Free Flowing or Dammed. April 1 1994 Miranda Rose (age 15) IE Weldon
Secondary School Lindsay, Ontario. Canada Email: <weldona@web.apc.org>
TO DAM OR NOT TO DAM
Many of our planet's rivers are no longer the wild, free-flowing
rivers that were discovered by the early explorers. From great rivers to
small streams,all our open water sources are being dammed for the benefit of
humans. Along with these benefits to humans comes a great price, not only
the cost in dollars but great costs socially and ecologically. The ecosystem
that is lost cannot be expressed in dollars. Modifications to any natural
water course will affect our world in many ways and, since free-flowing
rivers and streams are few and far between, it is important to understand the
economical, social and ecological impacts caused by dams.
Dams are constructed to play a vital role in a region's economic
development. These water projects supply the Power to Progress, cheap
hydro-electric power. At installed capacity of 1,000 dollars per kilowatt,
hydro-electricity costs much less than any other form of energy, including
thermal and nuclear power. On top of the inexpensiveness of hydro-
electricity, it has incredible potential, knowing that if all the power
enclosed in the rivers of the world were harnessed by dams, more energy
could be produced yearly by dams than the amount of energy produced by
12,000 nuclear reactors. Dams also provide water for irrigational purposes
which helps global food production. Irrigated agriculture is one of the
most efficient farming systems in the world. The earth's surface is
classified as being 50% arid or semi-arid, therefore, there is no hope of any
increase in the amount of irrigated land without increasing water supplies.
Rain water is the supply that seems to be most appropriate but it is too
disperse and unpredictable to be relied upon without the help of large
dams. Large dams terminate any unpredictability by storing water where it
is needed, for when it is needed. Dams are also built to regulate the flow
of rivers, for flood control purposes. Dams flood areas which are sparsely
populated to protect higher density communities downstream.
So what's wrong with dams? Many environmentalists have concluded that
dam projects have actually been disastrous, economically, socially and most
of all environmentally.
Economically, the negative effects of dams are most commonly kept
hidden from the public. During the 1980s, two thirds of the world's large
dams expected to be completed were located in Third World countries with
plans for rapid industrialization and urbanization. Caused by a drastic
increase of water demand, water supply and quality is deteriorating in these
regions. With a decrease of water availability, these new economies will be
affected. The economic effects of the new large dams will eventually
contribute considerably to already massive burdens of debt in these
countries. Large dam projects are believed to improve a region's economic
situation but if this is the case, large dams already in operation should
already have reached their economic goals.
Socially, the effects of dams are inconceivable. To construct a dam,
a large area above the dam site must be flooded causing the people that live
there to resettle willingly or unwillingly. Ghana's Volta Dam caused
approximately 78,000 people from 700 different towns to relocate for the
construction of the dam. The Pa Mong water project in Vietnam saw the
evacuation of 450,000 people due to the land flooding that needed to take
place. Future developments in the Philippines over the next 20 years could
possibly cause the resettlement of 1.5 million people. The resettlement
programs to date have caused nothing but misery to the humans involved.
"From the human point of view, relocation has been one of the
least satisfactory aspects of reservoir projects...Settlement
schemes have a high failure rate around the world. Even
where planning is effective, some (especially the aged) will
never come to terms with their new homes. For them, the
transition period ends only with death"
-Professor William Ackerman 1976
Bloodshed is not always avoided when resettlement schemes have been
involved. In the Philippines, conflict aroused during the planning stages
of the Chico dam project. The government brought in the army and police
units to destroy the opposition to the dam project. Arrests were not
uncommon and it is alleged that the assassination of a chief opponent to the
dam was the responsibility of the government. The Chico Dam project was
cancelled temporarily.
The lack of compensation and inferior land, inappropriate housing and
major cultural conflicts are other social effects of dams and their
impoundments. The sad part of the social effect is, that those who have
economically the least to lose, suffer the greatest.
The environmental impacts of dams are not generally seen as reasons for
foregoing the water modification projects and yet, they are the most
destructive aspects of dams and their effects in general. Once a dam is
built, the damage is done and there is no possible way to return the river
or stream back to its natural state.
During the initial construction of a dam, due to the flooding that must
occur for the reservoir, not only must the people relocate but the animal
species must relocate. More often than not, a whole animal species will not
survive out of their natural habitat. The Nam Choan dam in Thailand will
affect the largest population of Asian elephants in Thailand and several
other species such as the gaur and the tapir could face destruction. In Sri
Lanka, the current water project will seriously disrupt valuable wetlands
along the Mahaweli. Along with the wetland occupants in Sri Lanka, such
species as the Indian elephant, the leopard, the red-faced malkoha, the swan
crocodile, the estuarine crocodile, the Bengal monitor and the python will
be affected.
The vast areas of land that have been flooded under the reservoirs of
dams, are very commonly thousands of acres of valuable agricultural land.
In Sri Lanka, 3,000 acres of cultivated land of tobacco, paddy, vegetables
and other food crops will be destroyed, as well as 2,000 acres of cultivated
mixed fruit, cocoa, coffee, coconut, spices, tubers and soft wood. On top
of that, 2,000 acres of pepper, rubber and sugar cane estates will be
demolished by the inundation.
A dam's loss of water from its reservoir can be astonishing.
In hot dry areas, up to 15 billion cubic meters of water can be lost due to
evaporation annually, enough water to irrigate 2 million acres of farmland.
Building vast reservoirs in regions where evaporation rates are incredibly
high is obviously inviting trouble. Evaporation rates are commonly
increased by the intrusion of aquatic weeds into the dam's reservoir.
Another major cause of water loss is the seepage from irrigational canals.
In many areas in the Middle East, anything between 10% and 70% of the total
volume of water that passes through the canals may be lost to seepage.
Seepage losses can be cut drastically but the cost of installing the
technology is out of the question for many Third World countries where
seepage often occurs.
A dam transforms a river or stream into a lake like environment causing
many ecological changes. The current is slowed due to the impoundment which
reduces the movement of the water leading to increased temperature. When
the water temperature rises, the rate of photosynthesis and plant growth
increases causing more plants to grow and die and require more bacteria to
help decompose. With an increase of the decomposition rate, a greater
demand for oxygen in the water occurs.(BOD) The life cycles of aquatic
insects speeds up and animals that feed on them can be negatively affected.
Birds that rely upon certain insects emerging at key periods during their
migratory flights are certainly affected. Increased temperature also
affects the sensitivity of the inhabitants to toxic waste, parasites and
disease. Fish may become more vulnerable to disease due to the rising water
temperatures or the decreasing oxygen levels.
When an artificial lake is created, the natural inhabitants of the area
are likely to disappear. Due to the changes of the substrate of the water
other species should emerge. Some will survive in the new lake and others
will thrive in the irrigational canals. Rooted aquatic plants flourish
along the shoreline, dragonflies, and damselfly nymphs become more common
and stonefly nymphs and mayfly nymphs become less common. Many of those new
species play a major role in the transmission of diseases. Malaria and
Schistosomiasis are two diseases that have increased tremendously due to
water projects.
Over a certain period of time, silt, sand and other important nutrients
become trapped by dams' reservoirs. They affect the downstream erosion rate
because the water released from the dams is filtered of silt and sand
causing the water to rush down the river scouring the riverbed. The
accumulation of these nutrients also shortens the life of a dam
dramatically. Once a dam's reservoir is filled with silt and sand, the dam
must be decommissioned. The amount of sediment in a reservoir changes
depending on the environment to which a dam belongs. The tropics are being
affected the most by sedimentation due to the increased erosion caused by
the incredible deforestation rate. (25 acres of rainforest per minute is
lost) Once a dam is out of commission, all that is left is a vast muddy
wasteland. The weight of the reservoirs water combined with the fine
particles of silt form a "brick-hard pan" as they build up. When the final
waters of the reservoir have drained away, the land beneath will not be
suitable for basin irrigation or any type of agriculture.
Fisheries are often set up in dam reservoirs, but most have only
enjoyed short term success. In the beginning the fish are trapped and
forced to survive in the impoundment therefore, the fishing industry
expands. Soon after the opening of the fishery, the vegetation below will
start to rot away due to exccessive salinity and nutrients will become less
and less readily available. Efforts to restock the lakes have proved
unsuccessful. Not only are the fish in reservoirs affected by dams but,
fish throughout the whole river basin are affected. Quite often, the loss
of fish throughout the whole river basin surpasses the fish gains of the
dams reservoirs. Dams also reduce the catch of migratory fish due to the
prevention of access to their spawning grounds and they reduce the flow of
rivers causing downstream fish life to be affected. Irrigational water
projects have led to increased salinity causing the extinction of many fresh
water fish in certain regions. The silt that is trapped in reservoirs
contains vital nutrients that are necessary for the survival of many aquatic
species. Aquatic weeds grown in reservoirs also affect the fish populations
by increasing water losses to evaporation, reducing habitat and consuming
valuable oxygen supply. Weeds also diminish the amount of sunlight
available to a dam, causing reduced biological productivity in a reservoir.
Finally, in an attempt to control the aquatic weeds, herbicides are used
which also may lead to the loss of fish life.
Despite the evidence that large modifications to a water's natural
course are detrimental to the economy, the people, and the environment,
there is not much hope of the termination of mega-dam projects. Greater
dams will be constructed with predictable consequences; massive debt, more
disease, poorly planned and harmful irrigational systems, forced major
resettlement of people and animals, higher concentrations of pollutants,
lower populations of fish and overall poor river quality. Dams are
destroying the earth's natural rivers. Destroying the world's rivers also
means, destroying the earth's primary source of fresh water, something which
necessary for human survival.
Miranda Rose
Email: <weldona@web.apc.org>