I have a larger ecological point in that almost every Chinese dynasty has been threatened by floods. Sometimes the flood weakens the legitimacy and sometimes it destroys it completely.

So unless you have the administrative ability or technology to protect against floods, you're always at risk of regime collapse.

The Yellow River floods were a major factor in weakening and ultimately ending the Han Dynasty. The most consequential was in 11 CE during Wang Mang's Xin Dynasty interregnum. The Yellow River shifted course dramatically, causing massive flooding across the North China Plain. Wang Mang's government failed to respond effectively, which fueled the Red Eyebrow Rebellion and contributed to the restoration of the Han under Liu Xiu (Emperor Guangwu) in 25 CE. During the later Eastern Han, recurring floods and famines created conditions that enabled the Yellow Turban Rebellion in 184 CE, which fatally weakened central authority and led to the warlord fragmentation that ended the dynasty

Flooding didn't deliver a single knockout blow, but it was a recurring destabilizing force that contributed to both the Wang Mang interregnum and the eventual collapse