asins 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 assessment6 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 flow7.
- 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 tides8.
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.
Leade