scholarly journals Seasonal Variation of Drainage System in the Lower Ablation Area of a Monsoonal Temperate Debris-Covered Glacier in Mt. Gongga, South-Eastern Tibet

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1050 ◽  
Author(s):  
Qiao Liu ◽  
Shiyin Liu ◽  
Wulong Cao
Keyword(s):  
Seasonal Variation ◽  
Dispersion Model ◽  
Drainage System ◽  
Hydrodynamic Dispersion ◽  
Ablation Area ◽  
Advection Dispersion ◽  
Dye Tracer ◽  
Eastern Tibet ◽  
Glacier Ice ◽  
Subglacial Drainage

Seasonal evolution of the subglacial drainage system in the lower ablation area of the Hailuogou glacier ice tongue were revealed by repeated dye tracer (Rhodamine WT) experiments during the 2009 ablation season. Between April and October, 18 dye tracer experiments were conducted by injecting the tracer at one location of the lower ablation area of the Hailuogou Glacier to diagnose the seasonal variation of the subglacial drainage system of this section of glacier ice tongue. Using a simple advection-dispersion model (ADM), the flow velocity, hydrodynamic dispersion coefficient, and degree of tracer spreading were deduced. Tracer transit velocity through the tested subglacial channel varied from 0.148 to 0.555 m s−1 during the 2009 ablation season. Dispersivity showed a relatively high value than that found at other glaciers, which varied between 27.05 and 287.49 m2 s−1. Seasonal changes of these indexes indicated that the subglacial drainage system of the lower ablation area of the Hailougou Glacier is a relatively stable existing system in the case of its longitudinal shape, whereas its hydraulic efficiency is low in the early and late ablation seasons and high during the middle of summer due to subglacial channel expansion.

scholarly journals Subglacial drainage processes at a High Arctic polythermal valley glacier

2005 ◽  
Vol 51 (172) ◽  
pp. 15-24 ◽  
Author(s):  
Robert G. Bingham ◽  
Peter W. Nienow ◽  
Martin J. Sharp ◽  
Sarah Boon
Keyword(s):  
Drainage System ◽  
Structural Evolution ◽  
Subsequent Development ◽  
High Arctic ◽  
Breakthrough Curves ◽  
Ice Flow ◽  
Dye Tracer ◽  
Arctic Glacier ◽  
Tracer Experiments ◽  
Subglacial Drainage

AbstractDye-tracer experiments undertaken over two summer melt seasons at polythermal John Evans Glacier, Ellesmere Island, Canada, were designed to investigate the character of the subglacial drainage system and its evolution over a melt season. In both summers, dye injections were conducted at several moulins and traced to a single subglacial outflow. Tracer breakthrough curves suggest that supraglacial meltwater initially encounters a distributed subglacial drainage system in late June. The subsequent development and maintenance of a channelled subglacial network are dependent upon sustained high rates of surface melting maintaining high supraglacial inputs. In a consistently warm summer (2000), subglacial drainage became rapidly and persistently channelled. In a cooler summer (2001), distributed subglacial drainage predominated. These observations confirm that supraglacial meltwater can access the bed of a High Arctic glacier in summer, and induce significant structural evolution of the subglacial drainage system. They do not support the view that subglacial drainage systems beneath polythermal glaciers are always poorly developed. They do suggest that the effects on ice flow of surface water penetration to the bed of predominantly cold glaciers may be short-lived.

Simulations expérimentale et numérique de la dispersion hydrodynamique d'un effluent pollué en milieu côtier estuarien

1996 ◽  
Vol 23 (4) ◽  
pp. 820-837
Author(s):  
Nicolas K. Gidas ◽  
Vladimir G. Koutitonsky
Keyword(s):  
Physical Model ◽  
Coastal Waters ◽  
Numerical Study ◽  
Dispersion Model ◽  
Field Measurements ◽  
Hydrodynamic Dispersion ◽  
Advection Dispersion ◽  
Tracer Dispersion ◽  
Before And After ◽  
Estuarine Coastal

An experimental and numerical study was performed to measure and simulate the hydrodynamic dispersion of a pollutant effluent discharged by an outfall diffuser into an estuarine coastal zone near Rimouski, Canada. Field measurements of currents, tides, salinity, and winds were obtained in the vicinity of the injection site, and two tracer dispersion experiments were carried on in these coastal waters. The measurements were taken before and after the construction of the marine outfall diffuser. The similitude between the plume of a tracer (physical model) released into the coastal waters before construction and that of the real effluent (prototype) discharged at the same site was studied. A new coefficient of similitude was established, which allows to transpose the concentrations of the physical model tracer to the waste water concentrations of the prototype. The numerical simulation (2D) is performed with a hydrodynamic model and an advection–dispersion model of the MIKE21 system from the Danish Hydraulic Institute, using the so-called telescopic approach. The objective of these simulations was to predict, among other things, the pollutant effluent concentrations for critical hydrodynamic conditions relative to the aquatic ecosystem to be protected. The methodology elaborated was used for the management of the coastal environments subjected to pollution. Key words: simulation, hydrodynamics, advection–dispersion, numerical model, similitude, tide, effluent.

scholarly journals Large-scale integrated subglacial drainage around the former Keewatin Ice Divide, Canada reveals interaction between distributed and channelised systems

2020 ◽  
Author(s):  
Emma L. M. Lewington ◽  
Stephen J. Livingstone ◽  
Chris D. Clark ◽  
Andrew J. Sole ◽  
Robert D. Storrar
Keyword(s):  
Spatial Distribution ◽  
Dynamic Response ◽  
Large Scale ◽  
Water Pressure ◽  
Pressure Fluctuations ◽  
Drainage System ◽  
Different Types ◽  
Form Part ◽  
Subglacial Meltwater ◽  
Subglacial Drainage

Abstract. We identify and map traces of subglacial meltwater drainage around the former Keewatin Ice Divide, Canada from ArcticDEM data. Meltwater tracks, tunnel valleys and esker splays exhibit several key similarities, including width, spacing, their association with eskers and transitions to and from different types, which together suggest they form part of an integrated drainage signature. We collectively term these features 'meltwater corridors' and propose a new model for their formation, based on observations from contemporary ice masses, of pressure fluctuations surrounding a central conduit. We suggest that eskers record the imprint of a central conduit and meltwater corridors the interaction with the surrounding distributed drainage system. The widespread aerial coverage of meltwater corridors (5–36 % of the bed) provides constraints on the extent of basal uncoupling induced by basal water pressure fluctuations and variations in spatial distribution and evolution of the subglacial drainage system, which will modulate the ice dynamic response.

scholarly journals A History of Jökulhlaups from Strandline Lake, Alaska, U.S.A.

1985 ◽  
Vol 31 (109) ◽  
pp. 272-280 ◽  
Author(s):  
Matthew Sturm ◽  
Carl S. Benson
Keyword(s):  
North America ◽  
Release Mechanism ◽  
Contour Maps ◽  
Outburst Floods ◽  
Before And After ◽  
Glacier Ice ◽  
History Of ◽  
Subglacial Drainage

AbstractJökulhlaups, also known as outburst floods, have occurred every 1 to 5 years from Strandline Lake, one of the largest glacier-dammed lakes in North America. The development of a distinct calving embayment in the lobe of Triumvirate Glacier which dams the lake, as well as the filling of a number of supraglacier pools, appear to be reliable precursors to a jökulhlaup. Analysis of contour maps made from photographs taken immediately before and after the jökulhlaup of 17 September 1982 indicate that over 95% of the lake drains, a volume of approximately 7 × 108 m3 of water. The glacier lobe which dams the lake fractures and subsides during a jökulhlaup, indicating that the release mechanism is hydrostatic lifting of the ice off of a sub-glacial spillway. Evidence from the ice-free margins of the glacier suggests that the spillway may be controlled by bedrock. Large variation in the refilling period of Strandline Lake indicates that the subglacial drainage tunnels can remain open for as much as a few years after a jökulhlaup, before they become sealed by sediments and/or glacier ice.

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