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Cards (25)
Groundwater (GW):
Is water stored in cracks in soil, sand and rock
Often below water table
Generally in saturated conditions
GW Problems:
Misuses
- waste, overuse
Contamination
Knowledge gap
,
user awareness
Aquifer
: underground water body
Soil Water
(SW):
Stored in
soil pores
(void space)
Above water table
Wet Bulk Density
P
w
=
Pw =
Pw
=
M
t
/
V
t
Mt / Vt
Mt
/
V
t
Dry Bulk Density
P
b
=
Pb =
P
b
=
M
s
/
V
t
Ms / Vt
M
s
/
V
t
Particle Density
P
p
=
Pp =
Pp
=
M
s
/
V
s
Ms / Vs
M
s
/
V
s
Gravimetric Water Content
θ
w
=
θw =
θw
=
M
w
/
M
s
Mw / Ms
Mw
/
M
s
Volumetric Water Content
θ
w
=
θw =
θw
=
V
w
/
V
t
Vw / Vt
V
w
/
V
t
θ
v
=
θv =
θ
v
=
θ
w
P
b
θw Pb
θwP
b
Density
of
water
=
1gcm^-3
Porosity
:
how
porous
the
soil
is
pores can be filled with
liquid
or
air
Void Ratio
e
=
e =
e
=
V
a
i
r
+
Vair +
Vai
r
+
V
w
a
t
e
r
/
V
s
o
l
i
d
s
Vwater / Vsolids
V
w
a
t
er
/
V
so
l
i
d
s
void ratio =
empty space / solid space
Water Filled Porosity
f
w
=
fw =
f
w
=
V
w
/
V
t
=
Vw / Vt =
V
w
/
V
t
=
θ
v
θv
θ
v
Air Filled Porosity
f
a
=
fa =
f
a
=
V
a
i
r
/
V
t
o
t
a
l
=
Vair / Vtotal =
Vai
r
/
V
t
o
t
a
l
=
f
−
θ
v
f - θv
f
−
θ
v
Total Porosity
f
=
f =
f
=
V
f
/
V
t
Vf / Vt
V
f
/
V
t
Saturation Ratio
θ
s
=
θs =
θ
s
=
θ
v
/
f
θv / f
θ
v
/
f
Porosity Factors
Packing
Grain shape
Grain size
Sorting
Grain orientation
Macropore >
Mesopore
>
Micropore
Saturated
: all
water
below
water table
(
groundwater
)
Cohesion
:
attraction
of
water molecules
to each other
Adhesion:
attraction
of
water molecules
from
solid surfaces
Surface Tension
:
force
of
attraction
between the
water molecules
on the
surface
Sphere drop
of
water
is caused by
pressure
from
air
(
balancing
of
pressure
)
Capillary Action
: movement of water through soil pores due to adhesion, cohesion, and gravity
Soil is just a bunch of
capillaries
(a
capillary system
)
