Hengyang is a prefecture-level city and sub-central city under the jurisdiction of Hunan Province, which is located in the south of China and the south-central part of Hunan Province. It is an important member of the urban agglomeration in the middle reaches of the Yangtze River and the political, economic, military and cultural center of southern Hunan [1].
Hengyang City, which straddles Xiangjiang River, is one of the important transportation hubs in Hunan Province and Central South China, where many important highways and railway trunk lines meet. Hengyang is located in the concave axis zone of south-central China, which constitutes a typical basin situation and belongs to subtropical monsoon climate.
Hengyang governs 5 districts, 5 counties and 2 county-level cities, with a total area of 153 10 square kilometers. According to the data of the seventh census, the permanent population of Hengyang is 6,645,243.