China Daily
February 22, 2006

Chinese scientists recently measured the length of the Yangtze River, China’s longest river, and found that it is 80-some kilometers shorter than believed.

The new measurement, made with remote sensing technology, shows that the river is 6,211.3 kilometers long, while the widely accepted length is 6,300 kilometers. But it is still the third longest river in the world.

“It does not mean the river shortened. This is the result of the improvement of measuring techniques and different starting and ending points,” said Liu Shaochuang, a researcher with the Institute of Remote Sensing Application under the Chinese Academy of Sciences.

Yi Shubai, director of the Policy Research Office of the State Bureau of Surveying and Mapping, said that the conclusion is only the experts’ study result, and therefore not official – it must be examined by the bureau before becoming national geographic data.

Liu, who headed the survey, said satellite remote sensing technology is far more accurate than the previous measuring method that relied on topographic maps.

“Although the change of the total length has little influence on residents’ life along the Yangtze River, it shows that people understand more about the earth. The figure will possibly be taken into consideration in the upgrading of national geographical data, ” Liu said.

Using nearly 40 images covering the mainstream of the Yangtze which were taken by a US satellite, researchers measured the river in downstream and upstream directions three separate times, then the data were calculated by computer.