The embankment, which separates the flooded township along the Dongting Lake in Hunan province and a nearby township, has reported multiple incidents of piping, China Central Television reported on Monday.
First respondents, working on the scene to seal off a dyke breach, rushed to the embankment to handle the new risks, the report said.
The dyke breach occurred at around 5:48 pm in Tuanzhou township of Huarong county in the city of Yueyang on Friday and authorities plan to close the gap by noon on Tuesday.
It was initially caused by piping accidents, which worsened to a breach after failed attempts.
The embankment, which is located about 2 kilometers from the breached dyke and is 14.3 kilometers long, is the divide between the flooded Tuanzhou township and nearby Qiannan township.
Local authorities said at a news conference on Sunday that more than 3,700 rescuers have worked around the clock to strengthen the embankment and conduct patrol. They have successfully handled seven leakage risks.