Warmer Climate May Derail Tibet Railway
[WTN-L World Tibet Network News. Published by The Canada Tibet Committee. Issue ID: 03/05/01; May 1, 2003.]
Global warming may prove the latest problem for designers and builders of the Qinghai-Tibet Railway in Northwest China.
Already racking their brains for a solution to building the world's highest railway on permafrost, scientists are finding it difficult to solve construction problems exacerbated by the warming climate.
Many scientists and research institutions were working to minimize the impact of global warming on the Qinghai-Tibet Railway, said Lu Chunfang, leader of the construction project.
The frozen earth of the Qinghai-Tibet Plateau is degenerating because of global warming and the increase in human activities in the region, according to recent studies.
Research produced by the Chinese Academy of Sciences revealed the perennial frozen earth on the plateau is now five to seven metres thinner than 20 years ago, while about 10 per cent of the plateau's frozen earth had vanished.
Meteorological statistics show the annual average temperature on the Qinghai-Tibet plateau has risen by 0.2-0.4 C from the 1970s to the 1990s. Scientists said the climate change had impacted on ground temperature to a depth of 40 metres, with greater changes in layers to a depth of 20 metres.
Global warming had accelerated the erosion of the frozen earth, exerting great pressure on the construction of the Qinghai-Tibet Railway and its future operation.
Scientists said the success of the construction, and maintenance of the railway, would be dependent on finding ways to stabilize the gradually thawing earth.
The permafrost layer thickens as the temperature drops and thins when temperatures increase, reducing the stability of the railway foundation. Scientists warned that fluctuations in stability caused by changes in the thickness of the permafrost layer could create future hazards if the problem was not resolved.
"We have taken the impact of global warming into consideration when plotting the route of the railway," said Lu Chunfang.
When scientists began designing the railway, they predicted the temperature on the Qinghai-Tibet Railway would rise only 1 C in the next 50 years.
But other scientists have estimated that the plateau temperature may rise by 2.2-2.6 C in the next 50 years, bringing greater pressure to bear on the design and construction of the railway.
Construction bosses have adopted three special measures to ensure the stability of the roadbed in the permafrost areas, including changing routes, building railway bridges along sections of complex geological conditions, and building soil layers that can insulate the ground from heat created by the railway.
A 550-kilometre section of the railway will traverse perennially frozen area, the longest stretch of its kind in the world.
The 1,956-kilometre Qinghai-Tibet railway will run from Xining, capital of Northwest China's Qinghai Province, to Lhasa, capital of Tibet Autonomous Region.
The section linking Xining and Golmud in Qinghai was completed in 1984. Construction of the 1,118-kilometre section connecting Golmud with Lhasa began in June 2001 and is expected to be completed by 2007.
The construction plan calls for a total investment of 16 billion yuan (US$1.9 billion) for the 554-kilometre permafrost section of the railway.
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