Tanghe, a tributary of Feiyun River.

The development of Feiyun River is restricted by geological structure and flows from west to east along Huaxia fault zone. Due to the influence of vertical and horizontal faults, most tributaries form pinnate water system, and the basin areas on the left and right banks are asymmetric. Generally, the tributaries on the south bank are short and small, and most of them are developed on the north bank. The main tributaries of Feiyun River are Yuquan River (Yimenxi), Gaolou River, Caocun Port and Jinchao Port, which are the four major tributaries of Ruian City. In addition, there are Shilongxi in longhu town, Darixi in Shuntai Township, Gexi in Pingyangkeng Town, Hexi in Meiyu Township, Shamenxi in Taoshan Town, Tongxi in Tongpu Township and Yuxi in Anyang Town, all of which are first-class tributaries. Most of them are mountainous rivers with small basin area, large slope and short source and rapid flow. After flowing into Feiyun River, these tributaries flow eastward into the sea.

Feiyunjiang River has five tributaries: Hongkou River, Zuo Zuo River, Sixi River, Yuquan River and Jinchao Port, with a drainage area of more than 200 square kilometers. They are all mountain streams with large drop and steep slope, and some slopes exceed 20‰.

Hongkouxi, a tributary on the right bank of Feiyun River, originates from Huangjiadai, Donggongshan, Taishun County, flows through Xianju to Zhangdian in the southeast, turns northeast, and flows into Baizhangkou to join Feiyun River. The river is 50 kilometers long, with a drop of 1.055 meters, an average gradient of 2 1.0‰ and a drainage area of 359 square kilometers.

Sixi, a tributary of the left bank of Feiyun River, originated in Jinzhuyong, wencheng county, and flowed into Baizhangkuang Reservoir in the southeast. There are Tou Mine, No.2 Mine and No.3 Mine in the 9 km reach above Wu Yong, with a concentrated drop of 320 meters, forming the famous Baizhang Mine Waterfall. It flows into Feiyun River at the headland. The river is 42 kilometers long with a drop of 730 meters, with an average gradient of 17.7‰ and a drainage area of 24 square kilometers. The river from Daxie Town to the estuary can be connected by bamboo rafts.

Maozuokouxi, also known as Xiaoxi, is a tributary of the left bank of Feiyun River. Originated in Xiayang Village, wencheng county, it flows to Sanbanqiao in the southeast, and Gaolingtou River flows into the right bank. It flows through Maozuokou and flows into Feiyun River at Xiaoxikou. The river is 4 1km long, with a drop of 834m, an average gradient of 20.6‰ and a drainage area of 287km2.

Yuquanxi, also known as Shumenxi, is a tributary of the left bank of Feiyun River. Originated in the foothills of Shiyuan Township, wencheng county, it flows southeast to Xiaojiaokou to join Feiyun River. The river is 40 kilometers long with a drop of 803 meters, with an average gradient of 19.9‰ and a drainage area of 275 square kilometers.

Jinchao Port is a tributary of the left bank of Feiyun River. Wu Shiping, which originated at the junction of Ruian and Qingtian counties, flows southeast through Chaoji to Shazhou and joins Feiyun River. The river is 43 kilometers long with a drop of 770 meters, with an average gradient of 18. 1‰ and a drainage area of 349 square kilometers. Above the tidal base, it belongs to the mountain stream channel, with steep slope and rapid water flow, while below the tidal base, it is affected by the tide.

Thirteen tributaries constitute small watersheds (the so-called small watersheds refer to relatively independent and closed natural watersheds, and in principle the rainwater harvesting area is 20 ~ 100 square kilometers). Thirteen small watersheds in Ruian City are all distributed in the western hilly areas, with a total watershed area of 749.5 1 km2, accounting for 55% of the total area of Ruian City. Because it is a mountain stream, influenced by topography, the river source is short, the riverbed is narrow, the slope is large, and the water flow is tortuous. The average slope of small watershed is about 3 ‰ ~ 5 ‰.

Other tributaries:

Li Guangxi, also known as Siqianxi, is located in Si Qian Town, Taishun County. The main stream originates from the southeast slope of Baiyun River in Wu Yanling Nature Reserve, with an altitude of1.200m.. The stream flows from west to east, passes through Yangliao Hydropower Station, reaches the water coming from Baishuitou Creek Pit in Nkenna, and goes down to Huilan Bridge in Si Qian Village. After the water coming from Nazuo Creek on the right bank meets, it is called Siqian Creek, then goes down to Nazhuli Creek on the left bank of Xikou, and goes east to Xikou Village. Li Guangxi River is 25.3 kilometers long, with a river drop of 65,438 0.079 meters, with an average gradient of 42.6‰, a drainage area of 65,438 0.54.08 square kilometers and a forest coverage rate of 94.96%.

Giant River, located in Giant Township, Taishun County, originated in the southern foot of Wudi Village, Guishan Township, wencheng county, with an altitude of 800 meters. The stream turns north and west to Wudi Village, passes through Ang Lee Yunshui Power Station and flows under Nanpu New Factory. It flows into Huatong Creek from the left bank, passes through Nanqiaowai Village, flows into Zhuao Creek at Guling Corner on the left bank, and reaches Pan Yang Village on the right bank. The river is 27.6 kilometers long, with a river drop of 725 meters, with an average gradient of 26.27‰, an average annual flow of 7.4 cubic meters per second, a drainage area of 175.3 1 km2 and a forest coverage rate of 66.27%.

Gaolouxi, formerly known as Panxi, is located in Gaolou Township, Ruian City. It originates from Wu Shiping on the southern slope of Golden Mountain at the junction of Rui 'an and qingtian county, with an altitude of11m. The stream flows southward, flows through the river bank and the outer dike, and reaches the right bank of Ganji to receive the water from Huangtankeng. The water comes from Nadong Pit on the right bank of Sanshitou. After passing through the warehouse, it reaches Yang Na Aoxi on the left bank of Aokou, Yang Na Pit in Kengkou, Namagangjiao on the right bank of Nanshan and Shuangkeng on the left bank of Zhuxi Village through the pier, and then flows through Shangyang, Dajing, Shangcun, Xia Ze and high-rise buildings, where it is injected into Feiyun at the foot of Xiashe Ridge in Xikou Village. Gaolouxi River is 26.5km long, with a natural drop of 84 1m, an average gradient of 3 1.74‰, a drainage area of 125.5 km2, and an average annual flow of 5.32m3 seconds.

Beixi was once considered as the source of Feiyun River. Originated in the southern foot of Chimushan Mountain in Jingning She Autonomous County, it flows through the Baihe River and flows into Dabaikeng, originating from Baiyun River in Shangyu Township, leaving Tangkou in Dongkeng Township (bordering wencheng county) and entering a tributary of Feiyun River. The domestic flow length is 3 1.9km, and the drainage area is 224.42 km2, accounting for 1 1.5% of the county's total area, with a gradient of 29. 1% and a drop of 927 meters. The downstream banks of Feiyun River are coastal plain water network areas, with Wenruitang River on the left (north) bank and Ruipingtang River on the right (south) bank.

Wenruitang River was dug manually in the Eastern Jin Dynasty, dredged on a large scale in the years of Tang Dahe and Huichang, and then built by the well-known sacred tree in the Southern Song Dynasty, forming the "80-mile lotus pond", which is an important symbol of Wenzhou's landscape city characteristics. Its water sources mainly come from Quxi, Xiong Xi, Guoxi (commonly known as Sanxi) and the mountain streams of Luoda Mountain and Jiyun Mountain. The total basin area is 740 square kilometers, the water surface area is 22 square kilometers, the irrigation area is 482,000 mu, the average rainfall for many years is 1.694.8 mm, and the annual runoff is 9 1.3 million cubic meters. The total length of the river network is 1 178.4 km, and the water storage capacity is 65 million cubic meters.

Ruipingtang River basin covers an area of 347.9 square kilometers, including 1 13.7 square kilometers in hilly areas and 234.2 square kilometers in plain areas. The main inland rivers are Beitang River, Dongtang River, Wuqiao River, Caocun Port and Tangxia River. Among them, the length of Beitang River is15.25km; Dongtanghe length13 km; Wuqiao River length10.2km; River length of Caocun Port 15km.