For centuries, the Yangtze River has been China’s vital lifeblood, yet its floods have claimed countless lives. To tame its waters, flood-control systems have evolved from ancient dykes to the engineering marvel of the Three Gorges DamBut a new study has uncovered a paradox: some human interventions may have inadvertently worsened the very flood risks they were built to mitigate. The team reconstructed 500 years of Yangtze River flood variability since 1500 using lake sediment archives, historical documents and high-resolution climate reanalysis data. They found that while climate remains the primary driver of flood occurrence, human interventions on the Yangtze River actually intensified climate-induced flood risks, rather than mitigating them. Their analysis showed that constructing embankments and lake enclosures for agricultural use amplified the magnitude of 100-year floods, which have a 1 per cent chance of happening in any year, by 18 and 8 per cent respectively.