scholarly journals Ground-penetrating radar measurements of debris thickness on Lirung Glacier, Nepal

2017 ◽  
Vol 63 (239) ◽  
pp. 543-555 ◽  
Author(s):  
MICHAEL McCARTHY ◽  
HAMISH PRITCHARD ◽  
IAN WILLIS ◽  
EDWARD KING
Keyword(s):  
Ground Penetrating Radar ◽  
Surface Energy Balance ◽  
Spatial Scales ◽  
Thickness Distribution ◽  
Ablation Zone ◽  
Ice Surface ◽  
Himalayan Glaciers ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Thickness Measurements

ABSTRACTSupraglacial debris thickness is a key control on the surface energy balance of debris-covered glaciers, yet debris thickness measurements are sparse due to difficulties of data collection. Here we use ground-penetrating radar (GPR) to measure debris thickness on the ablation zone of Lirung Glacier, Nepal. We observe a strong, continuous reflection, which we interpret as the ice surface, through debris layers of 0.1 to at least 2.3 m thick, provided that appropriate acquisition parameters were used while surveying. GPR measurements of debris thickness correlate well with pit measurements of debris thickness (r= 0.91, RMSE = 0.04 m) and two-way travel times are consistent at tie points (r= 0.97). 33% of measurements are <0.5 m, so sub-debris melting is likely important in terms of mass loss on the debris-covered tongue and debris thickness is highly variable over small spatial scales (of order 10 m), likely due to local slope processes. GPR can be used to make debris thickness measurements more quickly, over a wider debris thickness range, and at higher spatial resolution than any other means and is therefore a valuable tool with which to map debris thickness distribution on Himalayan glaciers.

The spatial correlation between track roughness and ground-penetrating radar inferred ballast degradation

2018 ◽  
Vol 232 (7) ◽  
pp. 1917-1931
Author(s):  
Kirk M Scanlan ◽  
Michael T Hendry ◽  
C Derek Martin ◽  
Douglas R Schmitt
Keyword(s):  
Ground Penetrating Radar ◽  
Large Scale ◽  
Spatial Scales ◽  
Radar Data ◽  
Detection Tool ◽  
Heavy Haul ◽  
Surface Measurements ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Heavy Haul Railway

Ballast degradation is considered to be a primary factor that contributes to the development of track roughness, and as such it is important to develop efficient techniques to assess the condition of the ballast. Ground-penetrating radar is one method that has been applied in a variety of railway foundation studies including those attempting to non-destructively assess ballast degradation. However, there has yet to be a large-scale study that attempts to correlate the ground-penetrating radar-based estimates of ballast degradation with the observed track roughness. This study investigates this correlation along a 335 km-long heavy-haul railway subdivision in Alberta, Canada. Track roughness is quantified from repeated track alignment and surface measurements spanning 15 months prior to the ground-penetrating radar data acquisition. Three sets of 400 MHz ground-penetrating radar measurements were performed in August 2012, one along each ballast shoulder and one along the track centreline. The results of this study reveal that significant correlations between the observed track roughness and the ground-penetrating radar-based interpretation of ballast degradation are rare and only exist when the data are compared at very small spatial scales. The absence of significant correlations between track roughness and the estimates of ballast degradation is primarily interpreted as being the result of ambiguous ground-penetrating radar data caused by local-scale variations in the track foundation unrelated to ballast degradation. To address these issues, potential improvements in the application of ground-penetrating radar as a ballast degradation detection tool are proposed.

scholarly journals Ice thickness distribution of all Swiss glaciers based on extended ground-penetrating radar data and glaciological modeling

2021 ◽  
pp. 1-19
Author(s):  
Melchior Grab ◽  
Enrico Mattea ◽  
Andreas Bauder ◽  
Matthias Huss ◽  
Lasse Rabenstein ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Thickness Distribution ◽  
Radar Data ◽  
Tourism Industry ◽  
Swiss Alps ◽  
Ice Thickness ◽  
Hazard Management ◽  
Bed Topography ◽  
Ice Volume ◽  
Ground Penetrating

Abstract Accurate knowledge of the ice thickness distribution and glacier bed topography is essential for predicting dynamic glacier changes and the future developments of downstream hydrology, which are impacting the energy sector, tourism industry and natural hazard management. Using AIR-ETH, a new helicopter-borne ground-penetrating radar (GPR) platform, we measured the ice thickness of all large and most medium-sized glaciers in the Swiss Alps during the years 2016–20. Most of these had either never or only partially been surveyed before. With this new dataset, 251 glaciers – making up 81% of the glacierized area – are now covered by GPR surveys. For obtaining a comprehensive estimate of the overall glacier ice volume, ice thickness distribution and glacier bed topography, we combined this large amount of data with two independent modeling algorithms. This resulted in new maps of the glacier bed topography with unprecedented accuracy. The total glacier volume in the Swiss Alps was determined to be 58.7 ± 2.5 km3 in the year 2016. By projecting these results based on mass-balance data, we estimated a total ice volume of 52.9 ± 2.7 km3 for the year 2020. Data and modeling results are accessible in the form of the SwissGlacierThickness-R2020 data package.

Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar

2009 ◽  
Vol 40 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Nils Granlund ◽  
Angela Lundberg ◽  
James Feiccabrino ◽  
David Gustafsson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Laboratory Test ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Relationship

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

Large-area high-resolution ground-penetrating radar measurements for archaeological prospection

2018 ◽  
Vol 25 (3) ◽  
pp. 171-195 ◽  
Author(s):  
Immo Trinks ◽  
Alois Hinterleitner ◽  
Wolfgang Neubauer ◽  
Erich Nau ◽  
Klaus Löcker ◽  
...  
Keyword(s):  
High Resolution ◽  
Ground Penetrating Radar ◽  
Large Area ◽  
Archaeological Prospection ◽  
Radar Measurements ◽  
Ground Penetrating

Ice thickness, volume and subglacial relief of Ashuu-Tor, Bordu, Kara-Batkak and Golubina glaciers (Central-Asia) derived from GPR measurements and different approaching methods

2020 ◽  
Author(s):  
Lander Van Tricht ◽  
Philippe Huybrechts ◽  
Jonas Van Breedam ◽  
Johannes Fuerst ◽  
Oleg Rybak ◽  
...  
Keyword(s):  
Central Asia ◽  
Thickness Distribution ◽  
Mass Conservation ◽  
Tien Shan ◽  
Ice Age ◽  
Ice Thickness ◽  
Mountain Range ◽  
Lake Formation ◽  
Ground Penetrating ◽  
Thickness Measurements

&lt;p&gt;Glaciers in the Tien Shan (Central-Asia) mountains contribute a considerable part of the freshwater used for irrigation and households in the dry lowland areas of Kyrgyzstan and its neighbouring countries. Since the Little Ice Age, the total ice mass in this mountain range has been decreasing significantly. However, accurate measurements of the current ice volume and ice thickness distribution in the Tien Shan remain scarce, and accurate data is largely lacking at the local scale. In 2016, 2017 and 2019, we organized 1-month field campaigns in Central-Asia to sound the ice thickness of four different glaciers in the Tien Shan using a Narod ground penetrating radar (GPR) system.&lt;/p&gt;&lt;p&gt;Here, we present and discuss our in-situ ice thickness measurements of the four glaciers. We performed in total more than 1000 GPR soundings. We found a maximum ice thickness of 200 meters in the central part of the southern facing Ashuu-Tor glacier. On both Bordu and Golubina, we measured ice thicknesses up to 140 meters. Kara-Batkak was found to have the thinnest ice which is in agreement to the large average slope of this glacier. We extended all the ice thickness measurements to the entire glacier surfaces using three different methods based on the assumption of plastic flow (method 1) and the principle of mass conservation (method 2 &amp; 3) and assessed their differences.&lt;/p&gt;&lt;p&gt;In this research, we show a detailed ice thickness distribution of Ashuu-Tor, Bordu, Golubina and Kara-Batkak glaciers. This can be used for glaciological modelling and assessing ice and water storage. We also point out the locations of potential lake formation in bedrock overdeepenings as a succession of glacier retreat.&lt;/p&gt;

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