Permafrost Hydrology

Abstract

Permafrost is earth material that has temperature at or below 0°C for at least two consecutive summers. Above the permafrost is the active layer, a zone that freezes in winter and thaws in summer. Even though the principles governing water movement in permafrost areas are the same as those in more temperate regions, interactions of extremes in climate and the land surface characteristics render permafrost hydrology different from the hydrology of temperate latitudes. Ice‐rich permafrost prevents infiltration of rainfall or snowmelt water, often maintaining a moist to saturated active layer where the permafrost table is shallow. Most hydrologic activities are confined above ground or in the thin active layer, which supplies summer moisture to plants and for evaporative flux. Limited storage capacity of the thawed zone does not support extended baseflow in a stream, though the proportion of baseflow increases as the percentage of permafrost extent decreases. In areas where permafrost is discontinuous or where it has thawed substantially near the surface, local hydrology may display a marked different character as there are stronger exchanges between the surface water and the ground water system, or water may drain laterally resulting in drier surface conditions. Runoff paths range from interhummock cracks, soil pipes, water tracks to distinct channels; and permafrost affects the ground water and contaminant migration pathways. Understanding the interdependence of permafrost, hydrology, and ecosystems is critically important to enable accurate projections of future conditions in the high latitudes.

The role of advective heat transport in talik development beneath lakes and ponds in discontinuous permafrost

“…Two mechanisms are commonly cited for lake drainage. The first, and most commonly observed, is the development of drainage channels from lakes in response to permafrost thawing and ice wedge melting or the intersection of existing drainage networks by expanding lakes [ Harry and French , 1983; Brewer et al , 1993; Marsh and Neumann , 2001; Hinzman et al , 2005a; Jorgenson and Shur , 2007; Hinkel et al , 2007; Marsh et al , 2009; Labrecque et al , 2009]. The second mechanism, documented on the Seward Peninsula in Alaska [ Yoshikawa and Hinzman , 2003; Hinzman et al , 2005b], involves the downward expansion of a talik (perennially thawed ground) beneath lakes through the entire thickness of permafrost.…”

“…First, these models have focused on lakes located in settings with thick (≥400 m) permafrost with near‐surface ground temperatures around −6 to −8°C and mean annual air temperatures between −6 and −10°C [ Burn , 2002; Ling and Zhang , 2003; West and Plug , 2008; Plug and West , 2009]. Second, these modeling efforts have examined the impact of heat transport by conduction only, neglecting advective heat transport by moving groundwater; this is a valid assumption for regions where surface and groundwater systems are largely isolated from one another [ Hinzman et al , 2005a]. In discontinuous permafrost, however, permafrost is warm (>−2°C), relatively thin (20 to 60 m), and mean annual air temperatures are around −2°C [ Yoshikawa and Hinzman , 2003; Jorgenson et al , 2010].…”

“…In discontinuous permafrost, however, permafrost is warm (>−2°C), relatively thin (20 to 60 m), and mean annual air temperatures are around −2°C [ Yoshikawa and Hinzman , 2003; Jorgenson et al , 2010]. In these regions, subsurface flow represents a potential source of heat to the system affecting the distribution and thawing of permafrost [ Williams and van Everdingen , 1973; Woo , 1986; Kane et al , 2001; Hinzman et al , 2005a; Mikhailov , 2008].…”

Introduction: hydrologic effects of a shrinking cryosphere

“…Hinzman et al, 2005). It is the impermeable nature of permafrost that often gives the false impression of northern areas having a large abundance of water, simply because so much is stored on the surface and unable to rapidly drain into groundwater systems as occurs in warmer environments.…”

Vegetation mapping and estimation of the extent of near-surface permafrost in Mackenzie Delta, Northwest Territories

“…Vegetation type can be a good indicator of the spatial distribution of permafrost since permafrost acts as an impervious ground mass through which roots and water can seldom penetrate. Most hydrologic activities are confined above ground or in the moist to saturated active layer, which supplies summer moisture to plants and the evaporative flux (Hinzman et al 2005). The local predominance of certain tree and shrub species at sites in a region underlain by discontinuous permafrost can be a strong indicator of the specific presence of permafrost and of the thickness of the active layer.…”