The "three rivers" in Ningbo's "three mouths" refer to Yaojiang, Fenghua and Yongjiang; Yaojiang River and Fenghua River meet at Sanjiangkou, called Yongjiang River, and then flow into the East China Sea.

Yaojiang

Yaojiang originated in Gangshan, northeast of Xiajialing in Siming Mountain, and its source is called Liangnongxi. After receiving water at the Kantou of Tongmingyan River, Yaojiang entered Ningbo in Shangchen Village, Mazhu Town, Yuyao City, and injected into Siming Lake Reservoir in Liangnong Town. After leaving the reservoir, the river flows northward into the Shili River in Xinjiangkou, also called Siming River. The back reach of Xinjiangkou, formerly known as Yaojiang River, turns northeast and joins Shili River and Mazhu Henghe River in turn. The East Zhejiang Canal thus entered the natural waterway and started the Ningbo section. After that, the river passes through Yuyao city and is divided into three branches: north, middle and south. The northern branch is called Hou Qing River, and the southern branch is called Lanshu River, which is also called the best river. After leaving the city, the three rivers meet and meander to the southeast. After merging with many streams, it enters Sanjiangkou, Zhang Ting in Zhang Ting Town and joins Cijiang River. After that, they entered downtown Ningbo eastward and split into two roads in Wantou area. Among them, the eastward branch is 5 kilometers long and becomes a blind end because of cutting and straightening. The other tributary is the artificial river, which joins the original river after passing through the Yaojiang sluice, and then reaches the Sanjiangkou of Ningbo, with a total length of 3.3 kilometers, and joins the Fenghua River to form the Yongjiang River.

Fenghua river

Fenghua River originates from Xiujian Mountain at the eastern foot of Siming Mountain, with a main stream of 98 kilometers long and a drainage area of 2,223 square kilometers. Fenghua River has four tributaries: Shanhe, Xianhe, Dongjiang and Yinjiang. Fenghua River passes through Fenghua, Yuyao and Cixi, joins Yaojiang River originating from Siming Mountain in Shangyu at Sanjiangkou, Ningbo City, and flows into the East China Sea at Haikou, Ningbo Town.

Hydrologically, the average ratio of Fenghua River dropped to 8. 1‰, with a drainage area of 2,223 square kilometers. Among them, the average gradient of the river below the Sanjiangkou of Fangqiao is less than1100000. This section of the river twists and turns, forming a lot of bends. The biggest bend is Shaji Bay, with a circumference of 3.5 kilometers, but the distance between its upper and lower mouth is only 350 meters. Tongpenpu Bay is the second largest bay in Fenghua River, with a perimeter of 1.87 km and a distance of 250 meters between the upper and lower ports. It has been cut and straightened.

Yongjiang

Yongjiang River is the mother river of Ningbo, which is formed by the confluence of Fenghua River and Yaojiang River. It is one of the seven major water systems in Zhejiang Province. The total length of Yongjiang River is 105km, and the drainage area is 45 18km2.