1. GEOLOGICAL & ENVIRONMENTAL INVESTIGATIONS

2. Geological and environmental impact of dams
How the impact is different from a hazard
Purpose of construction of dam
Geological impact of construction of dams
Environmental impact of construction of dams
Measures to reduce the impact of construction of proposed dam

3. How the impact is different from a hazard
A proposed dam project may have various impacts. All these can be predicted well in advance at the time of preparation of Environmental Impact Assessment (EIA) report.
Various Impacts of the dam project are
Impact on Environment
Impact on Economy
Impact on Culture
Impact on Society.

4. PURPOSE OF DAMS Water supply for irrigation, drinking, industry
Hydro power generation
Flood control
Navigation
Recreation
Diversion from one river basin to other river basin
Water storage for wild animals in forest areas

5. Geological impact of construction of dams
Any lapse in selection of suitable site/ sound rocks at the base for construction of dam and reservoir leads to failure and results in disaster.
Failure in identification of geological structures such as faults leads to disaster
Construction of major dams in seismically sensitive zones – if seismicity is not taken in to account it results in disaster

6. ENVIRONMENTAL IMPACT OF DAMS
Construction of dams will also have negative impact on environment
Loss of forest land
Loss of agricultural land
Loss of wild life
Submergence of villages in upstream/ reservoir area
Change in natural flow of water

7. Loss of forest land Loss of Green Cover/tress, shrubs wooden material
Loss of tribal culture
Loss of forest produce
- nuts, leaves , spices, gum, fruits, honey, plant based medicines, fiber, timber, fire wood etc.
Impact on climate, rain fall,
Loss of carbon absorption capacity
Loss of bio diversity
Reduction in cleaning capacity of pollutants

8. Loss of forest land
Loss of tourism Loss of aesthetic effect Forest reduces run off and increases infiltration Reduction in infiltration will leads to reduction in availability of groundwater Contributes to floods Loss of ecological benefits Loss of cultural and historical benefits

9. Loss of forest land

10. Loss of wild life
Loss of shelter to wild life will lead to migration of wild animals
Loss of bio diversity
Species may become extinct
Livelihood of tribals will get effected

11. Loss of agricultural land
Construction of major dams & reservoirs leads to inundation of several villages and thousands of hectares of farmland.
Farmers loose their lands and it effects the livelihood of farmers and leads to migration.
Reduction in agricultural productivity which inturn effects the agricultural based industry.
Farm labour will not have work in that area and this forces to migration

12. Submergence of villages in upstream/ reservoir area
All the effected families to be rehabilitated
Effected families loose their livelihood and shelter
All of them can not afford to construct a new shelter
They need to search for employment

13. Submergence of villages in upstream/ reservoir area

14. Submergence of villages in upstream/ reservoir area

15. Change in natural flow of water
Down stream flow is being blocked and it effects the survival of aquatic animals
effects the availability of water for animals and birds living in down stream.
Effects the groundwater in down stream.
Fishermen depending on fishing activity in down stream will get effected

16. Loss of tribal culture
Tribals living in effected area are forced to migrate to other regions.

17. Loss of forest produce nuts leaves spices gum fruits honey
plant based medicines
fiber, timber, fire wood etc.

18. Impact on climate and rain fall
Loss of forest cover results in reduction in co2 absorption capacity in turn capacity to give O2 also comes down
Increase in temperature in adjoining areas

19. Other effects Submergence of construction materials
Submergence of mineral resources
Submergence of archeological, historical and places of tourism.
Papikondalu in proposed polavaram dam project.

20. Change in natural flow of water
Dams require close monitoring of water inflow and out flow. Any human error in this regard will lead to disaster of floods
Ex. Large dam incidence in 2014 lead to loss of 24 lives of college students
Man made reservoirs some times may lead to abnormal floods
Ex : floods received in river Krishna in 2009

21. Change in natural flow of water

22. Seismicity
Construction of major dams some times may lead to reservoir induced seismicity.
Koyna dam in Maharashtra

23. Disputes between states and countries
Some times construction of major dams leads to disputes between two states
Proposed polavaram dam on river godavari

25. To interlink Godavari (Polavaram) & Krishna (Vijaywada) just before they merge into sea. (observe map)
To Store water at Polavaram dam in West Godavari district.
To Irrigate ~3 lakh hectre agricultural land.
To generate 950+ MW hydro-electricity
To Supply Water for vizag and steel plant

26. Why objection to Polavaram DAM?
ODISHA
Height of this dam should be low.
else, Malkangiri forest area will be submerged in water.  (~650 ht.)
CHHATTISGARH
Dam will submerge villages along Sabari river. (~800 ht.)
TELANGANA
Dam will submerge villages of Khammam district.Polvaram project won’t give any water to us.
EIA
Environmental impact assessment (EIA) says >250 villages and >1.5 lakh villagers will be affected.

27. Geological investigations

28. Geological and environmental investigations
The purpose of geological and environmental investigation is to identify a suitable site for construction of dam and reservoir
- site should be safe,
- stable
- cost of construction should be economic
- cause less damage to the natural and man
made environment
We need to identify at least two or more sites, evaluate and finally select the site having minimum damage to the environment , safe , stable and economic.

29. Geological investigations
We need to look for solid rocks at the base
Avoid the locations where shale rock/ clay is occurring at base
Area shall be free from major faults, minor faults can be treated.
Rocks occurring at reservoir shall be water tight( porous and permeable rocks can not hold water in the reservoir/ loss of water will be more in to the ground
Rocks shall not dip towards down stream
Support of hillocks on either sides of dam with reasonably narrow cross section is preferable
Topography should be convenient to hold adequate quantity of water for reservoir

30. Environmental investigations
Detailed investigations are essential to assess the impact of the proposed dam on natural and man made environment
Impact on forestland
Wild life
Agricultural land
Human settlements
Economy
Ecological
Aesthetic
Social
Cultural
Submergence of villages, townships