Climate Change & Hydro: Mutually Damming

Katy Yan
Wednesday, October 10, 2012
A partially dried reservoir in Yingtan, Jiangxi province, China, 29 Oct 2009
A partially dried reservoir in Yingtan, Jiangxi province, China, 29 Oct 2009
Photo: Reuters/stringer

Originally published in China Water Risk

At the 2009 climate summit in Copenhagen, China announced that it would reduce its carbon intensity at least 40% by 2020. Achieving this ambitious goal has become an overriding priority for the Chinese government ever since. As a result, the latest 12th Five-Year Plan 2011-2015 (12FYP) has been described as China’s “greenest” five-year plan to date. In August, the government released targets for renewable energy that aim to cut its carbon emissions by 17% by 2015 from 2010 levels.

While these national goals are admirable, what is hidden behind the targets is the large number of conventional hydropower in the renewable energy mix. China proposes to add 120GW of new conventional hydropower capacity by 2015, which is equivalent to building one Three Gorges each year for five years, and would mean one of the most relentless dam-building efforts that any nation has ever undertaken. Megadams are planned for already heavily dammed rivers such as the Upper Yangtze and the Lancang, as well as some of China’s wildest glacier-fed rivers, such as the Nu and the Yarlung Tsangpo. Also in the mix are highly controversial – and uneconomic – projects like Xiaonanhai, a pet project of recently deposed politician Bo Xilai.

Dams are a maladaptation to climate change

Traditional dam planning has always been based on the assumption that future stream-flow patterns will mirror those of the past, but this is no longer true. Climate change will significantly and unpredictably change precipitation patterns. More frequent droughts will make many hydropower projects uneconomic, while more extreme rainfall will increase the siltation of dams (thereby reducing their useful lifetimes) and increase the risk of dam failures and catastrophic flood releases.

The notion that dams are clean energy is also a misconception, as nearly all dam reservoirs emit greenhouse gases, and some are as highly polluting as fossil fuel plants (the amount depends on their age, carbon inputs, and reservoir profile). Especially in the tropics, dam reservoirs are a globally significant source of methane, one of the most potent greenhouse gases. Even outside of the tropics, some dams can be significant sources of methane, as researchers have found for the draw-down zone at Three Gorges Dam. Currently measuring reservoir emissions is not required for new projects, even though strong guidelines have been developed by UNESCO and the International Hydropower Association, of which China is a member.

Healthy rivers are critical for supporting life on Earth. Large dams however make it harder for people and ecosystems downstream to adapt to climate change, by reducing water quality and quantity, drying up forests and wetlands, flooding productive land, and destroying fisheries. Free-flowing rivers also play a crucial role in helping trap carbon. Scientists predict that damming the Amazon, the Mekong, the Congo and other high flow rivers in warm-ocean areas, could reduce the planet’s ability to mitigate climate change.

China’s dam-building hotspots collide with climate change

China is home to half of the world’s dams. These projects have forced more than 23 million people from their homes and land, and many are still suffering the impacts of displacement. Dams have also taken a huge toll on China’s biodiversity, causing fisheries to suffer and driving endemic species such as the Baiji (Yangtze River dolphin) to extinction.

Despite the poor record of dam construction and resettlement in China, the ambitious plans for developing huge dam cascades on some of China’s most pristine and diverse river basins in the southwest present serious safety and security challenges. Many of the proposed dams are located in seismic and biodiversity hotspots, including the Three Parallel Rivers World Heritage Site, one of the most spectacular and biologically rich areas of the world. This region is also one of China’s most seismically active as well as ecologically fragile.

According to a government climate change assessment published last year, the concentration of rain during summer and autumn will increase, overwhelming rivers in the south, while long dry winters will increase and be especially crippling for those living in parched northwestern provinces. This collision of climate change impacts and China’s dam-building boom will likely result in the following:

  • Higher risk of dam failures. China’s dams are not prepared for an increase in extreme weather events such as floods and heavy rains. The Nu Valley, for instance, experiences deadly mudslides during the wet season every year. A proposed dam cascade on the Nu River could exacerbate the impacts of greater precipitation in this region by increasing the risk of mudslides as a result of the removal of vegetation along the steep banks during construction. Planners need to consider the risk of dam breaches from both increased flows and seismic activity.
  • Dam mismanagement exacerbates drought conditions. China’s plans to build more dams for power generation may increase tensions between upstream and downstream users during the dry season, and between the often conflicting objectives of energy, irrigation, flood control and ecosystem services. For instance, in 2011, central China was hit by its worst drought in five decades, which sharply reduced the power generation of the Three Gorges Dam and spurred widespread criticism of its role in potentially exacerbating drought conditions downstream. Modeling how climate change will affect water availability and river flows is difficult, but thus far, dam developers are simply ignoring such impacts on hydrology when designing new dam projects.
  • Reduced run-off decreases water availability for dams and hydropower generation. According to the government’s climate change assessment, since the 1950s, more than 82% of glaciers have been in a state of retreat; and the pace has accelerated since the 1990s6. Many of the major river basins slated for dam construction, such as the Nu, Lancang, and Jinsha, flow from the Tibetan Plateau. While in the short term, this may increase river run-off, in the long term, this will pose a huge risk for China’s major glacier-fed rivers. In addition, researchers warned earlier this year that melting permafrost could decrease river runoff in the Yangtze, which is already starting to experience a decrease in flow.
  • Sediment build-up behind dams reduces deltas’ capacity to mitigate sea level rise. Sea level rise combined with sediment build-up behind dams poses a threat to China’s three major deltas, the Yellow, the Yangtze, and the Pearl. These are all on the world’s top 11 highest risk deltas. The Pearl River Estuary in particular could see an increasing risk of flood disasters in the future. According to the government’s assessment, China’s efforts to protect vulnerable coastal areas with embankments are inadequate to protect them against the projected increase in typhoons and flood tides.

Reducing risks, increasing resilience

Reducing the risk of climate change impacts in China will require both global action to cut emissions and national-level policy reforms that prioritize climate-friendly and climate resilient projects above conventional energy sources like coal and large hydro, and that promote the ecological health of rivers and lake systems. It will also mean reforming the grid sector by increasing grid interconnections to bring other energy sources such as wind closer to load centers, adapting hydropower design to reduce climate risks and the impacts of dams on critical ecosystems that are key for adaptation, and adjust hydropower tariffs to reflect their true social and environmental costs.

Leadership on these fronts is already evident. At the end of last year, the National Development and Reform Commission and the Ministry of Environmental Protection released two documents related to Environmental Impact Assessments and hydropower plans that highlight the importance of a river’s ecological value and the need for public participation. While these guidelines go a long way toward mitigating potential impacts, they will require strong implementation by local and national authorities, greater inter-agency collaboration, and greater participation and monitoring by civil society in order to shift the discourse away from conventional high-risk projects towards more climate resilient, innovative, and long-lasting solutions. Climate change is indeed one of the most serious threats of our time, but if China succeeds in building dams on the scale that ise currently proposed, it will irrevocably destroy its great rivers and the ecological services that they provide for present and future generations.

Katy Yan is the China Program Coordinator and climate campaigner at International Rivers. She blogs at

More information: 
  • To read more analysis and opinions on China's water and energy crisis, visit China Water Risk 
  • Read a review of HSBC's latest report on China's water-dependent power sector, No Water, No Power