Simulating the influences of groundwater on regional geomorphology using a distributed, dynamic, landscape evolution modelling platform

A dynamic landscape evolution modelling platform (CLiDE) is presented that allows a variety of Earth system interactions to be explored under differing environmental forcing factors. Representation of distributed surface and subsurface hydrology within CLiDE is suited to simulation at sub-annual to centennial time-scales. In this study the hydrological components of CLiDE are evaluated against analytical solutions and recorded datasets. The impact of differing groundwater regimes on sediment discharge is examined for a simple, idealised catchment, Sediment discharge is found to be a function of the evolving catchment morphology. Application of CLiDE to the upper Eden Valley catchment, UK, suggests the addition of baseflow-return from groundwater into the fluvial system modifies the total catchment sediment discharge and the spatio-temporal distribution of sediment fluxes during storm events. The occurrence of a storm following a period of appreciable antecedent rainfall is found to increase simulated sediment fluxes

Geologic and Geomorphologic Interpretation of the Perimeter Trail, Ouray, Colorado: A Virtual Field Trip Application

Each year many people seek respite from their busy lifestyles by traveling to state or national parks, and national forests. The majority of these parks were established to help preserve natural heritage, including wildlife, forests, and the beauty of landscapes formed from years of geologic and geomorphologic processes. Although the public has the opportunity to enjoy the peaceful tranquility of nature, tourists are deprived of a more in-depth educational experience because they either lack a geologic background and or no interpretation or guide to the geology and geomorphology of the area exists. One such location that attracts a large number of tourists is the Perimeter Trail in Ouray, Colorado. The Perimeter trail is a ~9.3 km (~5.8 mi) trail that circumnavigates Ouray. Located in Southwestern Colorado, Ouray is situated in the San Juan Mountain Range, which is accessed by the “Million Dollar Highway.” Ouray is a popular destination for summertime tourism because of its unparalleled scenery and historical significance, but it is also situated in an area that contains numerous geologic and geomorphic features. These features range from a textbook angular unconformity, to glacial and periglacial landscapes, to mass movement and fluvial features, which have been sculpted from metasedimentary, sedimentary, and volcanic rocks. In the study area, The San Juans have been modified by an array of major faulting events; glacial, landslide and fluvial activities; as well as volcanic processes Hiking the Perimeter Trail is an exceptional experience, but could be enhanced with the development of an interactive application that provides the public with a virtual tour guide. For an application of this nature to be useful, a presentation of the geology and geomorphology of the Perimeter Trail must be generalized, well-illustrated, and tied to specific geographic locations. Unfortunately, no such application exists to provide this information. Thus, the objective of this thesis is to investigate the geology and geomorphology of the Ouray area, specifically focusing on the Perimeter Trail. Additionally, a major contribution of this thesis is the development of a smartphone, tablet, and computer application, which provides location-specific descriptions of the geology and geomorphology encountered on the Perimeter Trail. The application is based on an interactive base map, which can be zoomed to various scales. The app hosts a locational service that uses the respective onboard GPS of the device to fix the location of the hiker on the trail. As a hiker traverses the trail, the application contains geographically specific waypoints that have generalized descriptions accompanied with well-illustrated photographs to convey an understanding of the respective geologic and geomorphologic features. The goal of this thesis is the development of a simple, yet effective application that guides hikers along the trail and contributes to expanding the knowledge of individuals who hike the Perimeter Trail

A unified variational eigen-erosion framework for interacting brittle fractures and compaction bands in fluid-infiltrating porous media

The onset and propagation of the cracks and compaction bands, and the interactions between them in the host matrix, are important for numerous engineering applications, such as hydraulic fracture and CO2 storage. While crack may become flow conduit that leads to leakage, formation of compaction band often accompanies significant porosity reduction that prevents fluid to flow through. The objective of this paper is to present a new unified framework that predicts both the onset, propagation and interactions among cracks and compaction bands via an eigen-deformation approach. By extending the generalized Griffith’s theory, we formulate a unified nonlocal scheme that is capable to predict the fluid-driven fracture and compression-driven anti-crack growth while incorporating the cubic law to replicate the induced anisotropic permeability changes triggered by crack and anti-crack growth. A set of numerical experiments are used to demonstrate the robustness and efficiency of the proposed model

Evaluating lithology as an erosional control on a fluviokarst system in northeastern Kentucky

Longitudinal stream profiles can be used to evaluate landscape evolution. Lithology as a control on a stream profile is especially of interests because fluviokarst systems are characterized by the contact of carbonate and non-carbonate rocks at the surface. Due to the difference in weathering processes between carbonates and non-carbonate rocks, it is likely that there is a difference in their rates of erosion. Cave Branch and its tributary Horn Hollow, are fluviokarst systems located in northeastern Kentucky. This area is primarily comprised of sandstone and limestone. The objectives of this study were to determine if variation in lithology was creating a state of disequilibrium in the Cave Branch and Horn Hollow watersheds, determine whether sandstone or limestone erode at a faster rate in this system, and to assess how erosional resistance is related to the overall development of the system. Stream profiles were compared by calculating stream power values using an integral approach in which chi plots were created. This method allows for the comparison of streams of different drainage areas because erosion is scaled with drainage area. It was determined that sandstone watersheds were generally in a greater degree of equilibrium than the limestone watersheds, but whether variation in lithology was creating a state of disequilibrium in the whole watersheds was inconclusive. Limestone streams were determined to have a greater steepness index, greater resistance, than sandstone streams. The greater degree of disequilibrium and observed greater resistance of the limestone is related to the soluble nature of limestone, and the glacial-fluvial development of this area

A unified variational eigen-erosion framework for interacting brittle fractures and compaction bands in fluid-infiltrating porous media

The onset and propagation of the cracks and compaction bands, and the interactions between them in the host matrix, are important for numerous engineering applications, such as hydraulic fracture and CO2 storage. While crack may become flow conduit that leads to leakage, formation of compaction band often accompanies significant porosity reduction that prevents fluid to flow through. The objective of this paper is to present a new unified framework that predicts both the onset, propagation and interactions among cracks and compaction bands via an eigen-deformation approach. By extending the generalized Griffith’s theory, we formulate a unified nonlocal scheme that is capable to predict the fluid-driven fracture and compression-driven anti-crack growth while incorporating the cubic law to replicate the induced anisotropic permeability changes triggered by crack and anti-crack growth. A set of numerical experiments are used to demonstrate the robustness and efficiency of the proposed model

Geomorphology of the upper Mkhomazi River basin, KwaZulu-Natal, South Africa, with emphasis on late Pleistocene colluvial deposits

We present a 1:50 000 scale geomorphological map of the upper Mkhomazi River basin, located in the foothills of the Drakensberg mountains in KwaZulu-Natal Province, South Africa. The sub-horizontal strata of the Permo-Triassic Beaufort Group forms plateau interfluves with a concave valley slope morphology. Locally, thick sequences of late Pleistocene colluvial deposits and associated buried paleosols (Masotcheni Formation) infill first-order tributary stream valleys and extend across the adjacent lower slopes. Surface runoff processes preferentially incise into the poorly consolidated, highly erodible sediments causing severe gully erosion that is responsible for widespread land degradation and desertification phenomena. The main purpose of this work is to derive a geomorphological map of the study area focussing on the erosional landforms to understand their spatial distribution and their relation to the colluvial deposits. Finally, a local and regional stratigraphic correlation of colluvial deposits and associated buried palaeosol profiles is proposed

Insolation-paced sea level and sediment flux during the early Pleistocene in Southeast Asia

Global marine archives from the early Pleistocene indicate that glacial-interglacial cycles, and their corresponding sea-level cycles, have predominantly a periodicity of ~ 41 kyrs driven by Earth’s obliquity. Here, we present a clastic shallow-marine record from the early Pleistocene in Southeast Asia (Cholan Formation, Taiwan). The studied strata comprise stacked cyclic successions deposited in offshore to nearshore environments in the paleo-Taiwan Strait. The stratigraphy was compared to both a δ18O isotope record of benthic foraminifera and orbital parameters driving insolation at the time of deposition. Analyses indicate a strong correlation between depositional cycles and Northern Hemisphere summer insolation, which is precession-dominated with an obliquity component. Our results represent geological evidence of precession-dominated sea-level fluctuations during the early Pleistocene, independent of a global ice-volume proxy. Preservation of this signal is possible due to the high-accommodation creation and high-sedimentation rate in the basin enhancing the completeness of the stratigraphic record

Human Impacts on Erosion in Starved Rock State Park, Illinois, Usa

State and National parks are some of the most visited wildlife areas within the United States, making local geologic features more susceptible to human-induced change. As more people visit these parks throughout the year, we see major impacts on the interactions between biological and geological processes. This study determines if human activity, through rock carvings, influence erosion within Starved Rock State Park and provides a new perspective on our compounding anthropogenic influence on Earth. Through natural stream and artificial human erosion, the base of the bedrock slope potentially changes at a much faster rate than the upper portion of the outcrop. By monitoring the fragile sandstone cliffs that preserve these humancreated carvings, specific erosion data were collected in four different canyons within the park. Canyon wall data were collected and monitored using an Empire contour gauge, a Schmidt rebound hammer, and an iPhone 13 LiDAR camera with the 3D Scanner app program to determine seasonal variations in erosion throughout the park as well as the influence of surficial case hardening on the outcrops. The contour gauge and Schmidt hammer data collected suggest the bedrock of the area is affected on a small, millimeter scale within the course of a year. Data collected from the carvings compared to bedrock that is naturally eroding without human influence exhibits short-term localized changes to the bedrock that is greater than the long-term erosion of these surfaces. Analysis of Schmidt hammer values and thin sections indicate that some locations have stronger rock surfaces driven by differences in cement concentrations from the surface to the interior of the rock outcrops. Differences in rock strength produce variation in erosion across the canyons and provide context to seasonal processes that influence weathering. Future research identifying the magnitude of this impact over a longer period, as well as potential difference between lithologies, can prove to be valuable in increasing education and awareness at other state or national parks

Master of Science

thesisVerification and validation (V&V) principles are applied to assess massively parallel simulations of hypervelocity perforation of a well bore casing and subsequent penetration into oil-laden sandstone via shaped-charge jet. This technique for liberating oil from geological formations has the potential to be optimized through development of robust and accurate computational frameworks. Accordingly, the overarching objective of this research is to systematically assess the accuracy of the numerical algorithms used (verification) and the appropriateness of those equations for this engineering purpose (validation). Automated methods for single-element verification of constitutive models under a variety of loading modes are developed. This modular test suite incorporates previously documented verification tests, both generally applicable to plasticity models reducing to von Mises plasticity, as well as model specific tests of the geomechanics model (Arenisca) under continual development. These tools are extended to extract the deformation histories of single particles from full-scale Material Point Method (MPM) simulations, which helps to analyze problematic loading modes of a larger simulation on a single-processor workstation. The velocity gradient in these single-element tests must be evaluated in a manner consistent with the underlying integration algorithm used in the source simulation, which is a nontrivial observation making this new capability novel. Testing capabilities are extended to provide arbitrary loading paths similar to those extracted from full-scale penetration problems to serve as robustness and verification tests in future regression testing. A key focus of the work was devising methods to automate the testing of Arenisca and its implementation. As MPM is a relatively new approach to modeling large deformation problems, novel visualization methods are developed along with supporting Python postprocessing scripts. Analytical penetration models in the literature, which have historically been developed for hydrodynamic flow of metals, are tested for their applicability to the penetration of sandstone. A representative sampling of simulation results (some using new methods to account for confining stress) are presented to illustrate how full-scale V&V trend testing often reveals issues not evident in smaller tests, thereby helping code developers better understand, and eliminate, undesired trends or anomalies in the results