by Judith Curry
China is engaged in a push to build hydroelectric dams on a scale unprecedented in human history. While being touted for producing lower-emission electricity, these massive dam projects are wreaking havoc on river systems across China and Southeast Asia. – Charlton Lewis
Yale Environment 360 has a good article on hydropower China’s Great Dam Boom: A Major Assault On Its Rivers, written by Chinese historian Charlton Lewis. Excerpts:
In their search for renewable electric power, China’s engineers have been building mega-dams at a rate unmatched in human history.
The government is now engaged in a new expansion of dams in great staircases, reservoir upon reservoir — some 130 in all across China’s Southwest. The government declares that such dams are safe, avoid pollution, address future climate change, control floods and droughts, and enhance human life.
These assertions are largely untrue. Instead, China’s mega-dams block the flow of rivers, increase the chances of earthquakes, destroy precious environments and shatter the lives of millions of people. Rather than benefiting populations with non-polluting power, China’s dam builders are making a Faustian bargain with nature, selling their country’s soul in their drive for economic growth.
Since the 1950s the Chinese have built some 22,000 dams more than 15 meters tall, roughly half the world’s current total. During the 1990s, as economic growth surged and air pollution spurred the need for clean energy, they turned increasingly to huge mega-dams.
About 100 dams are in various stages of construction or planning on the Yangtze and its tributaries — the Yalong, Dadu, and Min. Two dozen more will be built on the Lancang, called the Mekong in Southeast Asia, and still more on the last two of China’s free-flowing rivers — the Nu, called the Salween in Burma, and the Yarlung Tsangpo, known as the Brahmaputra in India and the Jamuna in Bangladesh. All these rivers flow off the Tibetan Plateau, a geologically unstable region that averages 4,500 meters (14,800 feet) high. As they flow down through the soft, sedimentary rock, the rivers carve steep canyons, many deeper than the Grand Canyon. The risk of earthquakes is high.
Dams themselves may cause quakes. The seasonal rise and fall of reservoirs places extra stress on nearby rock formations. In 2007 and 2008, the reservoir filled, with major fluctuations in the water level. In May 2008, the 7.9-magnitude Wenchuan quake occurred only 5.5 kilometers downstream, killing 80,000 people. Since then, more than 50 studies have found evidence that the reservoir triggered small quakes through the fault system, culminating in the large quake.
Until recently, there have been no EIAs for dams in cascades. Since river valleys tend to follow earthquake fault lines, a series of dams down a valley may compound the risk of quakes. Should one dam fail, the rush of water could overwhelm the next dam downstream, causing dams to collapse like dominos.
Although hydroelectric dams produce considerably fewer carbon emissions than coal-fired power plants, China’s assertions that dams provide clean energy are substantially untrue. The rotting of inundated trees and vegetation in reservoirs emits the greenhouse gasses, carbon dioxide and methane, that rise from reservoir surfaces. Over a projected lifetime of a dam in temperate regions, emissions could be from roughly one-third to nearly two-thirds that of a natural gas plant.
Nor do big dams protect from floods and droughts. They store water during the wet season and release it during the dry season, thus reversing the natural flow of rivers. Deprived of their annual inundations, downstream marshes, lakes, and wetlands dry out and can no longer absorb floodwaters. During the record-breaking summer flood of 2010, the Three Gorges reservoir rose to 12 meters above “alarm level.” To protect the dam, its operators opened the floodgates to the maximum. Downstream some 968 people were killed, 507 more were missing and economic losses totaled $26 billion.
Drier floodplains intensify droughts; when rivers diminish, dam operators preserve their hydropower potential by withholding water. On the upper reaches of the Yellow River to the north, a string of large dams has exacerbated recent droughts on the North China Plain.
The damage that dams cause to river ecosystems is immense, turning free-flowing waterways into lifeless lakes, killing plants and trees, blocking fish migration and breeding, driving species to extinction, and devastating established patterns of human life.
Dams also pollute. Their reservoirs capture chemicals, fertilizer runoff, human waste and all kinds of trash. During the 2010 flood, floating refuse backed up behind the Three Gorges Dam over an area of more than 50,000 square meters, so thick, according to the Hubei Daily “that people can literally walk on the water’s surface.” Without annual floods, dammed rivers fail to flush contaminants downstream. As the rivers percolate into the ground, they deliver pollutants into the aquifers — this in a country where nearly 60 percent of groundwater in 198 cities has been measured as poor, according to a report this year by the Ministry of Land and Resources.
Dam reservoirs trap silt, which decreases their storage capacity and reduces power generation. Silt no longer carries nutrients down the rivers, and without protective silt, salt water encroaches on estuaries and damages croplands. Estuaries also become more vulnerable to rising sea levels.
Great dams also devastate human populations. During the past half-century about 16 million Chinese have been relocated to make way for hydroelectric projects, and of these 10 million live in poverty, according to China Youth Daily.
China’s dam projects also threaten livelihoods in other countries. Since 1997 China’s government has declined to sign the United Nations water-sharing convention that would govern its major transnational rivers, yet it continues to build dams without consulting its downstream neighbors.
On the Mekong, China’s dams are affecting agriculture and fisheries. In Laos and Thailand, crops are regularly washed away before harvest time as upstream dams release their water. Nutrient-rich silt no longer reaches the Mekong delta, which is reducing fish stocks. In Burma and Thailand, environmental groups have spoken out about the threats to wildlife and populations from dams now planned for China’s Nu/Salween. A colossal 38,000-megawatt project has been proposed at Motuo on the Yarlung Tsangpo in Tibet. The project would pose a serious threat not only to the Tibetan Plateau but to India and Bangladesh, where the Yarlung becomes the Brahmaputra and Jamuna rivers.
Asian Riparian Security Threats
Several years ago, my company CFAN had a project funded by the Office of the Secretary of Defense to look at climate-related security concerns. One of the things we looked at was that riparian threats associated with the circum-Himalayan Rivers. Below are some excerpts of background information from our report:
Major rivers originating in the Himalayas include the Ganges, Indus, Brahmaputra, Yangtze, Mekong, Irrawaddy, and Yellow Rivers. Their combined drainage basin is home to 3 billion people, including Afghanistan, China, India, Pakistan, and Bangladesh. The headwaters of these rivers lie in the Himalayas in Tibet, parts of which are under the control of the People’s Republic of China. Given the large and growing population of South and Southeast Asia and the increasing demand for water for irrigated farming and industry, transboundary disputes over water are ongoing and are significant and growing concerns, particularly if a major drought looms in the future. These disputes are central to food security, energy needs and resources and the future of water resources in the region. Riparian security issues are key for two major rivers in the region – the Ganges and Brahmaputra Rivers – and climate change (particularly drought) might act as a threat accelerant in riparian conflicts in South Asia.
Brahmaputra River
The Brahmaputra River is a transboundary river that spans China, India, and Bangladesh. It begins in southwestern Tibet (in China), flows through the Himalayas into India. In India it transverses the Indian states of Arunachal Pradesh and Assam, and then enters Bangladesh. In Bangladesh it eventually merges with the Ganges River to create a significant delta area, and ultimately empties into the Bay of Bengal.
Competition over water resources uses, including power, agriculture, and navigation, are the primary issues facing China, India, and Bangladesh with regards to the Brahmaputra. In its upper Himalayan reaches, the Brahmaputra is considered the last major undammed river in Chinese Tibet. China is currently in the midst of constructing a series of massive facilities on the upper reaches of the Brahmaputra, in the Himalayas. Construction was once considered to have been infeasible because of the altitude and rugged terrain – but recent engineering achievements and advances have made the possibility of dam construction a reality. China has planned construction of a series of 28 dams. The Zhangmu facility is amongst these and is projected to be completed in 2015. It is predicted to provide 450-500 MW per year. While the Zhangmu Dam is large, it is dwarfed by the planned Yarlung Tsangpo facility. This planned dam facility will provide 38 GW, and will be 50 % larger than China’s Three Gorges dam. Some analysts have described the potential power output of Yarlung Tsangpo as having “a capacity nearly half as large as the UK’s national grid.”
The Zhangmu and Yarlung Tsangpo facilities are ostensibly intended to provide only power for China and not to divert water. However, some downstream users in both India and Bangladesh are apprehensive that the waters of the Brahmaputra – currently used for agriculture and navigation – will be diverted permanently out of the system. The Chinese government has insisted, however, that these dams will be used only for hydropower, and not for water supply storage and not for eventual diversion.
Even if the water is used solely for hydropower purposes, given the size of some of these facilities, the timing of dam releases will be of critical importance for downstream agricultural users. Similar to the Mekong and Indus Rivers – if adequate flows are not released during the dry seasons, the value of the water for downstream agricultural users drops significantly. This is a very real and very serious issue with regards to dam operations. While hydropower dams may not involve geographic water diversion – they can, and often have, involved what we refer to as ‘temporal diversion.’ Temporal diversion is the storage of water in impoundments whereby it is released downstream at a later point in time than would have occurred in the natural environment. As a result, downstream ecosystems and users (irrigated agriculture, for example) are negatively – and potentially, severely, impacted. For example, low dry season flow could lead to salt water intrusion through the deltas. Given the vast numbers of people in northern India and Bangladesh that rely on the waters of the Brahmaputra River for agricultural purposes, the temporal diversion of its waters may cause as much social and economic havoc as geographic diversion.
Temporal diversion of waters need not be a necessary consequence of hydropower operations, however. The monitoring, collection and sharing of flow data above and below dams can be used to help guide the operation of hydropower facilities so that they can simultaneously release water at the rates necessary to produce needed power, as well as serve the needs of downstream communities – even in the dry season. This process of data collection and sharing is, of course, successfully facilitated through the framework of a transboundary agreement – in this case between China, India, and Bangladesh. As noted below, however, such an agreement does not exist at this time. As a result, the threat of temporal diversions with regards to dam construction on the Brahmaputra River remains a visceral threat that could become a significant source of regional instability under drought conditions.
The Chinese construction of these hydropower facilities must also be viewed in the context of regional geo-political competition between India and China. As it develops economically, India also has sizable power needs. The Guardian newspaper references a number of Chinese engineers who see the dam construction “as the ultimate goal in an accelerating race with India to develop water resources in one of the planet’s last remote regions.”1 India has responded by beginning the planning process for hydropower dam construction along its stretches of the Brahmaputra. Jairam Ramesh, the Environment Minister for India is quoted in The Guardian: “India needs to be more aggressive in pushing ahead hydro projects [on the Brahmaputra]… That would put us in better negotiating position [with China]…”
No major international agreements exist for resolving and coordinating the use of the resources in the Brahmaputra River basin.
Ganges River
The Ganges River flows through India and into Bangladesh. Its headwaters sit within India’s portion of the Himalayan Mountains. Flowing in a southeasterly direction, it transverses northern India, enters Bangladesh where it ultimately joins with the Brahmaputra River in a great delta and empties into the Bay of Bengal.
Use of the Ganges River water resources by India and Bangladesh are currently governed under the 1996 Ganges Water Sharing Treaty. While this agreement has resulted in improved coordination and use of Ganges waters, it succeeds a series of failed agreements between the two nations. The primary point of contention between India and Bangladesh is the Indian diversion of water from the Ganges, resulting in damages to Bangladeshi agriculture, navigation, and public health.
In 1975, India completed construction of a dam and canal project, known as the Farakka diversion. The diversion is located in West Bengal, and sits only 10 km from Bangladesh. This project diverts flow from the Ganges system to the Bhagirathi-Hooghly River, which empties close to the Indian city and port of Calcutta. The intent of the Farakka diversion was to increase flows in the Bhagirathi-Hooghly in order to keep the port open during the dry season, and to also keep the port functioning by flushing the harbor of silt deposits.
Bangladesh was opposed to the project even before it was completed. Bangladeshi concerns – which ultimately proved valid – were that the reduced flow in the Ganges River would result in the negative impacts to fishing and navigation interests, and that salt-water intrusion into Bangladeshi agricultural areas would increase. This did, in fact, play out. In addition, Bangladesh has suffered human health impacts as a result of decreased fresh water flows. In addition, Bangladeshi migration to India has increased since 1975, in part because of the decreased economic opportunities that resulted as a function of the diversion.
Between 1975 and 1996, India and Bangladesh signed a series of water-sharing agreements to govern and coordinate more adequately the diversion of Ganges River water. Most of these were short-term agreements, however. Invariably, as soon as the terms of the agreements were complete, India would unilaterally reduce flows again. Understandably, this raised tensions between the neighboring countries.
The Ganges Water Sharing Treaty, signed in 1996, has proved to be a more sustainable and successful framework document for Ganges River water resource governance than earlier iterations. First, the agreement is intended to last 30 years – significantly longer than earlier agreements.3 This provides a sense of surety and predictability – especially to Bangladesh, the downstream user. The agreement also has a number of important triggers that govern when and under what conditions water will and will not be diverted from the Ganges. In general terms, the treaty guarantees Bangladesh dry season (January-May) flows. In more specific terms: below certain flow rates, Bangladesh and India will share half of the water; if the flow is above a certain level, Bangladesh is guaranteed a minimum flow; and if the flow exceeds a higher, identified level, India will withdraw a defined amount and Bangladesh will receive the balance of the flow. Significantly – and as a foundational element of the treaty – the agreement recognizes Bangladesh’s right as a lower riparian user under international law. This results in an obligation for Bangladesh to receive an equitable share of existing flow.
While the 1996 Ganges Water Sharing Treaty has been successful at coordinating the use of Ganges River water resources – and, significantly, in reducing tensions between India and Bangladesh – issues do remain. Chief amongst these are the provision and perceived reliability of data. India does not provide its river flow data to Bangladesh, and hence the only upstream information Bangladesh has is from flow meters near the border. This makes water resource management decisions more difficult – and sustains uncertainty for water users.
JC comments: Here are some other articles related to hydropower from my file, that may be of interest:
- Will huge new hydro projects bring owed to Africa’s people?
- Building small hydro in Norway
- Colorado River High Flow Cuts Hydropower
The utility of hydropower, and its adverse impacts, vary widely with geographic region, river structure and streamflow, as well as societal infrastructures. The unintended, adverse consequences of hydropower can be large, and the circum Himalayan rivers originating in Tibet are of particular environmental and geopolitical concern.
This is a topic that I would like to learn more about, I look forward to hearing from those of you with expertise in this area and also experiences with hydropower from other countries. My personal research interest in hydropower is in providing probabilistic forecasts of streamflow and hydropower, we are currently providing such forecasts for the Columbia River Basin in NW U.S. My company CFAN provides forecasts are used by natural gas traders, to anticipate market demand relative to hydropower variations.