The Luan River (, formerly known as ''Lei Shui'', or ''Ru Shui'') is a

river A river is a natural flowing watercourse, usually freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the ...

in China.

River

The river flows northwards from its source in the province of

Hebei Hebei or , (; alternately Hopeh) is a northern province of China. Hebei is China's sixth most populous province, with over 75 million people. Shijiazhuang is the capital city. The province is 96% Han Chinese, 3% Manchu, 0.8% Hui, and ...

into the province of

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for ...

, and then flows southeast back into

to its mouth on the

Bohai Sea The Bohai Sea () is a marginal sea approximately in area on the east coast of Mainland China. It is the northwestern and innermost extension of the Yellow Sea, to which it connects to the east via the Bohai Strait. It has a mean depth of a ...

. The headstream is known as Shandian River. This part of the river flows near the ancient Mongol capital city of

Shangdu Shangdu (, ), also known as Xanadu (; Mongolian: ''Šandu''), was the summer capital of the Yuan dynasty of China before Kublai decided to move his throne to the former Jin dynasty capital of Zhōngdū () which was renamed Khanbaliq (pre ...

. Another important settlement in this section is Duolun. From here, the river's course turns to the southeast. Its length is about 600 km. One subsidiary is the Yixun He, which runs through Hebei. During its course, the Luan also passes by the Great Wall. After Chengde, the river is navigable. The largest city along the river's course is

Chengde Chengde, formerly known as Jehol and Rehe, is a prefecture-level city in Hebei province, situated about 225 km northeast of Beijing. It is best known as the site of the Mountain Resort, a vast imperial garden and palace formerly used by t ...

Impact crater

Geological evidence such as the presence of suevite suggests there is an

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

in the area. It is estimated to be between 70–170 km in diameter with an age of 129 ± 3 Ma. The circular course of Luan River as it goes from Inner Mongolia back to Hebei is said to define part of the crater's outline.

References

Rivers of Hebei Rivers of Inner Mongolia {{China-river-stub