More than half of the rivers previously thought to exist in China appear to be missing, according to the 800,000 surveyors who compiled the first national water census, leaving Beijing fumbling to explain the cause.
Only 22,909 rivers covering an area of 100sq km were located by surveyors, compared with the more than 50,000 in the 1990s, a three-year study by the Ministry of Water Resources and the National Bureau of Statistics found.
Officials blame the apparent loss on climate change, arguing that it has caused waterways to vanish, and on mistakes by earlier cartographers. But environmental experts say the disappearance of the rivers is a real and direct manifestation of headlong, ill-conceived development, where projects are often imposed without public consultation.
The UN considers China one of the 13 countries most affected by water scarcity, as industrial toxins have poisoned historic water sources and were blamed last year for turning the Yangtze an alarming shade of red.
This month, the carcasses of about 16,000 pigs dumped in the river were pulled from its waters, and 1000 dead ducks were found dumped this week in the Nanhe River in Sichuan province.
Ma Jun, a water expert at the Institute of Public and Environmental Affairs, said the missing rivers were a cause for "great attention" and underscored the urgent need for a more sustainable mode of development.
"One of the major reasons is the over-exploitation of the underground water reserves, while environmental destruction is another reason, because desertification of forests has caused a rain shortage in the mountain areas," Mr Ma said.
Large hydroelectric projects such as the Three Gorges Dam, which diverted trillions of litres of water to drier regions, were likely to have played a role, he said.
The census also charted a decline in water quality. The report came as new Premier Li Keqiang pledged greater transparency on pollution, which Communist Party rulers fear is a potential catalyst for social unrest.
"We must take the steps in advance, rather than hurry to handle these issues when they have caused a disturbance in society," Mr Li said, according to state media.
The missing rivers provoked wistful recollections among Chinese internet users. "The rivers I used to play around have disappeared; the only ones left are polluted, we can't eat the fish in them, they are all bitter," a person using the name Pippi Shuanger wrote on Weibo, the Chinese version of Twitter.