Why has the Huang He caused serious flooding in Henan?

The Huang He (Yellow River) has historically caused serious flooding in Henan primarily due to its massive sediment load and the resulting elevation of its riverbed.12

As the river flows through the Loess Plateau, it gathers an enormous amount of silt. When it reaches the flat North China Plain, its velocity decreases, causing this sediment to settle and build up the riverbed. Over centuries, human efforts to contain the river using levees have inadvertently exacerbated the issue; by confining the water, the silt is forced to deposit within the dikes, raising the riverbed higher than the surrounding countryside.123

In many parts of northern Henan, the riverbed now sits significantly above the adjacent land. When these levees fail—often due to the pressure of high-water levels or seasonal flow variations—the river spills onto the plain, causing catastrophic flooding, waterlogging, and famine. While modern dam projects like the one at Sanmen Gorge have been implemented to help control flood stages, the river's unique geological and human-altered characteristics remain a persistent challenge.3412