Chinese Dams in this issue of "Science"

Science 12 March 2010: Vol. 327. no. 5971, p. 1311 DOI: 10.1126/science.327.5971.1311

NEWS OF THE WEEK

ECOLOGY:

Severe Drought Puts Spotlight on Chinese Dams

Richard Stone

XISHUANGBANNA, CHINA—Smoky haze hangs over the hills in this subtropical corner of China bordering Laos and Myanmar. The smoke is familiar: During the dry season, farmers across Yunnan Province burn fallen leaves, banana fronds, and more to make ash-based fertilizer. More unusual here, and more troubling, are the sickly yellow bamboo stands and the exposed bed of the Lancang River. "It's the worst drought in that region since 1949," the founding of the People's Republic of China, says Lu Juan, vice director of the Institute of Water Resources and Hydropower Research in Beijing.

Southwest China's monsoon-driven climate doesn't bring much precipitation in autumn and winter. But this year's dry season—coupled with a late start and early end to last year's rainy season—has left the region parched. Yunnan officials estimate that some 6 million people are short of drinking water and that the dry spell has ravaged winter wheat and other crops, inflicting $1.5 billion in losses.

The drought's effects have spilled across China's borders, stoking tensions with neighbors and prompting scientific debate. Rice yields in Thailand are expected to take a big hit, and the Mekong River—the name for the Lancang south of China—is in many stretches less than a meter deep, its lowest level in decades, making it impassable to tour boats and cargo ships. Researchers worry about how the low water level may affect fisheries and critically endangered species such as the Mekong giant catfish, which in the coming weeks would normally spawn in the upper Mekong.

Environmental groups in Thailand and elsewhere lay at least part of the blame on China's doorstep. They claim that China's management of a series of dams on the Lancang has aggravated the unfolding crisis. The Thai media has helped stir up emotions; one editorial in the Bangkok Post last month was headlined "China's dams killing Mekong." Yet Chinese engineers and some other scientists say the criticism is unfounded.

Rising tensions in Asia could usher in a protracted regional conflict over resources, especially as many key rivers cross several borders. In Asia, "competition for transboundary water utilization will be fierce," says He Daming, director of the Asian International River Centre of Yunnan University in Kunming. China will be at the center of many squabbles. With some 110 rivers and lakes straddling its borders with 19 countries, says He, "China is the most important upstream riparian country in Asia, even in the world."

A major feature in this vast waterworks is the 800,000-square-kilometer Lancang-Mekong basin, home to some 60 million people. From glacier-fed headwaters on the Qinghai-Tibetan plateau, the Lancang wends 2160 kilometers through southwestern China before entering the Golden Triangle region of Burma, Laos, and Thailand. The river finally spills into the South China Sea off Cambodia. In the late 1980s, China began work on eight cascades, or hydroelectric dams, on the Lancang's lower reaches, aiming to supply 15.6 gigawatts a year. Four have been completed, including Xiaowan, the tallest at 292 meters.

Some environmental groups contend that the Mekong flow regime has been altered by dredging and dam construction, suppressing fish catches. Living River Siam, a nonprofit based in Chiang Mai, Thailand, has called on governments to "immediately stop all works on hydropower and river development on the Lancang-Mekong."

Yet the dams on the lower Lancang reduce runoff only during the rainy season, when reservoirs are filling, according to Chen Guanfu of Hydrochina Corp. Dry season water releases should increase river volume by 35%. "There are a lot of accusations that the dams in China are exacerbating the current low water levels, but the Chinese have informed [downstream nations] that they will not fill any reservoir during the dry season," says Roger Mollot, a fisheries expert with the World Wide Fund for Nature in Vientiane, Laos. The dams would also help rein in flooding, says Zhou Shichun of the General Institute of Hydropower and Water Resource Planning and Design in Beijing.

The biggest ecological impact could be less sediment swept downstream as silt accumulates in the reservoirs. But that would be a good thing, Zhou insists: It would "facilitate irrigation and navigation" on the Mekong. Others, however, point out that decreased sediment loads will likely lead to erosion of downstream riverbanks and the Mekong Delta.

Hydropower authorities have taken ecological effects into consideration, Zhou says. Work on one dam—the Mengsong Cascade, which would be sited nearest the border—has been postponed indefinitely, he says, to protect four species of migratory fish, including the giant pangasius (Pangasius sanitwongsei), whose conservation status is uncertain (Science, 22 June 2007, p. 1684). The freshwater goliath has not been reported above the Mengsong dam site, so the other dams would not affect it, Zhou says.

The first victim of an ecological crisis could be the Mekong giant catfish, which has been on the ropes for years. "It isnot clear if the current drought conditions will impact successful spawning of the wild population of giant catfish, but low water levels may make them more vulnerable to fishing pressure," says Mollot.

Things may get worse due to climate change. After examining weather and tree ring data, Fan Ze-xin, a tree physiologist at Xishuangbanna Tropical Botanical Garden, has found that in the past 40 years Yunnan has grown warmer and drier—a trend that started long before the dams were built. In a nature reserve near the botanical garden, he grabs leaves from a seedling; dry as parchment, they disintegrate. "Some of these leaves are fresh," Fan says. "I haven't seen it as bad as this."

New Chinese Pollution Census Data Released - NY Times

Very glad that there's a more comprehensive survey of pollution out there. Unfortunately, it shows a lot more work is needed -- and that past statistics (especially on water pollution) could be problematic.

P.S. At the end of January, Ministry of Environmental Protection announced that two new pollution indicators, NOx ("discharged from vehicles and power plants and causes acid rain") and ammonia nitrogen ("another major measure of water quality") were introduced into the emission control list for the 12th Five-Year Plan (2011-15).

Currently, the pollutants they are focusing on are SO2 for air, and chemical oxygen demand (COD) for water. China is apparently on track to meet its target of reducing 10% of emissions below 2005 levels, by 2010. (Not including this new census data, which takes into account agricultural pollution).

China Report Shows More Pollution in Waterways
By JONATHAN ANSFIELD and KEITH BRADSHER
The New York Times / February 10, 2010

BEIJING — China’s government on Tuesday unveiled its most detailed survey ever of the pollution plaguing the country, revealing that water pollution in 2007 was more than twice as severe as official figures that had long omitted agricultural waste.

The first-ever national pollution census, environmentalists said, represented a small step forward for China in terms of transparency. But the results also raised serious questions about the shortcomings of China’s previous pollution data and suggested that even with limited progress in some areas, the country still had a long way to go to clean its waterways and air.

The pollution census, scheduled to be repeated in 2020, took more than two years to complete. It involved 570,000 people, and included 1.1 billion pieces of data from nearly 6 million sources of pollution, including factories, farms, homes and pollution-treatment facilities, the government announced at a news conference.

But the comprehensiveness of the survey also resulted in stark discrepancies between some of the calculations and annual figures that the government has published in the past. By far the biggest of these involved China’s total discharge of chemical oxygen demand — the main gauge of water pollution. These discharges totaled 30.3 million tons in 2007, the census showed.

In recent years the Ministry of Environmental Protection has done a much narrower calculation of these discharges, excluding agricultural effluents like fertilizers and pesticides as well as fluids leaking from landfills. By that narrower measure, discharges came to only 13.8 million tons in 2007, which officials described at the time as a decline of more than 3 percent from 2006 and a “turning point.”

Water, water ... (Plus, pollution in the Yellow River)

Great posting at Green Leap Forward on water availability in China. (I know some of you guys are "wet side" in CEE!)

"A look at a new report by McKinsey that analyzes the economics of water solutions in developing countries. It finds that in China, 55 different solutions exist to close its imminent water availability gap that actually results in a net savings, rather than expenditure, of $21 billion by 2020."

And in other water-intersects-energy news:

"Chinese authorities are scrambling to protect the drinking water for tens of millions of people after a massive fuel leak into the Yellow River spilled into a reservoir yesterday [January 5]. A diesel pipeline from Lanzhou, in Gansu province, to Changsha, in Hunan province, was found leaking last Wednesday near the Chishui River, a tributary of the Weihe River, which flows into the Yellow River. The fuel reached the Sanmenxia reservoir on the Yellow River despite a huge effort to halt its spread."

Spill puts China water supplies at risk (The Australian)

Photo from NYTimes

Reporting on the original fuel spill last week here:

Large Oil Spill Reported in China (NYTimes)
China oil spill hits Yellow River (AFP)

Water pollution remains one of the most serious environmental challenges that China faces. As the AFP piece notes, "More than 30 years of unbridled economic growth have left most of China's lakes and rivers heavily polluted, while the nation's urban dwellers also face some of the world's worst air pollution. More than 200 million Chinese currently do not have access to safe drinking water, according to government data."