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 2nd largest tributary (after Min River) in terms of surface runoff, the 5th largest tributary by drainage area of the Yangtze tributaries. The river flows generally northeast through Guangxi and Hunan two provinces, its tributaries reach 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 . Geography The Upper Xiang River has two large Branches, the West (left) and East (right). The West Branch is traditionally known as the main stream, originating from the Haiyang Mountains in Guilin of Guangxi. In Hunan, there had been debate on whether or not this tradition of regarding the West Branch as the main stream is actually founded. According to the 2011 national Water Census of China, 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