Permafrost Absent
Birch Hill Dominance
Tanana-Chena Alluvium Aquifer Dominance
Near Surface
Near Surface
Permafrost Present to
Unspecified Depth
Depth
Depth
Permafrost Extends Into
Bedrock
Figure 23. Hydrogeological concepts of deep aquifer flow paths depicted for two scenarios: where Birch Hill
dominates and where a subregional aquifer dominates. We assumed ground water flow within the bedrock not to
be significant. The direction and velocity of flow for both scenarios may differ significantly in the subpermafrost
aquifer because of thaw zones that intercept it. The effect of the large area of sediments frozen to bedrock is evident
for both scenarios. The prevailing flow below permafrost, regardless of source, may result in off-site migration of
aquifer south of the Chena River as opposed to
cent suprapermafrost aquifers. An aquifer sur-
one in Birch Hill will generate a more northerly
rounded on four sides by permafrost would have
component than when there is less difference in
a water table rising or falling in concert with
recharge or discharge from the subpermafrost
early 1997 demonstrate this to be the case in the
aquifer. Seepage velocity and direction would,
area northwest of the landfill (Lawson et al. 1997,
therefore, be a response to the subpermafrost
in prep.).
gradient. A strong gradient in the subpermafrost
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