Dams and Landslides

Chapter 2 – What Dam Builders Don’t Want You to Know: A Summary

Nine experts were invited by Probe International to review the Canadian dam builders’ Three Gorges Water Control Project Feasibility Study. In this chapter, the editors summarize their key findings. The nine chapters to follow provide our experts’ detailed analysis.

On Resettlement:

The Canadian dam builders conclude that the people who will be flooded off their land can be resettled onto upland areas.

Our experts have found:

1. The only replacement land available in the region is too steep, too elevated, and too poor to farm.
2. The dam builders know that the most fertile land in the valley would be lost to the reservoir, yet they estimate that one hectare of new land could grow the equivalent of one hectare of submerged land.
3. Farmers who now live above the proposed reservoir level but cultivate land that would be submerged would not receive compensation or replacement land.
4. If people cannot be resettled within the Three Gorges region, the Chinese government could deport them to distant areas now predominately populated by minority groups. The dam builders do not mention this scenario as it would conflict with the World Bank’s policy on tribal people and jeopardize future World Bank involvement in the project.
5. The dam builders found that the Chinese government overestimated the amount of available land by 50 percent.

The dam builders extol China’s new resettlement policy as being among the best in the world.

Our experts have found:

1. The Chinese government has no intention of compensating from 10 to 30 percent of the people who have illegally migrated to urban centres that would be flooded by the reservoir.
2. The Canadian dam builders consulted with representatives of the central regime who do not necessarily reflect the interests of the local people. The dam builders provide no evidence that local people have had any legitimate input to the project.
3. The resettlement and compensation estimates exclude hundreds of thousands of people who would either lose their farmland permanently or be victim to increasingly severe flooding in the vicinity of Chongqing and in tributary valleys upstream of the dam.
4. The resettlement estimates do not account for natural growth and migration rates to the region which could increase the number of people who would have to be resettled by an additional 100,000 people.
5. Our experts also note that 30 to 40 percent of the 10 million people who have been resettled to make way for large dams in China since the 1950s are still impoverished and lack adequate food and clothing.

On Environment:

The dam builders conclude that impacts which may occur downstream of the Three Gorges Project could enhance the environment.

Our experts have found:

1. The Canadian dam builders based their assessment on a previous Chinese government environmental impact statement, which dismissed the project’s environmental effects as insignificant. The Chinese impact statement failed to meet China’s National Environmental Protection Agency guidelines.

2. The Canadian dam builders’ conclusions are inadequate, misleading, and irresponsible because they neglected the inevitable social and environmental disruption which the dam would cause to the following:

  • the 75 million people who live along the Yangtze River downstream of the Three Gorges whose subsistence economies are inextricably tied to the ecosystems along the Yangtze and around the downstream lakes and wetlands.

  • land use patterns due to resettlement.

  • downstream lakes and wetlands which support productive fisheries and provide critical habitat for endangered Asian waterfowl such as the Siberian crane.

  • riparian, estuarine and marine fisheries that are already suffering a serious decline in productivity due to pollution, dammed tributaries, and overfishing.

  • coastal flooding and erosion of hundreds of kilometres of China’s best farmland.

  • the municipality of Shanghai’s already saline water supplies during the dry season, which could become even more saline when the river’s flow is reduced by operations at the dam.

  • wildlife such as the Yangtze River dolphin, the Chinese sturgeon, the finless porpoise and the Yangtze alligator, which are already endangered and could become extinct.

The dam builders state that the most significant environmental impact would be impoundment of the river.

Our experts have found:

1. In addition to creating a 600-kilometre lake, impoundment of the river would flood upstream tributaries and valleys, which would effectively increase the reservoir area by 50 percent over that designated by the dam builders. The dam builders neglected to assess the social and environmental impacts of flooding upstream tributaries and their valleys.

The dam builders predict that both natural fish populations and aquacultural production would increase in the reservoir.

Our experts have found:

1. World experience with large reservoirs is well-documented and shows that aquacultural productivity in reservoirs plummets after an initial boom in fish populations; there is no evidence in the study to suggest that the Three Gorges reservoir would be an exception.
2. The dam builders base their assumptions about reservoir productivity on outdated data gathered in the 1950s.

On Flood Control:

The dam builders state that flood control is the primary need for the Three Gorges Project.

Our experts have found:

1. There is confusion and inconsistency in the dam builders’ study as to the area that the Three Gorges Dam would actually be able to protect from Yangtze floodwater.
2. A crude method of analysis was used to determine flooding patterns downstream of the dam.
3. The dam builders fail to demonstrate that more people would be protected from flooding downstream by operation of the dam, than would be flooded out as the reservoir level rises during major floods.
4. Flood benefits are calculated by assuming high growth rates in highly flood-prone areas – a practice which is considered conjectural and invalid by some flood protection agencies.
5. The area within the reservoir, used for flood storage in the event of a flood, would remain populated with nearly one-half million people. These people, who previously were safe from flooding, would face an increased risk of flooding without any compensation. If compensation was provided the project’s cost would increase by 20 percent.

The dam builders predict that up to one-half million people living around the reservoir could be flooded off their land once in their lifetime.

Our experts have found:

1. People around the reservoir could be flooded off their land far more frequently than predicted by the dam builders because their flood probabilities are based on historical records that do not account for increased flooding due to massive deforestation in the watershed. Also, the dam builders do not consider sedimentation in the reservoir or changes in reservoir operation to maximize power generation as factors which could increase the frequency of flooding people living within the reservoir.

On Sedimentation:

The dam builders claim that the Three Gorges reservoir storage capacity can be “preserved indefinitely.”

Our experts have found:

1. CYJV arrived at this conclusion without verifying YVPO’s original sedimentation data, even though CYJV acknowledged that “the quality and quantity of basic field data is of crucial importance to the sediment load investigation.”
2. CYJV admits elsewhere in its study that, after 100 years, 50 percent of the reservoir will be filled. Even after 100 years, sediment build-up in the reservoir will continue.
3. CYJV accepted YVPO’s estimate that the bed load (sediment larger than 1 mm) conveyed by the Yangtze is 0.05 percent of the total sediment, an amount so small CYJV decided to count it as 0 in its analysis. This estimate is grossly at odds with the Yichang Hydrological Gauging Station’s statistics, which indicate bed load is 1.6 percent of total sediment.
4. If CYJV’s calculations are wrong, as the evidence suggests, CYJV’s prediction of the amount of reservoir storage that can be preserved by flushing sediment through the dam is greatly exaggerated. This means that the dam would silt up and have to be decommissioned much sooner than planned.

The dam builders claim to have developed a dam design and operation methodology to deal completely and effectively with the sedimentation problem.

Our experts have found:

1. The operation and design proposed by CYJV to minimize sedimentation problems is unproven. The only attempt to control a river with sediment discharges of this magnitude – at the Sanmenxia Dam on China’s Yellow River – is widely recognized as a costly failure.
2. CYJV’s dam design and operation methodology is based on untenable, unsubstantiated, and flawed assumptions.
3. In particular, CYJV’s prediction that 90-95% of the sediment entering the reservoir will be flushed through, and CYJV’s recommended method for doing so, exceed the confidence limits of the science of sediment hydraulics and fluvial geomorphology, and defy characteristics of the Yangtze River for the following reasons:

  • Because the flow, sediment transport, and channel characteristics of the Yangtze River and Three Gorges reservoir would be complex, highly variable, and three-dimensional, CYJV’s prediction that sediment would deposit in the reservoir at an equilibrium slope – allowing the same quantity of sediment entering the reservoir to be flushed out – is highly unreliable.

  • By underestimating bed load, CYJV has underestimated the effect that coarser bed load material has on making the equilibrium slope steeper over time. A steeper slope would cause increased flooding upstream, and shoaling of the navigation channel impeding ship traffic to Chongqing.

4. The “reservoir trap efficiency method” CYJV used to calculate reservoir sedimentation is unable to estimate sedimentation in the active flood storage zone, and underestimates sedimentation in the dead storage zone of the reservoir.

5. CYJV underestimated total sedimentation rates by ignoring the effect of landslides which could fill several cubic kilometres of the reservoir, further impeding the flushing of sediments through the dam.

The dam builders claim that “reservoir sedimentation will not limit the useful life of the project.”

Our experts have found:

1. CYJV’s analysis has failed to predict realistically the actual performance of the reservoir. Nor has it carried out a systematic sensitivity analysis of the cumulative effects of uncertainties in its predictions.

2. There is a significant risk that sedimentation in the reservoir would:

  • cause aggradation of the river bed upstream past Chongqing, flooding hundreds of thousands of people.

  • decrease flood storage capacity and thereby increase the risk of flooding for millions of people who have been induced to move into flood-prone areas downstream.

  • cause degradation of the river bed downstream for hundreds of kilometres, eroding flood control embankments, undermining bridge crossings and changing the hydrologic regime of the river on which millions of people depend.

  • accelerate coastal erosion, including near Shanghai.

  • substantially impair the performance of the project in its economic lifetime.

3. If the Three Gorges Project is completed as planned, it is probable that within a few hundred years the reservoir will almost entirely silt up, creating an unprecedented hazard for the millions of people living downstream.

On Alternatives to the Three Gorges Project:

The dam builders imply that the Three Gorges Project must be built to alleviate China’s energy crisis.

Our experts have found:

1. China has a shortage of electricity in its urban centres due to grossly inefficient energy use. The electricity services now being met could be delivered using just 60 percent of the country’s existing hydroelectric capacity, leaving China with a reserve of the remaining 40 percent of hydroelectric capacity and all of its fossil fuel plants.

2. Rather than build the Three Gorges Project, a more environmentally sound and cost-effective alternative would be energy efficiency improvements and conservation measures through technology innovations and price reforms.

The dam builders state that there is no practical flood protection alternative in the middle reach of the Yangtze River.

Our experts have found:

1. The dam builders themselves conclude that flood protection dykes surrounding refuge centres are justified wherever the annual probability of flooding is more than 1.5 percent, which is the case for several large areas downstream of the Three Gorges.
2. Flood reduction strategies could achieve superior flood benefits through a combination of upgrading critical dykes, modifying overflow areas, providing refuge centres and protective dykes, improved flood-proofing and flood-warning systems, development zoning, and reforestation.
3. If development in highly flood-prone areas were restricted to 40 percent of that predicted for some of the downstream urban areas, such as the city of Wuhan, the flood damage avoided would equal the dam builders’ predicted reduction in flood damages with the project.

On Navigation:

The dam builders conclude that the Three Gorges reservoir would improve navigation between Yichang and Chongqing.

Our experts have found:

1. Navigation on the Yangtze River would be seriously disrupted for at least 18 years while the dam was under construction. 2. The increase in shipping traffic predicted to follow the dam’s construction is unsupported by any studies.
3. The dam builders acknowledge that sedimentation in the upstream end of the reservoir could obstruct navigation near Chongqing, but fail to assess the feasibility and cost of massive dredging operations, which could be required.
4. The dam builders acknowledge that shipping traffic could be tripled without the dam by a combination of better traffic control procedures, more powerful tug boats, and extended navigation hours. These improvements to navigation could be made without the risk of obstruction due to sedimentation, as is expected with the dam.

On Design and Safety:

The dam builders claim they have completed an adequate design and safety analysis.

Our experts have found:

1. The dam builders provide an inadequate analysis of a reservoir-induced earthquake.
2. The dam builders provide an inadequate analysis of structural stability.
3. The dam builders underestimate the risks of a catastrophic landslide.
4. The dam builders underestimate the risk of spillway failure.
5. The dam builders fail to consider the downstream effects of cofferdam failure.
6. The dam builders fail to consider the potential dangers of increased sedimentation in the reservoir which would reduce the dam’s ability to hold back large floods.

On Economic Aspects

The dam builders state that the purpose of their study is “to establish firmly whether the Three Gorges Project is technically, economically, and financially feasible on a basis acceptable to international financing institutions.”

Our experts have found:

1. The dam builders used a 10 percent discount rate instead of the 12 percent rate which the World Bank, a likely financier, has applied in its economic appraisals of other projects. Using 12 percent, the Three Gorges’ net benefits decline by 59 percent.
2. The dam builders used the Chinese government’s artificial exchange rate of 3.7 yuan per U.S. dollar, instead of 5 or 6 yuan to the dollar. At 6 yuan per U.S. dollar, construction costs increase by 30 percent.

Our experts also note:

1. In China, 2-to-5 year delays in construction are normal. Such a delay would make the project totally unattractive economically. Even a delay of a single year would reduce net benefits by 22.5 percent.
2. Many factors – such as transmission and distribution losses, and uncounted people in need of resettling – were ignored. Counting these costs would likely make the project non-viable even if everything else went well, which rarely happens.


US $10.7 billion


Sandouping Village

Xiling Gorge (Three Gorges)

Construction Duration

18 years

Reservoir Length

500 to 600 kilometres

Counties Affected


Total Pop. of Counties

14 million


727, 000 people

Urban Centres

Submerged – Fuling

80,000 population


140,000 population

Number of Towns Submerged


Cultivated Land Submerged

14,500 hectares

Cultural/Historical Sites Lost

108 sites identified by CYJV (some dating back to 10,000 B.C.)
Some specific examples include:
-two iron Buddhas, Tianfu Temple, Fengdu City, dating back 600 years through the Ming and Qing Dynasties.
-ancient plank road of the Han Period (A.D. 64) along the Daning River through the counties of Wuchan and Wuxi

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