Where is the mouth of Mulan River?

Mulan River is the largest river in Fujian and the mother river of Putian people. It is located at118 38 ′ ~1/kloc-9 06 ′, 25 22 ′ ~ 25 25 ′ north latitude, with a drainage area of 1732 square kilometers (where the drainage area above Laixi Wenzhan is/kloc-) The larger tributaries of Mulan River system are Yanshou River, Zhongyue River, Daji River, Xikou River, Longhua River, Songban River, Xianshui River and Kuxi River. Yanshou Creek, also known as Nanfeng Luxi, originated in Linquan Temple, zhongshan town, Xianyou County, where streams such as Jiulihu Creek, Juxi Creek, Changling Creek and Yucang Creek meet. After entering Putian Plain, Yanshou River is divided into many ditches, which often flow into towns such as Taitai, Suburb and Hanjiang River, and then into Mulan River. The total length of trunk and tributary is 189 km, and the rainwater collection area is 386 square kilometers. The total length of Mulan River is 105km, with an average gradient of 0.45‰ and an average annual runoff of 985m cubic meters, in which the section from Mulan Skin to Sanjiangkou is 25.8km tidal, and the basin area of Mulan River is 1732 km2, in which Xianyou is located in the middle and upper reaches, with a basin area of17km2. The lower reaches are Chengxiang, Licheng and Hanjiang, with a drainage area of 7 15 square kilometers. The landform type is mainly plain, surrounded by hills, terraces and Mulan River. Xinghua Plain is divided into south, north and west, commonly known as the North-South Ocean. The soil types are paddy soil, red soil, yellow soil and alluvial soil, and the soil quality is mainly acidic.

The main tributary of Mulan River is Xianyou Daji River, with a total length of 24 kilometers and a drainage area of 76.4 square kilometers. Longhua Creek, with a river length of 26 kilometers and a drainage area of 1 13 square kilometers; Chaiqiaotou Creek, with a river length of 20 kilometers and a drainage area of 85.4 square kilometers; Xianshuixi, with a river length of 29 kilometers and a drainage area of 176 square kilometers; Yanshou River passes through Xianyou, Chengxiang and Licheng, with a length of 565,438+0 km and a drainage area of 386 square kilometers. Dongzhen Reservoir, with a storage capacity of 430 million cubic meters, was built in 1958, located in the middle and lower reaches of Yanshou River in Changtai Town. South-North Yanghe River network on Xinghua Plain, in which Mulan skin, the ditch of Nanyang River network, is located in the lower reaches of Mulan River, under Mulan Mountain, about 4 kilometers away from the urban area. It is the ancient tableland that cut off Mulan River, and it is one of the most intact ancient large-scale water conservancy projects in China. Mulan River, located in the southeast coast of Fujian Province, is one of the "five rivers and one stream" and the largest river in Fujian. She originated in Bijia Mountain, a branch of Dai Yun, entered Huangkeng Village, Xiyuan Township, Xianyou, and flowed through Dehua, Yongchun and Xianyou for 33 kilometers from northwest to southeast. The towns and villages that flow through Putian City are Dewey, Daji, Licheng, Chengdong, Laidian, Gaiwei, Huating, Suburb, Xindu, Huangshi and Hanjiang, which run through Putian City, bypass Xinghua Plain and flow into Xinghua at Sanjiangkou. Mulan River originates from Daiyun Mountain in Dehua County, flows through Xianyou Basin, crosses Putian County, divides Xinghua Plain into two oceans, and finally flows into Xinghua Bay in Sanjiangkou to the East China Sea. The main stream of Mulan River is 105 km long, and the water system is dendritic, winding and circuitous, with short source and rapid flow. The natural drop is 784 meters, and the upper reaches are dominated by middle and low mountains, composed of Mesozoic volcanic rocks, and the riverbed slope is steep, belonging to a mountain stream river. The middle and lower reaches of the river are wide, the water flow is gentle, and the river slope is about 1.5‰. The downstream Xinghua Plain (also known as Pu Xian Plain) is one of the four major plains in this province. The length from Mulan North to Sanjiangkou is about 26 kilometers, which is a tidal reach with great tidal influence. There are many tributaries, mainly Xianshui River, Yanshou River, Longhua River, Daji River and Chaiqiaotou River. The annual runoff distribution in the basin decreases from northwest to southeast, and the mountain area is larger than the plain. According to the data of Laixi Station, the average annual runoff for many years is 985 million cubic meters (4.57 ~168 million cubic meters), the runoff modulus is 29.2 liters/km2 second, the runoff depth is 920.8 mm, and the average annual runoff for many years is 30.9 cubic meters/second. Runoff changes greatly during the year, with the annual average maximum discharge of 53.2 m3/s (1952) and the minimum discharge of 14.5 m3/s (1967), with a difference of 3.6 times. Runoff is unevenly distributed during the year, accounting for 23.2% in spring, 53.5% in summer, 17.6% in autumn and 5.7% in winter. The maximum flood season is from June to August, accounting for 53.5%, and the maximum flood season is June, accounting for 22. 1%. The smallest hidden month is 65438+February, accounting for 1.4%. The historical maximum flood peak discharge is 4500 m3/s( 1.906), and the maximum flood peak discharge after the founding of the People's Republic of China is 37 10 m3/s( 1.973). The minimum flow is only 0. 1 m3/s, which is close to cutoff (1956). Below the north of Mulan is the north-south ocean, with criss-crossing ditches and dense river networks. The length of ditches in Nanyang river network is 199.8km, the design flow of intake is 1 1.0m3/s, and the storage capacity of ditches is 17m3. The length of Beiyang river network is 109.7km, the design flow of intake is 5.5 m3/s, and the water storage of the river is140,000m3. Due to the water resistance of Mulan Bay, the runoff entering the tidal reach is very small, and the lower reach is actually a trumpet-shaped tidal inlet. The tidal capacity per tide is more than 25 million cubic meters. According to the analysis of tidal level data in Sanjiangkou, it is a semidiurnal tidal area with an average tidal range of 4. 1 m, with an average high tide duration of 5 ∶ 50 ′ and a low tide duration of 6 ∶ 35 ′. The tidal current is semidiurnal, with an average velocity of 0.57m/s and a maximum velocity of 0.94m/s; The average speed of ebb tide is 0.65m/s, and the maximum speed is 0.95 1 m/s. ..

The average amount of sediment discharged into the sea for many years is 468,000 tons, with the maximum annual amount of 6,543,800+0,470 tons and the minimum annual amount of 6,543,800+0,350 tons. The average sediment concentration for many years is 0.3kg/m3, and the average sediment transport rate is 10.9kg/s, which is mainly concentrated in six to eight months, accounting for 72.4% of the whole year.