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Articles 31 - 60 of 107
Full-Text Articles in Geomorphology
Climatic Controls On The Kinematics Of The Hooskanaden Landslide, Curry County, Oregon, Kara Kingen
Climatic Controls On The Kinematics Of The Hooskanaden Landslide, Curry County, Oregon, Kara Kingen
Dissertations and Theses
Slow-moving earthflows represent major sources of sediment transport and erosion and are problematic for the management of critical infrastructure. The Hooskanaden Landslide -- a slow-moving earthflow on the southwest coast of Oregon -- crosses US Highway 101 and has been a site of continued interest to the Oregon Department of Transportation (ODOT) due to the weak lithology, erosive environment, and recurrent surge behavior (every ~15 years). Past surges, including the most recent (2019), have occurred during the winter, suggesting that velocity changes are predominantly controlled by climatic inputs. To examine the response of the Hooskanaden Landslide to seasonal and other …
Evaluation Of Manual And Semi-Automated Deep-Seated Landslide Inventory Processes: Willapa Hills, Washington, Tiffany E. Justice
Evaluation Of Manual And Semi-Automated Deep-Seated Landslide Inventory Processes: Willapa Hills, Washington, Tiffany E. Justice
Dissertations and Theses
Recent advances in remote sensing data and technology have allowed for computational models to be designed that successfully extract landforms from the landscape. The goal of this work is to create one such semi-automated model to extract deep-seated landslides located in complex geomorphic terrain. This is accomplished using geographic object-based image analysis (GEOBIA) techniques, considered by leaders in the field of image analysis to have an advantage over traditional automated classification methods. GEOBIA methods can mimic human visual interpretation by including more characteristic features used to assess the relationship between image data and the ground surface such as color reflectance …
Bed Particle Displacements And Morphological Development In A Wandering Gravel-Bed River, Ryan Mcqueen, Peter Ashmore, T Millard, N Goeller
Bed Particle Displacements And Morphological Development In A Wandering Gravel-Bed River, Ryan Mcqueen, Peter Ashmore, T Millard, N Goeller
Geography & Environment Publications
Bed particles were tracked using passive integrated transponder tags in a wandering reach of the San Juan River, British Columbia, Canada, to assess particle movement around three major bars in the river. In-channel topographic changes were monitored through repeat LiDAR surveys during this period and used in concert with the tracer data set to assess the relationship between particle displacements and changes in channel morphology, specifically, the development and re-working of bars. This has direct implications for virtual velocity and morphologic based estimates of bedload flux, which rely on accurate estimates of the variability and magnitude of particle path lengths …
Aeolian Sand Stringers In The Upper Midwest, Usa: Morphology, Stratigraphy, And Paleoenvironmental Significance, Kenzie L. Shandonay
Aeolian Sand Stringers In The Upper Midwest, Usa: Morphology, Stratigraphy, And Paleoenvironmental Significance, Kenzie L. Shandonay
All Graduate Theses, Dissertations, and Other Capstone Projects
Sand stringers are subtle (~1-10 m high), elongate (several km long, up to 100 m wide) aeolian landforms that lack a slip face and generally have a northwest-southeast orientation. They are ubiquitous across the Upper Midwest, including southeast Minnesota and western Wisconsin. Despite their prevalence, the timing, processes, and environmental conditions during sand stringer formation and evolution are poorly understood. This research aims to describe sand stringer morphology and stratigraphy, reconstruct regional paleoclimate, and characterize the timing and geomorphic processes of sand stringer formation and evolution in response to shifts in environmental conditions. This study investigates two sand stringers: Good-1 …
A Karst Feature Prediction Model For Prince Of Wales Island, Alaska Based On High Resolution Lidar Imagery, Alexander Lyles
A Karst Feature Prediction Model For Prince Of Wales Island, Alaska Based On High Resolution Lidar Imagery, Alexander Lyles
Master's Theses or Doctor of Nursing Practice
Investigation into surface karst formation is significant to hazard prediction, hydrogeologic drainage, and land management. Southeast Alaska contains over 600,000 acres of mapped carbonate bedrock, and some of the fastest recorded karst dissolution in the world. The objectives of this study are to develop and compare multiple semi-automated models to map and delineate karst features from bare-earth LiDAR imagery using ArcGIS Desktop 10.7, and to apply a preliminary geostatistical analysis of sinkhole morphometric parameters to highlight potential spatial patterns of karst evolution on Prince of Wales Island, Alaska. A semi-automated approach of mapping karst features provides a dataset that minimizes …
The Use Of Green Pond Conglomerate As Building Stone In Morris County, New Jersey, Gregory A. Pope
The Use Of Green Pond Conglomerate As Building Stone In Morris County, New Jersey, Gregory A. Pope
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Green Pond Conglomerate (GPC) is a maroon colored quartzite with white quartz pebbles, a classic “puddingstone”. GPC derives from a NW-SW-trending sliver of Paleozoic sediments, the “Green Pond Outlier”, surrounded by older metamorphic and igneous rocks of Morris and Passaic Counties. Buildings, retaining walls, field fences, and monuments incorporate the durable and attractive stone, in a distinct geographic area of Morris County. Several instances of structures completely constructed or faced with GPC occur in and around Morristown, limited to affluent houses and one prominent church. In these cases, GPC stones were dressed and faced, a labor-intensive effort. Elsewhere in the …
Geology, Soils And Climate Of The Margaret River Wine Region, Peter J. Tille, Angela Stuart-Street, Peter S. Gardiner
Geology, Soils And Climate Of The Margaret River Wine Region, Peter J. Tille, Angela Stuart-Street, Peter S. Gardiner
All other publications
This report is an extract from the broader description and analysis of the Geology, soils and climate of Western Australia's wine regions. It expands on the brief descriptions in the second edition of 'Viticulture' (Coombe & Dry 2004) concerning the soils and landscapes of Western Australia’s main wine growing regions. We have tailored this report extract to the specific needs of the Margaret River wine region. It contains local soil names and soil-landscape zones and systems maps.
The wine industry recognises the importance of giving customers an understanding of the vines’ environment and how that may influence wine character …
Geospatial Analyses Of Seismic Hazards And Risk Perception In Libya, Somaia Suwihli
Geospatial Analyses Of Seismic Hazards And Risk Perception In Libya, Somaia Suwihli
Graduate Theses and Dissertations
Libya is not considered a highly active seismic region. However, several earthquakes of magnitude >5.0 have occurred there. This dissertation analyzes the seismicity of Libya in order to better understand earthquake hazards, related geomorphic features, and the current evolution of Libyan perceptions of seismic risk. The first article developed a baseline of past and current seismic inventory in Libya, which represented an assessment of Libya seismic hazard by translating, analyzing, and compiling historical sources and archaeological data. This study shows that Libya has experienced earthquakes in varying degrees since ancient times. Through the spatial and temporal distribution of earthquakes from …
Spatial Analysis Of Soil Creep Rates On Mount Sequoyah, Fayetteville Arkansas, Amy Suzanne Morris
Spatial Analysis Of Soil Creep Rates On Mount Sequoyah, Fayetteville Arkansas, Amy Suzanne Morris
Graduate Theses and Dissertations
Mount Sequoyah in Fayetteville, Arkansas, is a part of the Boston Mountains, which are considered a deeply dissected plateau. The area is prone to mass wasting, which is the general downslope movement of sediments, soils, and rock through different processes that cause instabilities along a hillslope, and in its soil and loose rubble mantle. For this study, we looked at soil creep, which is the small-scale movement of soil downhill because of gravity, wetting and drying cycles, and heating and cooling cycles.
By measuring the tilt of utility poles, we determined multiple causes of soil creep. The variables that are …
Geomorphology And Chronology Of Sand Stringer Deposition Beyond The Ice Margin: Southeastern Minnesota And Western Wisconsin, Usa, Richard J. Mataitis
Geomorphology And Chronology Of Sand Stringer Deposition Beyond The Ice Margin: Southeastern Minnesota And Western Wisconsin, Usa, Richard J. Mataitis
All Graduate Theses, Dissertations, and Other Capstone Projects
The purpose of this Master’s thesis is to investigate linear, aeolian deposits termed “sand stringers” located within western Wisconsin and southeastern Minnesota. Previous research has investigated their spatial distribution, and to a minor extent, their composition and absolute age. However, further sedimentological and absolute age data are needed from a greater distribution of sand stringers to understand their formation and depositional chronology. To build on previous research we 1) remotely mapped the spatial distribution and orientation of sand stringers in western Wisconsin and southeastern Minnesota, 2) collected absolute age data using optically stimulated luminescence (OSL) from four stringers in western …
Mapping Surficial Geology In The New River Gorge National River And Bluestone National Scenic River, West Virginia, Using Lidar-Derived Digital Elevation Data, Marla K. Denicola
Mapping Surficial Geology In The New River Gorge National River And Bluestone National Scenic River, West Virginia, Using Lidar-Derived Digital Elevation Data, Marla K. Denicola
Graduate Theses, Dissertations, and Problem Reports (ETD)
The purpose of this thesis was to determine if the surficial geology of Bluestone National Scenic River (BLUE) and New River Gorge National River (NERI), two areas of similar geology, can be mapped using visual interpretation methods applied to digital elevation models (DEMs) derived from light detection and ranging (LiDAR) data. Surficial geology in BLUE was field mapped using GPS, following definitions and characterizations for surficial geology units established with the guidance of Dr. J. Steven Kite. A 2m x 2m LiDAR-derived DEM was used for BLUE and most of NERI using US Army Corps of Engineers (USCOE) LiDAR data, …
Integrating Geochronologic And Instrumental Approaches Across The Bengal Basin, Elizabeth L. Chamberlain, Steven L. Goodbred, Richard Hale, Michael S. Steckler, Jakob Willinga, Carol Wilson
Integrating Geochronologic And Instrumental Approaches Across The Bengal Basin, Elizabeth L. Chamberlain, Steven L. Goodbred, Richard Hale, Michael S. Steckler, Jakob Willinga, Carol Wilson
OES Faculty Publications
Constraining time is of critical importance to evaluating the rates and relative contributions of processes driving landscape change in sedimentary basins. The geomorphic character of the field setting guides the application of geochronologic or instrumental tools to this problem, because the viability of methods can be highly influenced by geomorphic attributes. For example, sediment yield and the linked potential for organic preservation may govern the usefulness of radiocarbon dating. Similarly, the rate of sediment transport from source to sink may determine the maturity and/or light exposure of mineral grains arriving in the delta and thus the feasibility of luminescence dating. …
The Importance Of Landscape Position Information And Elevation Uncertainty For Barrier Island Habitat Mapping And Modeling, Nicholas Matthew Enwright
The Importance Of Landscape Position Information And Elevation Uncertainty For Barrier Island Habitat Mapping And Modeling, Nicholas Matthew Enwright
LSU Doctoral Dissertations
Barrier islands provide important ecosystem services, including storm protection and erosion control to the mainland, habitat for fish and wildlife, and tourism. As a result, natural resource managers are concerned with monitoring changes to these islands and modeling future states of these environments. Landscape position, such as elevation and distance from shore, influences habitat coverage on barrier islands by regulating exposure to abiotic factors, including waves, tides, and salt spray. Geographers commonly use aerial topographic lidar data for extracting landscape position information. However, researchers rarely consider lidar elevation uncertainty when using automated processes for extracting elevation-dependent habitats from lidar data. …
The Structure And Dynamics Of A River Delta Are Related Through Its Nourishment Area, Suggesting Optimality, Christopher A. Cathcart
The Structure And Dynamics Of A River Delta Are Related Through Its Nourishment Area, Suggesting Optimality, Christopher A. Cathcart
Graduate Theses and Dissertations
Scaling relations in tributary network geomorphology are well understood with respect to optimality. However, the scaling relations between structure and dynamics in distributary network geomorphology are less well understood. This is primarily due to the fact that nourishment area boundaries are difficult to map compared to tributary network catchment area boundaries. Furthermore, most previous work has focused either on the distributary channel networks or the delta’s partitioning of discharge. Here we show that, on the Wax Lake Delta (WLD) in Louisiana, the asymmetry in nourishment areas and downstream nourishment boundary width (∏) at a channel bifurcation, acts as a control …
Lidar-Based Sinkhole Detection And Mapping In Knox County, Tennessee, J Clint Shannon, David Moore, Yingkui Li, Cathy Olsen
Lidar-Based Sinkhole Detection And Mapping In Knox County, Tennessee, J Clint Shannon, David Moore, Yingkui Li, Cathy Olsen
Pursuit - The Journal of Undergraduate Research at The University of Tennessee
Sinkholes are one of the major causes of damage to roads, buildings, and other infrastructure throughout the US. Sinkholes near or on roads are especially costly and occasionally deadly. Knox County and much of East Tennessee are located within karst areas (comprised of porous and soluble limestone and dolomite), deeming it at risk for sinkholes. Currently, Knox County uses contour maps to manually identify sinkholes. Supported by a geographic information system (GIS), we developed a streamlined model to identify the locations and extents of potential sinkholes using 1.3-ft resolution LiDAR (Light Detection and Ranging) data and applied it to the …
A Tourism Impact Index For Water-Based Natural Attractions Field-Tested In Subarctic And Maritime Climates, Jason Fox
Masters Theses & Specialist Projects
Tourism in cold and cool-climate regions is largely characterized by recreational and sightseeing activities at water-based natural attractions such as beaches, coastal cliffs, and waterfalls. While the economic benefits of the tourism industry can contribute to a sustainable future for these regions, the environmental implications of a hastilydeveloped industry cannot be ignored given that cold-climate and cool-climate landscapes are at risk of rapid environmental change from a warming climate and other environmental concerns. This study consisted of the development of the Tourism Impact Index for Water-Based Natural Sites, the first of its kind, and its application and refinement in the …
Detecting Coastal Marsh Change From Aerial Imagery Using Spectral And Textural Methods: Pascagoula River Estuary, Mississippi, 1955-2014, Margaret Claire Bell Waldron
Detecting Coastal Marsh Change From Aerial Imagery Using Spectral And Textural Methods: Pascagoula River Estuary, Mississippi, 1955-2014, Margaret Claire Bell Waldron
Master's Theses
As sea level rise accelerates, coastal marsh ecosystems are increasingly vulnerable. Vertical accretion rates must exceed or keep pace with rates of sea level rise to prevent transition to open water or inland migration of marsh vegetation. While some marsh systems along the northern Gulf of Mexico coast have remained stable, others, e.g., the marshes of the Louisiana Gulf Coast, have experienced high rates of conversion to open water. This study examined the historical extent of intertidal marsh at the mouth of the Pascagoula River in Jackson County, Mississippi to determine whether marsh extent changed during the period 1955-2014 and …
Vulnerability Of Industrial Facilities In The Lower Mississippi River Industrial Corridor To Relative Sea Level Rise And Tropical Cyclone Storm Surge, Joseph Blake Harris
Vulnerability Of Industrial Facilities In The Lower Mississippi River Industrial Corridor To Relative Sea Level Rise And Tropical Cyclone Storm Surge, Joseph Blake Harris
LSU Doctoral Dissertations
Relative sea level rise (RSLR) and tropical cyclone-induced storm surge are major threats to the Lower Mississippi River Industrial Corridor (LMRIC) which has approximately 120 industrial complexes located within the corridor. Spatial interpolation methods were applied to the 2004 National Oceanic and Atmospheric published Technical Report #50 subsidence dataset and cross-validation techniques were used to determine the accuracy of each method. Digital elevation models (DEMs) were created for the years 2025, 2050, and 2075, based on these predictive surface of subsidence rates. Future DEMs were utilized to model RSLR and determine the extent of storm surge on the LMRIC by …
Short Communication: Challenges And Applications Of Structure-From-Motion Photogrammetry In A Physical Model Of A Braided River, Peter Ashmore, Pauline Leduc, Sarah Peirce
Short Communication: Challenges And Applications Of Structure-From-Motion Photogrammetry In A Physical Model Of A Braided River, Peter Ashmore, Pauline Leduc, Sarah Peirce
Geography & Environment Publications
For extending the applications of structure-from-motion (SfM) photogrammetry in river flumes, we present the main challenges and methods used to collect a large dataset ( > 1000 digital elevation models, DEMs) of high-quality topographic data using close-range SfM photogrammetry. Automatic target detection, batch processing, and considerations for image quality were fundamental to the successful implementation of the SfM technique on such a large dataset, which was used primarily for capturing details of gravel-bed braided river morphodynamics and sedimentology. While the applications of close-range SfM photogrammetry are numerous, we include sample results from DEM differencing, which was used to quantify morphology change …
Mass Wasting Investigation And Assessment In The Midwest: Case Study Of The Minnesota River Valley, New Ulm To St. Peter, Minnesota, Usa, Melissa Kohout
Mass Wasting Investigation And Assessment In The Midwest: Case Study Of The Minnesota River Valley, New Ulm To St. Peter, Minnesota, Usa, Melissa Kohout
All Graduate Theses, Dissertations, and Other Capstone Projects
Many mass- wasting studies have been conducted worldwide, however, investigations have focused in mountainous or coastal regions. This has proven problematic in areas lacking those features yet are experiencing mass wasting. Several anthropogenic risks, economic loss, and environmental issues are associated with mass wasting such as destruction of property, loss of life, and sediment pollution. The midwestern USA, is generally considered a low relief region, therefore limited data exist for mass wasting occurrence. Within the last decade, however, several events have occurred across Minnesota with little understanding of the ongoing hillslope processes leading to failure. The Minnesota River valley is …
Cliff-Top Dunes In The Lower Chippewa River Valley Of West-Central Wisconsin, Jason Millett
Cliff-Top Dunes In The Lower Chippewa River Valley Of West-Central Wisconsin, Jason Millett
All Graduate Theses, Dissertations, and Other Capstone Projects
The purpose of this Master’s thesis is to investigate recently identified cliff-top sand dunes located within the Lower Chippewa River Valley (LCRV), Wisconsin, USA. Research within the LCRV notes the existence of a variety of aeolian deposits, but a comprehensive explanation of their complete spatial distribution, genesis, age, and paleoenvironmental significance does not exist. In particular, stabilized cliff-top dunes with a parabolic form remain poorly understood. This problem is exacerbated by a lack of clarity in the literature regarding the genesis of dunes in a cliff-top position. Therefore, this thesis begins by reviewing the literature concerning sand dunes in cliff-top …
Middle To Late Holocene (7200-2900 Cal. Bp) Archaeological Site Formation Processes At Crumps Sink And The Origins Of Anthropogenic Environments In Central Kentucky, Usa, Justin Nels Carlson
Middle To Late Holocene (7200-2900 Cal. Bp) Archaeological Site Formation Processes At Crumps Sink And The Origins Of Anthropogenic Environments In Central Kentucky, Usa, Justin Nels Carlson
Theses and Dissertations--Anthropology
Though some researchers have argued that the Big Barrens grasslands of Kentucky were the product of anthropogenic land clearing practices by Native Americans, heretofore, this hypothesis had not been tested archaeologically. More work was needed to refine chronologies of fire activity in the region, determine the extent to which humans played a role in the process, and integrate these findings with the paleoenvironmental and archaeological record. With these goals in mind, I conducted archaeological and geoarchaeological investigations at Crumps Sink in the Sinkhole Plain of Kentucky. The archaeological record and site formation history of Crumps Sink were compared with environmental …
Timing And Formation Of Linear Dunes South Of The Niobrara River Valley, North-Central Nebraska Sand Hills, Ashley K. Larsen
Timing And Formation Of Linear Dunes South Of The Niobrara River Valley, North-Central Nebraska Sand Hills, Ashley K. Larsen
Department of Geography: Dissertations, Theses, and Student Research
The Nebraska Sand Hills is a vast (7,500 square kilometer) area of grass-stabilized sand dunes. Larger dunes in the Nebraska Sand Hills formed primarily during the Late Pleistocene, but many underwent widespread reactivation during the Holocene. Recent Optically Stimulated Luminescence (OSL) dating indicates that the last major phase of reactivation in the Sand Hills was during the Medieval Warm Period, approximately 800 years ago. Nevertheless, many questions about the evolution of the dunes remain unanswered, particularly regarding the formation of linear dunes in portions of the Sand Hills.
This study seeks to understand more about the formation of linear dunes …
Keeping Pace With Relative Sea Level Rise: Marsh Platform Monitoring Shows Minimal Sediment Deficit Along The Louisiana Coast, Kelly Marie Sanks
Keeping Pace With Relative Sea Level Rise: Marsh Platform Monitoring Shows Minimal Sediment Deficit Along The Louisiana Coast, Kelly Marie Sanks
Graduate Theses and Dissertations
Recent reports estimate that the marshes of the Mississippi Delta receive just 30% of the sediment necessary to sustain current land area1. An extensive monitoring campaign by the USGS and LCPRA provides direct measurements of sediment accumulation, subsidence rates, and deposit characteristics along the coast over the past 10 years2, allowing us to directly evaluate this sediment balance. By interpolating bulk density, organic fraction, and vertical accretion rates from 273 sites, a direct measurement of organic and inorganic sediment accumulation can be made. Results show that a total of 82 MT/year of sediment is delivered to the coast. Using a …
Rates Of Planimetric Change In A Proglacial Gravel-Bed Braided River: Field Measurement And Physical Modeling, Lara Middleton, Peter Ashmore, Pauline Leduc, Darren Sjogren
Rates Of Planimetric Change In A Proglacial Gravel-Bed Braided River: Field Measurement And Physical Modeling, Lara Middleton, Peter Ashmore, Pauline Leduc, Darren Sjogren
Geography & Environment Publications
Planimetric change was measured on daily hydrographs over two meltwater seasons using time-lapse images of the proglacial, gravel, braided, Sunwapta River, Canada. Significant planimetric change occurred on 10-15 days per year. Area of planimetric change correlated with peak and total daily meltwater hydrograph discharge. A clear threshold discharge can be identified below which no planform activity occurs, an intermediate range over which change occurs conditionally, and a peak flow range at which significant change always occurs. Field conditions were reproduced in a physical model in a laboratory flume. Photogrammetric DEMs of bed morphology and measurements of bedload output were made …
Evolution Of Grain Size Distributions And Bed Mobility During Hydrographs In Gravel-Bed Braided Rivers, Sarah Peirce, Peter Ashmore, Pauline Leduc
Evolution Of Grain Size Distributions And Bed Mobility During Hydrographs In Gravel-Bed Braided Rivers, Sarah Peirce, Peter Ashmore, Pauline Leduc
Geography & Environment Publications
Evolution of bed material mobility and bedload grain size distributions under a range of discharges is rarely observed in braiding in gravel-bed rivers. Yet, the changing of bedload grain size distributions with discharge is expected to be different from laterally stable, threshold, channels on which most gravel bedload theory and observation are based. Here, simultaneous observations of flow, bedload transport rate, and morphological change were made in a physical model of a gravel-bed braided river to document the evolution of grain size distributions and bed mobility over three experimental event hydrographs. Bedload transport rate and grain size distributions were measured …
The Variability In The Morphological Active Width: Results From Physical Models Of Gravel‐Bed Braided Rivers, Sarah Peirce, Pauline Leduc, Peter Ashmore
The Variability In The Morphological Active Width: Results From Physical Models Of Gravel‐Bed Braided Rivers, Sarah Peirce, Pauline Leduc, Peter Ashmore
Geography & Environment Publications
The morphological active width, defined as the lateral extent of bed-material displacement over time, is a fundamental parameter in multi-threaded gravel-bed rivers, linking complex channel dynamics to bedload transport. Here, results are presented from 5 constant discharge experiments, and three event hydrographs, covering a range of flow strengths and channel configurations for which morphological change, bedload transport rates, and stream power were measured in a physical model. Changes in channel morphology were determined via differencing of photogrammetrically-derived digital elevation models (DEMs) of the model surface generated at regular intervals over the course of ~115 hours of experimental runs. Independent measures …
Assessing Land Deformation And Sea Encroachment In The Nile Delta, Egypt, Esayas Gebremichael
Assessing Land Deformation And Sea Encroachment In The Nile Delta, Egypt, Esayas Gebremichael
Research and Creative Activities Poster Day
Persistent scatterer interferometric analyses were conducted on a stack of 84 Envisat ASAR scenes spanning 7 years (2004 to 2010) over the entire Nile Delta of Egypt and surroundings to monitor the ongoing spatial and temporal land deformation, identify the factors controlling the deformation, and model the interplay between sea level rise and land subsidence to identify areas and populations threatened by sea encroachment by the end of the 21st century. Findings include: (1) general patterns of subsidence in the northern delta, near-steady (none) subsidence in the southern delta, separated by a previously mapped flexure zone undergoing uplift; (2) high …
Expanding The "Active Layer", Peter Ashmore, Sarah Peirce, Pauline Leduc
Expanding The "Active Layer", Peter Ashmore, Sarah Peirce, Pauline Leduc
Geography & Environment Publications
Church and Haschenburger (2017) make helpful distinctions around the issue of defining the active layer, with which we agree. We propose expanding discussion and definition of the ”active layer” in fluvial bedload transport to include the concept of the “morphological active layer”. This is particularly applicable to laterally unstable rivers (such as braided rivers) in which progressive morphological change over short time periods is the process by which much of the bedload transport occurs. The morphological active layer is also distinguished by variable lateral and longitudinal extent continuity over a range of flows and transport intensity. We suggest that the …
Flume Tests On Fluvial Erosion Mechanisms In Tillbed Channels, L Pike, Peter Ashmore, S Gaskin
Flume Tests On Fluvial Erosion Mechanisms In Tillbed Channels, L Pike, Peter Ashmore, S Gaskin
Geography & Environment Publications
Semi-alluvial stream channels eroded into till and other glacial sediments are common in areas of extensive glacial deposition such as the Great Lakes region and northern interior plains of North America. The mechanics of erosion and erosional weakness of till results in the dominance of fluvial scour and mass erosion due to spontaneous fracture at planes of weakness under shearing flow. There have been few controlled tests looking at erosional mechanisms and resistance of till in river channels.We subjected small blocks of till to unidirectional flows in a laboratory flume to measure the threshold shear stress for erosion and observed …