imagery and related to ground-measured biomass using linear regression models. I accurately estimated shrub biomass using an area-weighted vegetation index derived from visible-light imagery that fused spectral and structural information into one parsimonious model. For herbaceous vegetation, combining visible-light and multispectral texture information derived from vegetation indices was the best approach to biomass estimation, and I was able to quantify the relative contributions of photosynthetic and non-photosynthetic vegetation within total biomass. I then modelled the distribution of shrub and herbaceous vegetation biomass across the study site and a workflow for collecting and analyzing UAS imagery for vegetation biomass monitoring was developed. The methods and maps of grassland vegetation produced in this study will provide the data and workflow necessary to monitor fine-scale impacts of bison on vegetation in Banff National Park, supporting conservation and management of this ecologically important species. This research also increases general knowledge of remote sensing of vegetation and provides an approach to fine-scale vegetation characterization suitable for ecological investigations in grasslands ecosystems
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    Pre- and Post-Disaster Remote Sensing with Drones for Supporting Disaster Management
    (2023-04-27) Kucharczyk, Maja; Hugenholtz, Chris H.; Geldsetzer, Torsten; Hay, Geoffrey J.; Moorman, Lynn; Slick, Jean
    Small (< 25 kg) aerial drones have expanded the remote sensing toolkit for disaster management activities, resulting in hundreds of published case studies in the past two decades. The overall goal of this doctoral research, which comprises three related studies, is to evaluate drone-based pre- and post-disaster remote sensing as a tool to support disaster management. The first study provides a critical review of drone-based remote sensing in natural hazard-related disasters to highlight research trends, biases, and expose new opportunities. Recommendations for future research include a greater focus on demonstrating and evaluating drone-based support of pre-disaster data acquisition (a preparedness activity) and rapid damage assessment (a response activity). As such, the second study presents the first pre-disaster drone-based mapping mission over an urban area (downtown Victoria, British Columbia) approved by Transport Canada. The objective was to assess the quality of 3D data obtained with the only legally approved drone. Finally, the third study demonstrates rapid mapping of hurricane roof damage using artificial intelligence (deep learning) and drone imagery, including an accuracy assessment. Overall, this doctoral research identified critical knowledge gaps in the field of pre- and post-disaster remote sensing with small aerial drones, and then demonstrated and evaluated drone-based support of two building-damage-related activities that were recommended for future research.
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    Reported UAV incidents in Canada: analysis and potential solutions
    (NRC Research Press, 2017-06-01) Nesbit, Paul R.; Barchyn, Thomas E.; Hugenholtz, Chris H.; Cripps, Sterling; Kucharczyk, Maja
    UAV incidents were analyzed using data from Transport Canada's Civil Aviation Daily Occurrence Reporting System (CADORS). Between 05 November 2005 and 31 December 2016 a total of 355 incidents were reported in Canadian airspace. The largest number involved UAV sightings (66.5%) and close encounters with piloted aircraft (22.3%). These incidents increased markedly after 2013, with the highest number in British Columbia, followed by Ontario, Quebec, Alberta, and Manitoba. The vast majority of UAV incident reports were filed by pilots of piloted aircraft. Typically, airspace at altitudes greater than 400 feet above ground level (AGL) is off limits to UAVs; however, of the 270 incidents in the CADORS database with UAV altitude reported, 80.4% were above 400 feet AGL and 62.6% were above 1000 feet AGL. Of the 268 incidents with reported horizontal distance to the nearest aerodrome, 74.6% occurred or likely occurred within 5 nautical miles (nm), and of those 92.4% and 76.6% were reported above 100 and 300 feet AGL, respectively. Collectively, the CADORS data indicate that the overwhelming majority of UAV incidents reported in Canada were airspace violations. These results can guide future risk mitigation measures, hardware/software solutions, and educational campaigns to increase airspace safety.