Ground‐penetrating radar profiles of rubble‐covered temperate glaciers: Results from the Tasman and Mueller glaciers of the Southern Alps of New Zealand

1994 ◽  
Author(s):  
David C. Nobes ◽  
S. F. Leary ◽  
M. P. Hochstein ◽  
S. A. Henry
Keyword(s):  
New Zealand ◽  
Ground Penetrating Radar ◽  
Southern Alps ◽  
Ground Penetrating

scholarly journals Assessing Ground Penetrating Radar's Ability to Image Subsurface Characteristics of Icy Debris Fans in Alaska and New Zealand

2018 ◽  
Vol 23 (4) ◽  
pp. 423-436 ◽  
Author(s):  
Robert W. Jacob ◽  
Jeffrey M. Trop ◽  
R. Craig Kochel
Keyword(s):  
New Zealand ◽  
Ground Penetrating Radar ◽  
Transverse Electric ◽  
Transverse Magnetic ◽  
Glacial Ice ◽  
Signal Velocity ◽  
Alpine Regions ◽  
Flow Processes ◽  
Ground Penetrating ◽  
Antenna Polarization

Icy debris fans have recently been described as fan shaped depositional landforms associated with (or formed during) deglaciation, however, the subsurface characteristics remain essentially undocumented. We used ground penetrating radar (GPR) to non-invasively investigate the subsurface characteristics of icy debris fans (IDFs) at McCarthy Glacier, Alaska, USA and at La Perouse Glacier, South Island of New Zealand. IDFs are largely unexplored paraglacial landforms in deglaciating alpine regions at the mouths of bedrock catchments between valley glaciers and icecaps. IDFs receive deposits of mainly ice and minor lithic material through different mass-flow processes, chiefly ice avalanche and to a lesser extent debris flow, slushflow, and rockfall. We report here on the GPR signal velocity observed from 15 different wide-angle reflection/refraction (WARR) soundings on the IDFs and on the McCarthy Glacier; the effect of GPR antenna orientation relative to subsurface reflections; the effect of spreading direction of the WARR soundings relative to topographic contour; observed differences between transverse electric (TE) and transverse magnetic (TM) antenna polarization; and a GPR profile extending from the McCarthy Glacier onto an IDF. Evaluation of the WARR soundings indicates that the IDF deposits have a GPR signal velocity that is similar to the underlying glacier, and that the antenna polarization and orientation did not prevent identification of GPR reflections. The GPR profile on the McCarthy Glacier indicates that the shallowest material is layered, decreases in thickness down fan, and has evidence of brittle failure planes (crevasses). The GPR profile and WARR soundings collected in 2013 indicate that the thickness of the McCarthy Glacier is 82 m in the approximate middle of the cirque and that the IDF deposits transition with depth into flowing glacial ice.

scholarly journals Assessment of a snow storage gradient across a maritime mountain environment: a ground penetrating radar investigation

2021 ◽  
Author(s):  
◽  
Lawrence J. Kees
Keyword(s):  
Ground Penetrating Radar ◽  
Snow Depth ◽  
River Discharge ◽  
Measurement Techniques ◽  
Southern Alps ◽  
Study Region ◽  
Snow Storage ◽  
Atmospheric Circulation Indices ◽  
Snow Distribution ◽  
Ground Penetrating

<p>The Southern Alps of New Zealand experience some of the highest precipitation rates globally, and dramatic west to east climatic gradients. Our current knowledge of this precipitation distribution is based on weather station data and river discharge measurements, but there is a clear data gap in the high elevation, central Southern Alps. Here, estimates of precipitation strongly diverge. This problem exists because of the difficulties of quantifying the depth and distribution of snow in a remote, high-altitude mountainous region.  In order to improve our knowledge of snow distribution within this data-poor region, snow depths of (< 10m) were assessed parallel to the prevailing westerly wind direction at five locations across the mountain range, between the névé of Franz Josef Glacier, Waiho catchment, to the west and Jollie Valley, Pukaki catchment, in the east. The geophysical method of Ground Penetrating Radar (GPR) was used because of its ability to image the deep snow packs experienced in the study region.  Comparison of measurement techniques over the (< 3km) surveyed transects showed that ground-based GPR gave the best sample size (41000 samples) and accuracy due to the high spatial resolution. Airborne GPR (8571 samples) overestimated snow depth by 8 % in low-gradient homogenous terrain, and 24% in steep heterogeneous terrain. The difference is ascribed to the larger view area of the GPR in the airborne survey. Direct probing of snow depth also performed poorly in comparison to ground-based GPR when generalising snow distribution over an area.  Across-mountain precipitation peaked ~5 km west of the main divide, between 1700 and 2000 m a.s.l, providing the first empirical support to existing estimates of the location of peak precipitation. Results show decreasing precipitation from 12 ma-1 at Franz Josef Glacier, in the Waiho catchment, to 1.8 ma-1 at Jollie River valley, in the Lake Pukaki catchment, 25 km to the south-east.  Internal reflection horizons in snow-pack radargrams allowed snowfall events to be tracked, and a relationship lowland and mountain precipitation to be established. Snowfall accumulation 'factors' were derived for different atmospheric circulation indices, and these will enable improved accuracy in modelling of snow accumulation processes. Further research is required to refine the relationship between synoptic-classed accumulation rates and inter-annual variations in climatic circulation.  These refinements of measurement techniques and quantification of and snow distribution and depth allow for better estimation of river discharge and timing estimates for, hydroelectric power generation, and glacier mass balance.</p>

Complex internal architecture of a debris-flow deposit revealed using ground-penetrating radar, Cass, New Zealand

2013 ◽  
Vol 69 (1) ◽  
pp. 26-38 ◽  
Author(s):  
Colette C.A. Starheim ◽  
Christopher Gomez ◽  
Justin Harrison ◽  
Claire Kain ◽  
Nicholas J. Brewer ◽  
...  
Keyword(s):  
New Zealand ◽  
Debris Flow ◽  
Ground Penetrating Radar ◽  
Debris Flow Deposit ◽  
Flow Deposit ◽  
Ground Penetrating ◽  
Internal Architecture
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