The Xiang River is the chief river of the Lake Dongting drainage system of the middle Yangtze, the largest river in Hunan Province, China. It is the second-largest tributary (after the Min River) in terms of surface runoff, the fifth-largest tributary by drainage area of the Yangtze tributaries. The river flows generally northeast through the provinces of Guangxi and Hunan, its tributaries reaching into Jiangxi and Guangdong.
Traditionally, it was regarded that the West (left) Branch is the Main Stream of the Upper Xiang, which rises in the Haiyang Mountains between Xing'an and Lingchuan counties of Guangxi. In the 1st national water census of China in 2011, the East Branch Xiao River, was identified as the Main Stem of the Upper Xiang. The Ping Island of Yongzhou is the meeting of the two streams, the West source originating from Guangxi and the East source of the Xiao River originating from Lanshan County of Hunan.
With the tributaries, the Xiang has a river basin area of , of which Hunan has an area of . In a situation of Guangxi source, the Xiang has a length of . In another situation of Xiao River as the main source stream, the Xiang has a length of . it is the East Branch, not the West, that should be regarded as the main stream of the Xiang. This is because it is both longer and contributes a greater volume of water than the western branch. The east branch retains the name of Xiao River, and it rises in Yegou Mountain (野狗岭) of Xiangjiangyuan Township (湘江源瑶族乡) in Lanshan County, Hunan. The two branches converge at Ping Island to form the Main Stem of the Xiang. The Main Stem is located in the eastern part of Hunan. The Xiang generally flows southwest to northeast from Lingling District of Yongzhou to Xiangyin County, and empties into the Yangtze River via Lake Dongting.
Upper Course
The Left Branch, also known as the West Branch of the upper course is traditionally known the upper Xiang River, the portion of the Xiang River upstream called Xiangshui River (湘水). From the headwaters at Xing'an County, Guangxi, the West Branch flows approximately to Ping Island of Yongzhou, where it is joined by the Xiao River to form the middle Xiang River.
Historically it was recognized that the headwaters of the Xiang rise in Haiyang Mountains. People say the Xiang and the Li Rivers share the same origin, because the upper reaches of the two rivers are connected by the ancient Lingqu Canal, which is located in Xing'an County, Guangxi. According to a traditional saying, 70% of the water in Lingqu flows into the Xiang and 30% flows into the Li River. In the past, the canal, along with the Xiang River and the Gui River provided an important waterway connecting the Yangtze River with the Pearl River Delta.
Xiao River
The Xiao River is the East Branch of the upper course. As of 2011 Water Census of China, it may be regarded as the Main Stream of the upper Xiang River. Xiao rises in Xiangjiangyuan Township of Lanshan County, from the headwaters to Ping Island at the confluence with the West Branch (Left Branch) from Guangxi, it runs . With the tributaries, the Xiao River has a drainage basin area of .