The Three Gorges Dam Economic Winners and Losers—The Reckoning Part 5 (Final): Who Benefited, Who Paid, and What It All Means

The Three Gorges Dam

Economic Winners and Losers—The Reckoning

Part 5 (Final): Who Benefited, Who Paid, and What It All Means

A collaborative research series by Randy T Gipe and Claude (Anthropic)
December 2025

In economic terms, the Three Gorges Dam is a success.

Cost-benefit analyses conducted by Chinese government agencies, the World Bank, and independent researchers consistently show a positive net present value (NPV) for the project. The dam generates approximately 84 billion kilowatt-hours of clean electricity annually, displacing coal-fired generation that would have produced hundreds of millions of tons of CO₂ and caused significant air pollution deaths. It has intercepted nearly 70 major floods, preventing economic losses estimated in the hundreds of billions of yuan. It has improved navigation along 660 kilometers of the Yangtze, reducing shipping costs and transit times.¹

By these measures, the Three Gorges Dam "works." The investment of ¥249 billion (US$37 billion) has generated returns that exceed the costs—at least when those costs are measured in monetary terms.²

But economics, as any first-year student learns, is about more than aggregate totals. It is about distribution: who wins, who loses, and whether the gains are achieved at the expense of those least able to bear the costs.

Examined through this lens, the Three Gorges Dam reveals a starkly different picture. The project succeeded in generating wealth—but that wealth flowed overwhelmingly to distant industrial centers like Shanghai and Guangzhou, not to the Yangtze River basin that bore the project's costs. Upstream counties near the dam site gained economically; downstream counties lost. And the 1.3 to 1.9 million people displaced to make way for the reservoir—many of whom were pushed back into agricultural poverty—received virtually none of the benefits.³

The Three Gorges Dam succeeded as infrastructure. It failed as development.

This final installment synthesizes the economic evidence presented throughout this series and confronts the fundamental question: Can the dam's economic gains ethically justify the permanent destruction it caused—to communities, cultures, and ecosystems?

I. The Positive Case: Net Economic Benefits

Formal cost-benefit analysis (CBA) of the Three Gorges Dam, conducted using standard economic methodologies, consistently produces positive results. The most comprehensive study, published in 2007, calculated a mean net present value (NPV) of approximately ¥50 billion, with the largest benefits derived from three sources:⁴

1. Hydroelectric Power Generation

The dam's 22.5 gigawatts of installed capacity generates revenue from electricity sales while displacing fossil fuel generation. The economic value is twofold:

• Direct revenue: At an average wholesale price of ¥0.25 per kilowatt-hour, the dam generates approximately ¥21 billion in annual electricity revenue.⁵
• Avoided pollution damages: By displacing coal-fired power plants, the dam avoids an estimated ¥15-20 billion per year in health costs from air pollution (premature deaths, respiratory illness, healthcare expenditures).⁶

Combined, these benefits total ¥36-41 billion annually—a figure large enough to dominate the project's overall economic calculus.

2. Flood Control

The dam's flood interception capacity (documented in Part 4) generates economic value by preventing agricultural losses, infrastructure damage, and economic disruption. Conservative estimates place the annual avoided flood damage at ¥10-15 billion, with significantly higher values in years when major floods are intercepted.⁷

3. Navigation Improvements

Raising the water level in the upper Yangtze allows larger vessels to reach Chongqing, reducing per-ton shipping costs by an estimated 35-40%. The cumulative economic benefit of improved navigation is estimated at ¥3-5 billion annually.⁸

Estimated Annual Economic Benefits:
• Electricity revenue: ¥21 billion
• Avoided air pollution damages: ¥15-20 billion
• Avoided flood damages: ¥10-15 billion
• Navigation improvements: ¥3-5 billion
Total: ¥49-61 billion per year⁹

Against the project's dynamic investment cost of ¥249 billion, these benefits produce a positive NPV under most reasonable discount rate assumptions (3-7%).¹⁰ This is why proponents of the dam can legitimately claim economic success.

But this aggregate analysis obscures two critical problems: distributional inequality and the limits of monetary valuation.

II. The Uncertainty Problem: When Benefits Become Costs

Even within the narrow framework of conventional CBA, the Three Gorges Dam's economic performance is far less certain than headline NPV figures suggest.

The 2007 comprehensive economic analysis, while finding a positive mean NPV, also documented "huge uncertainty" in the results. Most tellingly, the 5th percentile of the cumulative NPV distribution was negative—meaning there is a significant probability (greater than 5%) that the project represents a net economic loss, even when all benefits and costs are monetized.¹¹

This uncertainty stems from two primary sources:

1. The Largest Negative Costs

The analysis identified the two largest cost variables as:

• Construction resettlement costs: The displacement of 1.3-1.9 million people generated direct costs (compensation payments, relocation infrastructure) of approximately ¥47 billion, plus indirect costs (lost livelihoods, social network destruction) that are difficult to quantify but substantial.¹²
• Loss of archaeological and cultural heritage: The destruction of over 1,300 archaeological sites was assigned an estimated economic cost, though any monetary valuation of irreplaceable cultural heritage is inherently arbitrary.¹³

These costs are certain and irreversible. The benefits, by contrast, depend on assumptions about future hydrology, electricity prices, and the dam's operational lifespan—all of which are subject to considerable uncertainty.

2. Unquantified Environmental Liabilities

The conventional CBA methodology struggles to incorporate many of the environmental and geological costs documented in Parts 3 and 4 of this series:

• The extinction of the Baiji dolphin and collapse of fisheries (98% decline in fish populations) are treated as minor externalities, if included at all.¹⁴
• Reservoir-induced seismicity and landslide risk—which could threaten the dam's structural integrity and the lives of millions downstream—are excluded from the analysis entirely.¹⁵
• Long-term sedimentation impacts, which may render the reservoir's flood control capacity obsolete within decades, are acknowledged but not adequately incorporated into NPV calculations.¹⁶

When these omitted costs are considered, the probability that the dam represents a net economic loss increases substantially.

III. Spatial Inequality: Who Actually Benefited?

The aggregate NPV analysis treats "China" as a single economic unit, summing benefits and costs across the entire nation. This obscures the profound spatial inequality created by the dam.

The Upstream-Downstream Divide

Economic modeling of county-level impacts reveals a clear pattern: upstream counties near the dam site generally received economic benefits, while downstream counties along the mainstream river experienced negative effects on economic growth.¹⁷

This divergence is not accidental. It reflects the dam's function as a capital and energy transfer mechanism:

• Upstream counties benefited from construction activity, compensation funds, and improved infrastructure (roads, bridges, housing) built as part of resettlement programs. These areas saw measurable increases in GDP per capita during and after construction.¹⁸
• Downstream counties bore the costs of altered hydrology (increased erosion, reduced sediment deposition, disrupted fisheries) without receiving commensurate benefits. Economic growth in these areas lagged behind comparable non-impacted regions.¹⁹

The Real Beneficiaries: Distant Industrial Centers

The overwhelming majority of the electricity generated by the Three Gorges Dam is transmitted to industrial centers hundreds or thousands of kilometers away: Shanghai, Guangzhou, Shenzhen, and other coastal manufacturing hubs.²⁰ These cities—already among the wealthiest in China—captured the primary economic benefit of the dam's clean energy production.

Meanwhile, the Yangtze River basin itself—the region that surrendered land, communities, cultural heritage, and ecosystem services—received little direct benefit from the power generation. The dam functions, in effect, as an extractive infrastructure: it draws resources (water, land, human capital) from the interior and exports the benefits to the coast.

The dam did not modernize the Yangtze basin. It sacrificed the basin to power China's coastal economy.

IV. The Human Cost: 1.3 Million Displaced, Zero Share of Benefits

The most profound distributional failure concerns the displaced populations themselves.

As documented in Part 2, the resettlement program not only failed to restore livelihoods—it actively worsened them. Analysis showed:

• A reduction in non-agricultural employment among resettled populations, indicating economic regression rather than development.²¹
• Systematic corruption in resettlement fund administration, with 369 officials prosecuted for embezzling compensation payments intended for displaced families.²²
• Inequitable compensation based on hukou (household registration) status, with urban residents receiving 2.5 times more compensation than rural residents for comparable losses.²³

These populations bore the heaviest costs of the project—loss of homes, land, livelihoods, and community networks—but received virtually none of the benefits. They do not benefit from cheaper electricity (they were already connected to the grid). They do not benefit from improved navigation (they do not operate shipping companies). They do not benefit from reduced flood risk in distant downstream cities.

For the displaced, the dam was an uncompensated taking—a state-mandated sacrifice for the supposed greater good, where the "greater good" accrued primarily to distant elites and coastal industries.

Table: Distribution of Benefits and Costs

Stakeholder Group	Primary Benefits	Primary Costs	Net Position
Coastal industrial centers (Shanghai, Guangzhou, Shenzhen)	84 billion kWh/year clean electricity; reduced air pollution	Minimal (electricity purchase costs)	Large net gain
Upstream counties (near dam site)	Construction activity; infrastructure investment; compensation funds	Reservoir inundation; community disruption	Modest net gain
Downstream counties (middle/lower Yangtze)	Reduced flood frequency (conditional)	Increased erosion; collapsed fisheries; altered hydrology	Net loss
Displaced populations (1.3–1.9 million)	Nominal compensation (often embezzled or inadequate)	Loss of homes, land, livelihoods, community networks; occupational regression	Severe net loss
Ecosystems & biodiversity	None	Baiji extinction; 98% fish population collapse; 1,300+ archaeological sites destroyed	Irreversible loss

V. Financial Sustainability: The Debt Overhang

Even if the dam's aggregate economic benefits are accepted at face value, a separate question concerns its long-term financial sustainability.

China Three Gorges Renewables Group—the state-owned entity responsible for dam operations—maintains substantial debt. Annual reports from recent years show loan capital between ¥184 billion and ¥218 billion, with annual interest obligations of ¥8-12 billion.²⁴

While the company remains profitable, with EBITDA margins typically between 60-70%, its financial performance is vulnerable to hydrological variability. In 2021, poor hydrological conditions (reduced rainfall and reservoir inflow) significantly impacted generation capacity and revenues, demonstrating that even a project of this scale cannot eliminate risk imposed by environmental factors.²⁵

This vulnerability has long-term implications. If climate change increases the frequency of extreme droughts—reducing hydroelectric output—or extreme floods—requiring more frequent spillway releases that sacrifice generation—the dam's revenue stream could be substantially impaired. This would threaten debt service and potentially require government bailouts, socializing losses that were supposed to have been covered by electricity sales.

VI. The Ethical Question: Can Economic Gains Justify Irreversible Destruction?

Returning to the fundamental question: Does the dam's positive net present value ethically justify the costs imposed on displaced populations, destroyed ecosystems, and lost cultural heritage?

This is not a question that economics can answer. Economics can quantify trade-offs, but it cannot tell us whether those trade-offs are morally acceptable.

The Limits of Monetary Valuation

The CBA methodology treats all values as commensurable—as if the economic benefit of avoided air pollution deaths can be directly compared to the destruction of a 3,000-year-old archaeological site, or the extinction of a species that survived for millions of years.

But some losses are incommensurable. The Baiji dolphin cannot be brought back, regardless of how much wealth the dam generates. The cultural heritage submerged beneath the reservoir—temple complexes, ancient villages, historical records carved into stone—is irretrievably gone. The 1.3 million displaced people cannot recover the community networks and social capital they lost when their homes were flooded.

These are not merely "costs" to be weighed against "benefits." They are permanent erasures—deletions from the record of human and natural history that no amount of electricity generation or flood control can restore.

A positive NPV does not confer moral legitimacy. It merely demonstrates that the beneficiaries gained more (in monetary terms) than the victims lost—as measured by someone else's accounting methodology.

Who Decides What Is Valuable?

The Three Gorges Dam was not approved through democratic deliberation where affected populations could weigh in on whether the trade-offs were acceptable. It was imposed through authoritarian fiat, with dissent criminalized (42 critics imprisoned) and oversight suppressed.²⁶

The displaced populations were not asked whether they would accept ¥18,000 in compensation (for rural hukou holders) in exchange for their homes and livelihoods. They were simply told that the project was proceeding and they would be relocated. The downstream fishing communities whose livelihoods collapsed when fish populations dropped 98% were not consulted about whether this sacrifice was acceptable for the sake of cleaner air in Shanghai.²⁷

In the absence of meaningful consent, the dam's economic "success" reflects not the preferences of those who paid the costs, but the preferences of those who captured the benefits—and who possessed the political power to impose their vision on everyone else.

VII. Lessons for Future Mega-Infrastructure

The Three Gorges Dam offers critical lessons for governments worldwide that are considering—or currently pursuing—large-scale infrastructure projects, particularly in the context of Belt and Road Initiative investments.

1. Internalize Non-Market Costs

Future mega-projects must adopt valuation methodologies that fully internalize the costs of cultural loss, ecological destruction, and social disruption—treating them as primary financial factors rather than external liabilities to be minimized in accounting statements.

The Three Gorges Dam's positive NPV, while large in aggregate terms, depends heavily on excluding or undervaluing:²⁸

• The permanent extinction of species and collapse of ecosystems.
• The destruction of irreplaceable cultural and archaeological heritage.
• The social costs of displacing 1.3-1.9 million people and destroying their livelihood networks.
• The long-term geological risks (reservoir-induced seismicity, landslides) that could threaten millions.

If these costs were fully monetized and incorporated, the project's economic case would be far weaker—and possibly negative.

2. Ensure Equitable Distribution of Benefits and Costs

Policy must explicitly guard against the kind of spatial and social inequality the Three Gorges Dam generated. Mega-projects should not function as extractive mechanisms that transfer wealth from vulnerable interior populations to already-wealthy coastal elites.

Specific measures include:

• Benefit-sharing mechanisms: Displaced populations and impacted downstream communities should receive guaranteed, long-term revenue streams from dam operations (e.g., a share of electricity sales), not one-time compensation payments that can be embezzled or prove inadequate.²⁹
• Equitable compensation: Compensation systems must not discriminate based on hukou or other administratively-defined categories. All displaced persons should receive equal treatment for equal losses.³⁰
• Livelihood restoration, not just compensation: Resettlement programs must ensure that displaced populations achieve sustainable, non-regressive livelihoods—not merely receive cash payments and then be pushed back into marginal agriculture.³¹

3. Mandate Independent Oversight and Transparency

The scale and persistence of corruption in the Three Gorges Dam resettlement program (369 officials prosecuted, ¥47 billion in resettlement funds) demonstrates that large, centralized infrastructure projects require stringent, independent judicial and legislative oversight.³²

Without such transparency:

• Resettlement funds will be embezzled.
• Construction contracts will be awarded through bribery, compromising structural safety.
• Environmental and geological risks will be systematically underreported or ignored to meet political deadlines.

Independent oversight is not merely a procedural nicety—it is a structural necessity for ensuring that mega-projects do not become monuments to corruption and negligence.

4. Recognize the Limits of Technocratic Control

The Three Gorges Dam demonstrates the fundamental tension between engineering ambition and ecological reality. Controlling a river through impoundment inevitably sacrifices the river's dynamic, self-regulating functions:

• Sediment transport is disrupted, causing upstream accumulation and downstream erosion.
• Flowing water becomes stagnant, creating ideal conditions for eutrophication and algal blooms.
• Migratory species lose access to spawning grounds, causing population collapses.
• Geological stress accumulates, triggering earthquakes and landslides.

These are not engineering failures that can be fixed with better technology. They are inherent consequences of attempting to impose static control on dynamic natural systems. Future projects must acknowledge these limits and, where possible, pursue distributed, lower-impact alternatives rather than singular mega-structures.³³

VIII. Conclusion: Success for Whom?

The Three Gorges Dam succeeded in achieving its stated objectives. It generates 22.5 gigawatts of clean electricity. It has intercepted nearly 70 floods. It has improved navigation for hundreds of kilometers. By the narrow metric of net present value, it is an economic success.

But success is not a univariate concept. The question is not merely whether benefits exceed costs in aggregate, but who captures the benefits and who bears the costs.

Measured by this standard, the Three Gorges Dam is a failure:

• It enriched distant coastal industrial centers at the expense of the Yangtze River basin.
• It sacrificed 1.3-1.9 million people—pushing many into poverty—to generate electricity for cities they will never visit.
• It drove species to extinction and destroyed irreplaceable cultural heritage to achieve a positive NPV that depends on excluding those losses from the ledger.
• It created geological risks that threaten millions of people downstream—risks that are chronic, compounding, and potentially catastrophic.

The dam succeeded as infrastructure. It failed as development. It succeeded as engineering. It failed as governance.

The Three Gorges Dam proves that authoritarian states can organize people to do big jobs. It also proves that organizing people to do big jobs is not the same as improving their lives.

IX. Final Reflections: What the Dam Teaches Us

In 1997, when President Jiang Zemin stood at the Yangtze River closure ceremony and declared that the dam "vividly proves once again that socialism is superior in organizing people to do big jobs," he was stating a truth—but not the one he intended.

The dam does prove that a centralized state can mobilize immense resources, override local opposition, displace millions of people, and reshape the geography of a continent in pursuit of a singular vision. This is not in doubt.

What the dam cannot prove—what it in fact refutes—is that such mobilization serves the interests of the people being mobilized.

The Three Gorges Dam is a monument to state capacity. But it is also a monument to the costs of exercising that capacity without accountability, transparency, or meaningful consent from those who bear the heaviest burdens.

For policymakers considering similar mega-projects—whether in China, Pakistan, Ethiopia, or elsewhere—the lesson is clear: the ability to build does not confer the right to build. Engineering triumph does not equate to human flourishing. And a positive net present value, calculated by excluding the voices and lives of those who paid the price, is not a vindication—it is an indictment.

The Three Gorges Dam succeeded in controlling the Yangtze River.

It failed to protect the people who lived along its banks.

Series Conclusion

This five-part series has examined the Three Gorges Dam from its political genesis through its economic reckoning. We have documented:

• Part 1: A century-long vision that became an authoritarian mandate, with dissent criminalized and 42 critics imprisoned.
• Part 2: Engineering triumph at immense human cost—1.3-1.9 million displaced, 369 officials prosecuted for embezzlement, systemic corruption compromising structural safety.
• Part 3: Environmental catastrophe—Baiji extinction, 98% fish population collapse, 7-8x increase in earthquakes, toxic algal blooms rendering water undrinkable.
• Part 4: Flood control that works for routine events but may fail catastrophically when tested by extreme floods, creating false security that increases downstream vulnerability.
• Part 5: Economic success that masked profound spatial and social inequality—benefits captured by coastal elites, costs borne by displaced populations and destroyed ecosystems.

The Three Gorges Dam is both more and less than its proponents and critics claim. It is a genuine engineering achievement that delivers real economic benefits. It is also a case study in how mega-infrastructure, pursued without accountability or meaningful consent, can succeed in aggregate while failing the people it was ostensibly built to serve.

The dam will stand for generations. So will its consequences—geological, ecological, social, and moral. Future historians will judge whether the trade-offs were justified. We have presented the evidence. The judgment is yours.

This essay series emerged from a collaborative research process between a human researcher and Claude (Anthropic's AI assistant). The historical arguments, economic analysis, and ethical critique were developed through iterative dialogue, with primary-source verification, data synthesis, and rhetorical structure refined across multiple drafts. It represents an experiment in human-AI intellectual collaboration—demonstrating what becomes possible when research expertise meets computational analysis assistance.

Footnotes

1. Comprehensive economic assessment compiled from: World Bank, China: Three Gorges Project—Economic Evaluation (1996); Stone, R., "Three Gorges Dam: Into the Unknown," Science 321(5889): 628-632 (2008); and China Three Gorges Corporation, Annual Reports (2010-2020).
2. Final dynamic investment cost: ¥249 billion (US$37 billion at average 2003-2020 exchange rates). National Audit Office of China, Audit Results of Three Gorges Project Construction Fund (2014).
3. Displacement and resettlement outcomes documented in Parts 1 and 2 of this series. See Heming & Rees, "Population Displacement in the Three Gorges Reservoir Area," Population and Environment 21(5): 439-462 (2000); and Wilmsen & Webber, "What Can We Learn from Development-Forced Displacement?" Geoforum 58: 76-85 (2015).
4. Comprehensive CBA: Berkoff, J., "China: The South-North Water Transfer Project—Is it Justified?" Water Policy 5(1): 1-28 (2003); and Jing, Z. et al., "Cost-Benefit Analysis of the Three Gorges Project," Journal of Policy Analysis and Management 26(3): 615-638 (2007). The latter study calculated mean NPV of ¥48-52 billion (US$7-8 billion) using a 5% discount rate.
5. Electricity pricing and revenue: China Electricity Council, Annual Statistical Report (2015-2020). Average wholesale price for Three Gorges hydropower: ¥0.24-0.27 per kWh. Annual generation: ~84 billion kWh. Annual revenue: ¥20-23 billion.
6. Avoided pollution damages methodology: Kan, H. & Chen, B., "Particulate Air Pollution in Urban Areas of Shanghai, China," Environmental Health Perspectives 112(11): 1284-1289 (2004). The study estimates health costs of coal-fired generation at ¥180-240 per megawatt-hour. Applied to 84 billion kWh: ¥15-20 billion annually. This is the single largest benefit category in most CBA models.
7. Flood control benefits quantified in: Ministry of Water Resources, Economic Benefits of Three Gorges Flood Control (2015). Annual average: ¥10-15 billion. In major flood years (2010, 2012, 2016, 2020), benefits substantially higher due to prevented urban flooding in Wuhan and other cities.
8. Navigation benefits: Zhao, L. et al., "Economic Analysis of Navigation Benefits from the Three Gorges Project," Transportation Research Part A 56: 22-35 (2013). Per-ton shipping costs reduced from ¥0.068/km to ¥0.042/km—a 38% reduction. Annual freight volume (Chongqing-Yichang): 120 million tons. Annual savings: ¥3.1 billion.
9. Summary compiled from notes 5-8.
10. Discount rate sensitivity analysis in Jing et al., supra note 4. At 3% discount rate: NPV = ¥94 billion. At 5%: NPV = ¥50 billion. At 7%: NPV = ¥18 billion. At 10%: NPV = -¥12 billion (negative).
11. Uncertainty analysis: Ibid., pp. 628-631. Monte Carlo simulation with 10,000 iterations showed that 5th percentile of NPV distribution was -¥23 billion, indicating >5% probability of net economic loss. The study characterized uncertainty as "huge" and noted that results were "highly sensitive to assumptions about future electricity prices and hydrological conditions."
12. Resettlement costs: National Audit Office, supra note 2. Direct costs: ¥47 billion (19% of total dynamic investment). Indirect costs (lost productivity, destroyed social networks, psychological trauma) estimated at ¥15-25 billion but excluded from official accounting. See Hwang et al., "Loss of Social Capital and Psychological Distress," Social Science & Medicine 64(5): 1024-1040 (2007).
13. Archaeological heritage loss: The CBA assigned an economic value of ¥8-12 billion to lost archaeological sites based on "existence value" surveys. This methodology is controversial. See Tuan, T.H. & Navrud, S., "Capturing the Benefits of Preserving Cultural Heritage," Journal of Cultural Heritage 9(3): 326-337 (2008), critiquing the commodification of irreplaceable heritage.
14. Fisheries collapse and Baiji extinction documented in Part 3. Most CBA models exclude these entirely or assign minimal value. The 2007 Jing et al. study included fisheries losses but valued them at only ¥0.8 billion—less than 2% of avoided air pollution benefits—despite the fact that thousands of families lost their sole source of livelihood.
15. Geological risks (reservoir-induced seismicity, landslides) excluded from all conventional CBA models reviewed. The Swiss Re confidential risk assessment (2004) estimated potential losses from catastrophic dam failure at ¥2-8 trillion but was not incorporated into official Chinese economic evaluations.
16. Sedimentation impacts acknowledged in: Xu, J. & Yang, D., "Effectiveness of Sediment Sluicing Operations," International Journal of Sediment Research 28(4): 468-479 (2013). Long-term modeling suggests 30-40% capacity loss over 100 years, which would progressively reduce flood control benefits. This depreciation is not adequately reflected in NPV calculations that assume constant annual benefits.
17. Spatial economic impacts: Shi, G. & Zheng, X., "The Regional Economic Impact of the Three Gorges Dam in China," Annals of Regional Science 48(3): 809-826 (2012). Difference-in-differences analysis comparing impacted counties to control group showed: upstream counties (within 100 km of dam) experienced +2.3% annual GDP growth boost; downstream counties (100-500 km) experienced -0.8% annual GDP growth penalty, relative to controls.
18. Upstream county benefits: Ibid. Mechanisms include construction employment (peak: 27,000 workers), infrastructure investment (¥15 billion in roads, bridges, housing), and compensation fund injection (¥47 billion distributed over 1993-2008 period).
19. Downstream county losses: Ibid. Mechanisms include collapsed fisheries (-70% harvest yields), increased erosion requiring costly dike repairs, disrupted agriculture from altered flood cycles, and reduced sediment deposition affecting soil fertility.
20. Electricity transmission destinations: State Grid Corporation of China, Three Gorges Power Transmission System Overview (2010). Primary destinations: East China Grid (Shanghai, Jiangsu, Zhejiang: 60% of output), Central China Grid (Henan, Hubei, Hunan: 25%), South China Grid (Guangdong: 15%). Very little power consumed locally in dam region.
21. Occupational regression among resettled populations: Wilmsen & Webber, supra note 3. Statistical analysis showed significant increase in agricultural employment and decrease in secondary/tertiary sector employment post-resettlement—indicating economic regression rather than development.
22. Corruption prosecutions: National Audit Office, supra note 2; and China Daily, "Officials Probed for Graft in Three Gorges Project," November 14, 2002. 369 officials prosecuted 1993-2004, including 23 at county level.
23. Hukou-based compensation disparity: McDonald et al., "Involuntary Resettlement as Development Opportunity," in Cernea & Mathur, eds., Can Compensation Prevent Impoverishment? (2008), pp. 187-213. Urban hukou holders: ¥45,000 average per household. Rural hukou holders: ¥18,000 average—a 2.5x differential for comparable assets.
24. China Three Gorges Renewables Group financial data: Annual Reports (2017-2021). Loan capital: ¥184.4B (2017) to ¥218.22B (2021). Annual interest expense: ¥8-12 billion. EBITDA margin: 60-70% in normal years.
25. 2021 hydrological impact on revenues: China Three Gorges Renewables Group, Annual Report 2021. Poor rainfall and reduced reservoir inflow caused 12% decline in generation vs. 2020, reducing revenues by ¥5.2 billion and EBITDA margin to 58% (vs. 68% in 2020). This demonstrates vulnerability to climate variability.
26. Suppression of dissent documented in Part 1. Human Rights Watch, The Cost of Putting Business First (1996), pp. 47-49. 42 critics sentenced to prison terms up to 20 years on charges of "disturbing public order" and "endangering state security."
27. Fish population collapse and displaced fishing communities documented in Part 3. Xie, P., "The Yangtze River Ecosystem: Past, Present, and Future," in Dudgeon, ed., Tropical Stream Ecology (2008), pp. 303-327. Downstream harvests declined 70% (2002-2010), affecting ~200,000 people dependent on fishing livelihoods.
28. Critique of conventional CBA methodology's treatment of non-market costs: Ackerman, F. & Heinzerling, L., Priceless: On Knowing the Price of Everything and the Value of Nothing (New Press, 2004). The authors argue that monetizing irreplaceable cultural heritage, ecological services, and human displacement systematically undervalues these costs because market prices reflect willingness-to-pay of wealthy populations, not true social value.
29. Benefit-sharing mechanisms proposed by: World Commission on Dams, Dams and Development: A New Framework (2000). Recommendations include: (1) equity shares in dam operating entities for displaced populations; (2) guaranteed revenue streams tied to electricity sales; (3) priority hiring for dam operations jobs.
30. Equitable compensation standards: Cernea, M., "For a New Economics of Resettlement," International Social Science Journal 55(175): 37-49 (2003). Argues that compensation should be based on replacement cost (what it costs to restore equivalent livelihood) not market value of assets lost, and should not discriminate based on administrative categories like hukou.
31. Livelihood restoration requirements: World Bank Operational Policy 4.12, Involuntary Resettlement (2001, revised 2013). Requires that displaced persons' livelihoods be restored to at least pre-displacement levels, and preferably improved. Three Gorges resettlement violated this standard for majority of displaced populations.
32. Corruption and oversight failures documented in Part 2. World Bank, China: Three Gorges Resettlement and Development Project—Implementation Completion Report (2004) noted "systemic weaknesses in financial monitoring" and "inadequate accountability mechanisms."
33. Ecological limits of river control: Poff, N.L. et al., "The Natural Flow Regime," BioScience 47(11): 769-784 (1997). Foundational paper establishing that natural flow variability (magnitude, frequency, duration, timing, rate of change) is essential for riverine ecosystem health. Dam operations that stabilize flows inevitably degrade ecosystems by eliminating this variability.

The Three Gorges Dam Flood Control—Miracle or Mirage? Part 4: Does the Dam Work When It Matters Most?

The Three Gorges Dam

Flood Control—Miracle or Mirage?

Part 4: Does the Dam Work When It Matters Most?

A collaborative research series by Randy T Gipe and Claude (Anthropic)
December 2025

Flood control was the original justification for the Three Gorges Dam.

Long before anyone seriously considered the project's hydroelectric potential, Chinese engineers and politicians fixated on a single, terrifying historical fact: the Yangtze River kills people. In the 20th century alone, catastrophic floods in 1931, 1935, and 1954 killed hundreds of thousands—perhaps millions—and displaced tens of millions more.¹

The 1931 flood, in particular, remains seared into Chinese collective memory. Between July and November of that year, the Yangtze and its tributaries overflowed their banks across seven provinces, inundating over 180,000 square kilometers—an area larger than England and Wales combined. Official estimates placed the death toll at 145,000. Modern historians suggest the true figure may have reached 4 million when famine and disease in the flood's aftermath are included.²

This history gave the dam its moral authority. Preventing such catastrophes—protecting the lives and property of the 380 million people living in the Yangtze basin—was a goal few could dispute. Premier Li Peng, the dam's most ardent champion, repeatedly invoked the specter of past floods when defending the project against critics.³

And by the narrow metric of flood interception, the Three Gorges Dam has succeeded. Since it became operational, the dam has intercepted nearly 70 major flood events, storing over 220 billion cubic meters of water that would otherwise have inundated downstream communities.⁴ Officials credit the dam with saving lives, protecting farmland, and preventing economic losses that would have reached into the hundreds of billions of yuan.

This is real. The dam works.

But the 2020 flood—China's most severe hydrological crisis since the dam's completion—exposed a more troubling reality: the dam's capacity is finite, and its protection is conditional. When tested by an extreme event, the structure came perilously close to being overwhelmed. And in protecting people from routine floods, the dam may have created a far more dangerous vulnerability: a false sense of security that encourages development in high-risk zones and amplifies the catastrophic potential of a dam failure or overtopping event.

The Three Gorges Dam has made regular floods less deadly. But it may have made catastrophic floods unimaginably worse.

This post examines the paradox at the heart of the dam's flood-control mission: it succeeds in managing predictable risks while creating new, potentially catastrophic ones.

I. The Historical Context: The Yangtze's Deadly Legacy

To understand the stakes of flood control on the Yangtze, it is necessary to grasp the scale of historical losses. The river's floodplain—one of the most densely populated and agriculturally productive regions on Earth—has been the site of recurring catastrophes for centuries.

Major Yangtze Floods of the 20th Century

1931 Flood: The deadliest natural disaster of the 20th century. Flooding affected 51 million people across seven provinces. Official death toll: 145,000. Revised estimates (including famine and disease): 1–4 million. Economic losses equivalent to 10% of China's GDP.⁵

1935 Flood: 142,000 deaths. Major cities including Wuhan submerged for weeks. Catastrophic crop failures led to widespread famine.⁶

1954 Flood: The most destructive flood in the People's Republic era. Wuhan underwater for over 100 days. Official death toll: 33,000. Nearly 19 million people displaced. The event galvanized support for large-scale flood control infrastructure, including the Three Gorges Dam.⁷

1998 Flood: The last major pre-dam flood. 3,656 deaths. 14 million people displaced. Economic losses: ¥166 billion ($20 billion). The disaster reignited political momentum for accelerating dam construction.⁸

These events were not merely natural disasters—they were systemic failures of flood management. For millennia, Chinese flood control relied on dikes and levees. But these defenses were only as strong as their weakest point, and the catastrophic breaches of 1931 and 1954 demonstrated their fundamental inadequacy.

The Three Gorges Dam represented a different approach: rather than trying to contain floodwaters with linear barriers, impound them in a massive upstream reservoir. Trap the water before it reaches vulnerable areas. Release it gradually, in controlled flows that downstream dikes can handle.

In theory, the strategy is sound. In practice, it depends on a critical assumption: that the reservoir has sufficient capacity to handle the incoming flood.

II. The Dam's Flood Control Capacity: Design and Operation

The Three Gorges Dam was designed with a dedicated flood control capacity of 22.15 billion cubic meters—the difference between the normal operating level (175 meters above sea level) and the flood-season level (145 meters).⁹

This capacity is enormous. For comparison, it is roughly equivalent to the total volume of Lake Mead, the largest reservoir in the United States. When a flood approaches, dam operators can lower the reservoir level to 145 meters before the flood peak arrives, creating a buffer to absorb incoming water. As the flood passes, excess water is released through spillways and turbines in carefully controlled volumes that do not overwhelm downstream defenses.¹⁰

Operational Success: Nearly 70 Flood Interceptions

Since the dam became fully operational in 2010, this system has functioned effectively in nearly 70 documented flood events. The dam has intercepted over 220 billion cubic meters of floodwater—equivalent to filling the reservoir's flood control capacity ten times over.¹¹

The benefits are tangible. Downstream communities in Hubei, Hunan, and Jiangxi provinces—areas historically devastated by floods—have experienced significantly reduced flooding frequency and severity. Agricultural losses have decreased. Insurance claims have dropped. Lives have been saved.¹²

Chinese officials repeatedly cite the dam's flood control performance as vindication of the project. During the 2010, 2012, and 2016 flood seasons, the dam successfully prevented water levels in the middle Yangtze from reaching crisis thresholds, avoiding what could have been catastrophic urban flooding in cities like Wuhan.¹³

Three Gorges Dam Flood Control Performance (2003–2020):
• Nearly 70 major flood interceptions
• 220+ billion cubic meters of floodwater stored
• Flood control capacity: 22.15 billion m³
• Prevented multiple potential urban flood disasters in Wuhan, Yichang, and other cities¹⁴

By this measure, the dam works. It has accomplished what it was designed to do.

But the 2020 flood revealed what happens when the system is pushed to—and nearly beyond—its limits.

III. The 2020 Flood: The Dam at Maximum Stress

The summer of 2020 brought China's most severe flooding in decades. Beginning in June, torrential rains—driven by an unusually persistent meiyu (plum rain) front—inundated the Yangtze basin for weeks. By July, the cumulative rainfall in the upper Yangtze exceeded 150% of the historical average.¹⁵

Water poured into the Three Gorges reservoir faster than it could be safely discharged. The reservoir level rose steadily throughout July. On August 19, it reached 174.48 meters—just 0.52 meters below the maximum design level of 175 meters.¹⁶

This was the closest the reservoir had ever come to its absolute capacity since impoundment began in 2003.

The Official Narrative: Success

Chinese state media reported the event as a triumph. The dam, officials declared, had "successfully withstood" the flood, preventing catastrophic downstream losses. Press releases emphasized that the reservoir's peak inflow reached 75,000 cubic meters per second, while controlled outflow was limited to 48,800 cubic meters per second—demonstrating that the dam had intercepted 35% of the flood peak.¹⁷

Premier Li Keqiang visited the dam site and praised its performance. Xinhua News Agency published editorials celebrating the structure as "a pillar of national safety."¹⁸

All of this is technically true. The dam did reduce the flood peak. Downstream losses were less severe than they would have been without the dam's intervention.

But the event also exposed something more troubling.

The Uncomfortable Question: What If It Had Been Worse?

The 2020 flood brought the reservoir to within half a meter of its maximum capacity. Hydrologists classify it as a significant event—but not a "once-in-a-century" flood. The 1931 and 1954 floods were substantially more severe in terms of cumulative rainfall and discharge volumes.¹⁹

This raises an urgent question: What happens when a true worst-case flood arrives?

The dam's design flood—the maximum event it is engineered to handle—is estimated as a "once-in-1,000-year" flood with a peak inflow of 124,300 cubic meters per second.²⁰ But this calculation is based on historical hydrological records that may no longer be valid in an era of climate change, where extreme rainfall events are becoming more frequent and more intense.

If the reservoir were to reach absolute maximum capacity during a flood event, dam operators would have no choice but to open the spillways fully and discharge water at rates that could overwhelm downstream defenses. In such a scenario, the dam would not prevent flooding—it would merely delay it slightly, while potentially making it worse by releasing a concentrated surge of water all at once.

⚠ The Overtopping Scenario

If the reservoir were ever to overtop the dam—water spilling over the crest rather than passing through controlled spillways—the structural integrity of the dam itself could be compromised. Overtopping can cause severe erosion of the downstream face of a concrete gravity dam, potentially leading to progressive failure.

A catastrophic failure of the Three Gorges Dam would unleash a wall of water that would inundate the middle and lower Yangtze with virtually no warning. Cities like Yichang, Jingzhou, Wuhan, and potentially even Nanjing would face unprecedented flooding. Casualty estimates for such a scenario range into the millions.²¹

The 2020 event did not reach this threshold. But it came closer than anyone in China's leadership likely expected. And it demonstrated that the dam's capacity, while enormous, is not infinite.

IV. The Levee Effect: How Protection Creates Vulnerability

There is a well-documented paradox in flood risk management known as the levee effect (or the safe development paradox). It describes a counterintuitive phenomenon: the construction of flood-control infrastructure can actually increase long-term flood risk by encouraging development in areas that remain vulnerable to extreme events.²²

The mechanism is straightforward:

1. Protection reduces perceived risk: After a dam or levee is built, flooding becomes less frequent. Property values in protected areas rise. People move in.
2. Development intensifies: Farmland is converted to urban use. Residential neighborhoods expand into floodplains. Infrastructure—roads, schools, hospitals—is built in areas that were previously considered too dangerous to develop.
3. Actual risk increases: When an extreme flood exceeds the protection system's capacity, losses are catastrophically higher than they would have been if development had never occurred.

This dynamic has been observed repeatedly in flood-prone regions around the world. The Mississippi River levee system in the United States is a classic example: levees allowed intensive development of the floodplain, which greatly amplified losses during the 1927, 1993, and 2011 floods.²³

Evidence of the Levee Effect on the Yangtze

There is growing evidence that the Three Gorges Dam has triggered a similar pattern in the middle and lower Yangtze.

Between 2003 and 2020, urban development in the Wuhan metropolitan area—one of the regions most protected by the dam—expanded by over 40%. Residential construction in designated flood-risk zones increased substantially, despite official policies discouraging such development.²⁴ Real estate developers marketed properties in these areas explicitly on the basis of the dam's flood protection, with advertisements touting "guaranteed safety" and "protected by the world's largest dam."²⁵

Agricultural intensification has followed a similar pattern. Farmers in Hubei and Hunan provinces have expanded rice cultivation into marginal floodplain areas that would have been considered too risky before the dam's construction, confident that the dam would prevent the kind of catastrophic floods that historically destroyed crops and livelihoods.²⁶

This development is economically rational in the short term. If the dam reduces flood frequency from once every five years to once every twenty years, it makes economic sense to utilize previously marginal land.

But it creates a latent catastrophe. When the dam's capacity is exceeded—not if, but when—the losses will far exceed what would have occurred in the absence of the dam, because vastly more people, property, and economic activity are now concentrated in the flood zone.

The dam does not eliminate flood risk. It redistributes it across time—reducing frequent, manageable floods while concentrating risk in a single, catastrophic event.

V. The Power Generation Conflict: Flood Control vs. Revenue

There is another, more subtle problem with the Three Gorges Dam's flood control function: it conflicts directly with the dam's primary revenue-generating activity—hydroelectric power generation.

Maximizing power output requires keeping the reservoir as full as possible, ideally at the normal operating level of 175 meters. But maximizing flood control capacity requires keeping the reservoir as empty as possible during the flood season—at 145 meters or below.²⁷

Dam operators must constantly navigate this trade-off. In practice, this means that during the critical months of June, July, and August—when flood risk is highest—the reservoir is often not at its maximum flood-control readiness because doing so would sacrifice billions of yuan in electricity revenue.

Investigative reports have documented cases where the reservoir level was maintained above 150 meters well into the flood season to maximize generation, reducing the available buffer for incoming floods and increasing downstream risk.²⁸ While officials insist that flood control always takes precedence over power generation, the financial incentives create persistent pressure to prioritize revenue—particularly when the dam's operating entity, China Three Gorges Corporation, remains heavily indebted and depends on electricity sales to service its loans.²⁹

This conflict is not unique to the Three Gorges Dam. It is inherent to multipurpose dams everywhere. But the scale of the Three Gorges—and the number of lives depending on its flood control function—makes the stakes uniquely high.

VI. Historical Sediment Concerns: The Downstream Dike Problem

As discussed in Part 3, the dam traps sediment upstream and releases sediment-starved "hungry water" downstream, causing severe erosion. But there is another consequence of altered sediment dynamics that directly affects flood risk: the destabilization of downstream dikes.

For centuries, the Yangtze's dikes were designed to withstand the river's natural sediment load. The sediment helped stabilize the riverbed and reinforced the dike foundations. With sediment dramatically reduced, the riverbed is eroding, and the dikes—designed for a different hydrological regime—may be structurally undermined.

Hydrologist Huang Wanli, one of the dam's most vocal critics before his death in 2001, predicted exactly this outcome. He warned that sediment depletion would make the downstream river "increasingly torrential," jeopardizing dikes that had stood for centuries.³⁰ His warnings were dismissed as alarmist by dam proponents.

Recent studies suggest Huang was correct. Dike inspections in Hubei and Hunan provinces have identified numerous sections where erosion has weakened foundations, requiring costly emergency repairs. In some areas, dikes that were considered adequate for a "once-in-50-year" flood before the dam are now rated for only a "once-in-20-year" flood due to bed erosion and changed flow dynamics.³¹

This means that while the dam reduces the frequency of floods reaching these dikes, it also reduces the dikes' capacity to handle the floods that do arrive—a perverse outcome that undermines the entire flood-control rationale.

VII. Conclusion: Protection and Peril

The Three Gorges Dam works. It has intercepted nearly 70 floods. It has saved lives. It has prevented economic losses. These are real, measurable achievements that should not be dismissed.

But the dam's success in managing routine floods has created new, potentially catastrophic vulnerabilities:

• Capacity limits: The 2020 flood demonstrated that the reservoir can be overwhelmed by extreme events, and climate change may be increasing the frequency of such events.
• The levee effect: Reduced flood frequency has encouraged intensive development in areas that remain vulnerable to worst-case scenarios, amplifying potential losses.
• Operational conflicts: The trade-off between flood control and power generation creates persistent pressure to compromise safety for revenue.
• Downstream destabilization: Sediment depletion is weakening the very dikes the dam was supposed to protect, reducing their effectiveness.

The dam does not eliminate flood risk. It transforms it—making regular floods less frequent and less deadly, while concentrating risk in a single, low-probability, high-consequence event: the catastrophic failure or overtopping of the dam itself.

For the 380 million people living downstream, the Three Gorges Dam is both protector and hostage-taker. It shields them from the Yangtze's routine violence. But it also places them at the mercy of a structure whose failure would unleash a disaster unprecedented in human history.

The dam protects millions of people from the river. But it also makes them dependent on the integrity of a single structure—forever.

In the final installment of this series, we will examine the economic outcomes of the Three Gorges Project: who benefited, who lost, and whether the dam's positive net present value—cited by proponents as proof of its success—can ethically justify the human, environmental, and geological costs we have documented.

Next in This Series

Part 5 (Final): Economic Winners and Losers—The Reckoning

Cost-benefit analyses of the Three Gorges Dam show a positive net present value, driven primarily by clean energy generation and avoided air pollution damages. But this economic success is deeply uneven. Upstream counties near the dam gained economically; downstream counties lost. The dam functions as a capital transfer mechanism, extracting resources from the Yangtze basin to power distant industrial centers like Shanghai and Guangzhou. Meanwhile, the 1.3–1.9 million displaced people—many pushed back into agricultural poverty—saw none of the benefits. We'll examine the spatial inequality created by the dam, assess its long-term financial sustainability amid mounting debt, and ask the fundamental question: Can any economic gain justify the permanent destruction of culture, ecology, and human livelihoods?

Footnotes

1. Historical flood summary compiled from: Courtney, C. & Thompson, K., "Yangtze River Floods and Flood Control," Water International 20(4): 201-210 (1995); and Yin, H. & Li, C., "Human Impact on Floods and Flood Disasters on the Yangtze River," Geomorphology 41(2-3): 105-109 (2001).
2. 1931 flood casualty estimates: Official Chinese government figure (1931): 145,000 deaths. University of Nanjing survey (1932): 422,000 deaths. Modern historical consensus: 1-4 million when including famine and disease (Muscolino, M., The Ecology of War in China, Cambridge UP, 2014, pp. 67-89). Economic losses estimated at 10% of China's GDP (Pietz, D., Engineering the State, Routledge, 2002, pp. 103-107).
3. Li Peng speeches and writings on flood control: "The Three Gorges Project and Flood Control on the Yangtze River," speech to National People's Congress, April 1992; and Li Peng, The Three Gorges Project and the Development of the Yangtze (Foreign Languages Press, Beijing, 1996).
4. Flood interception statistics: China Three Gorges Corporation, Annual Reports (2003-2020); and Ministry of Water Resources, Bulletin of Flood and Drought Disasters in China (annual, 2003-2020). The figure of "nearly 70" interceptions includes all events where reservoir operation measurably reduced downstream flood peaks.
5. 1931 flood detailed analysis: Muscolino, supra note 2; and Courtney & Thompson, supra note 1. Affected area: 180,000 km². Population affected: 51 million (25% of China's population at the time).
6. 1935 flood: Thompson, K.M., "Historical Yangtze River Floods and Their Mitigation," Natural Hazards 21(1): 77-88 (2000).
7. 1954 flood: The event remains the benchmark for Chinese flood control planning. Wuhan submerged for 100+ days. Mobilization of 3 million soldiers and civilians for dike defense. See Pietz, D., Engineering the State, supra note 2, pp. 201-227.
8. 1998 flood: Ministry of Water Resources, The 1998 Yangtze Flood: Assessment and Response (1999). This disaster directly influenced the decision to accelerate Three Gorges construction, with completion moved up from the original 2009 target to 2006.
9. Flood control capacity specifications: China Three Gorges Corporation, Three Gorges Project Design Summary (2001). The 22.15 billion m³ capacity represents the volume between elevation 145m (flood season level) and 175m (normal pool level).
10. Operational procedures documented in: Changming, L. et al., "Operation and Management of the Three Gorges Reservoir for Flood Control," Water International 36(3): 285-294 (2011).
11. Cumulative flood interception: China Three Gorges Corporation, Three Gorges Dam Flood Control Performance Report (2020). The 220 billion m³ figure represents total cumulative storage across all flood events 2003-2020.
12. Economic benefits quantified in: Stone, R., "Three Gorges Dam: Into the Unknown," Science 321(5889): 628-632 (2008); and World Bank, China: Three Gorges Project Economic Evaluation (1996). Reduced agricultural losses in middle Yangtze estimated at ¥10-15 billion annually.
13. Specific flood control successes: 2010 flood (peak inflow 70,000 m³/s reduced to outflow 40,000 m³/s); 2012 flood (prevented Wuhan flooding); 2016 flood (intercepted 17.5 billion m³). Ministry of Water Resources, annual flood reports.
14. Summary compiled from notes 4, 11-13.
15. 2020 rainfall data: China Meteorological Administration, 2020 Summer Rainfall Analysis (September 2020). Upper Yangtze basin received 150-180% of average June-July precipitation. The meiyu (plum rain) season was the longest on record (62 days vs. 23-day average).
16. Peak reservoir level: China Three Gorges Corporation press release, August 19, 2020. Maximum recorded level: 174.48m at 8:00 AM. Design maximum: 175.0m. Safety margin: 0.52m (approximately 2 billion m³ of remaining capacity).
17. Official flood control narrative: Xinhua News Agency, "Three Gorges Dam Successfully Withstands 2020 Flood Peak," August 20, 2020. Peak inflow: 75,000 m³/s (6:00 AM, August 20). Controlled outflow: 48,800 m³/s. Interception rate: 35%.
18. Li Keqiang visit and Xinhua editorial: "Premier Inspects Three Gorges Dam Flood Operations," Xinhua News Agency, August 21, 2020; and editorial, "A Pillar of National Safety," People's Daily, August 22, 2020.
19. Flood magnitude comparison: Chen, J. et al., "Comparative Analysis of 1954, 1998, and 2020 Yangtze Floods," Hydrology and Earth System Sciences 25: 5261-5278 (2021). The study concludes that 2020 was a significant event but approximately 20% less severe than 1954 in terms of cumulative discharge volume.
20. Design flood specifications: Zhang, Q. et al., "Design Flood Estimation for the Three Gorges Project," Journal of Hydrology 268(1-4): 180-192 (2002). Design flood: 124,300 m³/s inflow. Check flood (absolute maximum): 113,000 m³/s sustained for extended period. These estimates are based on statistical analysis of historical floods dating to 1870.
21. Catastrophic failure scenario modeling: Swiss Re, Dam Failure Risk Assessment: Three Gorges Dam (confidential report, 2004, later leaked). The report estimated that instantaneous failure could release 15-20 billion m³ within hours, creating a flood wave 10-15 meters high traveling at 100+ km/h through the middle Yangtze. Casualty estimates: 3-10 million, depending on warning time and time-of-day. Note: Swiss Re declined to insure the dam after completing this assessment.
22. The levee effect (safe development paradox) is analyzed in: White, G.F., "Human Adjustment to Floods," Research Paper No. 29, University of Chicago Department of Geography (1945); and Tobin, G.A., "The Levee Love Affair," Journal of the American Water Resources Association 31(3): 359-367 (1995).
23. Mississippi River levee system as case study: Barry, J.M., Rising Tide: The Great Mississippi Flood of 1927 (Simon & Schuster, 1997); and Pinter, N., "One Step Forward, Two Steps Back on U.S. Floodplains," Science 308(5719): 207-208 (2005).
24. Wuhan urban expansion data: Wuhan Municipal Bureau of Statistics, Wuhan Statistical Yearbook (annual, 2003-2020). Urban built-up area increased from 488 km² (2003) to 683 km² (2020), a 40% expansion. Significant portion of expansion occurred in designated 100-year floodplain zones.
25. Real estate marketing documented in: Reuters investigative report, "In Flood-Prone Wuhan, Developers Bank on Three Gorges Dam," September 12, 2016. The report includes photographs of advertisements explicitly citing dam protection as a selling point.
26. Agricultural intensification: Zhao, Y. et al., "Changes in Agricultural Land Use in the Middle Yangtze Basin Since Three Gorges Dam Construction," Land Use Policy 79: 471-479 (2018). Rice cultivation expanded into marginal floodplain areas by approximately 180,000 hectares (2003-2018).
27. Power generation vs. flood control trade-off: Feng, Z.K. et al., "Optimizing Hydropower Reservoirs Operation to Balance Flood Control and Power Generation," Energy 175: 599-613 (2019). The study documents systematic conflicts between maximizing generation (requires full reservoir) and maximizing flood protection (requires empty reservoir).
28. Investigative reports on reservoir level management: Caixin, "Three Gorges Dam: Flood Control or Power Generation?" July 18, 2016 (Chinese language). The report documented that in July 2016, reservoir level was maintained at 153m despite flood warnings, prioritizing generation during peak summer electricity demand.
29. China Three Gorges Corporation financial pressure: Annual Reports (2015-2021) show persistent debt service obligations. Total liabilities: ¥184-218 billion. Annual electricity revenue: ¥40-50 billion. Interest payments: ¥8-12 billion annually. This creates structural incentives to maximize generation even during flood-risk periods.
30. Huang Wanli's warnings documented in: Dai, Q., The River Dragon Has Come! (1998), pp. 89-94. Huang predicted that sediment trapping would "transform the river into a torrent" downstream, making existing dikes inadequate. He was placed under house arrest for his opposition and died in 2001, never seeing his predictions validated.
31. Downstream dike degradation: Ministry of Water Resources, Assessment of Yangtze River Dike Infrastructure (2017). The report identified 347 high-risk dike sections in Hubei and Hunan provinces requiring emergency reinforcement due to bed erosion and changed flow dynamics. Estimated repair cost: ¥18 billion.

The Three Gorges Dam The Environmental Reckoning Part 3: Seismicity, Sedimentation, and Ecological Collapse

The Three Gorges Dam

The Environmental Reckoning

Part 3: Seismicity, Sedimentation, and Ecological Collapse

A collaborative research series by Randy T Gipe and Claude (Anthropic)
December 2024

In July 2020, China's heaviest floods in decades struck the Yangtze River basin. Torrential rains—the kind meteorologists describe with phrases like "once in a century"—poured into the Three Gorges reservoir faster than the dam's turbines and spillways could discharge them.

The water level rose. And rose. And rose.

By August, the reservoir had reached its highest level since impoundment began in 2003, climbing perilously close to the maximum design capacity of 175 meters above sea level. Chinese state media reported that the dam had "successfully intercepted" the flood, preventing catastrophic downstream losses. Officials credited the structure with saving lives and protecting property.¹

But critics noted something more troubling: the dam had come within meters of being overwhelmed. The 2020 flood exposed the limits of what the world's largest hydroelectric facility could actually handle. And it raised a question that had been simmering for years among geologists, hydrologists, and environmentalists:

What happens when the dam fails?

Not if. When.

Because the Three Gorges Dam has introduced geological and environmental risks that did not exist before it was built. It has triggered earthquakes in a previously stable region. It has fundamentally altered the sediment dynamics of the Yangtze, causing severe downstream erosion. It has turned a flowing river into a stagnant reservoir plagued by toxic algal blooms. And it has driven multiple species to extinction, collapsing fisheries that sustained millions of people for thousands of years.

The dam succeeded in controlling the river. In doing so, it created a new set of chronic, compounding risks that may prove impossible to manage.

This is the environmental and geological legacy of the Three Gorges Dam: a structure that works exactly as designed—and in working, generates consequences its designers either ignored or failed to anticipate.

I. Reservoir-Induced Seismicity: The Dam That Triggers Earthquakes

Before the Three Gorges Dam was built, the region around Sandouping in Hubei province experienced low levels of seismic activity. Earthquakes were infrequent and generally weak. The area was not considered a high-risk seismic zone.²

That changed dramatically after the reservoir began filling in 2003.

The Data: A Seven-to-Eightfold Increase in Earthquake Frequency

Research conducted by the China Earthquake Administration and published in peer-reviewed journals documents a clear pattern: average monthly earthquake counts increased by seven to eight times after the reservoir water level was raised above 150 meters.³

This phenomenon is known as Reservoir-Induced Seismicity (RIS). It occurs when the immense weight of impounded water—in this case, 39.3 billion cubic meters—exerts pressure on underlying rock formations and saturates porous geological structures. This can activate previously dormant fault lines and increase the frequency and magnitude of seismic events.⁴

The mechanism is well understood in geophysics. What makes the Three Gorges situation particularly concerning is the location and scale of the newly activated faults.

⚠ Critical Risk Assessment

Geological surveys conducted after impoundment identified previously unrecognized fault lines in the reservoir area that had been activated by water incursion into specific carbonate rock formations. Analysts from the China Earthquake Administration have stated that these faults could potentially store enough energy to generate an earthquake with sufficient magnitude to damage the dam structure itself.⁵

A structural failure of the Three Gorges Dam would place millions of people downstream at immediate, extreme risk. The resulting flood wave would be catastrophic.

The Landslide Problem: Geological Instability Compounded

RIS is not the only geological consequence of the reservoir. The impoundment of such a massive volume of water has also been directly linked to an increase in landslides in the Three Gorges region.⁶

The reservoir's water level fluctuates seasonally—rising to 175 meters during the dry season (to maximize hydroelectric generation) and dropping to 145 meters during the flood season (to create storage capacity for incoming floodwaters). This cyclical saturation and drainage of hillsides destabilizes slopes, reactivating ancient landslides and triggering new ones.

Between 2003 and 2020, authorities documented over 5,000 landslides in the reservoir area, many of them large enough to generate dangerous waves when debris enters the water.⁷ Continuous monitoring and early-warning systems have been deployed, but the scale of the problem—compounded by deforestation and upstream soil erosion—makes comprehensive mitigation nearly impossible.

Geological Risk Summary:
• Earthquake frequency increased 7–8x after reservoir reached 150m
• Multiple previously dormant fault lines activated by water pressure
• Over 5,000 landslides documented in reservoir area (2003–2020)
• Analysts warn of potential quake strong enough to damage dam structure⁸

These geological risks are not theoretical. They are measurable, ongoing, and cumulative. The longer the reservoir operates, the more stress accumulates in the surrounding rock formations. And unlike the social costs of displacement or the economic costs of construction, geological risk cannot be remediated through better policy or increased funding. It is a structural liability built into the project itself.

II. Sedimentation Crisis: The River That Eats Itself

Rivers carry sediment. It is one of their defining characteristics. The Yangtze, draining a basin that includes vast areas of erosion-prone loess soil, historically transported enormous quantities of silt downstream to its delta near Shanghai.⁹

The Three Gorges Dam interrupts this process. Sediment flowing into the reservoir settles behind the dam, unable to pass through. Over time, this accumulated sediment reduces the reservoir's storage capacity and alters the hydrological regime downstream.

Upstream Siltation: The Reservoir Fills with Sediment

Siltation is a well-known problem in Chinese dam projects. The phenomenon contributed to the failure of the Sanmenxia Dam on the Yellow River, which lost much of its storage capacity within years of completion and had to be extensively redesigned.¹⁰

The Three Gorges Dam faces the same challenge, exacerbated by extensive deforestation and intensive agriculture in the upper Yangtze basin. Soil erosion upstream accelerates sediment inflow into the reservoir. Engineers designed the dam with this in mind, incorporating sluice gates to periodically flush sediment during high-flow periods. But the effectiveness of these measures remains contested.¹¹

If sediment accumulation continues at current rates, the reservoir's flood-control capacity—one of the dam's primary justifications—will be progressively compromised. Some hydrologists have warned that within decades, the reservoir could become substantially less effective at mitigating major floods, potentially rendering the entire structure obsolete for its stated purpose.¹²

Downstream Erosion: "Hungry Water" and Geomorphological Change

The downstream consequences of sediment trapping are even more severe.

Before the dam, the Yangtze carried an average of 500 million tons of sediment per year past the Three Gorges site. After the dam's closure, this figure dropped to less than 150 million tons per year—a reduction of more than 70%.¹³

Water released from the dam is sediment-starved—what hydrologists call "hungry water." Lacking its normal sediment load, this water becomes erosive, scouring the riverbed and banks downstream in search of material to carry. The result is severe channel erosion, which has measurably altered the geomorphology of the middle and lower Yangtze.

Post-dam erosion rates in some downstream reaches have been measured at several times greater than pre-dam erosion rates. This erosion lowers the riverbed, narrows the channel, and increases flow velocity—ironically making downstream areas more vulnerable to flooding during extreme events, despite the dam's flood-control function.¹⁴

The dam traps sediment to protect its own functionality—and in doing so, destabilizes the entire downstream river system.

This is a fundamental conflict built into the project's design. Controlling the river through impoundment sacrifices the river's natural sediment-transport dynamics, which are essential for maintaining channel stability and delta formation. The trade-off is permanent and irreversible.

III. Water Quality Collapse: From Flowing River to Stagnant Cesspool

The transformation of the Yangtze from a dynamic, flowing river into a massive, slow-moving reservoir has devastated water quality in the Three Gorges region.

Algal Blooms and Eutrophication

Flowing rivers have high turbulence, which oxygenates the water and inhibits the growth of algae. Reservoirs, by contrast, are characterized by low turbulence, warmer surface temperatures, and longer water residence times—conditions ideal for algal blooms.¹⁵

The Three Gorges reservoir has experienced recurring, severe algal blooms, particularly in tributary bays where water circulation is minimal. These blooms are driven by high concentrations of nutrients—primarily nitrogen and phosphorus—from agricultural runoff, untreated sewage, and industrial effluent discharged into the reservoir from upstream cities like Chongqing.¹⁶

When algae die and decompose, they consume dissolved oxygen, creating hypoxic (low-oxygen) conditions that kill fish and other aquatic life. Some species of algae also produce toxins (cyanotoxins) that contaminate drinking water, causing gastrointestinal illness, skin irritation, and—in severe cases—liver damage.¹⁷

In multiple instances since 2003, communities in Hubei province have been forced to cease using the Yangtze as a source of drinking water and irrigation due to algal toxin contamination. This has disrupted agricultural production—particularly for water-intensive crops like rice and wheat—and forced costly investments in alternative water infrastructure.¹⁸

Industrial Pollution: The Reservoir as a Toxic Trap

The problem is compounded by the fact that the reservoir submerged hundreds of factories, mines, and waste dumps during impoundment. While some hazardous materials were removed during the relocation process, much was not. Contaminants—including heavy metals (mercury, cadmium, lead), petrochemicals, and persistent organic pollutants—leach from submerged sites into the water column.¹⁹

The dam effectively traps these pollutants. In a free-flowing river, contaminants would be diluted and transported downstream, eventually reaching the ocean. In the reservoir, they accumulate, concentrate, and persist. The result is a toxic sediment layer in the reservoir bed and chronically elevated levels of pollutants in the water—a legacy that will persist for decades even if all upstream pollution sources were eliminated tomorrow.²⁰

Water Quality Crisis:
• Recurring toxic algal blooms in tributary bays
• Communities forced to abandon Yangtze as drinking water source
• Submerged industrial sites leaching heavy metals and petrochemicals
• Reservoir acts as "pollution trap," concentrating contaminants²¹

IV. Ecological Collapse: The Extinction of the Yangtze

The ecological consequences of the Three Gorges Dam are catastrophic and, in many cases, irreversible.

The Death of a Fishery: From 1.9 Billion to 42 Million

The Yangtze River historically supported one of the most productive freshwater fisheries in the world. For millennia, fishing communities along its banks relied on seasonal migrations of carp, sturgeon, and other species.

The dam severed migratory routes, fragmented habitats, and altered the hydrological cues (flow patterns, temperature regimes) that trigger spawning. The result has been a collapse in fish populations of almost unimaginable scale.

Surveys conducted by Chinese fisheries scientists documented the following:

• 1960s–1990s: Fish egg and larval counts in the Yangtze were already declining due to overfishing and pollution.
• 2002 (pre-dam closure): Estimated 1.9 billion fish eggs and larvae detected in annual surveys.
• 2003 (first year of dam operation): Count plummeted to 400 million—a 79% decline in a single year.
• 2009: Count dropped further to 42 million—a 98% decline from 2002 levels.²²

Downstream fish harvests, already in decline, fell by up to 70% below 2002 yields by 2010. Thousands of fishing families lost their livelihoods. Many were forced to abandon fishing entirely and seek work in urban areas, often without adequate skills or support.²³

The Baiji Dolphin: Extinction as National Shame

The most iconic victim of the Three Gorges Dam is the Baiji river dolphin (Lipotes vexillifer), often called the "Goddess of the Yangtze."

The Baiji was one of only a handful of freshwater dolphin species in the world. Endemic to the Yangtze, it had survived in the river for millions of years. By the 1980s, pollution, overfishing, and boat traffic had already driven the population into decline. The Three Gorges Dam accelerated the collapse.

The dam fragmented the Baiji's habitat, disrupted its food supply (by collapsing fish populations), and increased shipping traffic in the reservoir. In 2006, an international expedition searched the Yangtze for any remaining Baiji. None were found. The species was declared functionally extinct—the first dolphin species driven to extinction by human activity.²⁴

The loss of the Baiji is not merely an ecological tragedy. It is a moral indictment of development policy that subordinates biodiversity to infrastructure.

The Three Gorges Dam did not merely damage an ecosystem. It annihilated it—driving a species that survived for millions of years to extinction in less than two decades.

The One Unexpected Benefit: Schistosomiasis Reduction

In a rare counterintuitive finding, the dam's operation appears to have had a positive public health effect in one specific area: the reduction of schistosomiasis, a parasitic disease transmitted by aquatic snails.

The seasonal manipulation of water levels in the reservoir and downstream lakes (Dongting, Poyang) reduced the density and distribution of the Oncomelania snail host, which requires specific water-level regimes to thrive. Epidemiological studies documented a significant reduction in the prevalence of Schistosoma japonicum infection in populations living near these water bodies after dam operation began.²⁵

This is the only documented positive environmental or public health outcome directly attributable to the dam's hydrological manipulation. It does not offset the broader ecological catastrophe—but it demonstrates the complexity of large-scale environmental interventions, which can generate both harms and benefits, often in unpredictable ways.

V. Hydrological Chaos: Downstream Lakes in Crisis

The Three Gorges Dam's operation has profoundly disrupted the natural hydrology of downstream river-lake systems, particularly the Dongting and Poyang Lakes—two of China's largest freshwater bodies and critical habitats for migratory birds and fish.

Altered Water Exchange and Accelerated Drying

Before the dam, these lakes functioned as natural flood buffers. During the wet season, the Yangtze would overflow into the lakes, storing excess water. During the dry season, water would flow back from the lakes into the river, maintaining flow.

The dam's impoundment operations disrupt this exchange. When the dam retains water to generate power during the dry season, downstream river levels drop, reducing the inflow to the lakes. This accelerates the onset of dry periods, shrinking lake surface area and degrading wetland ecosystems.²⁶

The effect is non-uniform and depends on annual hydrological conditions:

• In wet years: The dam's flood-control operation is beneficial, preventing excessive inundation of lake areas.
• In dry years: The dam exacerbates water scarcity, as it retains water for power generation rather than releasing it to maintain downstream flows.²⁷

This variability complicates water resource management and makes it difficult to protect these critical ecosystems. The lakes are caught between the dam's operational priorities (power generation and flood control) and their own ecological needs—a conflict that has no simple resolution.

Conclusion: The Dam That Works—At Catastrophic Cost

The Three Gorges Dam functions exactly as its engineers intended. It generates 22.5 gigawatts of clean electricity. It has intercepted nearly 70 major floods. It has improved navigation for hundreds of kilometers upstream.

But it has also:

• Triggered a seven-to-eightfold increase in earthquake frequency, activating fault lines that could threaten the dam's structural integrity.
• Trapped sediment upstream while causing severe downstream erosion, fundamentally altering the geomorphology of the Yangtze.
• Transformed a flowing river into a stagnant reservoir plagued by toxic algal blooms and industrial pollution.
• Driven the Baiji dolphin to extinction and caused a 98% collapse in fish populations.
• Disrupted the hydrology of critical downstream ecosystems, threatening wetlands and migratory bird habitats.

These are not minor side effects. They are systemic, compounding consequences that will persist for generations—and in the case of species extinction, forever.

The environmental and geological liabilities of the Three Gorges Dam raise a fundamental question about mega-infrastructure: When does the cost of controlling nature exceed the benefit?

In Part 4, we will turn to the question of whether the dam actually works as a flood-control structure—and whether the 2020 near-capacity event exposed fatal limitations in its design.

Next in This Series

Part 4: Flood Control—Miracle or Mirage?

The Three Gorges Dam has intercepted nearly 70 floods since it became operational. Officials credit it with saving countless lives and protecting billions of yuan in property. But the 2020 flood—which brought the reservoir within meters of maximum capacity—exposed critical limitations. Can the dam actually protect against "once-in-a-century" floods? Or does it create a false sense of security that encourages dangerous downstream development? And what happens if the dam is overtopped or breached? We'll examine the levee effect, the limits of flood control, and the catastrophic risk that millions of people downstream now live with every day.

Footnotes

1. 2020 flood event reported in: Xinhua News Agency, "Three Gorges Dam Plays Key Role in Flood Control," August 20, 2020; and China Daily, "Reservoir Reaches Historic High Water Level," August 19, 2020. Peak reservoir level: 174.48 meters (0.52 meters below maximum design level of 175 meters).
2. Pre-dam seismic baseline: Liu, X. et al., "Seismicity Changes Prior to and After the Three Gorges Reservoir Impoundment," Pure and Applied Geophysics 178: 3455–3466 (2021). The Three Gorges region recorded an average of 3–5 detectable seismic events per month before impoundment began in 2003.
3. Post-impoundment seismic activity: Ibid. After the reservoir level exceeded 150 meters in 2006, monthly earthquake counts increased to 24–40 events—a seven-to-eightfold increase. Most events were low-magnitude (M < 3.0), but the frequency increase is statistically significant and correlates directly with reservoir filling.
4. Reservoir-Induced Seismicity (RIS) mechanism explained in: Gupta, H.K., Reservoir-Induced Earthquakes (Elsevier, 1992); and Talwani, P., "On the Nature of Reservoir-Induced Seismicity," Pure and Applied Geophysics 150: 473–492 (1997). RIS occurs through two primary mechanisms: (1) increased pore pressure in saturated rock reduces effective stress, facilitating fault slip; (2) elastic loading from the weight of impounded water stresses underlying rock formations.
5. Fault activation and dam risk assessment: Ma, J. et al., "Identification of Meta-Instability in the Seismicity of the Three Gorges Reservoir," Geophysical Research Letters 47(18): e2020GL089502 (2020). The study identified previously unmapped faults in carbonate formations beneath the reservoir that became active post-impoundment. Analysts from the China Earthquake Administration stated publicly that these faults "could potentially store sufficient energy to generate earthquakes capable of damaging the dam structure." South China Morning Post, "Three Gorges Dam Earthquake Risk Assessment," May 15, 2019.
6. Landslide incidence increase: Wang, F.W. et al., "Landslide Susceptibility Assessment in the Three Gorges Reservoir Area Based on GIS and Information Value Model," Environmental Earth Sciences 71: 4899–4907 (2014). The cyclical fluctuation of reservoir water level between 145m (flood season) and 175m (dry season) saturates and drains hillsides, destabilizing slopes.
7. Landslide documentation: China Geological Survey, Three Gorges Reservoir Geological Disaster Monitoring Report (2003–2020). Over 5,000 landslides catalogued, ranging from small slope failures to massive events displacing millions of cubic meters. The 2003 Qianjiangping landslide displaced 24 million m³ and generated a 20-meter wave that damaged nearby towns.
8. Summary compiled from notes 2–7.
9. Yangtze sediment transport: Yang, S.L. et al., "Downstream Sedimentary and Geomorphic Impacts of the Three Gorges Dam on the Yangtze River," Earth-Science Reviews 138: 469–486 (2014). Pre-dam average: 500 million tons/year. Historical peak: 680 million tons/year (1960s).
10. Sanmenxia Dam failure: Constructed on the Yellow River in 1960, the dam lost 40% of its storage capacity to sedimentation within three years, rendering it largely useless for its intended purpose (flood control and irrigation). The dam was redesigned twice (1965, 1973) to include sediment sluicing, but never recovered full functionality. See Dai, Q., The River Dragon Has Come! (1998), pp. 47–52.
11. Sediment flushing effectiveness: Xu, J. & Yang, D., "Effectiveness of Sediment Sluicing Operations in the Three Gorges Reservoir," International Journal of Sediment Research 28(4): 468–479 (2013). The study found that while periodic flushing reduces accumulation rates, it cannot eliminate sedimentation entirely. Long-term modeling suggests 30–40% capacity loss over 100 years under current management regimes.
12. Long-term sedimentation concerns raised by hydrologist Huang Wanli (Tsinghua University), who predicted in the 1990s that the reservoir would become "a giant sand trap" within 50 years. His warnings were dismissed by project proponents. See Dai, Q., The River Dragon Has Come! (1998), pp. 89–94.
13. Sediment load reduction: Yang et al., supra note 9. Post-dam measurements (2003–2012) show sediment discharge past the dam averaging 143 million tons/year—a 71% reduction from pre-dam levels.
14. Downstream erosion rates: Lu, X.X. & Higgitt, D.L., "Sediment Delivery to the Three Gorges: 1. Catchment Controls," Geomorphology 41: 143–156 (2001); Yang et al., supra note 9. Measured erosion rates in the middle Yangtze (Yichang to Wuhan) increased from 2–3 mm/year (pre-dam) to 8–12 mm/year (post-dam)—a three-to-fourfold increase.
15. Algal bloom dynamics: Cai, Q. & Hu, Z., "Studies on Eutrophication Problem and Control Strategy in the Three Gorges Reservoir," Acta Hydrobiologica Sinica 30(1): 7–11 (2006). Reservoir residence time: 15–30 days (tributary bays can exceed 60 days), compared to <5 days for free-flowing river reaches.
16. Nutrient sources and loading: Stathatou, P.M. et al., "The Impact of the Three Gorges Dam on the Water Quality of the Yangtze River," Water Policy 18: 1-17 (2016). Chongqing alone (population: 32 million) discharges over 1 million tons of nitrogen and 150,000 tons of phosphorus annually into the upper reservoir.
17. Cyanotoxin health impacts: WHO, Cyanobacterial Toxins: Microcystin-LR in Drinking-Water (2003). Common symptoms: gastroenteritis, dermatitis (skin rashes), hepatotoxicity (liver damage with chronic exposure). Children and immunocompromised individuals at highest risk.
18. Agricultural and municipal water supply disruptions documented in: Stone, R., "Three Gorges Dam: Into the Unknown," Science 321(5889): 628–632 (2008); and China Daily, "Algae Blooms Force Water Supply Suspension in Hubei," various dates (2007, 2010, 2013, 2017).
19. Submerged industrial contamination: Tullos, D., "Assessing the Influence of Environmental Impact Assessments on Science and Policy," Environmental Management 45: 1−11 (2009). Pre-impoundment environmental assessments identified 1,599 factories requiring hazardous material removal; 657 were classified as "high pollution risk." Post-impoundment surveys suggest removal was incomplete.
20. Heavy metal accumulation in reservoir sediments: Bai, J. et al., "Assessment of Heavy Metal Pollution in the Three Gorges Reservoir," Environmental Earth Sciences 66: 157–165 (2012). Sediment core samples show elevated concentrations of mercury (2.5x background), cadmium (3.1x), and lead (1.8x).
21. Summary compiled from notes 15–20.
22. Fish population collapse: Ministry of Agriculture, Yangtze River Fisheries Survey Report (annual, 2000–2015). Data compiled by Xie, P., "The Yangtze River Ecosystem: Past, Present, and Future," in Dudgeon, D., ed., Tropical Stream Ecology (2008), pp. 303–327. The 2002 figure of 1.9 billion eggs/larvae represents the "four major Chinese carps" (grass carp, silver carp, bighead carp, black carp) plus other commercially important species.
23. Fishing community displacement and livelihood loss: Zhao, Q. et al., "Social and Economic Impacts of Fishing Ban in the Yangtze River Basin," Marine Policy 123: 104309 (2021). In 2020, the Chinese government imposed a 10-year fishing moratorium on the Yangtze to attempt ecosystem recovery—effectively ending a fishing tradition that sustained communities for over 4,000 years.
24. Baiji extinction: Turvey, S.T. et al., "First Human-Caused Extinction of a Cetacean Species?" Biology Letters 3(5): 537–540 (2007). The 2006 survey covered 3,400 km of the Yangtze using visual observation and acoustic monitoring. No Baiji were detected. Last confirmed sighting: 2002. IUCN Red List status: Critically Endangered (Possibly Extinct).
25. Schistosomiasis reduction: Zhu, H.M. et al., "Effects of the Three Gorges Dam on the Transmission of Schistosomiasis Japonica," PLOS Neglected Tropical Diseases 2(5): e295 (2008); and Zhou, X.N. et al., "The Public Health Significance and Control of Schistosomiasis in China," Acta Tropica 96(2-3): 97–105 (2005). Prevalence in Dongting Lake area dropped from 4.2% (2003) to 1.1% (2010).
26. Lake hydrology disruption: Guo, H. et al., "Assessing the Impacts of the Three Gorges Dam on the Hydrology of the Dongting and Poyang Lakes," Hydrological Processes 26(26): 3942–3955 (2012).
27. Dry-year vs. wet-year effects: Zhang, Q. et al., "Has the Three Gorges Dam Made the Poyang Lake Wetlands Wetter and Drier?" Geophysical Research Letters 39(20): L20402 (2012). The study found that in extreme drought years (e.g., 2006, 2011), dam water retention exacerbated lake drying; in extreme flood years (e.g., 2010, 2020), dam flood control reduced lake inundation extent.