scholarly journals Character of the Englacial and Subglacial Drainage System in the Lower Part of the Ablation Area of Storglaciären, Sweden, as Revealed by Dye-Trace Studies

1988 ◽  
Vol 34 (117) ◽  
pp. 217-227 ◽  
Author(s):  
Sheliah Z. Seaberg ◽  
John Z. Seaberg ◽  
Roger Leb. Hooke ◽  
Daniel W. Wiberg
Keyword(s):  
Hydraulic System ◽  
Dispersion Coefficient ◽  
Water Pressure ◽  
Drainage System ◽  
Water Velocity ◽  
Northern Sweden ◽  
Late Season ◽  
Valley Glacier ◽  
Small Valley ◽  
Glacial Streams

AbstractDuring the 1984 and 1985 melt seasons, flow velocities and dispersive characteristics of the englacial and subglacial hydraulic system on Storglaciären, a small valley glacier in northern Sweden, were studied with the use of dye-trace tests. Similar tests conducted on one of the two principal pro-glacial streams provided a basis for comparison of the combined englacial-subglacial system with the pro-glacial one. Velocities in the two systems were broadly comparable after compensating for the effect of slope differences. However, velocities in the glacial conduits increased almost linearly with discharge. Analysis suggests that this can be explained by an increase in water pressure in the conduits, combined with a decrease in effective sinuosity, as discharge increases. Dispersivity (the ratio of the dispersion coefficient to the water velocity) in the glacial system is high early in the season but decreases progressively during July. This is believed to reflect a change from an extensively braided to a more integrated drainage system. Dispersivity is only slightly lower in the pro-glacial streams than in the late-season glacial conduits, suggesting similar degrees of braiding. However, retardation of dye due to temporary storage is greater in the glacial conduits. This suggests that the glacial streams have a larger number of stable eddies in which dye can be trapped for extended periods of time.

scholarly journals Character of the Englacial and Subglacial Drainage System in the Lower Part of the Ablation Area of Storglaciären, Sweden, as Revealed by Dye-Trace Studies

1988 ◽  
Vol 34 (117) ◽  
pp. 217-227 ◽  
Author(s):  
Sheliah Z. Seaberg ◽  
John Z. Seaberg ◽  
Roger Leb. Hooke ◽  
Daniel W. Wiberg
Keyword(s):  
Hydraulic System ◽  
Dispersion Coefficient ◽  
Water Pressure ◽  
Drainage System ◽  
Water Velocity ◽  
Northern Sweden ◽  
Late Season ◽  
Valley Glacier ◽  
Small Valley ◽  
Glacial Streams

AbstractDuring the 1984 and 1985 melt seasons, flow velocities and dispersive characteristics of the englacial and subglacial hydraulic system on Storglaciären, a small valley glacier in northern Sweden, were studied with the use of dye-trace tests. Similar tests conducted on one of the two principal pro-glacial streams provided a basis for comparison of the combined englacial-subglacial system with the pro-glacial one. Velocities in the two systems were broadly comparable after compensating for the effect of slope differences. However, velocities in the glacial conduits increased almost linearly with discharge. Analysis suggests that this can be explained by an increase in water pressure in the conduits, combined with a decrease in effective sinuosity, as discharge increases. Dispersivity (the ratio of the dispersion coefficient to the water velocity) in the glacial system is high early in the season but decreases progressively during July. This is believed to reflect a change from an extensively braided to a more integrated drainage system. Dispersivity is only slightly lower in the pro-glacial streams than in the late-season glacial conduits, suggesting similar degrees of braiding. However, retardation of dye due to temporary storage is greater in the glacial conduits. This suggests that the glacial streams have a larger number of stable eddies in which dye can be trapped for extended periods of time.

scholarly journals Determining the extent of pressurized flow beneath Storglaciären, Sweden, using results of tracer experiments and measurements of input and output discharge

1995 ◽  
Vol 41 (138) ◽  
pp. 217-231 ◽  
Author(s):  
Jack Kohler
Keyword(s):  
Open Channel ◽  
Drainage System ◽  
Tracer Tests ◽  
Tracer Experiment ◽  
Northern Sweden ◽  
Discharge Data ◽  
Input And Output ◽  
Valley Glacier ◽  
Small Valley ◽  
Tracer Experiments

AbstractTwo experiments were conducted on the drainage system beneath the Lower part of the ablation zone of Storglaciären, a small valley glacier in northern Sweden. In the first experiment, over 70 tracer tests were performed in a cluster of moulins during a 1 month period, at sub-daily intervals. In the second experiment, input- and output-discharge signals were measured on the supraglacial melt stream emptying into a moulin and on the proglacial stream to which the moulin drains. The data from these two experiments are used in an idealized model of the subglacial drainage system to calculate the percentage of the system flowing as an open channel. Results from the tracer experiment suggest that the system is pressurized to within 60-340 m of the snout, while analysis of the discharge data indicates pressurized ronduits to within 0-415 m of the snout.

scholarly journals Determining the extent of pressurized flow beneath Storglaciären, Sweden, using results of tracer experiments and measurements of input and output discharge

1995 ◽  
Vol 41 (138) ◽  
pp. 217-231 ◽  
Author(s):  
Jack Kohler
Keyword(s):  
Open Channel ◽  
Drainage System ◽  
Tracer Tests ◽  
Tracer Experiment ◽  
Northern Sweden ◽  
Discharge Data ◽  
Input And Output ◽  
Valley Glacier ◽  
Small Valley ◽  
Tracer Experiments

AbstractTwo experiments were conducted on the drainage system beneath the Lower part of the ablation zone of Storglaciären, a small valley glacier in northern Sweden. In the first experiment, over 70 tracer tests were performed in a cluster of moulins during a 1 month period, at sub-daily intervals. In the second experiment, input- and output-discharge signals were measured on the supraglacial melt stream emptying into a moulin and on the proglacial stream to which the moulin drains. The data from these two experiments are used in an idealized model of the subglacial drainage system to calculate the percentage of the system flowing as an open channel. Results from the tracer experiment suggest that the system is pressurized to within 60-340 m of the snout, while analysis of the discharge data indicates pressurized ronduits to within 0-415 m of the snout.

scholarly journals Water pressure and basal sliding on Storglaciären, northern Sweden

1995 ◽  
Vol 41 (138) ◽  
pp. 232-240 ◽  
Author(s):  
Peter Jansson
Keyword(s):  
Water Pressure ◽  
Surface Velocity ◽  
Northern Sweden ◽  
Overburden Pressure ◽  
Weakly Coupled ◽  
Basal Sliding ◽  
Order Of Magnitude ◽  
Image Position ◽  
Hydraulic Jacking ◽  
Small Valley

AbstractThe subglacial hydrology of the ablation area of Storglaciären, a small valley glacier in northern Sweden, is dramatically affected by a subglacial ridge, or riegel. Water pressures above this riegel are relatively constant, while down-glacier from it they vary significantly. The lower part of the glacier accelerates in response to peaks in basal water pressure. The upper part may be weakly coupled to the lower part during these peaks.A power-law fit of observed basal water pressures and measured surface velocities yieldswhereusis the surface velocity andPEis the effective water pressure (ice overburden pressure minus subglacial water pressure). Data from Findelengletscher, reported by Iken and Bindschadler (1986), yield an identical exponent and a coefficient one order of magnitude larger. The similar exponent implies that the process producing the velocity variations on both glaciers is similar. The variations in velocity are inferred to be due to hydraulic jacking on both glaciers.

Character of the Englacial and Subglacial Drainage System in the Upper Part of the Ablation Area of Storglaciären, Sweden

1988 ◽  
Vol 34 (117) ◽  
pp. 228-231 ◽  
Author(s):  
Roger Leb. Hooke ◽  
Sarah B. Miller ◽  
Jack Kohler
Keyword(s):  
Coming Out ◽  
Drainage System ◽  
Tracer Tests ◽  
Equilibrium Line ◽  
Injection Point ◽  
Warm Up ◽  
Glacier Terminus ◽  
Valley Glacier ◽  
Pressure Melting ◽  
Small Valley

AbstractOn 4 July 1986, dye was injected at a point slightly above the equilibrium line on Storglaciären, a small valley glacier in northern Sweden. Just below the equilibrium line, the glacier bed is over-deepened. The dye re-appeared in a stream at the glacier terminus over the next 35 d. This stream normally carries relatively little sediment, in constrast to the situation in another nearby stream that also emerges from the glacier. This suggests that the dye traveled in englacial rather than subglacial conduits. Tracer tests utilizing salt in bore holes in the overdeepening support this interpretation, as the bore holes were draining well above the bed. The dye appeared during three distinct events, suggesting that it became divided into at least three separate parcels shortly after injection. This probably occurred in the crevassed area in the vicinity of the injection point.The englacial location of the drainage may be explained by the fact that, in order to remain at the pressure melting-point, water in subglacial conduits coming out of the overdeepening may have had to warm up faster than would be possible by viscous heating alone. Such conduits would thus tend to freeze closed.

scholarly journals TV-video observations of bed and basal sliding on Storglaciären, Sweden

1993 ◽  
Vol 39 (131) ◽  
pp. 111-118 ◽  
Author(s):  
Veijo Allan Pohjola
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Northern Sweden ◽  
Stress Release ◽  
Video Observations ◽  
Valley Glacier ◽  
Local Topography ◽  
Basal Sliding ◽  
Background Motion ◽  
Small Valley

AbstractFour boreholes in Storglaciären, a small valley glacier in northern Sweden, were inspected with a video camera. In two of the boreholes, the apparent glacier bed was filmed. In one borehole, the bed was found to be composed of soft sediment, but in the other it consisted of bedrock. In the latter, the camera moved 5.6 mm relative to the bed during an 80 min period. The recorded camera movement showed a background motion which is in the expected range of basal sliding. Superimposed on the background motion, a jerky motion of a high-speed spike was found. The jerky motion is interpreted as a stress release induced by local topography at the ice–bed interface.

scholarly journals Water pressure and basal sliding on Storglaciären, northern Sweden

1995 ◽  
Vol 41 (138) ◽  
pp. 232-240 ◽  
Author(s):  
Peter Jansson
Keyword(s):  
Water Pressure ◽  
Surface Velocity ◽  
Northern Sweden ◽  
Overburden Pressure ◽  
Weakly Coupled ◽  
Basal Sliding ◽  
Order Of Magnitude ◽  
Image Position ◽  
Hydraulic Jacking ◽  
Small Valley

AbstractThe subglacial hydrology of the ablation area of Storglaciären, a small valley glacier in northern Sweden, is dramatically affected by a subglacial ridge, or riegel. Water pressures above this riegel are relatively constant, while down-glacier from it they vary significantly. The lower part of the glacier accelerates in response to peaks in basal water pressure. The upper part may be weakly coupled to the lower part during these peaks.A power-law fit of observed basal water pressures and measured surface velocities yieldswhere us is the surface velocity and PE is the effective water pressure (ice overburden pressure minus subglacial water pressure). Data from Findelengletscher, reported by Iken and Bindschadler (1986), yield an identical exponent and a coefficient one order of magnitude larger. The similar exponent implies that the process producing the velocity variations on both glaciers is similar. The variations in velocity are inferred to be due to hydraulic jacking on both glaciers.

scholarly journals Character of the Englacial and Subglacial Drainage System in the Upper Part of the Ablation Area of Storglaciären, Sweden

1988 ◽  
Vol 34 (117) ◽  
pp. 228-231 ◽  
Author(s):  
Roger Leb. Hooke ◽  
Sarah B. Miller ◽  
Jack Kohler
Keyword(s):  
Coming Out ◽  
Drainage System ◽  
Tracer Tests ◽  
Equilibrium Line ◽  
Injection Point ◽  
Warm Up ◽  
Glacier Terminus ◽  
Valley Glacier ◽  
Pressure Melting ◽  
Small Valley

AbstractOn 4 July 1986, dye was injected at a point slightly above the equilibrium line on Storglaciären, a small valley glacier in northern Sweden. Just below the equilibrium line, the glacier bed is over-deepened. The dye re-appeared in a stream at the glacier terminus over the next 35 d. This stream normally carries relatively little sediment, in constrast to the situation in another nearby stream that also emerges from the glacier. This suggests that the dye traveled in englacial rather than subglacial conduits. Tracer tests utilizing salt in bore holes in the overdeepening support this interpretation, as the bore holes were draining well above the bed. The dye appeared during three distinct events, suggesting that it became divided into at least three separate parcels shortly after injection. This probably occurred in the crevassed area in the vicinity of the injection point.The englacial location of the drainage may be explained by the fact that, in order to remain at the pressure melting-point, water in subglacial conduits coming out of the overdeepening may have had to warm up faster than would be possible by viscous heating alone. Such conduits would thus tend to freeze closed.

scholarly journals TV-video observations of bed and basal sliding on Storglaciären, Sweden

1993 ◽  
Vol 39 (131) ◽  
pp. 111-118 ◽  
Author(s):  
Veijo Allan Pohjola
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Northern Sweden ◽  
Stress Release ◽  
Video Observations ◽  
Valley Glacier ◽  
Local Topography ◽  
Basal Sliding ◽  
Background Motion ◽  
Small Valley

AbstractFour boreholes in Storglaciären, a small valley glacier in northern Sweden, were inspected with a video camera. In two of the boreholes, the apparent glacier bed was filmed. In one borehole, the bed was found to be composed of soft sediment, but in the other it consisted of bedrock. In the latter, the camera moved 5.6 mm relative to the bed during an 80 min period. The recorded camera movement showed a background motion which is in the expected range of basal sliding. Superimposed on the background motion, a jerky motion of a high-speed spike was found. The jerky motion is interpreted as a stress release induced by local topography at the ice–bed interface.

Nuovi dati sul popolamento nella pianura di Tarquinia durante la romanizzazione. Il caso della località "Il Giglio"

2008 ◽  
Vol 1 ◽  
pp. 123-135
Author(s):  
Maria Gabriella Scapaticci
Keyword(s):  
Middle Ages ◽  
Hydraulic System ◽  
Drainage System ◽  
Natural Fertility ◽  
Second Punic War ◽  
System Part ◽  
The Military ◽  
The Hill ◽  
Military Enterprise ◽  
The Middle Ages

During works for a communal athletic-ground at Tarquinia in the district “Il Giglio”, which took place between 2000 and 2001, some slight remains of ancient structures of the Late-Republican and Early-Imperial Age were accidentally discovered. The Soprintendenza per i Beni Archeologici dell’Etruria Meridionale then undertook extensive excavations, documenting a farm and an interesting hydraulic system, part of which had already been found not far from there, at Tarquinia in the district “Gabelletta”. The part of the plain of Tarquinia that is located at the foot of the hill, where Corneto was later established in the Middle Ages, was intensively cultivated with a drainage system and very extensive canalizations, because of the natural fertility of the soil and the richness of water-supplies in this region. It is thus likely that the flax for which Tarquinia was famous in antiquity was cultivated in these fields, and that, towards the end of the second Punic War, this farmland supplied Rome with the flax to make the sails destined for the military enterprise.

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