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Three Gorges Dam


Jason Boccaccio

April 4
, 2007

ENVS 250

Research Paper

Three Gorges Dam
: Economic and Energy Advantage or Environmental Disaster?

The Three Gorges Dam project in China has been an issue of controversy
for at least the
last 20 years. While supporters of th
e project

namely the Chinese government

hail it as the
world’s largest hydroelectric dam, opponents claim it could be the one of the nation’s biggest
. According to historical accounts,
the idea of the Three Gorges Dam
goes back

to the early 1900s and Sun Yat
Sen (
“Terrible,” 2006
). The Chinese government has
persisted with the plan to build the dam in spite of great criticism from both the internati
community and within China.

The actual structure, which is built on the Ya
ngtze River,

is 1.4
miles long and 600 feet tall.
It is estimated that the dam

cost China $30 billion dollars

required the work of 10,000 laborers

a small price to pay, according to the Chinese government
who believes that the project is a major coup

for hydropower production and flood prevention

(Lei, 1998)
. They believe it is the type of project needed to support China’s fast
economy, but dissenters say that this concrete beast is a threat to the area’s ecosystem. While
Chinese leaders are

excited about the benefits of the Three Gorges Dam, such as electricity
generation, flood control and improved navigation on the river corridor, opponents of the project
say that the dam will
be harmful to the environment by blocking sediment, endangering

and allowing harmful

to spread more rapidly

Three Gorges Dam will undoubtedly produce large amounts of hydroelectricity. This is
one aspect of the dam which is not only economically pleasing, but also favorable to the
Hydroelectricity does not produce the greenhouse gas emissions that coal burning
does. Officials involved in planning and building the monstrous dam have claimed that the dam
Three Gorges Dam


will produce 84.7 billion kilowatts of electricity
per year

(Lynch, 2003)
e 84.7 billion
kilowatts will be produced by the dam’s 2
6 turbine generators
This should effectively reduce
the demand for

coal burning in a country that

suffers from severe air pollution
. Some estimates
say that the dam will reduce carbon dioxide emiss
ions by 100 million tons and conserve 50
on tons of coal each year (Lei
, 1998).
Besides being the world’s largest hydroelectric dam,
Three Gorges is also hailed as a tool for flood control.

The mighty Yangtze has always been a river prone to floodin
g, and government officials
always used flood control as the main justi
fication for the dam project. In 1931, a flood
ravaged the river corridor and submerged over 140,000 people and later, i
n 1954, a torrential
flood on the Yangtze cla
imed the lives

of 30,000 people (Lynch, 2003). While the Yangtze’s

do not cause as much damage and death as the floods of the Yellow River, it does
flood about once ever
y ten years. Residents of the Yangtze r

orridor have long tried to
defend themselves

from the raging, overflowing currents of the Yangtze by building their own
earthen dikes. It is said that increasing the size of these dikes would only i
ncrease the
destruction if there

happened to be a breach. Chinese leaders and other supporters of th
e Three
Gorges project feel that the building the dam is most
effective way to combat the problem of
flooding in the Yangtze watershed in the long
term (Hoh, 1996).

The last major benefit of the dam touted by the Chinese government is its ability to
itate navigati
on along the Yangtze

The size of the reservoir created by the dam could allow
ships of up to 10,000 tons to reach the important industrial city, Chongqing.
If commercial ships
could get that far, government officials have estimated that sh
ipping costs could be reduced by as
much as 30% and Chongquing’s port could see five times the business (Lei, 1998).

going ships to reach that far into China’s mainland would undoubtedly facilitate trade and

Three Gorges Dam


serve as an additional econo
mic benefit to the Three Gorges project (Lynch, 2003).

While the dam may allow
more navigation, it will trap sediment

which would
otherwise flow freely down the Yangtze and be deposited into the river delta. This sediment
buildup could, in actualit
y, have the reverse effect of hindering navigation on the river corridor
for large commercial ships.
Project planners decided to build the dam in such a way that the
reservoir behind it would be 175 meters deep. The rationale behind making the reservoir
as deep
as possible is that maximizing depth will allow more power generation. The biggest problem
with creating such a large reservoir is that with an increase in depth comes in increase in the
amount of silts and sediments which will build up in the imp
oundment. The possibility of
massive sediment buildup is almost certain at Three Gorges considering the Yangtze River has
the fourth largest silt load in the world, which measures in at an average of 520 million tons
annually (Lei, 1998). According to en
vironmental engineers, this type of silt buildup will
severely harm water quality in the Yangtze watershed
. They also advise that the dam’s sluice

which regulate the flow of sediment

may n
ot work as they are designed
which could lead
a disastro
us, messy
sediment buildup at the mouths of the Yangtze’s tributaries



Project designers h
ave planned to store water that

is clear and carries less of a silt load in
the months after the flood season has passed
. T

when the next f
lood season arrives, they
hope to use the sluice gates to release water high in silt load

and lower the overall water level of
the reservoir by flushing out large amounts of water through the dam. The problem with this
plan is that it works against the id
ea flood prevention and control which has always been used as
a rationale for pushing the Three Gorges project to the Chinese people. If dam outflow
operations follow this plan, releases of silt
laden water will
be very large during the peak of
Three Gorges Dam


flood seas
on (Lei, 1998). If the dam’s main goal was to prevent flooding, an effort would have
to be made to minimize outflows during normal flood season.

At the proposed depth of 175 meters, the dam would be able to generate more
hydroelectricity; however

the l
arger silt deposits created by making the reservoir deeper could

adversely affect navigation. As previously mentioned, o
ne of the foreseen benefits of the Three
Gorges project is that it would allow massive commercial ships of up t

10,000 tons to
fully navigate the Yangtze and arrive as far as Chongquing, an important industrial city
(Hoh, 1996). However, the bu
ildup of silt caused by impeding the flows of the mighty Yangtze
and its massive sediment loads
could significantly clog the harbors in th
e Chongqing area which
would block the outlet of the Jialing River as it enters the Ya
It is highly possible that such
a large silt load would not allo
w large, commercial
ships to reach Chongqing, thus canceling
one of the perceived
efits of the T
hree Gorges project. It is very difficult to predict
the amount of silt deposit that will result in relation to how successful the planned storage and
increased outflow periods are. Scientists have attempted to use mathematical models and
xperiments based on hydraulic data to predict how Three Gorges will handle the Yangtze’s silt
load and the predicted results show that approximately 30
40% of the river’s sediment could be
released from the dam within the first 30
50 years of its operation

and the silt deposit and
releases could be equalized at 80 years after the dam begins its operations (Lei, 1998). Because
there are really no precedents for such a large scale project, predictions are exactly that;
predictions. No person or mathematical

model can completely forecast the effects of a project
like Three Gorges Dam.

re are additional problems that

could be caused by the silt buildup created by Three
Gorges Dam.

The effects of the impeded flow of the great Yangtze are felt all the way d
own in
Three Gorges Dam


the East China Sea where it deposits its fresh water and sediment load. A team of researchers
has been examining the health of the East China Sea’s ecosystem since 1998. They claim that
since the reservoir was filled, sediment loads in the river d
elta have fallen approximately 55%

(Marshall, 2006)
. A
s a result of less fresh water and sediment being introduced into the sea at


erratic intervals, the numbers of phytoplankton have fallen and the remaining population
has made a change from silicac
eous diatoms to flagellate species. According to scientists,
healthy ecosystems generally have an abundance of silicaeceous
species of


flagellate species can kill fish populations by decreasing the water’s oxygen content
and discha
rging toxins. A large presence of silicaceous phytoplankton is beneficial to fisheries
because they are eaten and their nutritional value is passed upwards through the food chain. The
water stored behind the large d
am retains silicates and prev
ents many of them from
reaching the East China Sea, which severely impacts the ecosystem and the fishery


Moreover, the reduced sediment load robs the phytoplankton of the silicon which gives
the predators which feed on them the nutrients

necessary to building their shells. In another
study, researchers measured sediment loads just barely downstream of the dam and found that
the river carries only 20% of the sediment that it did before the dam’s construction

According to

the research team from the National Taiwan Ocean University

levels of
in the East China Sea
ar the mouth of the Yangtze
decreased by 86% within
two m
onths of the dam’s construction

(Marshall, 2006).

With this great of a reduction in
oplankton, the researchers have predicted that yearly catch rates could drop off by
approximately one million tons in comparison with catches before the dam’s construction.

would be a huge blow to
the East China Sea

which is
one of the mo
st prolific
fisheries in the

near the Yangtze delta

Three Gorges Dam


One of the other predicted outcomes of the sediment buildup behind Three Gorges Dam
is the disappearance of tidal wetlands close to Shanghai on the Yangtze delta. The severe
reduction of sediment

in the dam’s discharge has caused the eroding of these valuable wetlands.
The effects of this erosion of wetlands can be placed into two major categories. First, the coastal
ecosystems will be severely altered.
The Yangtze River creates wonderful farm
land in its valley
by depositing its large silt loads into the land. The reduction of this sediment is likely to have a
harmful effect on agriculture in the region.
the erosion of wetlands equals less land
which translates into less room for the
expansion and development of Shanghai; something
which big bus
iness is likel
y to take issue


“Dam puts


The damming of the Yangtze will also have great

effects on its own aquatic biodiversity

It will flood more than 600 kilometers of the ma
in river channel and severely alter the habitats of
many aquatic and terrestrial species (Brosse et al., 2003). S
cientists say the river is home to 350
species of fish (112 of which are endemic)

and 261 of these
are prevalent in the upper river alone
ng, 2001). The Three Gorges project will completely change the characteristics of the
river’s main channel which will result in the loss of the natural habitats of 162 species of fish, 44
of these endemic to the region (Zhong & Power, 1996).

The dam pose
s a
n especially

threat to th
ese endemic species. Because they only exist in this region, t
hey could end up extinct
if no
attempts are made to conserve them. Some of the most notable endemic species in
the Three Gorges region are the Chine
se sturgeon, river sturgeon, and Chinese paddlefish.
Numerous other migratory fish species are threatened by the dam (J Wu et al., 2004).
Additionally, it is believed that the impeded flows will possibly endanger the Chinese alligator,
the finless porpoi
se, the white crane and the
Chinese R

. This river dolphin is
endemic to the Yangtze and is a 30 million year old species

(Topping, 1995).

Three Gorges Dam


Brosse et al. (2003) have studied the situation and


posed conservation efforts that

would invo
lve relocating some of these endemic species into some of the Yangtze’s upper
tributaries which

t provide similar habitats that

could be

sufficient for sustaining the
existence of these endemic species. The results of such efforts are difficult to for
Furthermore, even if the relocations were successful in sustaining the
species, they might have
the undesired effects of
harming or eve
n wiping out other
species that

naturally occur in the proposed reserves.

ile certain life
forms will be decimated by the damming of the Yangtze, others will
flourish, which is not necessarily a good thing.
The dam, when completed

is forecasted to
permit the increase of serious waterborne diseases and infections. Of these, th
e most notable and
probable t
o be increased are schistosomiasis and


The Oriental schistosome,
Schistosoma japonicum
, has a long history in China. It is
endemic to China and the Philippines and causes the disease, schistosomiasis japonica, in
umans and animals.
These schistosomes can be transmitted to humans and animals by
trematode worms which live in fresh
water. During transmission, they enter the skin of humans
and mammals which become the host for schistosomiasis. The problems for the h
ost begin when
the eggs

of the schistosome

are stuck in the liver and other tissues. The disease is
ften fatal.
Humans and
other mammals

come into contact
with water that carries

the parasite can be
infected. Estimates say that
about 865,
000 human
s are currently infected with the parasite in
, a much smaller number than the 12 million people who were infected in 1949 when the
country first began to conduct large
scale epidemiological surveys (Mao, 1986).
Scientists fear
that the closure of th
e dam will join two endemic areas of schistosomiasis which are located on
different parts of the Yangtze. This fear is well
supported by other examples of similar projects
Three Gorges Dam


throughout the world.

According to Li et al. (2001), t
he construction of the Aswan

Dam in
Egypt, the Tigay Dam in Ethiopia, the Kossou and Taabo Dams in Cote d’Ivoire, Diama Dam in
Senegal, and the Manan
tali Dam in Mali have all sparked severe

ks of schistosomiasis.

Nobody can totally predict how schistosomiasis will spread afte
r the dam is fully operational,
however, if history is any guide, the future of the epidemic looks bleak for those who live in the
Three Gorges region.

While supporters of the Three Gorges Dam project were successful in pushing it through
by highlighting
the perceived economic benefits (some of which are also environmentally
friendly, i.e. reduced carbon emissions), it appears as though there are many more environmental
risks than benefits associated with damming the mighty Yangtze River. Undoubtedly, the

heavy silt load will be blocked by the dam and massive sediment deposits could occur if the
dam’s sluic
e gates do not function according to plan. This blockage of silt has many unfortunate
environmental consequences for not only the region downst
ream of the dam, but also the areas
that lie upstream of Three Gorges. The regions aquatic and terrestrial biodiversity will be
impacted and the impeded, stagnated flows are likely to promote the spread of dangerous
epidemics such as schistosomiasis and p
ossibly malaria. As if these environmental problems
were not alarming enough, the flooding of the reservoir area will force 1.2
1.5 million
pick up and relocate (Li et al., 2001).

While the Three Gorges project will undoubtedly have adverse e
ffects on the region’s
ecosystems, some scientists believe there are many lessons to be learned from the environmental
events which will be caused

by the dam

for years to come. J Wu et al. (2004) contend that since
the dam is already in place and nobody c
an turn back time and erase its effects, the scientific
community needs to seize the opportunity to conduct research and learn from Three Gorges.
Three Gorges Dam


They propose research in the areas of habitat fragmentation, impacts of habitat loss and changes
on terrestri
al and aquatic biodiversity, changes in water quality and biochemistry in the reservoir
on aquatic biodiversity, etc. They call for a concerted effort to conduct long
term monitoring
and research in the Three Gorges region.

rhaps evidence of the severe

environmental impacts
of the Three Gorges Dam might be used in the future to pre
vent another similar project fro
being implemented somewhere else in the world. Then again, even the most powerful evidence
of adverse environmental impact may do nothing to

slow a future project which promises
prestige and short
term economic benefits.

Three Gorges Dam



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fish species threatened by the Three Gorges Dam.
onservation Biology, 17


Chang, J. (2001). Conservation of endemic fish with catchment management of upper Yangtze.

In King, L., Metzler, M., & Jiang, T. (Eds.), Flood risks and land use conflicts in the

Yangtze catchment, China and at t
he Rhine River, Germany, strategies for a sustainable

flood management. Frankfurt: Peter Lang Publishing.

Dam puts Shanghai wetlands at the mercy of the sea. (2006).
New Scientist, 189
(2547), 22

Hoh, E. (1996). China’s greatest wall.
Natural History,
(7), 2

J Wu, et al. (2004). The Three Gorges Dam: an ecological perspective.
Frontiers in Ecology

and the Environment, 5
(2), 241

Lei, X. (1998). Going against the flow in China.
Science, 280
(5360), 24

Li, Y., McManus, D. P., Ross, A. G., Wi
lliams, G. M., Zheng, J., (2001). Dam worms.

(3), 121

Lynch, D. L. (2003, June 2). China’s audacious dam stops flow of Yangtze.
USA Today
, p. 07a.

Mao, S. P. (1986). Recent progress in the control of schistosomiasis in China.
Chinese M

Journal, 99
, 439

Marshall, J. (2006). Three Gorges Dam threatens vast fishery.
New Scientist, 189
(2540), 18

Perkins, S. (2006). Three Gorges Dam is affecting ocean life.
Science News, 169
(20), 318

Terrible beauty is born. (2006).
omist, 379
(8479), 39

Topping, A.R. (1995). Ecological roulette: Damming the Yangtze.
Foreign Affairs, 74


Three Gorges Dam


Upstream, first of many treatment plants tackles pollution. (2004).
ENR: Engineering News

Record, 253
(8), 23

Zhong, Y. & Power
, G. (1996). Environmental impacts of hydroelectric projects on fish

resources in China.
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