Lake-bottom thermal regimes, western Arctic coast, Canada

2005 ◽  
Vol 16 (4) ◽  
pp. 355-367 ◽  
Author(s):  
C. R. Burn
Keyword(s):  
Thermal Regimes ◽  
Lake Bottom ◽  
Western Arctic ◽  
Arctic Coast

Tundra lakes and permafrost, Richards Island, western Arctic coast, Canada

2002 ◽  
Vol 39 (8) ◽  
pp. 1281-1298 ◽  
Author(s):  
C R Burn
Keyword(s):  
Snow Cover ◽  
Active Layer ◽  
Open Water ◽  
Active Layer Thickness ◽  
Equilibrium Conditions ◽  
Lake Bottom ◽  
Near Shore ◽  
Western Arctic ◽  
Arctic Coast ◽  
Average Size

Lakes, of average size 33 ha, occupy a quarter of the surface area of Richards Island, Northwest Territories. Most of the lakes have a central pool deeper than the thickness of winter ice, and many have prominent, shallow, littoral terraces. The relatively warm lake bottoms cause considerable disturbance to the surrounding continuous permafrost. Water and lake-bottom temperatures, the configuration of permafrost, and active-layer thickness were measured at a tundra lake between 1992 and 1997. The lake is oval, 1.6 km long, 800 m wide, and as deep as 13 m. Sandy terraces, covered by less than 1 m of water, extend over 100 m from the shore. The terraces are underlain by permafrost, which terminates almost vertically at their edge. The annual mean temperature measured at lake bottom in the central pool ranged between 1.5°C and 4.8°C, depending on depth, and between –0.2°C and –5°C on the terraces, due to differences in snow cover and proximity to the central pool. In consequence, the temperature of permafrost at 7 m depth in the terraces also varied, from –2°C near shore to –5°C in mid-terrace. The active layer in the terraces was uniformly 1.4 m deep. Geothermal modelling of talik configuration indicates that there is no permafrost beneath the central pool of the lake. The modelling indicates that, under equilibrium conditions, about one quarter of the lakes on Richards Island have taliks that penetrate permafrost, and at least 10–15% of the island is underlain by talik. Short-term climatic changes predicted for the region imply a small increase in summer lake-water temperature and an extension of the open-water season, accompanied by thicker snow cover in winter. Following such changes, with longer freeze-up and warmer terrace temperatures in winter, permafrost may not be sustainable in the lake terraces.

A full-scale field experiment (1978–1995) on the growth of permafrost by means of lake drainage, western Arctic coast: a discussion of the method and some results

1997 ◽  
Vol 34 (1) ◽  
pp. 17-33 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Heat Transfer ◽  
Groundwater Flow ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Freezing Point ◽  
Three Dimensional ◽  
Negative Temperature ◽  
Lake Bottom ◽  
Western Arctic ◽  
Arctic Coast

On 13 August 1978, a lake on the western Arctic coast was artificially drained, in a multidisciplinary experiment on the growth of permafrost on the unfrozen bottom of the drained lake. A bowl-shaped talik (unfrozen basin) with a maximum depth of about 32 m underlay the lake bottom prior to drainage. In the first winter after drainage, downward freezing started on the exposed lake bottom and upward freezing from permafrost beneath the talik. After drainage, the soft lake-bottom sediments hardened from water loss and freeze–thaw consolidation. Gradual thinning of the active layer at many sites was accompanied by ground uplift and the growth of aggradational ice. Downward and upward freezing has resulted in solute rejection, freezing-point depressions, pore-water expulsion from the freezing of the saturated lake-bottom sands, and convective heat transfer from groundwater flow in an open hydrologie system. The increasingly saline intrapermafrost groundwater, flowing at an increasingly negative temperature because of a freezing-point depression, has accelerated the rate of permafrost growth in the interpermafrost zone in the direction of flow. The experiment has demonstrated that the growth of permafrost at the drained lake site, and at other sites with groundwater flow, requires a three-dimensional conductive–convective heat transfer approach.

The Growth of Pingos, Western Arctic Coast, Canada

1973 ◽  
Vol 10 (6) ◽  
pp. 979-1004 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Growth Rate ◽  
Pore Water ◽  
Closed System ◽  
Water Pressure ◽  
Ice Core ◽  
Growth Stages ◽  
Size And Shape ◽  
Western Arctic ◽  
Arctic Coast ◽  
Strong Control

The growth rates of 11 closed system pingos have been measured, by means of precise levelling of permanent bench marks anchored well down into permafrost, for the 1969–1972 period. As pingo growth decreases from the summit to the base, growth of the ice-core decreases from the center out to the periphery. The pingos have grown up in the bottoms of lakes which have drained rapidly and thus become exposed to permafrost aggradation. The specific site of growth is usually in a small residual pond where permafrost aggradation is retarded. The size and shape of a residual pond exercises a strong control upon the size and shape of the pingo which grows within it. The ice-core thickness equals the sum of the pingo height above the lake flat and the depth of the residual pond in which the pingo grew. Pingos tend to grow higher rather than both higher and wider. Pingos are believed to grow more by means of ice segregation than by the freezing of a pool of water. The water source, and the associated positive pore water pressure, result from permafrost aggradation in sands and silts in the lake bottom under a closed system with expulsion of pore water. The fastest growth rate of an ice-core, for the Western Arctic Coast, is estimated at about 1.5 m/yr, for the first one or two years. After that, the growth rate decreases inversely as the square root of time. The largest pingos may continue to grow for more than 1000 yr. Four growth stages are suggested. At least five pingos have commenced growth since 1935. As an estimate, probably 50 or more pingos are now growing along the coast.

scholarly journals PERFORMANCE OP SAND-FILLED TUBE SHORE PROTECTION TUKTOYAKTUK, NORTH WEST TERRITORIES, CANADA

1982 ◽  
Vol 1 (18) ◽  
pp. 114
Author(s):  
V.K. Shah
Keyword(s):  
Large Majority ◽  
Natural Stone ◽  
Alternative Form ◽  
Shore Protection ◽  
Experimental Basis ◽  
North West ◽  
Western Arctic ◽  
Arctic Coast ◽  
North West Territories ◽  
North Latitude

Seawalls, revetments and groynes designed to protect shorelines require normally timber, natural stone or concrete for their construction. In Tuktoyaktuk, none of these materials is available and to avoid excessive costs, an alternative form of construction, using long sausage shaped tubes filled with sand, was devised on an experimental basis. Tuktoyaktuk is situated on the eastern side of Kugmallit Bay in the Western Arctic at north latitude of 69 deg. 27' and west longitude of 133 deg. 02'. It is approximately 90 miles north of Inuvik and 1450 miles northwest of Edmonton (figure 1). The area is mainly comprised of a long, narrow, boot-shaped peninsula oriented in approximately north-south direction, a complex lagoon, which has been developed as a harbour, east of the peninsula and an island straddling the mouth of the lagoon (figure 2). Certain dwellings exist at the southern and southeasterly shores of Tuktoyaktuk Harbour. A large majority of the inhabitants reside in settlements developed on the peninsula and the southern area linking the peninsula with the mainland. Tuktoyaktuk is used as a transfer point linking the Mackenzie River barge transport with coastwide shipping serving the western arctic seaboard and inland settlements and bases. As a result of this the TCJK settlement has grown to be the largest of the western arctic coast settlements.

Ice wedges on hillslopes and landform evolution in the late Quaternary, western Arctic coast, Canada

1995 ◽  
Vol 32 (8) ◽  
pp. 1093-1105 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Active Layer ◽  
Late Quaternary ◽  
Chronological Age ◽  
Bottom Slope ◽  
Thermally Induced ◽  
Landform Evolution ◽  
Ice Wedge ◽  
Western Arctic ◽  
Arctic Coast ◽  
The Mean

In rolling to hilly areas of the western Arctic coast of Canada, anti-syngenetic wedges, which by definition are those that grow on denudational slopes, are the most abundant type of ice wedge. Through prolonged slope denudation, hilltop epigenetic wedges can evolve into hillslope anti-syngenetic wedges, and some bottom-slope anti-syngenetic wedges, by means of deposition from upslope, can evolve into bottom-slope syngenetic wedges. The axis of a hillslope wedge is oriented perpendicular to the slope, so the wedge foliation varies according to the trend of the wedge with respect to the slope. Because the tops of hillslope wedges are truncated by slope recession, the mean chronological age of anti-syngenetic wedge ice decreases with time, so the growth record for an old wedge is incomplete. Summer and winter measurements show that a thermally induced net movement of the active layer of hillslope polygons tends to transport material from their centres towards their troughs independent of the trends of the troughs relative to the slope. Wedge-ice uplift, probably diapiric, has been measured. Some hillslope polygon patterns may predate the development of the present topography. Many Wisconsinan wedges, truncated and buried during the Hypsithermal period, have been reactivated by upward cracking.

The first 7 years (1978–1985) of ice wedge growth, Illisarvik experimental drained lake site, western Arctic coast

1986 ◽  
Vol 23 (11) ◽  
pp. 1782-1795 ◽  
Author(s):  
J. Ross Mackay
Keyword(s):  
Growth Rates ◽  
Linear Expansion ◽  
Temperature Dependent ◽  
Frozen Ground ◽  
Ice Wedge ◽  
Western Arctic ◽  
Arctic Coast ◽  
Coefficient Of Linear Expansion ◽  
Lake Site ◽  
Crack Widths

A large lake, measuring 600 m × 300 m and with a depth of nearly 5 m, was artificially drained on 13 August 1978. Observations on the formation, width, and depth of thermal contraction cracks for the first 7 years show that the crack profiles and ice wedge growth rates differ markedly from those of old ice wedges reported in the literature. The first winter's cracks had box-like profiles, with surface widths to 10 cm and depths to 2.5 m. Some cracks continued to widen and deepen, once opened in early winter, and then narrowed or even closed completely in summer. Mean growth rates for the ice wedges for the first few years have been as much as 3.5 cm/year. Temperature gradients at the time of first cracking have been in the range of 10–15 °C/m. The growth rate of young ice wedges is site specific and temperature dependent, varying with factors such as the temperature gradient, vegetation, and snow cover, so an estimate of the age of an ice wedge from its width will usually be impossible. A study of crack widths indicates that the apparent coefficient of linear expansion of frozen ground may be several times that of ice. Upward cracking has been proven.

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