Chapter-IV POSITIVE AND NEGATIVE IMPACTS OF BIG DAMS A DEBATE (original) (raw)
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Dam: Historical perspectives and an overview of India
Dam is a barrier across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment. Exploitation of rivers with installation of dams on them is very old system experienced worldwide and has been multiplied manifold up to the present. Damming activities started mainly for the purpose of irrigation but later it has become multipurpose projects with facilities of flood control, fishing activities, hydroelectric power generation, domestic and industrial supply of water, tourism etc. Though large dams have multiple beneficiary effects but could not avoid its negative aspects inherent to dam building. Perspectives of dam have been changed both in spatial and temporal context with imposition of technocentrism on nature. The paper is an endeavor to examine the historical perspectives of dam globally and to assess an overview of dam in India from ancient to the recent time.
Impacts of Large Dams: Issues, Opportunities and Constraints
Impacts of Large Dams: A Global Assessment, 2012
From time immemorial, human beings have settled in the fertile plains of major rivers like the Nile in Africa, Euphrates-Tigris in Mesopotamia, and the Indo-Gangetic plain in the Indian subcontinent. In these areas, floods and droughts had to be managed to reduce losses to human and cattle populations and also to limit economic damage. During the past two centuries, hundreds of millions of people lived around rivers, which necessitated control of these rivers to provide assured water supply for domestic, agricultural and industrial purposes and to reduce flood and drought damages. Thus, the building of dams has gained steady momentum. More recently, after the 1930s, water requirements increased exponentially in countries where there was signifi cant immigration, such as Argentina, Australia, Brazil, Canada and the United States, to satisfy the needs of their expanding populations. Globally, with the passage of time, water control and assured availability of water of appropriate quality became essential requirements for continuing economic and social development.
POSITIVE AND NEGATIVE IMPACTS OF DAMS ON THE ENVIRONMENT
The human being has been struggling in order to shape the ecosphere in a manner he wants since the first day. The period in which this struggle was observed most intensively was the period covering the transition from a migrant and primitive hunter society to a resident life and farming. The most deep-seated environmental modification against the nature that had been realized in the history of the human being has started at this time. Even the development and downfall of civilizations are correlated to this interaction between the human being and nature.
Sustainable Water Resources Management
Environmental flow is the minimum flow required in a fluvial system to maintain its ecological health and to promote socioeconomic sustainability. The present work critically examines the concept of the environmental flow in the context of dams and development using a systematic methodology to find out the previous works published during the last 3 decades (1990-2020) in different search engines and websites. The study reviews that structural interventions in the form of dams, barrages, weirs, etc. impede the natural flow of the rivers. Moreover, other forms of development such as industrialization, urbanization, and expansion of modern agriculture also exacerbate the problems of environmental flow across the world, especially in monsoon Asia. The present case of the environmental flow for the Damodar River portrays that the construction of dams and barrages under the Damodar Valley Project have significantly altered the flow duration, flood frequency, and magnitude (high-frequency low magnitude events in the post-dam period), while urban-industrial growth in the basin has polluted the river water (e.g., lower dissolved oxygen and higher biological oxygen demand). This typical alteration in the flow characteristics and water quality has threatened aquatic organisms, especially fish diversity and community structure. This review will make the readers aware of the long-term result of dam-induced fluvial metamorphosis in the environment through the assessment of environmental flow, species diversity, flow fluctuation, and river pollution. The study may be useful for policy-making for ushering in the sustainable development pattern that will attract future researchers, planners, and stakeholders.
Development and Large Dams: A global perspective
International Journal of Water …, 2001
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In the Ganges-Brahmaputra-Meghna (GBM) basin in south Asia, the Himalayan rivers offer a large number of sites suitable for the construction of storage dams to collect part of their very large monsoon runoff and generate a good amount of hydropower. A series of large dams proposed by the governments are facing strong opposition on social and environmental grounds. Additional water and hydropower supplies are needed badly to ensure economic development in this basin, where poverty is a widespread problem. The report of the World Commission on Dams (WCD) has been analysed in this paper to explore how much it can provide a new framework for decision making for these dams. It has been found that there are some important technical gaps in the WCD report, as a result of which it cannot help in answering some crucial technical questions raised by the debate on dams on the Himalayan rivers of the GBM basin.
Dams in Time of Water Nationalism
CBU International Conference Proceedings
A dam, in most cases is a large, impressive concrete structure. A commanding number of large dams exist with over 45000 estimated in the world. It is important to understand such a concrete structure not only from a technical perspective, but also from the view of local community in the region of the dam. Also, it is important to know the international impact of a dam on a river basin and the measures necessary for implementing a dam, as well as the positive and negative effects of dam construction itself. Preliminary measures aim to characterize a river regarding natural, geological, geographical patterns, human geographical distribution, and food production. Prospective trends, such as the need for augmented water volumes for a water-fed agriculture, industrialization, energy, and river transportation, can influence decisions connected to dam building. Recently, climate change, a phenomenon considered as human-induced, at least partially, and the prospect of a water-stressed world...
Environmental Management, 2002
In developing countries, large dam projects continue to be launched, primarily to secure a time-stable freshwater supply and to generate hydropower. Meanwhile, calls for environmentally sustainable development put pressure on the dam-building industry to integrate ecological concerns in project planning and decision-making. Such integration requires environmental impact statements (EISs) that can communicate the societal implications of the ecological effects in terms that are understandable and useful to planners and decision-makers.
Dams, The serious obstacles on sustainability
Severe Unsustainability results from the dams have an unbelievable damage on rivers and have increased dramatically the use of water resources rather than the normal rate of sustainability. The constructed dams have also the complex impact on transforming the face of a landscape and are deeply affecting the ability of local communities and ecosystems in sustaining life and food systems for humans and other fellow beings in Iran. Currently in Iran the severe trend of building dams leads to silence of the rivers that the silencing of these rivers has resulted in the construction of many ecosystems and spread of desertification in the country. In this paper we seek to compare the principle of dams constructions in Iran versus the principle of Agenda21 and prove that current trend totally contradict the principles of Agenda 21.