Transcript Wedge-shaped and sloping aquifers

Wedge-shaped and sloping
aquifers
Adam Forsberg
January 28, 2013
Until Now
• Thickness constant
• Water table horizontal
3 Cases:
1. Wedge shaped confined aquifers at unsteady-state
2. Sloping unconfined aquifers at steady-state
3. Sloping unconfined aquifers at unsteady-state
Wedge-shaped confined at
unsteady-state flow
• Assumptions
– Thickness of aquifer
varies exponentially in
direction of flow (xdirection)
• Constant in y-direction
– Homogeneous, isotropic
– Rate of change in aquifer
thickness < 0.20 in
direction of flow
Hantush’s inflection point method
Sloping, unconfined aquifers
steady-state
• Culmination-point method
– Slope of the water table = slope of impermeable
basement
• Assumptions
– Unconfined Aquifer with constant saturated
thickness
– Slopes uniformly in the direction of flow
Sloping, unconfined aquifers
steady-state
• Flow per unit width
– F = width where water is
drawn
– α= slope of the impermeable
base
• At some distance from the
well, the combined slopes
for α and dh/dx will equal
zero
– Inflection or culmination
point
Sloping, unconfined aquifers
unsteady-state
• Assumptions
– Unconfined
– Seemingly infinite areal
extent
– Isotropic, homogeneous,
and uniform thickness
– Prior to pumping, the
water table slopes in
direction of flow with
gradient < 0.2
– Unsteady-state
Sloping, unconfined aquifers
unsteady-state
• Hantush’s method
• i < 0.2