Aging dams present growing hazard: UN


IMAGE: Cover of the UNU-INWEH report, offered post-embargo at
view more 


By 2050, the majority of people in the world will live downstream of 10s of countless big dams integrated in the 20th century, a lot of them currently running at or beyond their style life, according to a UN University analysis.

The report, “Aging water facilities: An emerging international threat,” by UNU’s Canadian-based Institute for Water, Environment and Health, states the majority of the 58,700 big dams around the world were built in between 1930 and 1970 with a style life of 50 to 100 years, including that at 50 years a big concrete dam “would most likely start to reveal indications of aging.”

Aging indications consist of increasing cases of dam failures, gradually increasing expenses of dam repair work and upkeep, increasing tank sedimentation, and loss of a dam’s performance and efficiency, “highly adjoined” symptoms, the paper states.

The report states dams that are well created, built and preserved can “quickly” reach 100 years of service however forecasts a boost in “decommissioning”– a phenomenon getting speed in the U.S.A. and Europe– as financial and useful constraints avoid aging dams from being updated or if their initial usage is now outdated.

Worldwide, the substantial volume of water saved behind big dams is approximated at 7,000 to 8,300 cubic kilometres– sufficient to cover about 80% of Canada’s landmass under a meter of water.

The report offers an introduction of dam aging by world area and main function– supply of water, watering, flood control, hydropower, and entertainment.

It likewise information the increasing threat of older dams, the increasing upkeep expenditure, the decreasing performance due to sedimentation, the advantages of bring back or revamping natural surroundings, and the social effects– advantages and disadvantage– that requirement to be weighed by policymakers choosing what to do. Especially, “the nature of these effects differs substantially in between low- and high-income nations.”

The analysis likewise consists of dam decommissioning or aging case research studies from the U.S.A., France, Canada, India, Japan, and Zambia & & Zimbabwe.

Environment modification will speed up the dam aging procedure

” This report intends to bring in international attention to the sneaking problem of aging water storage facilities and promote global efforts to handle this emerging, increasing water threat,” states co-author Vladimir Smakhtin, Director of UNU-INWEH.

” Highlighted is the truth that the increasing frequency and intensity of flooding and other severe ecological occasions can overwhelm a dam’s style limitations and speed up a dam’s aging procedure. Choices about decommissioning, for that reason, require to be taken in the context of an altering environment.”

Notes lead author and UNU-INWEH Senior Scientist Duminda Perera: “This issue of aging big dams today challenges a reasonably little number of nations– 93% of all the world’s big dams lie in simply 25 countries.”

” Big dam building rose in the mid-20th century and peaked in the 1960s – 70s,” he states, “particularly in Asia, Europe and The United States And Canada, while in Africa the peak happened in the 1980s. The variety of newly-constructed big dams after that continually and gradually decreased.”

According to the report, the world is not likely to witness another big dam-building transformation as in the mid-20th century, however dams built then will undoubtedly be revealing their age.

China has 23,841 big dams (40% of the world’s overall). And 32,716 big dams (55% of the world’s overall) are discovered in simply 4 Asian nations: China, India, Japan, and the Republic of Korea– a bulk of which will reach the 50-year limit fairly quickly. The exact same holds true of numerous big dams in Africa, South America, and Eastern Europe.

The speed of big dam building has actually dropped significantly in the last 4 years and continues to decrease in part since “the very best places for such dams worldwide have actually been gradually lessening as almost 50% of international river volume is currently fragmented or controlled by dams,” the report states.

Also, there are strong issues relating to the ecological and social effects of dams, and big dams in specific, along with emerging concepts and practices on the alternative kinds of water storage, nature-based services, and kinds of energy production beyond hydropower.

Motorists of dam decommissioning

Public security, intensifying upkeep expenses, tank sedimentation, and repair of a natural river community are amongst the factors driving dam decommissioning.

Nevertheless, most dams got rid of to date have actually been little; decommissioning big dams (specified by ICOLD as 15 or more metres from least expensive structure to crest, or 5 to 15 metres taking more than 3 million cubic metres) is “still in its infancy, with just a couple of recognized cases in the last years.”

” A couple of case research studies of aging and decommissioned big dams highlight the intricacy and length of the procedure that is typically needed to manage the dam elimination securely,” includes co-author and UNU-INWEH Accessory Teacher R. Allen Curry, based at the University of New Brunswick.

” Even eliminating a little dam needs years (typically years) of constant professional and public participation, and prolonged regulative evaluations. With the mass ageing of dams well underway, it is very important to establish a structure of procedures that will assist and speed up the dam elimination procedure.”

Decommissioning will likewise have different favorable and unfavorable financial, social, and eco-friendly effects to be thought about in a regional and local social, financial, and geographical context “vital to safeguard the wider, sustainable advancement goals for an area,” the report states.

” General, dam decommissioning must be viewed as similarly crucial as dam structure in the total preparation procedure on water storage facilities advancements.”

” Eventually, valuation will figure out the fate of a lot of these big water storage structures. It is not a simple procedure, and therefore distilling lessons from and sharing dam decommissioning experiences must be a typical international objective. Absence of such understanding and absence of its reflection in appropriate regional/national policies/practices might gradually and negatively impact the capability to handle water storage facilities appropriately as it is aging.”


In addition to the 3 UNU-INWEH professionals, the report was co-authored by Spencer Williams, Graduate Institute of International and Advancement Researches, Geneva, Switzerland. and Taylor North of McMaster University, Hamilton, Canada.

The report is offered post-embargo at

By the numbers


58,700: big dams signed up in the International Commission on Big Dams (ICOLD) database, a big dam is specified as 15+ metres in height, determined from least expensive structure to crest, or 5 to 15 metres high taking more than 3 million cubic metres (0.003 km3). Within the 58,700 big dam overall, approximately one in 8 has a 100 million cubic metre (0.1 km3) capability

7,000 to 8,300 km3: volume of water saved behind big dams worldwide– about one-sixth of all river discharge around the world each year– sufficient to cover approximately 80% of Canada’s landmass under a meter of water

50 to 100 years: style life of dams built in between 1930 and 1970 (when most current big dams were constructed). Typical life span: 50 years

~ 16,000: big dams 50 to 100 years of ages in The United States and Canada and Asia .
~ 2,300: big dams 100+ years of ages in The United States and Canada and Asia

U.S.A./ Canada

56: typical age of 90,580 United States dams (all sizes)

85%+: United States dams in 2020 operating at or beyond their life span

75%: United States dam failures that happened after 50 years of age

US$ 64 billion: approximated expense to recondition United States dams

1,275: dams gotten rid of in 21 US states in the last thirty years; 80 gotten rid of in 2017 alone

50%+: big dams in Canada over 50 years old

Asia/ Pacific


56%: percentage of the world’s big dams found in China and the United States (the top 25 nations represent more than ~ 93%)

23,841: big dams in China (one of the most of any nation, and 40% of the world’s overall .
60 %: percentage of the world’s big dams in Asia .
55 %: percentage of the world’s big dams in simply 4 nations– China, India, Japan, and the Republic of Korea– most of which will quickly reach 50 years of age


1,115+: big dams in India that will be approximately 50 years old in 2025 .
4,250+: big dams in India that will be 50+ years of ages in 2050 .(* )64: big dams in India that will be 150+ years of ages in 2050 .
3.5 million: the approximate variety of individuals at threat if India’s Mullaperiyar dam, constructed 100+ years back, were to stop working. The dam, in a seismically active location, reveals substantial structural defects and its management is a controversial problem in between Kerala and Tamil Nadu States

100+ years: typical age of big dams in Japan


650: big dams in Australia, half of them 50+ years of ages; 50+ have actually functioned for 100+ years. Part of Australia’s electrical energy generation from hydropower: 65%

UK/ Europe

100+ years: typical age of big dams in the UK

~ 10%: big dams in Europe 100+ years of ages


2,000: big dams in Africa ( 1/4 of them in South Africa), the least of any continent; primarily utilized for watering


) is supported by the Federal government of Canada through Global Affairs Canada, and hosted by McMaster University, Hamilton, . UNU-INWEH’s Water Knowing Centre (

) uses complimentary courses to college student and practicing water specialists seeking to enhance their capability in numerous concentrated and multidisciplinary knowing locations. .

Leave a Reply

Your email address will not be published. Required fields are marked *