The number of rivers in China with catchment areas of at least 100 square kilometres has dropped by more than 50 per cent compared with 60 years ago, a landmark survey on national water resources reveals.
China’s Ministry of Water Resources on Tuesday released its first ever national census of water  – conducted by up to 800,000 surveyors.
The official study said there were 22,909 rivers in China which had catchment areas of at least 100 sq km – as of the end of 2011. This is less than half the government’s previously estimated figure of over 50,000.
The large fall in the number of these rivers has prompted fears that China’s rapid economic development has also caused considerable water and soil loss.
But Huang He, deputy director of the group in charge of the census, said the disparity in the numbers was caused mainly by inaccurate estimates in the past, as well as climate change and water and soil loss.
Due to limited technology in the past, the previous figures were estimated using incomplete topographical maps dating back to the 1950s, he explained.
Huang said many figures released in the new study had not been known before. “For example, we used to think China had 8,700 water reservoirs, but the census shows the number has now reached 98,002.” The latest research, which took three years to complete, is the first comprehensive study to show the precise number of waterways, reservoirs and irrigation zones in China. It also reveals the different infrastructure projects in place to protect China from natural disasters.
The findings also showed China still has a long way to go before it develops adequate flood prevention measures.
“Of all the river sections that require constructions for flood prevention, 33 per cent have been undergoing work, while only 17 per cent are qualified for use.” It noted that improvements to them were still inadequate – particularly for medium and small rivers.
The study revealed that China had over 93,000 reservoirs, but warned it had a limited ability to regulate and control water resources due to their small water capacities.
The mainland regularly battles deadly floods and downpours which affect millions each year. More than 66 per cent of the population and 90 per cent of all cities are located in regions threatened by floods. Last year, floods in Beijing killed more than 70 people and disrupted over 1.6 million residents.
Floods in China can be devastating. In 1998, a catastrophic flood in Yangtze River region killed more than 3,000, affected 223 million people and cost the mainland 167 billion yuan.