Huai He

From Freepedia

The Huai River (Chinese: 淮河; pinyin: Huái Hé) is about mid-way between the Yellow River (Huang He) and the Yangtze River. Like them it runs from west to east. However, it does not run all the way out to the sea. This makes it very vulnerable to flooding. The Huai River is considered - along with the Yangtze River - as one of the dividing lines between North China and South China. It has a length of 1,100 kilometers and a drainage area of 174,000 square kilometers.

The Huai River used to run all the way to the sea through present-day northern Jiangsu province. However, starting in 1194 the Yellow River to the north changed its course southwards to run into the Huai River, and changed back and forth several times over the next 700 years. The resulting silting was so heavy that after the Yellow River changed back to its northerly course for the last time in 1897, the Huai He is no longer able to go through its old course. Instead it pools up into Lake Hongze, and then runs southwards towards the Yangtze River. The North Jiangsu Irrigation Main Channel also diverts a bit of its water along its old historical course.

The unusual course of the river makes it extremely prone to flooding.