Groundwater
TOEFL頑張ります。
●過去問(中国語) ： past exam questions (in chinese)
https://chutai-ryugaku-report.info/wp-content/uploads/2017/02/TOEFL_reading.pdf
●回答 (中国語) ：Answer down below (in chinese)
https://toefl.xiaoma.com/tuofuyuedu/20120327/92017.html
●words
meteoric water：a water derived from precipitation(rain, snow)
precipitation：落下量、《気象》降水量
pebble：小石
gravel：砂利
glacial outwash：a particle carried in water from melting glaciers 洗い流されたもの
fanwise：扇形に(広げられた)
So much for：there is enough about
Consolidated：強固な
pore：気孔
porous：多孔性の、浸透性の
porosity：浸透性
permeability：透水性
plugged：filled up
percolate：[液体を]ろ過する、浸透する
basalt：玄武岩(げんむいわ) , a form of solidified volcanic lava
cavitity：空洞、虫歯の穴
crevicy：(岩などの)割れ目, crack
1. Groundwater is the word used to
describe water that saturates the ground,
filling all the available spaces. By far the
most abundant type of groundwater is
meteoric water; this is the groundwater that
circulates as part of the water cycle.
Ordinary meteoric water is water that has
soaked into the ground from the surface,
from precipitation (rain and snow) and from
lakes and streams. There it remains,
sometimes for long periods, before emerging
at the surface again. At first thought it seems
incredible that there can be enough space in
the “solid” ground underfoot to hold all this
water.
2. The necessary space is there, however,
in many forms. The commonest spaces are
those among the particles—sand grains and
tiny pebbles—of loose, unconsolidated sand
and gravel. Beds of this material, out of
sight beneath the soil, are common. They are
found wherever fast rivers carrying loads of
coarse sediment once flowed. For example,
as the great ice sheets that covered North
America during the last ice age steadily
melted away, huge volumes of water flowed
from them. The water was always laden with
pebbles, gravel, and sand, known as glacial
outwash, that was deposited as the flow
slowed down.
3.The same thing happens to this day,
though on a smaller scale, wherever a
sediment-laden river or stream emerges
from a mountain valley onto relatively flat
land, dropping its load as the current slows:
the water usually spreads out fanwise,
depositing the sediment in the form of a
smooth, fan-shaped slope. Sediments are
also dropped where a river slows on entering
a lake or the sea, the deposited sediments are
on a lake floor or the seafloor at first, but
will be located inland at some future date,
when the sea level falls or the land rises;
such beds are sometimes thousands of
meters thick.
4. In lowland country almost any spot on
the ground may overlie what was once the
bed of a river that has since become buried
by soil; if they are now below the water’s
upper surface (the water table), the gravels
and sands of the former riverbed, and its
sandbars, will be saturated with
groundwater.
5.So much for unconsolidated sediments.
Consolidated (or cemented) sediments, too,
contain millions of minute water-holding
pores. This is because the gaps among the
original grains are often not totally plugged
with cementing chemicals; also, parts of the
original grains may become dissolved by
percolating groundwater, either while
consolidation is taking place or at any time
afterwards. The result is that sandstone, for
example, can be as porous as the loose sand
from which it was formed.
6.Thus a proportion of the total volume
of any sediment, loose or cemented, consists
of empty space. Most crystalline rocks are
much more solid; a common exception is
basalt, a form of solidified volcanic lava,
which is sometimes full of tiny bubbles that
make it very porous.
7. The proportion of empty space in a
rock is known as its porosity. But note that
porosity is not the same as permeability,
which measures the ease with which water
can flow through a material; this depends on
the sizes of the individual cavities and the
crevices linking them.
8.Much of the water in a sample of
water-saturated sediment or rock will drain
from it if the sample is put in a suitable dry
place.█ But some will remain, clinging to
all solid surfaces.█ It is held there by the
force of surface tension without which water
would drain instantly from any wet surface,
leaving it totally dry.█ The total volume of
water in the saturated sample must therefore
be thought of as consisting of water that can,
and water that cannot, drain away.█
9. The relative amount of these two kinds
of water varies greatly from one kind of rock
or sediment to another, even though their
porosities may be the same. What happens
depends on pore size. If the pores are large,
the water in them will exist as drops too
heavy for surface tension to hold, and it will
drain away; but if the pores are small
enough, the water in them will exist as thin
films, too light to overcome the force of
surface tension holding them in place; then
the water will be firmly held.
●単語帳はこれさえやれば十分
●過去問
