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The Environmental and Social Impacts of Large Scale Dams


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Title: The Environmental and Social Impacts of Large Scale Dams

The Environmental and Social Impacts of Large
Scale Dams
  • Tony Devencenzi
  • Race, Poverty and the Environment
  • Professor Raquel R. Pinderhughes
  • Urban Studies Program
  • San Francisco State University
  • Spring 2003

The public has permission to use the material
herein, but only if author, course, university
and professor are credited
Image from http//
Patrick McCully
  • Massive dams are much more than simply machines
    to generate electricity and store water. They are
    concrete, rock and earth expressions of the
    dominant ideology of the technological age icons
    of economic development and scientific progress
    to match nuclear bombs and motor cars.

  • This presentation focuses on the negative impacts
    of large scale irrigation and hydroelectric dams
    from both an environmental and a social
    perspective. It is designed to describe how dams
    effect their surrounding physical environment, as
    well as their social impact on local people and
    their cultures. To do this, it focuses on the
    lifecycle of freshwater extraction at it largest
    scale through the use of gigantic concrete

  • Life on this planet has evolved around the
    availability, movement, and quality of water.
    Like every other living being on this planet,
    water is essential for human survival. Because
    of this, civilization has traditionally been
    structured around the natural spatial arrangement
    and flow of water systems. From nomadic trade
    routes that travel from oasis to oasis, to large
    modern port cities and blooming desert
    metropolises, humanity is inseparably linked to

Dam Uses
  • Direct Water Usage
  • Private / Domestic - Household purposes, Drinking
    water and landscape irrigation
  • Commercial - Restaurants, hotels, golf courses,
  • Irrigation Crop use. Water needs at the scale
    that large dams provide most often feed
    industrial farming practices.
  • Livestock Use for animal raising as well as
    other on-farm needs
  • Industrial Cooling water (power generation,
    refineries, chemical plants), processing water
    (manufacturing pulp and paper, food, high tech,
  • Mining hydraulic mining, various processes,
    settling ponds
  • General public supply Firefighting, public
    parks, municipal office buildings

Dam Uses
  • Indirect Uses
  • Hydroelectric Power Power generation is one of
    the most common purposes for the construction of
    large dams. It is promoted as a totally clean
    form of electricity.
  • Flood Control Dams even out the peaks and lows
    of a rivers natural flow cycle by calming
    seasonal flooding, then storing that water for
    gradual release year round.
  • Transportation Dam locks are used to move ships
    past large dams. This in conjunction with flood
    control make transportation feasible on rivers
    that were traditionally wild.

Distribution of Water Resources
  • Global distribution of water resources varies
    greatly by region. Climate, topography, geology,
    hydrology, upstream water usage, and historic
    water usage all come into play in determining the
    availability of water in any given region.

From http//
Distribution of Water Resources
  • This is not to say that everyone in these water
    rich areas has consistent, affordable, quality
    water that is assured to them.

Peru, The Democratic Republic of the Congo, and
Myanmar are examples of this
From http//
Hmm . . . Those countries sure seem to have a lot
of water, why dont they just build lots of large
dams to fix their problems??
But with lots of large dams they could provide
water for their thirsty masses and clean
electricity to fuel industrialization! Everyone
would benefit, it would be fabulous!
Well, you see Chuck, Its not quite that simple.

Oh boy . . . I think we better start at the
beginning . . .
Types of Large Dams
  • Large dams are built using several different
    methods. For the purpose of this project I will
    investigate the three main types of dams that can
    be built at extreme scales. These types are
  • Gravity dams
  • Arch dams
  • Buttress dams

Gravity Dams
  • Gravity Dams use their triangular shape and the
    sheer weight of their rock and concrete structure
    to hold back the water in the reservoir.

From http//
Gravity Dams
  • Gravity dams are the most common type of large
    dam in the world because they are easy and cheap
    to build. They can also be built across long
    distances over relatively flat terrain. This
    makes them very applicable in non-mountainous
    regions. The largest gravity dam in the world is
    the Aswan Dam in Egypt. (24)

Arch Dams
  • Arch Dams utilize the strength of an arch to
    displace the load of water behind it onto the
    rock walls that it is built into.

From http//
From http//
Arch Dams
  • Arch dams can only be built where the walls of a
    canyon are of unquestionable stability. They
    must also be impervious to seepage around the
    dam, as this could be a source of dam falure in
    the future. (24)
  • Because of these factors, Arch dams can only be
    built in very limited locations.
  • Arch dams use less materials than gravity dams,
    but are more expensive to construct due to the
    extensive amount of expertise required to build
    one. (25)

Buttress Dams
  • Buttress Dams use multiple reinforced columns to
    support a dam that has a relatively thin
    structure. Because of this, these dams often use
    half as much concrete as gravity dams

From http//
Composite Dams
  • Composite dams are combinations of one or more
    dam types. Most often a large section of a dam
    will be either an embankment or gravity dam, with
    the section responsible for power generation
    being a buttress or arch.

  • The Bloemhof Dam on the Orange River of South
    Africa is an excellent example of a
    gravity/buttress dam.

Buttress Dam
Gravity Dam
From http//
Wow! Thats great, now youve shown me all the
amazing techniques that I need to bring fresh
water to those people!! Yahoo! Lets Go!
Hold on there Buckaroo! You see, there are quite
a few environmental and social problems
associated with these here dams . . . Lets start
with the materials that theyre made of
  • Large amounts of soil, sand, stone and aggregate
    and concrete are need for dam construction.
  • If available, these materials will be collected
    as near to the site of the dam as possible.
  • The extraction of these materials requires large
    amounts of fossil fuels to operate the machinery.
  • Air and water pollution result from the dust and
    mud that is created from this process

Materials continued Concrete
  • Concrete is the primary ingredient in any large
    scale dam.
  • Concrete is basically a mixture of two
    components aggregates and paste. The paste is
    usually composed of Portland cement and water,
    and it binds together the fine and coarse
    aggregates. (20)
  • A typical mix is about 10 to 15 cement, 60 to
    75 sand/ aggregate, 10 to 20 water and 5 to 8
    air. (20)
  • Producing one ton of cement results in the
    emission of approximately one ton of CO2, created
    by fuel combustion and the calcination of raw
    materials (21)

Physical Impacts of Large Dams
  • The physical impacts of large scale dams fall
    into several categories
  • Upstream
  • On-site
  • Downstream
  • Global Scale

Physical Impacts Upstream
  • Loss of Land
  • Destruction of peoples property in the reservoir
    zone. Loss of possible agricultural, range or
    forest lands.
  • Stagnant Water Table
  • Water from unnatural reservoirs seeps down into
    the water table. This excess water can overload
    the natural watertable, slowing down its flow, so
    that it ultimately may go stale. This can be
    damaging to surrounding flora, and has the
    potential to harm the well water of surrounding
  • Habitat Destruction
  • The area that is covered by the reservoir is
    destroyed, killing whatever habitat existed there
  • Habitat destruction also happens far upstream
    from a dam. Migratory fish can no longer travel
    upstream past large dams in order to reach their
    spawning grounds.

Physical Impacts On-site
  • Change in Water Characteristics
  • Temperature Large reservoir of water heat up as
    more water is exposed to the sun for longer
    periods of time. Aquatic life that is sensitive
    to temperature cannot adjust to this change in
    their aquatic climate.
  • Salinity The rise in a rivers salinity due an
    unnatural reservoir is due to increased
    evaporation rates.
  • Sediment Load Sediments that wash down the
    river settle into large reservoirs. In rivers
    that have high sediment loads this usually
    determines the life
  • Nutrient content Natural nutrients build up in
    reservoirs, causing eutrophication.
  • O2 content each of these elements results in a
    lower oxygen content, further harming aquatic

Physical Impacts On-site
  • Dust, Noise pollution from Construction
  • Water Pollution
  • Industrial and residential pollutants, as well as
    agricultural runnoff (including high nitrate
    loads, fertilizers and pesticides). On lake
    sources such as boats and jet skis add oil and
    other chemical pollutants to waste water.
  • These chemicals build up to toxic levels in
    reservoirs, especially during dry seasons when
    little water leaves.
  • Habitat Destruction
  • Loss of local ecosystem covered by the reservoir.
  • Damage caused by improved access to humans
    roads, transmission lines, increased migration

Physical Impacts On-site
  • Exotic species introduction
  • Aggressive, non-native species of fish are often
    introduced to reservoirs for farming and sport
  • Disease
  • Vector borne diseases increase in tropical areas
    due to the creation of large areas of still
    water. This encourages mosquito breeding, the
    main vector for the transmission of malaria and
  • Schistostomaiasis is a water borne disease that
    comes from snails that breed on the upstream side
    of dams.

On-Site ImpactsReservoir-Induced Seismicity
  • There is a correlation between the creation of a
    large reservoir, and an increase in seismic
    activity in an area
  • The physical weight of unnatural reservoirs can
    cause seismic activity. While not the direct
    cause of earthquakes, the weight of reservoirs
    can act as a trigger for seismic activity.
  • Although not much direct research is available on
    the subject, the proposed explanation is that
    when the pressure of the water in the rocks
    increases, it acts to lubricate faults which are
    already under tectonic strain, but have been
    prevented from slipping by the friction of the
    rock surfaces.
  • As of now, it is not accurately possible to
    predict which large dams will produce RIS or how
    much activity will be produced. Earthquakes that
    are produced as the result of dams are not
    usually major, but they still pose a major threat
    to dam stability and the safety of people living

Physical Impacts Downstream
  • Flow Reduction
  • The downstream impacts of the net flow reduction
    due to extraction upstream can be extensive. They
    include habitat destruction far downstream at the
    mouth of the river, natural water table
  • Change in water characteristics
  • The changes in water characteristics that are
    mentioned above continues in the water that is
    discharged downstream. The cumulative effect of
    many dams on a single river magnifies each of
    these factors.

In Central Asia the Aral Sea shrank by half of
its original volume after the Soviets began
diverting water for electrical generation, as
well as for cotton and other crops. Although
this may be one of the most visible example,
overextraction of water resources and the
resulting drops in local water tables are
happening worldwide.
From http//

Physical Impacts Downstream
  • Change in natural flood patterns
  • Natural floods inundate downstream regions with
    nutrient rich sediments. Traditional farming
    systems in countries like Egypt (the Nile) and
    Bangladesh (the Ganges) were dependant upon
    seasonal floods to wash nutrient rich sediment
    upon the lower shores of the river.
  • They also seasonally clear out blocked waterways,
    which prevents larger floods from causing massive

From http//
Named Chinas Sorrow for its history of ruinous
floods, the Yellow River now barely trickles in
its lower reaches and in recent years has gone
dry due largely to heavy irrigation upstream.
Its not alone The once mighty Nile, Ganges, and
Colorado Rivers barely reach the sea in dry
Social Impacts Access to Water
From http//
Water flows past these squatters in gigantic
pipes on its way to high paying customers in
Delhi. Where they can, they get water from leaks
in the pipe. Otherwise they retrieve it from the
Ganges River (in the background). This water is
often of substandard quality, and seasonal floods
pose the threat of washing out this entire
settlement. (10)
Matamoros, Mexico
With no public funds left for waste-water
treatment plants, Matamoros canal system is
filled with raw sewage and industrial pollution.
In 2001, the overused Rio Grande dropped below
the citys water intake pipes, leaving the city
with no municipal fresh water for almost a month.
Social Impacts Price of Water
From http//
A drained aquifer, an inadequate water supply
system in its outer regions, and massive amounts
of poverty have left Mexico City as one of the
most water impoverished metropolitan areas in the
world. People are forced to pay almost 200 of
what wealthy residents with existing water
connections are charged. As shown in this
picture, the water is often stored in old barrels
that had previous industrial uses. (10)
Mexico City
Social Impacts Quality of Water
From http//
Santiago, Chile
By reducing the need for new water sources,
wastewater treatment plants offer a solution to
building large dams, for those who can afford it.
Worldwide, 2/3 of municipal wastewater doesnt
get treated, much less recycled. Most of it
returns to the river system, where many people
fish, drink, swim and bathe. An exception to
this case is Santiago, Chile, which plans to
treat all of its wastewater by 2009. (10)
  • When dams are constructed in populated areas,
    many people are forced to relocate.
  • Established communities are dispersed and often
    destroyed. The communities that are forced to
    absorb the influx of displaced people are
    strained to their maximum capacity.
  • The mass majority of people that are displaced by
    dam construction are poor.
  • The cost of moving is often placed upon the
    people being uprooted. This is extremely hard
    for poor, marginalized people to accomplish, and
    often leaves them poorer than before. This is
    especially true for small agricultural
    communities that, now forced into the urban
    settlements and its subsequent infrastructure,
    have no viable job skills in order to provide a
    living wage for themselves.

  • Because of limits to space and resources, people
    are often forced to move long distances from
    their original homes. This, coupled with the
    hard transition into urban areas, often destroys
    traditional cultures.
  • Because of limits to space and resources, people
    are often forced to move long distances from
    their original homes. This, coupled with the
    hard transition into urban areas, often destroys
    traditional cultures.

Displacement India and China
  • The problems of displacement are very acute in
    countries such as the Peoples Republic of China
    (PRC) and India that are already heavily
    populated, and have been aggressively building
    dams since post WWII.
  • An estimated 12.2 million people have been
    displaced over the last fifty years due to the
    PRCs dam building projects (9 a,b).
  • Although the number of new dams being built in
    these countries has decreased, the size and scale
    of the projects have been increasing.
  • 1.1 to 1.3 million people are expected to be
    displaced by the Three Gorges project (9a). With
    the price tag of the project at an estimated
    24.65 billion for the project alone, billions
    more are going to be spent on resettlement(26).

  • From http//

Social Impacts International
  • International water conflicts occur in regions
    where rivers cross the borders of one or more
  • Violent conflict has the possibility to occur
    when one country overdraws its share of the
    water, causing detrimental effects in the
    downstream countries
  • Rivers that have ongoing conflicts
  • The Nile
  • The Ganges
  • The River Jordan
  • The Colorado
  • The Parana

Types of Development
  • Developing countries have restructured their
    economic systems to pay their debt and export
    their way to prosperity.
  • To do this they are developing their water
    resources in the direction of rapid
    industrialization. In this mindset, massive
    hydroelectric dams are an absolute necessary in
    order to provide the water and electricity that
    industries need.
  • In otherwise resource poor countries, this is
    seen as the only answer to achieve modernization,
    and to escape their cycle of debt.
  • Once that problem has been met, then issues of
    water access and quality will be answered,
    because the country will have moved up to at
    least a 2nd world status.

Financial Issues
  • The finance that is needed for the construction
    of large dams causes many problems around the
    world especially in poor, underdeveloped
    countries that are currently trapped in a
    painfully binding cycle of debt.
  • Since large scale dams require massive amounts of
    capital investment, dam construction is one of
    the primary reasons that countries take out loans
    from international lending associations.
  • Countries often take out loans to build large
    hydroelectric dams in order to improve their
    industrial infastructure. The hope is that by
    boosting their industrial sector, that they will
    boost their economy into economic prosperity.

Debt and International Lending Associations
  • Depending on the site and the scale of the
    project, prices for each project varies greatly.
    Average costs for large projects are usually in
    the area of billions of dollars (US).
  • For smaller or less developed countries this cost
    is often more than their annual GDP, and is
    absolutely insurmountable without the help of
    outside financing.
  • The World Bank is the greatest single source of
    funds for large dam construction, having provided
    more than US50 billion (1992 dollars) for
    construction of more than 500 large dams in 92
    countries (27)

Water Privatization and Globalization
  • The goal (of water invested corporations) is to
    render water a private commodity, sold and traded
    on the open market, and guaranteed for use by
    private capital through global trade and
    investment agreements. These companies do not
    view water as a social resource necessary for all
    life, but an economic resource to be managed by
    market forces-like any other commodity. (12)
  • Corporate shareholders have a legal
    responsibility to maintain consistently
    increasing profits and are not concerned about
    sustainability or equity of water delivery.
  • The concentration of power in the hands of a
    single corporation and the inability of
    governments to reclaim management of water
    services allows corporations to impose their
    interests on government, thereby reducing the
    democratic power of citizens.

The Commodification of Water
  • Water promises to be to the 21st Century what
    oil was to the 20th Century The precious
    commodity that determines the wealth of nations
  • Forbes Magazine, May 2000 (22)

From http//
Major Water Companies of the World
Suez image http//
00/ Nestle Image http//
1.htm Vivendi Image http//
prises_2002.htm Saur image http//
index_fr.html Thames Image http//
u/images/main_occ_parent_logotw.gif Bechtel
Image http//
Municipal Water Control
  • Some of the largest corporations dealing with the
    development and management of water
    infrastructures are Vivendi Universal, Suez,
    Bouygues-SAUR, RWE-Thames, Bechtel-United
    Utilites, and Nestle (7).
  • At either the request of the government or the
    insistence of the World Bank, these corporations
    take over municipal water provision services.
  • The poorer, underdeveloped outlying areas of
    cities and countries are often neglected. If the
    country requires that services be provided to
    these areas, the companies often raise prices to
    ensure that full cost recovery for their expenses
    is recovered (6).
  • Once these companies are in control of water
    systems, water provision becomes commodified. The
    water is then provided on an ability-to-pay

So . . .
What should be done?
  • Using aggressive conservation approaches is one
    of the easiest and most cost effective ways to
    eliminating the need for new dams. Replacing
    old, leaking infrastructures is costly on the
    front end, and most municipalities in poor
    countries lack the funds to do it.
  • Different conservation techniques and
    technologies can be applied to all areas of water
    use, from industry to agriculture. What lacks in
    most countries is an incentive to conserve. With
    state subsidized water flowing to areas of
    industrialization, it is more costly for
    companies to conserve water than to waste it.
    The answer proposed by the neoliberal train of
    thought is the commercialization of water
    markets. By being forced to pay for their own
    water, people turn to conservation to reduce
    costs. This may work well for certain parts of
    the industrial and commercial sector, but local
    people can ill afford to pay for water to be
    delivered to their homes, let alone improve the
    leaking pipes in their homes.

Irrigation Techniques
Irrigated agriculture uses up to 70 of
freshwater in some countries. Nontraditional,
Industrial methods often flood fields, loosing
much of that water to evaporation.
Irrigation Techniques
Or this.
Correctly used, drip irrigation places the exact
amount of water where it is needed, when it is
needed. This can reduce the amount of water
needed for irrigation anywhere from 30 to 70
Water Integration and Management
  • Instead of providing people with an endless tap,
    demand side water management provides people with
    water when they need it in pre-planned
    quantities. This encourages conservation without
    raising costs or encouraging commodification. (8)
  • Water Integration refers to integrating water
    management policies into all levels of society,
    public and private. This leads to a separation
    who has power over water utilities, and can serve
    as a system of checks and balances. (5)

Stop Building Large Dams
  • The negative social and ecological effects of
    large scale dam building far outweighs the
    positive attributes that they bring to society.
  • Instead, small dams should be built, where
    needed, in the control of those who should have
    it the people.

Local Control
  • Local control of water systems is essential for
    feasible, equitable, and sustainable water
    resource development.
  • All decisions about water must be based on
    ecosystem and watershed-based management. Only
    through this method will the ecological
    limitations of watersheds and the damages that
    dams create be realized.
  • These decisions must be local in origin, as they
    directly effect the people that live in the
    watershed and the people that are receiving the
  • Having no vested interest in these local
    concerns, transnational corporations are
    instrumentally detrimental to the quality, cost
    and availability of water.

Alternatives and Conclusions
  • We may now be facing the greatest challenge of
    our time. As water is the very centerpiece of
    life, the fight against the globalization and
    commodification of water is the centerpiece in
    the fight for global, universal justice and
  • No partial, conservation oriented solution is
    going to prevent the collapse of whole societies
    and ecosystems. A radical rethinking of our
    values, priorities, and political systems is
  • There are many ways to assist the developing
    world in this crisis, the major among these is
    the cancellation of the Third World debt.
    Without the crushing load of debt, countries
    would be able to control their own resources, and
    would not be forced into models of development
    that are not right or natural for their country.
  • Water must be declared a basic human right. This
    might sound elemental, but at the World Water
    Forum in The Hague, it was the subject of heated
    debate, with the World Bank and the water
    companies seeking to have it declared a human
    need. This is not semantic. If water is a human
    need, it can be serviced by the private sector.
    You cannot sell a human right. (12)

We, as human beings, must change our behaviors.
We must emphasize identifying the capacity of our
watersheds and, as communities, identify the
limits we can place upon them. The world must
accept conservation as the only model for
survival, and we must all teach ourselves to live
within our environment's capacity. The insidious
problem with pricing and conservation by
commodification is that it actually undermines
environmental science and activism, as well as
governments' responsibility to protect their
citizens and the environment by buying into the
argument that the market will fix everything. At
stake is the whole notion of "the commons," the
idea that through our public institutions we
recognize a shared human and natural heritage to
be preserved for future generations. Citizens in
communities around the world must be the
"keepers" of our waterways and establish
community organizations to oversee the wise and
conservative use of this precious resource. Never
has there been such an urgent need to come to
terms with this seminal issue.
Maude Barlow
  • Blue Gold the Fight to Stop the Corporate Theft
    of the Worlds Water. M. Barlow, T. Clarke. The
    New Press, New York, 2002.
  • The California Water Atlas. Karl, William L. ed.
    State of California Office of Planning and
    Research, Sacramento. 1978
  • Water and Water Policy in World Food Supplies.
    Articles presented at Texas AM University on May
    26-30, 1985. Texas AM University Press, College
    Station, TX. 1987
  • Cadillac Desert. Mark Reisner. Penguin Books,
    New York, 1993
  • Justice and Natural Resources Concepts,
    Strategies, and Applications. K. Mutz, G. Bryner
    D. Kenney. Island Press, Washington, 2002
  • Silenced Rivers The Ecology and Politics of
    Large Dams. Patrick McCully, Zed Books, London,
  • The Water Manifesto Arguments for a World Water
    Contract. Petrella, Riccardo. Zed Books, London,
  • Integrated Approach for Efficient Water Use Case
    Study Israel Saul Arlosoroff, The World Food
    Prize International Symposium From the Middle
    East to the Middle West Managing Freshwater
    Shortages and Regional Water Security, Des
    Moines ,Iowa, USA October 24-25, 2002
  • http// The World Commission on Dams
  • Country Review Paper Experience with Dams in
    Water And Energy Resource Development In The
    Peoples Republic of China
  • Case Study Large Dams Indias Experience

  • Montaigne, Fen. Challenges for Humanity Water
    Pressure. National Geographic. Sept. 2002
    (pictures by Peter Essick)
  • http// The International Rivers
  • http//
  • http// Official page of the
    United States Geological Survey
  • http// USGS Toxic Substances
    Hydrology Program
  • http// The official website
    of the United States Environmental Protection
    Agencys Office of Water.
  • http// EPA Water
    Quality Inventory Report, 2000.
  • http// The World Banks
    official home page.

  • http// The Water Environment
    Federation homepage.
  • http// The Water Page
  • http// The
    American Concrete Institute Homepage
  • http//
  • http//
  • http//
  • http//
    htmgravity The University of Durham, UK
  • http//
    The Nelson Institute for Environmental
    Studies, University of Wisconsin Madison
  • http//
    CNN Report on the Three Gorges Dam
  • http//
  • http//