1. Environmental Management Module V
Amity Business School
Environmental Management Module V

2. Environmental Issues related to Mega Hydroelectric Projects- Dams, Resettlement & Rehabilitation of people- Problems Concerned

3. DAMS
Technically the term “dam” relates to the barrier constructed across a stream, valley or similar natural depression for the purpose of impounding water, but popular usage includes the impounded water along with the barrier. Apart from the obvious requirements of storage for community or stock water supply, the economic purposes served by impounding of water by dams are: land irrigation, generation of electricity by hydraulic power, navigation etc. Hydroelectricity is electricity produced by hydropower. It is a renewable source of energy, produces no waste, and does not produce carbon dioxide (CO2) which contributes to greenhouse gases. Hydroelectricity now supplies about 715,000 MW or 19% of world electricity (16% in 2003), accounting for over 63% of the total electricity from renewable in 2005.

4. EFFECT ON ENVIRONMENT Greenhouse gas emissions
The reservoirs of power plants in tropical regions may produce substantial amounts of methane, carbon di oxide. This is due to plant material in flooded areas decaying in an anaerobic environment, and forming methane, a very potent greenhouse gas.
Soil Erosion One of the first problems with dams is the erosion of land. Dams hold back the sediment load normally found in a river flow, depriving the downstream of this. In order to make up for the sediments, the downstream water erodes its channels and banks. This lowering of the riverbed threatens vegetation and river wildlife. One of the reasons dams are built is to prevent flooding. However, most ecosystems which experience flooding are adapted to this and many animal species depend on the floods for various lifecycle stages, such as reproduction and hatching. Annual floods also deposit nutrients and replenish wetlands.

5. Contd-
Species Extinction As fisheries become an increasingly important source of food supply, more attention is being paid to the harmful effects of dams on many fish and marine mammal populations. The vast majority of large dams do not include proper bypass systems for these animals, interfering with their lifecycles and sometimes even forcing species to extinction.
Changes to Earth's Rotation
NASA geophysicist Dr. Benjamin Fong Chao have found evidence that large dams cause changes to the earth's rotation, because of the shift of water weight from oceans to reservoirs. Because of the number of dams which have been built, the Earth's daily rotation has apparently sped up by eight-millionths of a second since the 1950s. Chao said it is the first time human activity has been shown to have a measurable effect on the Earth's rotation.

6. Contd-
Animal diseases Animals are subject to a similar range of water related diseases as humans. They may also act as reservoirs for human water-based infections. The promotion of animal husbandry as a secondary, income generating activity for farmers in newly irrigated areas should be carefully evaluated for its possible environmental and health risks. Aquatic weeds The main problems of aquatic weeds are that they reduce the storage and conveyance capacity of reservoirs, canals and drains and increase water loss through evapotranspiration. Most irrigation schemes suffer infestations of exotic species. They are difficult and expensive to control, though the use of linings, shade and intermittent drying out can compliment traditional techniques of mechanical removal, careful herbicide application and the introduction of weed eating fish and insects.

7. Rehabilitation and Resettlement of People
Towns and forests located in areas that will be inundated will have to be demolished and removed in order to increase navigability on the river. The overall objective of resettlement and rehabilitation is to ensure that the effected production base will be restored , labour force will be re-employed, and income and livelihood of people will be improved or at-least restored to their previous levels before resettlement.

8. Resettlement Principles
The resettlement plan shall be based on detailed inventory for land acquisition and house demolition
The resettlement shall be combined with local development, resource utilization and economic growth as wl as environment protection
The resettlement plan should be based on the principle “ beneficial to the production and convenient for living”.
Re-construction standard shall be based with the principle of recovery to the original standard, combining the local development the cost of raising standard and future plan shall be solved independently by local government and relevant department.
Fully utilize natural resource, build water conservancy facility, develop new farmland, improve land quality and strengthen agriculture.
Resettlement plan will include measures to improve basic livelihood and assist relocation and rehabilitation for extremely poor people affected by project.