Dam Types of Dam PURPOSES OF DAM Classification of Dams GEOLOGICAL PROBLEMS AT DAM SITE

1. DAMS &
RESERVOIRS

2. DAMS
A DAM may be defined as a solid barrier
constructed at a suitable location across a river
valley with a view of impounding water flowing
through that river.
Tehri Dam Nagarjuna Sagar
Dam

3. Parts and terminology of dam
 Spillway
 Heel
 Toe of Dam
 Axis of Dam
 Abutments
 Grouting
HEEL
TOE
DOWNSTREA
M
SIDE
UPSTREAM
SIDE
CRES
T
RESERVOI
R

4. PURPOSES OF DAM
 Providing water for irrigation facilities
Providing water supply for domestic and industrial use
Generation of hydroelectric power
Flood control
Erosion and sediment control

5. Classification of Dams
A) Classification according to use :
1. Storage dam :
Storage dams are constructed to store water during the rainy season when there
is a large flow in the river.
2. Diversion dam :
A diversion dam is constructed for the purposes of diverting water of the river into
an off-taking canal.

6. CLASSIFICATION OF
DAMS
A) Classification according to use :
3. Detention dam (Prevention) :
Detention dams are constructed for flood control. A detention dam retards the
flow of water in the river on its downstream during floods by storing some flood
water.
For Example -Debris dam

7. CLASSIFICATION OF
DAMS
B) Classification according to hydraulic design :
1. Overflow dam :
An overflow dam is the one which is designed to carry surplus discharge over its
crest. Its crest level is kept lower than the top of the order portion of the dam.Such
dams are generally made of concrete or masonry. An overflow dam is commonly
known as Spillway.
2. Non-overflow dam :
A non-overflow dam is the one in which the top of the dam is kept at a higher elevation
than the maximum expected high flood level. Water is not permitted to overtop the dam.
For Example,
- Gravity dam
- Rockfill dam
- Earthen dam

8. Classification of Dams
C) Classification according to materials :
1. Rigid dam :
Rigid dams are those which are constructed of rigid materials such as concrete, masonry,
steel , timber etc. these dams deflect and deform very little when subjected to water
pressureand other forces.
For Example,
- Concrete Gravity dam, Solid masonry dam, Steel dam, Arch dam, Timber dam
- 2. Non-rigid dam :
Non-rigid dams are those which are constructed of non-rigid materials such as earth or rockfill.
There are relatively large settlements and deformation in a non – rigid dam.
For Example,
-Earth dam
- Rockfill dam

9. Classification of Dams
D) Classification according to Structural behaviour : Based on
structural behaviour, dams are classified as,
 Gravity dam
 Arch dam
 Buttress dam
 Earthen dam
 Rockfill dam

10. GEOLOGICAL PROBLEMS AT
DAM SITE
 Dams on shale
 Dams on soluble rocks
 Dams on strata dipping upstream side
 Dams on strata dipping downstream side
 Dams built across strike of rocks
 Dams on jointed and permeable rocks
 Dam on faults
 Abutment problems

11. Dams on shale
CEMENTATION SHALES COMPACTION SHALES
Stronger Soft & Slake
Do not disintegrate disintegrate
Bearing Strength is high Bearing Strength is low
Structure can’t settles Structure can settles
Gravity dam can built on it Gravity Dam should be avoided
No Swelling and caving Swelling and caving may result

12. Dams on soluble rocks
 Limeston
e
 Dolomites
 Marbles

13. Dams on strata dipping:
W
Dams on strata dipping
DOWNSTREAM side
Dams on strata dipping
UPSTREAM side

14. Dams built across strike of
rocks

15. Dam on faults