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第一章
Porous media
: rocks or soils with pores
Porosity
: the ratio of voids to total volume of the soils
Effective porosity
: the ratio of interconnected voids to total volume of the soils
An aquifer
: a geologic unit that can store and transmit water to wells
Intrinsic permeability
:
it is a function of the size of the pore opening. The smaller
the size of the grains, the larger the surface area the water contacted. This increase
the frictional resistance to flow, which reduce the intrinsic permeability.
Aquitard
: a layer of low permeability that can store groundwater and also transmit it
slowly from one aquifer to another.
Aquifuge
:
a
relatively
impermeable
formation
neither
containing
or
transmitting
water
Aquiclude
:
a
saturated
but
relatively
impermeable
material
that
does
not
yield
appreciable quantities of water to wells
Confined aquifer or artesian
: it is overlain by a confining layer, which is a geologic
unit has little or no intrinsic permeability
Unconfined
aquifer
or
water-table
aquifer
:
aquifers
with
continuous
layers
of
materials of high intrinsic permeability extending from the land surface to the base
of the aquifer, it can be close to the land surface
A perched aquifer
：
in some cases, a layer with low permeability will be found as a
lens in more permeable materials
Specific storage
：
μ
s
( the elastic storage coefficient) the amount of water per unit
volume
of
a
saturated
formation
that
is
stored
or
expelled
from
storage
owing
to
compressibility of the mineral skeleton and the pore water per unit change in head
Specific yield
(S
y
): The ratio of water that drains from a saturated soil owing to the
attraction of gravity to the total volume of the soil
Specific retention
(S
r
): the specific retention of a rock or soil is ratio of the volume of
water a soil can retain against gravity drainage to the total volume of the rock
Seepage
:
substitute
hypothetical
fluid
for
ground
water,
based
on
the
following
assumptions
：
The hypothetical fluid has consistent property with real one
In every unit volume of soil, the applied resistance force on the hypothetical fluid is
consistent with the real one
The quantity of fluid that passed through every cross sectional area , the hydraulic
head or pressure of every point are to the real
Hydraulic
gradient(J)
:
the
decrease
in
hydraulic
head
divided
by
the
length
of
the
pipe
Hydraulic conductivity K
: a function of properties of both the porous medium and
the fluid passing through it
Intrinsic
permeabilityK
i
:
representative
of
the
properties
of
the
porous
medium
alone
Transmissivity
T
:
a
measure
of
the
amount
of
water
that
can
be
transmitted
horizontally
through
a
unit
width
by
the
full
saturated
thickness
of
the
aquifer
under a hydraulic gradient of 1
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