Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Geography (4)
- Social and Behavioral Sciences (4)
- Physical and Environmental Geography (3)
- Environmental Sciences (2)
- Geology (2)
-
- Hydrology (2)
- Sedimentology (2)
- Water Resource Management (2)
- Applied Statistics (1)
- Astrophysics and Astronomy (1)
- Climate (1)
- Fluid Dynamics (1)
- Geophysics and Seismology (1)
- Glaciology (1)
- Instrumentation (1)
- Multivariate Analysis (1)
- Oceanography and Atmospheric Sciences and Meteorology (1)
- Other Earth Sciences (1)
- Physical Processes (1)
- Physics (1)
- Soil Science (1)
- Statistics and Probability (1)
- Stratigraphy (1)
- The Sun and the Solar System (1)
- Publication
- Publication Type
Articles 1 - 7 of 7
Full-Text Articles in Geomorphology
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 …
Characterizing Ice-Wedge Polygon Geomorphology In The Haughton Impact Structure, Devon Island, Jordan Hawkswell
Characterizing Ice-Wedge Polygon Geomorphology In The Haughton Impact Structure, Devon Island, Jordan Hawkswell
Electronic Thesis and Dissertation Repository
Ice-wedge polygon networks are a common feature in periglacial environments formed through thermal contraction cracking and snowmelt infiltration. Polygons of similar morphology are ubiquitous throughout the mid-latitudes of Mars and are believed to have formed through thermal contraction processes. This study aims to characterize the polygons on Devon Island in the Canadian Arctic and the significant variations in geomorphology they display. The study uses LiDAR data to map, analyse, and compare three sites of polygonal terrain. Variations in polygon morphology such as size and orthogonality are observed in the relatively small study area. The results show that polygon morphologic variations …
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 Periglacial Landscape Of Mars: Insight Into The 'Decameter-Scale Rimmed Depressions' In Utopia Planitia, Arya Bina
Electronic Thesis and Dissertation Repository
Currently, Mars appears to be in a ‘frozen’ and ‘dry’ state, with the clear majority of the planet’s surface maintaining year-round sub-zero temperatures. However, the discovery of features consistent with landforms found in periglacial environments on Earth, suggests a climate history for Mars that may have involved freeze and thaw cycles. Such landforms include hummocky, polygonised, scalloped, and pitted terrains, as well as ice-rich deposits and gullies, along the mid- to high-latitude bands, typically with no lower than 20o N/S. The detection of near-surface and surface ice via the Phoenix lander, excavation of ice via recent impact cratering activity as …
Impact Craters On Titan: Finalizing Titan's Crater Population, Joshua E. Hedgepeth
Impact Craters On Titan: Finalizing Titan's Crater Population, Joshua E. Hedgepeth
Electronic Thesis and Dissertation Repository
Titan is one of the most dynamic moons in the solar system. It is smaller than Earth and much colder, yet Titan is eerily similar to Earth, with rivers, rain, and seas, as well as sand seas that wrap around the equator. However, the rivers are made of hydrocarbons rather than water and the sand made of organics rather rock. We can use Titan’s impact craters to study how these processes modify the surface by comparing the craters depths, diameters and rim heights of Titan’s craters with fresh craters. Therefore, we have used the complete data set from NASA’s Cassini …
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 …
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 …