Mulan River is one of the most important rivers in Fujian Province of "Five River and One Stream". The main stream runs 105 kilometers long and its watershed area is 1732 square kilometers. Mulanpi to Sanjiangkou in the lower reaches of Mulan River belongs to tidal reach, with flat and low-lying terrain, tortuous river, and narrow riverbed. People on both sides of the river suffer from floods, with more disasters every year, minor disasters every two years and major disasters every five years.