Dams serve several purposes such as generating hydroelectric power, providing water for irrigation and domestic consumption, and controlling floods and droughts. The document discusses the types of dams including gravity dams, earth dams, arch dams, and buttress dams. It also outlines both the benefits of dams such as water supply and flood control, as well as the environmental impacts including effects on fish, soil erosion, disease spread, and displacement of people. Examples of major dams in India are provided such as the Tehri Dam, Sardar Sarovar Dam, Nagarjuna Sagar Dam, and Bhakra Dam.

1. DAMS & their role
in Environment
BY-
S.Navjot Singh Kundan
Ruchir Bhatt Vikas Regar
Ayush Soni Bhavesh Soni

2. INTRODUCTION
TYPES OF DAMS- GRAVITY DAM,EARTH DAM, ARCH
DAM,BUTTRESS DAM
WORKING PRINCIPLE
ROLE IN ENVIRONMENT
DAMS IN INDIA
TOPIC COVERED -

3.  Definition of a dam- a solid barrier, constructed at a suitable location
across a river valley to store flowing water.
 Purpose of dams- to obtain hydropower, for irrigation, water for
dom. consumption, flood and drought control, for navigational
facilities & other uses- ex: developing fisheries
 Earliest Dams- Mesopotamia & the Middle East
-first known dam in Jawa, Jordan – gravity dam-flood control
-dated to 3000BC
INTRODUCTION

5. TYPES OF DAMS

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

8. 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

10.  These type of dams are
concrete or masonry dams
which are curved or convex
upstream in plan
 This shape helps to transmit the
major part of the water load to
the abutments
 Arch dams are built across
narrow, deep river gorges, but
now in recent years they have
been considered even for little
wider valleys.
Arch Dams:

12. Buttress Dam:
 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

14. Hydroelectric power
generation

17. Role of Dams in Environment

18. Irrigation
Water Supply
Flood Control
Hydroelectric
Recreation
Dams gather drinking water for
people.
Dams help farmers bring water
to their farms.
Dams help create power and
electricity from water.
Dams keep areas from
flooding.
Dams create lakes for people to
swim in and sail on.
Benifits of dams

19. Advantages of large dams 1/2
• It can produce cheap electricity (hydropower)
• It provides water for year round irrigation of cropland.

20. Advantages of large dams 2/2
Downstream flooding
is reduced
Reservoir is useful
for recreation
and fishing

21. Environmental Impacts of
Dams

22. Impacts on Fish
 Dams are created
in order to change
the currents of a
River .
 Changing the
current has an
immediate impact on
the ecosystem in the river .

23.  The dam changes the water qualities to
which organisms are used to
 Many animal’s life cycles are synced with the
annual floods that occur in an area;
therefore, those cycles are interrupted when
the floods stop because of the dam
 The dam basically acts as a barrier stopping
fish from going upstream or downstream;
thus, lifecycles of migratory fish are deeply
damaged, as they cannot go and spawn or
interact with others.

24. Soil Erosion
Before the Dam
 The sediment that the
water carries is blocked
by the dam; as time passes, it slowly builds up,
adding additional pressure to the dam wall
 In this way, serious accidents can occur: the dams are only
built to withstand a certain amount of water pressure; with
the pressure from the sediment in some time the wall either
explodes or water is caused to go above the dam, creating a
waterfall; in both cases, a lot of organisms, including humans
are in great danger .

25. Soil Erosion
After the Dam
 As sediment coming from the upper parts
is blocked, the water after the dam is
essentially “cleared” of all particles
 Once again, that interrupts the ecosystem
present
 The nutrients are blocked along with the
sediment
 The organisms that used the mud to hide
themselves now have no protection from
predators.

26. Disease Spread
 When sediment builds up, along with algae and
plants start developing; when they die, there is
a huge amount of organic material left, which
when decomposing, releases gases dangerous
for animals and people.
 The water that is blocked by the dam stays in
one place, and, consequently, can get very dirty
 It attracts mosquitoes and other disease-
carrying insects, which contaminate it

27. People Displacement
 When dams are built,
the settlements and habitats
that stand in their way are
generally demolished
 This way, a lot of people
are left without a home
and a job, which is a big
economical problem.

29. During the controlled floods, the river goes to the
farmlands, and problems are caused by the soil erosion
that follows -:
 When water is evaporated from the soil, salt is left and
the ground crystallizes
 The water is a breeding place for snails
carrying the
parasite bilharzia,
which is the second
worst disease after
malaria in Egypt .

30.  The physical environment is altered
 Cycles and variation of flow downstream are effected
 Standing water (reservoir) habitats replace flowing water habitats
 Nutrients are unable to move downstream
 Coastal erosion is increased due to loss of sediment transportation
 Productivity and species diversity of estuaries can be reduced due to
the reduction of freshwater flow
 Reduction of biodiversity occurs
 Ocean fish migrations are blocked, most notably the salmon and
steelhead
 Causes relocation

31. DAMS IN INDIA

32.  on BHAGIRATHI RIVER
near Tehri in Uttarakhand,
India
 Multi purpose rock and
earth fill embankment dam
 Highest dam in India and
8th highest dam in the
world

33.  Second largest concrete
gravity dam on Narmada
river in Gujarat
 Dam has the world’s
third largest spillway
discharging capacity

34.  World’s largest masonry
dam .
 Built across KRISHNA
river on NAGARJUNA
SAGAR, ANDHRA
PRADESH

35.  Gravity dam across
Sutlej river near Punjab
and Himachal Pradesh
 Largest dam of India
and highest gravity dam
in the world

36. Conclusion

37. THANK YOU