STANLEY N. DAVIS
Fig. 9. Groundwater circulation in homogeneous rocks within desert mountains.
Localized recharge causes groundwater mound under valley. Minor discharge produces small dimple in water surface.
order to transport the small amount of water available. The velocity of
flow is, therefore, very small. Equation (3) can be rewritten as
q = νθ = ~K(Ah/As)
(7)
where q, K, Ah, and As are as previously defined, v is the average velocity
of groundwater, and Θ is the effective pore space through which water will
move.
Two examples below will serve as limiting values to be expected in
desert regions.
EXAMPLE 1. Aquifer is fractured rock.
K = 0.1 meter/day (see Davis, 1969, for a representative range of
values)
Θ = 0.005, Ah/As = 0.001
v = (1/0.005) (0.1) (0.001) = 0.02 meter/day
EXAMPLE 2. Aquifer is permeable alluvium.
K = 100 meters/day (see Davis, 1969, for a representative range
of values)
Θ = 0.3, Ah/As = 0.0001
v = (1/0.3) (100) (0.0001) = 0.033 meter/day
14
Fig. 9. Groundwater circulation in homogeneous rocks within desert mountains.
Localized recharge causes groundwater mound under valley. Minor discharge produces small dimple in water surface.
order to transport the small amount of water available. The velocity of
flow is, therefore, very small. Equation (3) can be rewritten as
q = νθ = ~K(Ah/As)
(7)
where q, K, Ah, and As are as previously defined, v is the average velocity
of groundwater, and Θ is the effective pore space through which water will
move.
Two examples below will serve as limiting values to be expected in
desert regions.
EXAMPLE 1. Aquifer is fractured rock.
K = 0.1 meter/day (see Davis, 1969, for a representative range of
values)
Θ = 0.005, Ah/As = 0.001
v = (1/0.005) (0.1) (0.001) = 0.02 meter/day
EXAMPLE 2. Aquifer is permeable alluvium.
K = 100 meters/day (see Davis, 1969, for a representative range
of values)
Θ = 0.3, Ah/As = 0.0001
v = (1/0.3) (100) (0.0001) = 0.033 meter/day
14