GEOLOGICAL ENVIRONMENTAL INVESTIGATIONS Geological and environmental impact of

GEOLOGICAL & ENVIRONMENTAL INVESTIGATIONS

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

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.

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

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 •

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

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 •

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

Loss of forest land

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

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 •

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

Submergence of villages in upstream/ reservoir area

Submergence of villages in upstream/ reservoir area

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

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

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

Impact on climate and rain fall Loss of forest cover results in reduction in co 2 absorption capacity in turn capacity to give O 2 also comes down Increase in temperature in adjoining areas

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

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 •

Change in natural flow of water

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

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

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 hydroelectricity To Supply Water for vizag and steel

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.

Geological investigations

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.

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

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