DAMS AND THIER ENVIRONMENTAL IMPACTS

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 2 nd Semester [email protected] 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.

4. 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.

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

6. FLOOD CONTROL HYDROPOWER RECREATION NAVIGATION

7. TOURISM WATER DIVERSION

8. STRUCTURE OF DAM

9. 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.

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

11. 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)

12. BY USE DAMS CAN BE CLASSIFIED AS: Check dam Detention dam Diversionary dam Dry dam Saddle dam Storage dam Overflow dam Wing dam Cofferdam Check dam in HCU

13. ENVIRONMENTAL IMPACTS OF DAMS

14. 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

15. 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

16. DAM FAILURE DAM FAILURE

17. 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

18. LIST OF DAM FAILURES

19. 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

20. THANK YOU