Course changed

The river used to flow directly into the Yellow Sea, but as floods have greatly changed its course, it now forms a major tributary of the Yangtze River, which has experienced severe flooding recently.

Wu said that over thousands of years, the Yellow River, to the north, repeatedly changed course southward to flow into the Huaihe, creating new highlands and lakes, including Hongze Lake, the largest body of water in the Huaihe's drainage area.

"The bottom of Hongze Lake is actually higher than the Huaihe riverbed," he said.

Floodwater runs rapidly along the upper reaches of the Huaihe from Henan into Anhui, but is unable to pass easily through the central stretches and into the Yangtze, he added.

The river's total drainage area covers 270,000 sq km, about the size of New Zealand.

Lu, from the Huaihe River Course Administration, said, "Residents in the diversion area have to make a sacrifice for the good of those on the upper and lower reaches."

He said the local government and the public's willingness to make a sacrifice has been a key part of the so-called Wangjiaba Spirit, which has been hailed nationwide.