About dam introduction

2. Irrigation Structures are widely used in
Irrigation, water conservation, flood alleviation,
river works where water level and discharge
regulation are required.
These are hydraulic structures that are used to
regulate, measure, and/or transport water in
open channels.

3. A hydraulic structure is structure submerged or
partially submerged in any body of water, which
disrupts the natural flow of water.
They can be used to divert, disrupt or
completely stop the flow.
An example of a hydraulic structure would be
a dam, which slows the normal flow rate of the
river in order to power turbines.
A hydraulic structure can be built in rivers, a
sea, or any body of water where there is a need
for a change in the natural flow of water.

4. Hydraulic structures can be grouped into three
categories:
(i) Flow measuring structures, such as weirs
(ii) Regulation structures such as gates and
(iii) Discharge structures such as culverts.

5. DAMS

6. Dam
Dam is a solid barrier constructed at a suitable
location across a river valley to store flowing water.
A dam is a hydraulic structure of fairly impervious
material built across a river to create a reservoir on
its upstream side for impounding water for various
purposes.

7. Drinking
water
Navigation
Flood
control
Recreational
purposes
Irrigation
Hydropower

8. 1. Imbalance of the ecosystem
2. Decreased amount of downstream water
3. Spreading of some water-born diseases
4. Reduction in the fertility of farmlands

9. 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 diverge 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

10. Heel: contact with the ground on the
upstream side
Toe: contact with the ground on the
downstream side
Abutment: Sides of the valley on which
the structure of the dam rest
Galleries: small rooms like structure left
within the dam for checking operations.

11. Heel
Gallery
Toe
Spillway
(inside dam)
Crest
NWL
Normal
water level
MWL
Max. level
Free board
Sluice way
Upstream Down stream

12. Parts of Dams
Water intake structures
Flow
Sluiceway Dam body
Spillway
Reservoir

13. Upstream
Reservoir
Dam body
Spillway
Downstream

14. Upstream slope
Riprp
Top of dam
Principal chute spillway
Spillway training walls
Downstream slope
Right abutment
Left abutment
Toe of
embankment
Berm
Toe drain outlet

15. Classification of Dams
According to dams height
If crest elevation and foundation level is greater than
15 m then it can be considered as a Large Dam.
If dam height is less than 15 m then Small Dam.
If dam height is greater than 50 m then High Dam

16. Dams are classified on several aspects, some of the
important aspects are as follow:
1. Based on Hydraulic Design:
 Over flow dams (e.g. concrete dams)
 Non over flow dams (e.g. embankment dams)
2. Based on Structural Design:
 Gravity dams
 Arch dams
 Buttress dams
3. Based on Usage of Dam:
 Storage dams
 Diversion dams
 Detention dams

17. 4. Based on Construction Material:
 Concrete / Masonry dams
 Earthfill dams
 Rockfill dams
 Earthfill rockfill dams
 Concrete faced rockfill dams (CFRD)
5. Based on Capacity:
 Small dams
 Medium dams
 Large dams

18. A gravity dam resists the water pressure and
other forces due to its weight (or gravitational
forces). Thus the stability of a gravity dam
depends upon its weight. The gravity dams are
usually made of cement concrete.

21. An earth dam is made of earth (or soil).
The foundation requirements are less stringent than those of
gravity dams, and hence they can be built at the sites where the
foundations are less strong. They can be built on all types of
foundations.

22. Formed of loose rocks and boulders piled in the
river bed
Reinforced concrete is often laid across the u/s
face to make it watertight

23. Called arch dam because in plan it is just like an
arch
Load transferred to the abutments by means of
arching action
Can be constructed conveniently when height of
water stored is greater than the length of
barrier
Uplift pressure at base create no problem

25. ButtressDam:
Buttress - a support that transmits a force from a roof or wall to
another supporting structure
Buttress are used to support the vertical slab which hold water
Generally constructed with reinforced concrete
Uplift pressure is not so significant
This type of structure can be considered even if the foundation
rocks are little weaker
The meaning of BUTTRESS is
a projecting structure of
masonry or wood for supporting
or giving stability to a wall or
building.

26. Now a days used as coffer dam
Reinforced with timber or earth fill

27. Constructed of framework of timber struts and
beams with timber planks
An ideal temporary dam
Dam may last for 30-40 years

28. A kind of flexible dam, which can be inflated
and deflated quickly
Less cost, low maintenance need and easy
operational procedure
Dam bag is replaceable and can easily be
repaired and maintained

30. 1. Water storage should be largest for the
minimum possible height and length.
2. For safe and cheap construction good
foundation should be available at moderate
depth.
3. Good and suitable basin should be available.
4. Materials for construction should be available
at a dam site or near it.
5. There should be good and suitable site
available for spillway construction

31. 6. Property and land likely to be submerged
should be sufficiently low in comparison to
benefits expected
7. Dam site should be easily accessible in all the
seasons.
8. There should be a good catchment on the
upstream side of the site.
9. Suitable site should be available for providing
living accommodation to the labors and
engineering staff.
10. Social impact should consider for selecting a
dam site.

32. Following topographical and geological factors affect
the selection of a type of a dam –
Nature of Foundation
Sound rock formation is suitable to any type of dam
Earth dam is suitable to poor rock and earth
foundations
Nature of Valley
Narrow valley for arch dam
Gorge with rocky bed gravity dam
Wide valley and weak foundation buttress dam
Any width of valley with good foundation steel dam
Wide valley with gentle slope earth dam or rockfill
dam

33. Permeability of foundation material
For excessive uplift pressure in base arch dam is
suitable
For pervious foundation an earth dam is suitable
Suitable site for locating spillway
The availability of construction material

34. Actually the choice of the type of dam best
suited in a particular cases a matter of judgment
and wide experience.
The first consideration should be given to the
safety.
Secondly the choice of the type is generally limited
by the funds available.