Dam Boom in Himalayas Will Create Mountains of Risk
The Himalaya is one of the fastest changing regions of the world due to global warming. The mountains’ mighty glaciers, the source of most large Asian rivers and a critical “savings account” of South Asia’s water supply, are melting. In early February 2009, Chinese scientists warned that glaciers on the Tibetan plateau are melting at a “worrisome speed,” according to Xinhua news agency.
Against these dramatic developments, the governments of India, Pakistan, Nepal and Bhutan are planning to transform the Himalayan rivers into the powerhouse of South Asia. They want to build hundreds of mega-dams to generate electricity from the wild waters of the Himalayas. More than 150,000 megawatts (MW) of new hydropower is proposed to be built in the next 20 years in the four countries. At that rate, the Himalaya could become the most heavily dammed region in the world. Some of these dams – including the 3,000 MW Dibang project in India, the 1,000 MW Tala project in Bhutan, and the US$12.6 billion Diamer-Bhasha Dam in Pakistan – are among the world’s largest and most expensive planned dams.
Wrong Choice for a Warming World
A dam-building boom in the Himalayas in times of global warming is like investing billions of dollars in high-risk, non-performing assets. In the Himalayas, "melting glacier water will replenish rivers in the short run, but as the resource diminishes, drought will dominate the river reaches in the long term," says Xin Yuanhong, a senior engineer with a Chinese team that is studying the glaciers of the Tibetan plateau.
Both the initial increase in river flows as well as the subsequent decline threatens the safety and viability of the planned hydropower projects. As Dharmadhikary points out, “Most dams are designed based on historical data of river flows, with the assumption that the pattern of flows will remain the same as in the past. Climate change has effectively destroyed this assumption. It is likely that dams will be subjected to much higher flows, raising concerns of dam safety, increased flooding and submergence, or much lower flows, affecting the performance of such large investments.”
The International Centre for Integrated Mountain Development, ICIMOD, in Nepal and the Intergovernmental Panel on Climate Change agree that global warming will also lead to more storms and floods, especially in tropical and mountainous regions. A report by ICIMOD on the impact of climate change on Himalayan glaciers states: “On the Indian subcontinent, temperatures are predicted to rise between 3.5 and 5.5°C by 2100. An even higher increase is predicted for the Tibetan Plateau. Climate change is not just about averages, it is also about extremes. The change in climate is likely to affect both minimum and maximum-recorded temperatures as well as triggering more extreme rainfall events and storms.” These heavy storms and floods will jeopardize the economic profitability of hydropower projects, as well as the safety of these mountains of concrete.
The sudden bursting of glacial lakes is another major concern for the safety of planned dams, and ultimately the rivers and peoples of the Himalayas. Glacial lake outburst floods (GLOFs) are a recent phenomenon. As glaciers in high-altitude regions such as the Himalayas melt, they can form large lakes behind temporary dams of ice and rock. When these moraine dams collapse, millions of cubic meters of water are released, resulting in massive flash floods. The Dig Tsho GLOF in Nepal in 1985 was one of the most devastating glacial lake bursts in recent history. The bursting of this glacial lake near Mount Everest caused a huge flood wave that travelled down the valley, killing five people and destroying one hydropower station, many acres of cultivated land and 14 bridges.
In January 2009, the government of Bhutan identified more than 2,600 glacial lakes in the country, of which 25 are considered to be at high risk of bursting, according to Yeshi Dorji of Bhutan’s Department of Geology and Mines. While Bhutan is aware of the risk of GLOFs and is improving its early warning system, the country, together with India, is still currently constructing one of the largest hydropower dams in the region, the 90-meter-high Tala project on the Wangchu River.
One billion people in South Asia and many millions in China are dependent on the Himalayan rivers. While we can't predict the future course of change to these lifelines from global warming, we can no longer presume that there will always be abundant snow and glaciers in the Himalayas. If the Himalayan governments go forward with their planned dam boom, they deny that global warming is actually transforming their region and our planet. The prudent course would be for the Himalayan countries to develop water resources in a way that helps the people of the region adapt to the changing climate, and reduces their risks. This dam building plan does the opposite.