| Liao River | |
| Name Other: | Liao He |
| Map: | Liaorivermap.png |
| Subdivision Type1: | Country |
| Subdivision Name1: | China |
| Subdivision Type2: | Province |
| Subdivision Name2: | Hebei, Inner Mongolia, Jilin, Liaoning |
| Length: | 1345km (836miles) |
| Source1: | various sources of its tributaries |
| Mouth: | Liaodong Bay |
| Basin Size: | 232000km2 |
The Liao River is the principal river in southern Northeast China, and one of the seven main river systems in China. Its name is derived from the Liao region, a historical name for southern Manchuria, from which the Liaoning province, Liaodong Peninsula, and Liao dynasty also derive their names.[1] The river is also popularly known as the "mother river" in Northeast China.[2] Coursing 1345km (836miles) long, the Liao River system drains a catchment basin of over 232000km2, but its mean discharge is quite small at only about 500m3/s, about one-twentieth that of the Pearl River. The Liao River has an exceedingly high sediment load because many parts of it flow through powdery loess.
The Liao River is also an important geographical landmark, as it divides the modern Liaoning province into two broad regions — Liaodong ("east of Liao") and Liaoxi ("west of Liao"). Historically, this demarcation though was not based on the river itself, but on a large wetland that once existed on the right (west) bank of the lower Liao River known as the Liao Mire (辽泽), which stretched east of the Yiwulü Mountain to the Liao River from Xinmin to Panshan.
The Liao River is formed from the confluence of its two main tributaries, the Xiliao River from the west, and Dongliao River from the east. The western tributary resides entirely in Inner Mongolia, and is formed by the confluence of the Xar Moron River and the Laoha River at approximately 43° 25' N, 120° 45' E, before being reinforced by another tributary called the Xinkai River at its lower section. The eastern tributary arises in western Jilin Province, and goes through an S-shaped course before meeting its counterpart near the junction region of Liaoning, Jilin and Inner Mongolia, approximately 42° 59' N, 123° 33' E.
The resultant river, the Liao River proper, then enters Liaoning Province and courses southwards through the Northeast China Plain, receiving numerous tributaries along the way. It makes a westward turn near Pingdingbao Town, Tieling County, and after receiving more tributaries, earns an infrequently used nickname Juliu River (巨流河, "giant stream river"). The Liao River will then course southwest until it reaches near the Liujianfang Hydrological Station (六间房水文站) at Tai'an County, and historically bifurcates into two distributaries, forming the Liao River Delta (辽河三角洲). The western distributary of the delta, originally smaller, was called the Shuangtaizi River (双台子河) until 2011, receives the tributary Raoyang River at Panjin's Panshan County before draining into the Liaodong Bay of the Bohai Sea west of Dawa County. The eastern distributary, originally the larger and the main body of lower Liao River, was called the Wailiao River (外辽河, "Outer Liao River"). The Wailiao River travelled southwards to pick up two large tributaries, the Hun River and Taizi River, at a confluence locally referred as the "Trident River" (三岔河), where it then adopted the new name Daliao River (大辽河, "Great Liao River") and drained into the Liaodong Bay just west of Yingkou.
However, the Liao River Delta has a flat topography made up of soft sediment soil, with meandrous waterways that had a rich history of rerouting. This coupled with the risk of storm surges due to the region's low elevation, created a huge problem in flood control. This flood risk at the coastal section of the Liao River system was particularly threatening to Yingkou, a city immediately adjacent to the mouth of Daliao River and home to 2 million people. In 1958, the upriver of the Wailiao River at Liujianfang was blocked off via a river engineering project, redirecting the water flow from the Liao River proper entirely towards the Shuangtaizi River (which was renamed to simply the "Liao River" in 2011), effectively separating the Hun River and Taizi River from the Liao River system. Therefore, the Daliao River system is considered an independent water system of their own since 1958, and the Hun and Taizi River are no longer tributaries of the Liao River. Also, due to the Wailiao River's upstream flow being cut off, the Liao River no longer has any distributaries, therefore the Liao River Delta technically also ceased to exist from 1958 onwards, however the term remains in use to describe the area of Panjin between the Liao River's left bank and Wailiao/Daliao River's right bank.
These following tributaries drain into the Liao River proper throughout its course within the Liaoning Province.
Before 1958, the Hun River joins the Wailiao River and then the Taizi River near Haicheng — the confluence of the three rivers was also known as "the Trident River" — to form the Daliao River which drains into the Liaodong Bay. However in 1958, a river engineering project was conducted to address flood control problem in the coastal area near Yingkou. The upriver of the Wailiao River at Liujianfang was blocked off, diverting the Liao River stream away towards the Shuangtaizi River, effectively separating the Hun River and Taizi River from the main body of Liao River system. Therefore since 1958, the Hun and Taizi River were considered an independent river system of their own, no longer being tributaries of the Liao River.