Huai River

The Huai River, formerly romanized as the Hwai, is a major river in East China, about 1,110 km (690 mi) long with a drainage area of 174,000 km2 (67,000 sq mi). It is located about midway between the Yellow River and Yangtze River, the two longest rivers and largest drainage basins in China. Historically draining eastwards directly into the Yellow Sea, erosion from floods have changed the course of the river such that it now primarily discharges into the Yangtze. The Huai River is, to this day, notoriously vulnerable to flooding.

The Qinling–Huaihe Line, formed by the Huai River and the Qin Mountains, is sometimes regarded as the geographical dividing line between northern and southern China. This line approximates the 0 °C (32 °F) January isotherm and the 800 millimeters (30 in) isohyet in China.