The Huaihe, an important river in central China, flows from west to east, with the Huanghe in the north and Yangtze River in the south. Starting in the Tongbai Mountains in Henan, it has its upper reaches in Henan, its middle reaches in Anhui and its lower reaches in Jiangsu. Its trunk is about 1,000 kilometers long and its catchment area about 185,700 square kilometers. The Huaihe basin is mostly plain and has a cultivated area of more than 200 million mu.

The Huaihe had its outlet to the sea about eight centuries ago. In 1194, the Huanghe breached its own dykes and merged with the downriver course of the Huaihe. Before it reverted to its old course in mid-19th century, the Huanghe had deposited large amounts of mud and silt in the lower reaches of the Huaihe and sealed up the latter’s outlet to the sea. With the passage of time, the waters of the Huaihe converged to form two large lakes, Hongze and Gaoyou. In its high-water season the Huaihe flows through the Honze and Gaoyou lakes and the Grand Canal into the Yangtze River near Yangzhou before emptying into the sea. Because its lower reached its dykes and caused 250 major floods in the five centuries or more before 1949. Since the birth of the People’s Republic of China in 1949, many reservoirs and flood-detention projects have been built in its upper and middle reaches, new courses have been laid out in its lower reaches and its outlet to the sea has been widened. In this way, the greater part of its water now flows into the Yangtze River and the rest into the Huanghai Sea through the new channels. Today, the Huaihe basin has an irrigated area of about 100 million mu, and the disaster-ridden, low yielding region is on its way to prosperity.

(1 mu=0.1644 acre=0.0667 hectare; ha)