Dams are solid barriers constructed across rivers to store flowing water for uses like drinking water, irrigation, hydropower, flood control and recreation. The main purposes of dams worldwide are irrigation (48.6%), hydropower (17.4%), and water supply (12.7%). A dam has a dam body, reservoir, spillway, intake structures and may include a sluiceway or diversion facilities. Dams are classified by size, height, and structural design, with the main types being gravity dams, arch dams, buttress dams, embankment dams and composite dams. While dams provide benefits like food and energy, they can also cause issues like flooding, disruption of ecosystems and communities.

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4. What is dam?
 Dam is a solid barrier constructed at a
suitable location across a river valley to store
flowing water.
 Or
The arrangement made for systematic
control of water flow for better optimum
utilization of available water.
Humanity control over Natural resources

5. What is the purpose of dam?
 The purpose (requirement) of dam is following
Drinking water
Navigation
Flood control
Recreational purposes
Irrigation
Hydropower

6. Requirement of dam (world wide %)
48.60%
17.40%
12.70%
10.00%
5.30%
0.60% 5.40%
Irrigation
Hydropower
Water Supply
Flood Control
Recreation
Navigation and
Fishing
Others
Source: International Commission on Large Dams (ICOLD)

7. Parts of a dam
 Dam body: Body forms the main part of a dam as an
impervious barrier
 Reservoir: It is the artificial lake behind a dam body
 Spillway: is that part of a dam to evacuate the flood water from
reservoir.
 Water intake structures: is a facility to withdraw water from
a reservoir.
 Sluiceway: Gerektiğinde baraj gölünü tamamen boşaltmak,
dolusavak kapasitesini azaltmak, akarsu mansabına bırakılacak
suyu salmak amacına yönelik tesisler.
 Diversion facilities: To redirect the streamflow from
construction area

8. pstream
Spillway
Dam
body
Downstream
Reservoir

9. Types of dam?
ACCORDING to the SIZE of the DAM
1. Large (Big) dam
2. Small dam
International Commision on Large Dams, (ICOLD) assumes a
dam as big when its height is bigger than 15m.
If the height of the dam is between 10m and 15m and matches
the following criteria, then ICOLD accepts the dam as big:
If the crest length is bigger than 500m
If the reservoir capacity is larger than 1 million m3
If the flood discharge is more than 2000 m3/s
If there are some difficulties in the construction of
foundation

10. ACCORDING to HEIGHT of DAM
 High Dam or Large Dam
If the height of the dam is bigger than 100m
 Medium Dam
If the height of the dam is between 50m and 100m
 Low Dam or Small Dam
If the height of the dam is lower than 50m

11. ACCORDING to the STATICAL DESIGN of
DAM BODY
Gravity Dams
Arch Dams
Butress Dams
Embankment(Earth) Dams
Composite Dams

12. GRAVITY DAM
These dams are heavy and
massive wall-like structures of
concrete in which the whole
weight acts vertically
downwards
As the entire load is transmitted on the small area of foundation, such dams
are constructed where rocks are competent and stable.

13. Structure of Gravity Dam
Heel
Gallery
Toe
Spillway
(inside dam)
Crest
NWL
Normal
water level
MWL
Max. level
Free board
Sluice way
Upstream Down stream

14. Example of gravity dam.
• Bhakra Dam is the
highest Concrete Gravity
dam in Asia and Second
Highest in the world.

15.  Buttress Dam – Is a
gravity dam reinforced
by structural supports
 Buttress - a support that
transmits a force from a
roof or wall to another
supporting structure
This type of structure can be considered even if the foundation rocks are little
weaker

16. A buttress dam
Chief Joseph Dam, Washington State, USA

17. Hoover Dam, R.
Colorado, U.S.A
Strong rock abutments in
a narrow valley
Arch dams

19. Earth Dams:
 They are trapezoidal in
shape
 Earth dams are constructed
where the foundation or the
underlying material or rocks
are weak to support the
masonry dam or where the
suitable competent rocks are
at greater depth.
 Earthen dams are relatively
smaller in height and broad
at the base
 They are mainly built with
clay, sand and gravel, hence
they are also known as Earth
fill dam or Rock fill dam

20. ADVANTAGE OF DAM
 40 % Of world food production comes from Irrigated
forming out of which 16% is contributed due to
dams.
 30-40% of 268 million hectares of irrigated land is
watered from dams
 19% of world energy comes from hydro-electric
power ( which includes 150 countries)
 90% of 24 countries
 50% in 63 countries

21. DISADVANTAGE OF DAM
 FLOOD
 NOT ECONOMICAL
 TIME
 CULTURAL DAMAGE
 Loss of forests , wildlife habitat, the degradation of
upstream catchments

 Disruption of fishing and waterway traffic
The fragmentation and physical transformation
of rivers

22. Thank
You