Yiyang (simplified Chinese: 益阳; traditional Chinese: 益陽; pinyin: Yìyáng) is a prefecture-level city at the Zi River in Hunan province, People's Republic of China, straddling Lake Dongting and bordering Hubei to the north. According to the 2010 Census, Yiyang has a population of 4,313,084 inhabitants residing in an area of 12,144 km² (4,689 sq mi).