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! # !"" #$ % ! & ' ! () * + THE HYDROLOGIC CYCLE
A part of the precipitation falling on the surface runs off toward the farm pond or the river, where some is evaporated and returned to
the atmosphere. Of that part filtering into the ground, some is removed by the vegetation as evapotranspiration. Some part seeps down
through the zone of aeration to the water table. Below the water table the water moves slowly toward the stream, where it reappears as
surface water via springs in the streambed. Water in a confined aquifer can exist pressures as high as its source, hence the flowing
well. Water trapped above the upper clay layer can become perched and reappear as a small seep along the river bank. $ !"" #$ % ! & ' ! () * + ) " & !"" #$ % ! & ' ! () * + , + 3 +( ! # * ( 4
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7 , 7 , !"" #$ % ! & ' ! () * + : !"" #$ % ! & ' ! () * + ,! " = !"" #$ % ! & ' ! () * 1 (; + !* * dh
dr 2kπ
q = kiA = k ( 2π rh ) ∴
=
r
r
q
r2
r1 q
r
2
ln 1 = h12 − h2 ∴
kπ r2 3 (; ( k= % h1 hdh
h2 q ln r1 / r2
π ( h12 − h22 ) + 9 +: ! ) !"" #$ % ! & ' ! () * + Pumping from auger holes (FDOT type slug test) Water is either pumped out or, charged in.
Using the Ernst equation, the permeability k is found from
k= 40
r ∆y
l
y y ∆t
20 +
2−
r
r where r(m) is the radius of auger hole, and
y(m) is the average drop of the WT in time t(minutes)
FLOW THROUGH UNSATURATED SOILS.
When clay becomes unsaturated its k greatly diminishes, because the entry of air traps it
into a portion of the pores, and flow is confined to the smaller diameter pores. There can
be on order of change in the permeability for small changes in water content.
FLOW THROUGH ROCK.
Water flow through intact rock follows Darcy’s law. When the rock has open joints the
flow could become turbulent. In laminar flow, the permeability kE is
a2g
2a
*
3γ
b
where a = halfwidth of the joint (m)
b = joint spacing (m)
g = gravitational constant (9.81 m/sec2)
γ = viscosity of water kE = EXAMPLE: For a fissured schist, with 1mm wide joints spaced at 1m,
kE = 2 ( 0 . 0 0 5 m ) 3 ( 9 .8 1 m / s e c 2 )
2a a 2 g
*
=
= 8.3x104
b
3ν
3 (1m ) (1 X 1 0 − 6 m m 3 / m − s e c ) A Guide to the Coefficient of Permeability of Intact Rocks
(SOURCE: Based on Louis 1968; Serafim and Del Campo,
and Vutukuri, 1978) m/sec 1965; Serafim, 1968; Winterkorn and Fang, 1975; Lama and Rock Type Test Calcite
Slate
Granite (fresh)
Granite
(weathered)
Granite
Schists (fissured) Lab
Lab
Lab
Lab Coefficient of
Permeability
(m/sec)
(0.01 to 1) * 107
(0.1 to 1) * 109
(0.1 to 1) * 1010
(0.1 to 1) * 105 Field
Lab (0.1 to 1) * 104
(1 to 3) * 104 > !"" #$ % ! & ' ! () * + A Guide to the Coefficient of
Permeability of Intact Rocks
(SOURCE:
(SOURCE: Based on Louis 1968;
Serafim and Del Campo, 1965;
Serafim, 1968; Winterkorn and Fang,
1975; Lama and Vutukuri, 1978) Coefficient of
Rock Type Test Permeability
(m/sec) Calcite Lab (0.01 to 1) * 107 Slate Lab (0.1 to 1) * 109 Granite (fresh) Lab 10
(0.1 to 1) * 1010 Granite
Granite (Weathered) Lab (0.1 to 1) * 105 Field (0.1 to 1) * 104 Lab (1 to 3) * 104 Granite
Schists (fissured) 1 ( ,"" / !"" #$ % ! & ' ! () * + 85
?
, . 8/@ !B
(A C !"" #$ % ! & ' ! () * + (A B C
& ! # ( D " + E F G $ !"" #$ % ! & ' ! () * + ;   ! ! & !"" #$ % ! & ' ! () * + ! ! # ( " + " E F! G !
E F  !" G
E F ' ! ! # $%
/ !"" #$ % ! & ' ! () * + ΣFy = 0 & ' Ground Surface Discontinuous Moisture Zone vapor flow Capillary
Capillary Fringe Zone
hc B capillary
flow Capillary
Capillary Saturation Zone
Water Table z 100% Saturation Zone &///
()* + ,( &  8 . /' ...
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This note was uploaded on 09/11/2011 for the course CEG 4011 taught by Professor Staff during the Summer '10 term at FIU.
 Summer '10
 STAFF

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