What is the Dam? need of Dams ... Environmental impacts of Dams

1. DAMS AND THEIR
ENVIRONMENTAL IMPACTS
Presented by-
Mohd Salman
16LPMS06
MSc. Plant Biology and Biotechnology
2nd Semester
Mohdsalmanuoh@gmail.com
Mentor -
Dr. Rahul Kumar

2. CONTENTS:-
• What is Dam??
• What is function of Dam??
• Why Build Dams??
• Structure of Dam
• Types of Dams
• Environmental Impacts of Dams
• Non- Reciprocal Effects of Dams on Society
• Dam Failure
• List of Important Dams in INDIA

3. WHAT ARE DAMS ?
A DAM IS A BARRIER ACROSS FLOWING WATER
THAT OBSTRUCTS,DIRECTS OR RETARDS THE
FLOW OFTEN CREATING A RESERVIOR,LAKE OR
IMPOUNDMENTS.
OR
A DAM IS AN ARTIFIACIAL BARRIER USUALLY
CONSTRUCTED ACROSS A STREAM CHANNEL TO
IMPOUND WATER.
DAM REFERS TO THE RESERVIOR RATHER THAN
THE STRUCTURE.
DAMS ARE MADE FROM A VARIETY OF MATERIALS
SUCH AS ROCK, STEEL, WOOD, CONCRETE OR A
COMBINATION OF THESE MATERIALS.

5. WHAT IS THE FUNCTION OF A
DAM?
DAMS PROVIDE A MEANS OF
REGULATING DOWNSTREAM
SURFACE WATER FLOWS OVER
SPACE AND TIME BY ALTERING THE
NATURAL SPATIAL AND TEMPORAL
DISTRIBUTIONS OF STREAM FLOWS.

6. WHY BUILD DAMS?
TO IMPROVE THE QUALITY OF HUMAN LIFE BY
PROVIDING……
WATER QUALITYIRRIGATION

7. FLOOD CONTROL
HYDROPOWER
RECREATION
NAVIGATION

8. TOURISM WATER DIVERSION

9. STRUCTURE OF DAM

10. STRUCTURE OF DAM
 HEEL: CONTACT WITH THE GROUND ON THE UPSTREAM SIDE
 TOE: CONTACT ON THE DOWNSTREAM SIDE
 GALLERIES: SMALL ROOMS LIKE STRUCTURE LEFT WITHIN THE
DAM FOR CHECKING OPERATIONS
 SPILLWAYS: IT IS THE ARRANGEMENT NEAR THE TOP TO RELEASE
THE EXCESS WATER OF THE RESERVOIR TO DOWNSTREAM SIDE
 SLUICE WAY: AN OPENING IN THE DAM NEAR THE GROUND LEVEL,
WHICH IS USED TO CLEAR THE SILT ACCUMULATION IN THE
RESERVOIR SIDE
 DIVERSION TUNNEL: TUNNEL ARE CONSTRUCTED FOR DIVERTING
WATER BEFORE THE CONSTRUCTION OF DAM. THIS HELPS IN
KEEPING THE RIVER BED DRY.

11. BY SIZE DAMS ARE CLASSIFIED INTO TWO
TYPES:
1. Large dams ( higher than 15-20 meters)
e.g. Barrages dams
1. Major dams ( higher than 150-250 meters)
e.g. Nurek dam in Tajikistan

12. TYPES OF DAMS BASED ON STRUCTURE
e.g. Nagarjuna Sagar Dam (INDIA),
Grand Coulec Dam (USA)
e.g. Idukki Dam (INDIA),
Hoover Dam (USA)
e.g. Bartlett Dam (USA)
e.g. The Tehri Dam (INDIA)

13. BY USE DAMS CAN BE CLASSIFIED AS:
1. Check dam
2. Detention dam
3. Diversionary dam
4. Dry dam
5. Saddle dam
6. Storage dam
7. Overflow dam
8. Wing dam
9. Cofferdam
Check dam in HCU

14. ENVIRONMENTAL IMPACTS OF DAMS

16. ENVIRONMENTAL IMPACTS OF DAMS
 Terrestrial Ecosystems and Biodiversity
 Greenhouse Gas Emissions
 Downstream Aquatic Ecosystems and Biodiversity
 Impacts of changes in flow regimes
 Impacts of trapping sediments and nutrients behind a dam
 Blocking migration of aquatic organisms

18. NON RECIPROCAL EFFECTS OF DAMS ON
SOCIETY
 Hydropower
 Irrigation, Drainage & Flood control
 Displacement of People and Livelihoods
 Downstream Livelihoods
 Cultural Heritage
 Under-counting of the displaced
 Physically displaced populations enumerated but not resettled
 Socio-economic Impacts through the Planning and Project Cycle

20. DAM FAILURE
MAIN CAUSES OF DAM FAILURE-
 EARTHQUAKES
 EXTREME INFLOW
 POOR MAINTENANCE , ESPECIALLY OF OUTLET PIPES
 HUMAN, COMPUTER OR DESIGN ERROR
 INTERNAL IRROSION OR PIPING, ESPECIALLY IN EARTHEN DAMS
 SLIDING OF MOUNTAIN INTO RESERVOIR
 SUB-STANDARD CONSTRUCTION MATERIALS/TECHNIQUES
 SPILLWAY DESIGN ERROR
 GEOLOGICAL INSTABILITY CAUSED BY CHANGES TO WATER LEVELS
DURING FILLING OR POOR SURVEYING

21. LIST OF DAM FAILURES

23. REFERENCES
• Dams And Development- A New Framework
For Decision-making The Report Of The
World Commission On Dams
• www.wikipedia.com
• http://www.internationalrivers.org/
• International Congress On River Basin
Management