Hydrology
The
hydro
power
plays
very
important
role
in
the
development
of
the
country
as
it
provides
power
at
cheapest
rate
being
perpetual
source
of
energy.
Nearly
20%
of
the
total,
world
power
is
generated
using
hydro
plants.
There
are
some
fortunate
countries
in
the
world
where
99%
of
the
nation's
power'
requirement
is
met
by
hydro
power.
There
are
few
countries
like
USSR
and
Nepal
where
vast
hydro
resources
are
yet
to
be
harnessed.
As
per
the
estimate
of
the
World
power
Organisation,
the
world
hydro
potential
is
roughly
5000
GW
whereas
only
200
GW
is
presently
developed
(4%
only).
Rain
falling
upon
the
earth
surface
has
Potential
energy
relative
to
oceans
towards
it
flows.
This
energy
can
be
converted
into
shaft
work
passing
through
hydraulic
prime
mover
and
ultimately
into
electrical
energy.
The
quantity
of
water
available
and
head
are
equally
important
in
the
generation
of
power.
The
available
head
depends
upon
the
selection
of
site
for
hydraulic
power
plant.
The
site
of
the
power
plant
is
always
selected
for
the
highest
available
head
when
other
things
are
in
favour
of
site
selection.
The
quantity
of
water
available
at
the
selected
site
depends
upon
the
hy
drological
cycle
of
nature.
The
quantity
of
water
available
Can
be
determined
from
the
study
of
rainfall
and
run
off
in
that
area
or
rainfall
and
run
off
decides
the
site
for
the
power
plant.
As
the
availability
of
water
depends
on
the
natural
phenomenon
of
rain,
the
maximum
capacity
of
hydraulic
generating
plant
is
usually
fixed
on
the
basis
of
minimum
quantity
of
water
available.
Usually
storage
reservoirs
are
constructed
for
such
plants
in
order
to
store
the
water
during
peak
periods
of
run
off
and
supply
the
same
during
off
peak
periods
of
run
off.
The
study
of
rainfall
and
run
off
is
very
important
for
the
students
before
going
to
the
study
of
hydro
power
engineering.
This
study
helps
in
the
design
of
dams,
spillways
and
so
on.
Hydrology The
science
which
deals
with
rainfall
and
run
off
is
known
as
hydrology.
The
evaporation
of
the
water
from
the
surfaces
of
river
and
oceans
and
its
precipitation
on
the
earth
is
known
as
hydrological
cycle.
The
distribution
of
precipitation
on
the
earth
surface
and
beneath
the
earth
is
calculated
with
the
help
of
hydrological
considerations.
Water
is
evaporated
from
plants,
rivers;
oceans
and
carried
with
the
air
in
the
form
of
vapour
which
is
known
as
clouds.
When
the
vapours
in
the
atmosphere
are
cooled
below
dew
point
temperature.
if
fails
in
the
form
of
water
or
snow
depending
on
the
atmospheric
temperature.
This
evaporation
and
precipitation
is
a
naturally
Continuous
process
and
therefore
constitutes
a
perennial
source
of
energy
Most
of
the
water
resources
projects
are
multi
purpose
projects
as
irrigation,
navigation,
flood
control
and
generation
of
electric
power.
Problems
in
the
design
of
multi
purpose
projects
usually
are
how
much
water
is
needed
and
how
much
is
available.
These
are
the
most
difficult
problems
to
answer
to
all
the
design
problems
because
it
involves
social,
economic
and
engineering
aspects.
The
design
of
the
project
whether
it
is
multi
Purpose
or
single
purpose
depends
upon
the
availability
of
water.
Peak
rates
of
flow
are
the
basis
of
design
of
projects
to
control
the
excess
water
(Flood
control)
while
volume
of
flow
during
longer
periods
of
time
is
of
interest
in
designing
projects
for
use
of
water
(irrigation
or
power
generation
or
both).
The
answer
to
this
question
is
found
through
the
application
of
hydrology,
the
study
of
the
occurence,
and
distribution
of
the
natural
waters
on
the
earth.
Many
projects
are
designed
to
control
the
flood,
irrigation
and
power
generation
if
the
quantity
of
water
available
is
sufficient
for
the
required
purpose
and
site
is
as
per
requirements.
Many
projects
are
designed
only
for
irrigation
purposes
or
power
generation
purposes.
The
flood
control
is
one
of
the
considerations
in
the
design
of
the
project
whether
it
is
designed
for
power
generation
or
irrigation
as
it
cannot
be
avoided.
The
design
of
multipurpose
projects
is
always
difficult
compared
with
the
single
purpose
project
because
requirements
from
multi
purpose
are
varied.
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