Luanhe River is the only river in Bohai Sea, which belongs to the Luanhe River system. The ancient name Shui Pi is named after many hot springs where it originated. After the Tang Dynasty, it evolved into Luanhe River, and the Yuan Dynasty was also called "Royal River" or "Shangdu River".
Luanhe River has a long history and has accepted many tributaries along the way. Among them, there are 9 tributaries with basin area exceeding 1 10,000 square kilometers, namely Xiaoluan River, Xingzhou River, Yixun River, Wulie River, Niu Lao River, Liuhe River, Pupu River, Menghe River and qinglong river. Among the tributaries, the Yixun River basin has the largest area, and the qinglong river has the largest length and water volume.
River characteristics
Luanhe River system is mainly distributed in Bashang Plateau, Yanshan Mountains and Hebei Plain. Yanshan Mountain is a young mountain stream with strong undercutting and large river gradient, mostly 2/ 1000-6/ 1000, and some small and medium-sized tributaries can reach more than 20/ 1000. Most river valleys are V-shaped. The rivers flowing through Bashang Plateau, Yanshan Mountain intermountain basin and Hebei Plain are wide, shallow and winding. The river conditions in different reaches of Luanhe River are different.
Heyuan section: Above Waigoumenzi is Heyuan section. The river bed elevation drops from the source1800m to145m, with a drop of nearly 700m, with an average ratio of 2.5/ 1000. The valley is wide and shallow, and mainly flows through the grasslands of Inner Mongolia.
Upstream section: the upper reaches of Zhangbaiwan are upstream, and the riverbed elevation is reduced from1145m to 423m, with a drop of 720m, with an average gradient of 3.11000. Due to the lack of water and abundant hydraulic resources, the theoretical reserve is1100,000 kilowatts, and the unit energy storage is only 45,438+000 kilowatts. This section of the river runs through the dam edge and the northern part of Hebei Province, with severe undercutting and meandering development, and the bending coefficient is 2. The concave banks are mostly steep cliffs, and the convex banks are mostly gravel beaches. The riverbed is mostly composed of pebbles and coarse sand, and the floodplain is undeveloped. The valley is V-shaped, with a water surface width of 35-45 meters in normal times, which is a typical young valley landform.
Middle reaches: From Zhangbaiwan to Luanxian in the middle reaches, the river bed elevation is reduced from 423 meters to 25 meters, with a drop of nearly 400 meters, and the river slope is only11000. However, due to the increase of water volume, the theoretical reserve of hydropower is 300,000 kilowatts, and the unit energy storage is 758 kilowatts/kilometer. This section crosses the Yanshan Mountains, forming a landform with wide valleys and canyons. Mountain canyons are mostly V-shaped in the mountains, and wide valleys are formed in basin areas. Wide valleys and canyons are quite different in appearance, such as Luanhe River Valley in Qian 'an Basin and Sangyuan nearby. The valley above Panjiakou is very narrow and the river below is very wide. The riverbed is in the middle and old age, and meanders are developed in Jiang Xinzhou, with many tributaries and beaches. It is a braided water system with wide water surface, fine riverbed composition and sandy pebbles.
Downstream estuary section: Below Luanxian County is the downstream estuary section, which basically belongs to Luanhe River Delta. The river width is 400 meters in normal period and 2000 meters in flood period. The river valley is wide, meandering floodplain is developed and multi-branched. The riverbed is mainly composed of fine sand, and the floodplain is mainly composed of loam and sandy soil. Due to the small river gradient (only 0.28/ 1000), the flow velocity slows down, the sediment carrying capacity of water decreases, a lot of sediment is deposited, and the riverbed gradually rises, developing into an "overground river". Sediment is constantly accumulating in the estuary area, which makes the delta gradually push outward.