Global Dam Safety and Security Challenges

Katy Yan
Thursday, October 20, 2011

Originally published in Volume 10 Number 4 of the The CIP Report
Center for Infrastructure Protection and Homeland Security (CIP/HS)
George Mason University, School of Law

With over 54,000 large dams worldwide, dam safety is a major and growing global concern. In a changing climate, dam safety and security is no longer just an issue of aging infrastructure but also of intensifying water conflicts, food security, and appropriate adaptation measures to climate change. Below are just some of the many examples of dam safety and security issues from around the world.

Dam Safety and Earthquakes

While individual dams built today are likely to be much safer than those built 50 years ago, the global stock of dams as a whole is aging. Around the world, 5,000 large dams are at least 50 years old; the average US dam is in its 40s. The two main reasons for dam failures are dam bursts or ‘overtopping' (responsible for around 40 per cent of failures and often a result of flooding) and foundation problems (around 30 per cent). Over 12,000 people have been killed this century by dam-bursts outside of China for which data are available1 (within China, the worst dam burst disaster occurred in 1975 in Henan province, where official estimates say at least 26,000 people died from the incident).2

While earthquakes have damaged hundreds of dams, dams can also trigger earthquakes in a phenomenon known as Reservoir-Induced Seismicity (RIS). Globally, there are over 100 identified RIS cases.3 The most widely accepted explanation of how dams cause earthquakes is related to the extra water pressure created in the micro-cracks and fissures in the ground under and near a reservoir. When the pressure of the water in the rocks increases, it acts to lubricate faults that are already under tectonic strain, but are prevented from slipping by the friction of the rock surfaces.4

The most serious case may be the 7.9-magnitude Sichuan earthquake in May 2008, which killed an estimated 80,000 people and has been linked to the construction of the Zipingpu Dam. After the earthquake struck, the Ministry of Water Resources reported that as many as 2,380 dams were damaged in the earthquake. Scientists in China and the US fear that the earthquake may have been induced by the weight of the Zipingpu reservoir.5 Despite these concerns, China continues to plan major dam projects in its seismically active southwest.

Dams and Food Security

The impacts that dam building could have on regional food security is no more evident than in the Mekong basin in Southeast Asia. The Mekong River flows through Thailand, Laos, Cambodia and Vietnam, and supports the world's largest inland fishery. Its economic worth at first-sale value is at least US$2 billion per year and up to US$9.4 billion per year taking into account secondary industries.

Food security forms the basis upon which other forms of development are built, such as good health, education, and productivity. Wild-capture fisheries are especially important to those rural families that have limited access to land and other productive resources and with a low monetary income.6 However, the governments of Cambodia, Laos, and Thailand are considering plans to build eleven large hydropower dams on the Mekong River's lower mainstream. If built, these dams would block the major fish migrations that are essential to the life cycle of around 70 percent of the Mekong River's commercial fish catch.

For instance, a report published in 20097 revealed that the first dam planned for the lower Mekong, the Don Sahong Dam in southern Laos, would block the migration of many important fish species that move up and down the Mekong River throughout the year. As a result, the dam could seriously impact fisheries as far upstream as northern Laos and northern Thailand, and fish populations downstream would also be threatened, including important fisheries in the Tonle Sap in Cambodia and the Mekong Delta in Vietnam. In addition, the government of Laos is currently proposing to build the Xayaburi Dam despite opposition by its neighbors and civil society. A technical review8 in March 2011 by the Mekong River Commission could lead to the extinction of approximately 41 fish species, including the critically endangered Mekong Giant Catfish. These impacts in turn would affect the livelihoods and food security of millions of people in the region.

Regional and International Security

History is filled with examples of international disputes over shared freshwater resources.9 For instance, in the Middle East, hydropower and agricultural developments on the Euphrates River have been the source of considerable international concern. This river flows from the mountains of southern Turkey through Syria to Iraq before emptying into the Persian Gulf. Both Syria and Iraq depend heavily on the Euphrates River for drinking water, irrigation, industrial uses, and hydropower, and view Turkey's upstream dam development plans with great concern. When all of Turkey's projects are complete, the flow of the Euphrates River to Syria could be reduced by up to 40 percent, and to Iraq by up to 80 percent.10

Similarly, countries downstream of China are concerned that China's dam building upstream of major transboundary rivers such as the Mekong, the Salween, and the Brahmaputra rivers could leave thousands of communities downstream in Myanmar, India, and the greater Mekong region stranded without dependable water for their fields and fisheries. For instance, China intends to build as many as five dams on the middle reaches of the Yarlung Zangbo (known as the Brahmaputra in India). The 510 MW Zangmu hydroelectric power station is already underway,11 and talk about a massive project at the Great Bend (which would be twice the size of the Three Gorges Hydroelectric Project) is causing serious concern and speculation in India.

Challenges in a Changing Climate

Dam designers work on the assumption that historic hydrological variables such as average annual flow, annual variability of flow, and seasonal distribution of flow are a reliable guide to the future. As global temperatures increase, however, there are likely to be significant changes in seasonal and annual rainfall patterns and other factors affecting streamflow.12 Most of the world's dams have not been built to allow for the erratic hydrological patterns that climate change is bringing. More extreme storms and increasingly severe floods will have major implications for dam safety.

Floods exacerbated by dam bursts and inadequate safeguards are already a serious problem in many regions (particularly South Asia13) and are expected to increase under the new climate scenario.14 Flood damages have soared in recent decades, despite hundreds of billions of dollars spent on flood control structures. Improving our ability to cope with floods requires adopting a more sophisticated set of techniques than dams and levees - the "soft path" of flood risk management, which aims to understand, adapt to and work with the forces of nature.

"Soft-path" flood risk management seeks to reduce the damage from any size of flood and to respond to the hydrological changes caused by changing land use and river morphology.15 Flood risk management assumes that floods will happen and that we need to find better ways of reducing their speed, size and duration where possible. It assumes that all flood protection infrastructure can fail and that this failure must be planned for. It is also based on an understanding that all floods are not inherently bad - and indeed that floods are essential for the health of riverine ecosystems.

Dam Safety Concerns a Window of Opportunity

Incorporating dam removal into effective dam safety programs is well-established in a number of US states and in Europe.16 Though responsible dam decommissioning can have a large initial price tag, it can add up to long-term savings through the removal of insurance liability and maintenance and repair costs, enhanced ecological and property values, and even in reduced flood damage from the restoration of wetlands and floodplains.

For more information on dam safety and security, please visit:

1 McCully, P. 2001. Silenced Rivers. Zed Books Ltd, New York: p117.
2 Fu Wen, "Reservoirs Dogged." Global Times. 26 August 2011.
3 Gupta, H. K. 2002. "A review of recent studies of triggered earthquakes by artificial water reservoirs with special emphasis on earthquakes in Koyna, India." Earth-Science Reviews, 58 (3-4): 279-310.
4 Jauhari, V. P. 1999. Prepared for Thematic Review IV.5 "Options Assessment - Large Dams in India Operation, Monitoring, and Decommissioning of Dams." World Commission on Dams.
5 Gautam Naik and Shai Oster. "Scientists Link China's Dam to Earthquake, Renewing Debate." The Wall Street Journal. 6 February 2009.
6 Peterson, B. and Middleton, C. 2010. "Feeding Southeast Asia: Mekong River Fisheries and Regional Food Security." International Rivers.
7 Baird, I. 2009. "The Don Sahong Dam: Potential Impacts on Regional Fish Migrations, Livelihoods and Human Health."
8 Prior Consultation Project Review Report: Proposed Xayaburi Dam Project - Mekong River. Mekong River Commission Secretariat. 24 March 2011.
9 Gleick, P. H. 1993. "Water and Conflict." International Security: 18 (1): 79-112.
10 Ibid, p88.
11 Jiang Yannan and He Haining. "A new era for Tibet's rivers." chinadialogue. 17 January 2011.
12 McCully, p.145.
13 "Pakistan floods: why the fertile Indus river is so prone to flooding," BBC World Service interview with Dr. Daanish Mustafa; excerpted quotes.
14 McCully, P. 2005. "And The Walls Came Tumbling Down." World Rivers Review.
15 McCully, P. 2007. "Before the Deluge: Coping with Floods in a Changing Climate." International Rivers.
15 Lejon, A. et al. 2009. "Conflicts Associated with Dam Removal in Sweden." Ecology and Society 14(2): 4.