Downward water movement into frozen ground, western arctic coast, Canada

Abstract

Field studies carried out mainly since 1975 in permafrost areas of Alaska, Canada, China, and the Soviet Union have been combined with the results of laboratory investigations to show that in summer water can move from the thawing active layer into the subjacent frozen active layer and under certain conditions even into the top of permafrost. Direct field evidence discussed includes: data from drilling and neutron probe logging, which show a summer increase in the ice content of already frozen ground; summer heave of heavemeters, with heave occurring in the frozen active layer; and increase in the ice content of the subjacent frozen ground in both permafrost and non-permafrost areas, caused by snowmelt infiltration. Indirect field and laboratory evidence is also added to support the direct lines of evidence. The conditions that favor the downward migration of water from thawed to frozen ground are examined in terms of thermally induced hydraulic gradients, hydraulic conductivity, content of unfrozen pore water, temperature gradients, ice content, and gravity. Some geocryologic implications of the summer growth of ice in frozen ground, including the effects on water balance calculations and the origin of patterned ground, are briefly mentioned.

Bank‐collapse processes in a valley‐bottom gully, western Iowa

“…Frost heave sometimes continued briefly after increasing air temperatures exceeded 0°C ( Figure 9A and D), a phenomenon observed in other studies (Mackay, 1983;Cheng and Chamberlain, 1988;Zhang and Kushwaha, 1998) that probably reflects transient disequilibrium between air and ground temperature. Overall, however, our data ( Figure 9) provide little evidence for such disequilibrium, indicating perhaps that ice growth occurred in zones close to the ground surface or in cracks that intersected the ground surface.…”

Le pergélisol au Québec nordique : bilan et perspectives

“…En plus des observations et des descriptions de profils de sols et de fentes de gel, la mise en place d'instruments aux sites-échantillons est primordiale pour mesurer les dé-formations du terrain, de même que les variations de la teneur en eau et en glace du mollisol (cf. MACKAY, 1984MACKAY, , 1983MACKAY et MACKAY, 1976;MICHEL et FRITZ, 1978;SMITH, 1985).…”

The international structure of a pala and a peat plateau in the Rivière Boniface region, Québec: Interferences on the formation of ice segregation mounds

“…9). A dual origin was proposed for such layers: 1) enrichment in ice from infiltration of water in summer, from the active layer into the upper permafrost along the reversed thermal gradient and, 2) upward migration of the permafrost table following surface sedimentation or climatic cooling (Burn, 1988;Shur, 1988;Cheng, 1983;Mackay, 1983). Recently, An and Allard (1995) modeled that such ice enrichment takes place in palsas that have a peat cover thinner than the active layer and in "mineral" or "cryogenic" mounds that have no peat cover.…”