Soldiers battled over the weekend with floodwaters after a breach in a dyke, which is the last line of defence for the important Daqing oilfields in Heilongjiang province, the source of half the country's oil.
No respite is expected for weeks. The flood season is expected to last until the middle of next month both in the north-east and along the swollen Yangtze in central China, according to government forecasts.
Even then, China's problems will be far from over. Many die in China's annual flood season through epidemics, which continue after water levels have retreated.
The Ministry of Public Health has admitted the outbreak of cholera and snail fever (schistosomiasis) in disaster areas. Cholera posed "the greatest threat" to flood victims, said Zhang Wenkang, the director.
Some Western analysts suggested that the postponement of the state visit was diplomatically convenient, given Peking's unusually sharp comments recently about Japan's failure to deal with its economic problems.
This is not to minimise the devastation that has been caused by the floods. At Daqing, the Nen River flooding has inundated 2,500 oil wells, cutting crude oil output by about 10 per cent. After the collapse of two dykes, only one main embankment now protects the oilfields.
The nearby provincial capital of Harbin is battling against the surging Songhua River, with 400,000 soldiers and civilians piling up sandbags against record river levels.
Along the Yangtze, flood crests continue to bring new dangers every few days and the outlook is for the waters to remain at dangerous levels.
Peking remains reticent about the full extent of casualties and damage. The official death toll of "more than 2,000 people" is already almost three weeks old.
Under pressure from foreign donors, flood officials are to hold a press conference tomorrow at which they may provide a clearer picture.Reuse content