2. A dam is a hydraulic structure of impervious
material built across a river or stream to
create a reservoir on its upstream side for
storing water for various purposes.
These purposes may be irrigation, hydro-
power, water-supply, flood control,
navigation, fishing and recreation.
3.
4. Dams are classified on the basis of following
types:
By structure
By material
6. Situated at narrow
canyon with steep side
walls
Constant angle dams are
more common than
constant radius
Double curvature
Require good rock
foundation
7. Force that holds dam is
earth’s gravity pulling
down on mass of dam
Well suited for blocking
rivers in wide valleys
Dam is made from
concrete or masonry or
both
Foundation must have
high bearing strength
8. It has characteristics of
arch dam and gravity
dam
They are made up of
conventional concrete
or RCC or masonry
It is thinner than pure
gravity dams and
require less internal fill
9. Special kind of dam
which consist of a line
of large gates that can
be opened or closed to
control the amount of
water
Built at mouth of rivers
and often used to
control water flow for
irrigation system
10. These are embankments
of compact granular soil
in combination with
impervious areas
If clay is used then it is
composite dam
These dams are resistant
to damage from
earthquakes
11. They are generally made
up of one type of
material
Earthen dams can be
constructed from
materials found on site
or nearby
They are cost effective
13. •Steel dam is a type of dam that is
made of steel, rather than common
masonry ,earthworks , concrete or
construction material
•Steel dams - an experiment which
failed
•Maintenance cost is high due to rust
and corrosion
15. Timber dams were
widely used in early
part of industrial
revolution and rarely
used now
Suitable location for
construction
In order to maintain
water retension
property they must be
kept wet
16. Cofferdam : a barrier usually temporary,
constructed to exclude water from area that
is normally submerged
Natural dams : created by natural geological
forces. Volcanic dams are formed when
erupted lava intercept path of a stream.
Natural disasters like earthquake and
landslides frequently create landslide dams in
mountainous region. Eg. Usoi dam in
Tajikistan
17. Hydroelectricity
• Hydroelectricity is the term referring to
electricity generated by hydropower; the
production of electrical power through the
use of the gravitational force of falling or
flowing water.
• It is the most widely used form of renewable
energy, accounting for 16 percent of global
electricity generation 3,427 terawatt-hours
of electricity production in 2010.
• Hydropower is produced in 150 countries,
with the Asia-Pacific region generating 32
percent of global hydropower in 2010. China
is the largest hydroelectricity producer.
18. • The theory is to build a dam on a large river that has a
large drop in elevation .
• The dam stores lots of water behind it in the reservoir.
• Near the bottom of the dam wall there is the water intake.
Gravity causes it to fall through the penstock inside the
dam.
• At the end of the penstock
there is a turbine propeller,
which is turned by the
moving water.
• The shaft from the turbine
goes up into the generator,
which produces the power.
Power lines are connected
to the generator that carry
electricity to user .
WORKING PRINCIPLE
19. Pumped storage: Reusing
water for peak electricity
demand
Pumped storage is a method
of keeping water in
reserve for peak period
power demands by pumping
water that has already
flowed through the turbines
back up at storage pool
above the powerplant.
An advantage of pumped
storage is that hydroelectric
generating units are able to
start up quickly and make
rapid adjustments in output.
20. Disadvantages of big Hydroelectricity
plant
• Ecosystem damage and
loss of land
• Siltation and flow shortage
• Relocation of local people
• Failure risks