衡阳市位于湖南省中南部，湘江中游；地处东经110°32’16”-113°16’32”,北纬26°07’05”-27°27’24”。南北长150公里、东西宽173公里，总面积15310平方公里，合153.10万公顷，占全省土地面积7.23%，在全省各市、州中，幅员位居第2位。东邻株洲市，南抵郴州市，西南接永州市，西北挨邵阳市，北达娄底市、湘潭市。
地形地貌：衡阳市处于湖南省凹形面的轴带部分。周围环绕着古老宕层形成的断续环带的岭脊山地，内镶大面积白垩系和下第三系红层的红色丘陵台地，构成典型的盆地形势。衡阳盆地南高北低。盆地南面地势较高，1000米以上的山中东西连绵数十公里；盆地北面相对偏低，衡山山脉虽较高，但各峰呈峰林状屹立于中间，其东西两侧都有较低的向北通道，其东侧的湘江河谷两岸海拔高度均在100米以下。整个地形由西南向东北复合倾斜，而盆地由四周向中部降低，呈现1000米，800-700米、400-300米、150米四级夷为平面。四周山丘围绕，中部平岗丘交错。东部为罗霄山余脉天光山、四方山、园明坳；南部为南岭余脉塔山、大义山、天门仙、景峰坳；西部为越城岭的延伸熊罴岭、四明山、腾云岭；西北部、北部为大云山、九峰山和南岳衡山。整个地形比降为7.9‰。南部山峰大多海拔600米以上，常宁天堂山最高，海拔1265米。西部山峰多海拔500米以上，祁东腾云岭最高，海拔1044米。东北部除南岳衡山外，一般地面高程在海拔300米-500米。市境最高点为衡山祝融峰，根据国家最新的测量数据，海拔1300.2米；最低点为衡东的彭陂港，海拔仅39.2米。 地貌类型以岗丘为主。山地占总面积的21%，丘陵占27%，岗地占27%，平原占21%，水面占4%。中部大面积分布白垩系和第三系红层，面积3550平方公里，构成衡阳盆地的主体。境内有河长5公里或流域面积10平方公里以上的江河溪流393条，总境长达8355公里，河网密度为每平方公里0.55公里。发源于广西兴安的湘江干流，自祁东归阳镇入境，依次流经祁东县、衡南县、常宁市、市区、衡阳县、衡山县和衡东县，境内长226公里。境内流域面积在3000平方公里以上的湘江一级支流有舂陵水，蒸水，耒水、洣水。水电资源理论蕴藏量87.61万千瓦，可供开发量64.17万千瓦。
Hengyang City, Hunan Province in south-central, the Xiangjiang River; located in east longitude 110 ° 32'16 "-113 ° 16'32", latitude 26 ° 07'05 "-27 ° 27'24". North to south and 150 km, 173 km east to west, with a total area of 15,310 square kilometers, combined 1.531 million hectares, accounting for 7.23% land area of the province, in all cities, states, size ranked No. 2. East of Zhuzhou City, south of Chenzhou City, Southwest received Yongzhou, Northwest suffer Shaoyang City, north of Loudi City, Xiangtan City.
Topography: Hengyang City in Hunan Province, with a part of the concave surface of the shaft. Dang layer surrounded by an ancient form of intermittent mountain ridge belt loop, inserts a large area of Cretaceous and Tertiary red layer under the red hills mesa, constitutes a typical situation in the basin. Hengyang Basin in Southern than in the north. Basin south to higher ground, 1,000 meters above the mountain stretching hundreds of kilometers of things; basin north is relatively low, although higher Hengshan Mountain, but the peaks of the peak was like standing in the middle, the east and west sides to have a lower North Channel, the east side of the Xiangjiang River Valley both sides altitude of 100 meters. The whole complex terrain sloping from southwest to northeast, around the middle of the basin from the lower, showing a 700 m 1,000 m ,800-400-300 meters, 150 meters four flattened plane. Around the hills around the central square cross HILLY. Luo Xiao-Shan Mountains in eastern sky as the mountains, four mountain parks Ming Au; southern Tashan Nanling Mountains, Dayishan the days of Solomon cents, Prime Pass; the western extension of the more bears roots Ridge City Ridge, Siming Mountain, Teng Yunling ; the northwest, north for large Yunshan, Jiufeng and Hengshan Mountain. Reduced to the terrain than 7.9 ‰. Most of the southern mountains over 600 meters above sea level, often Ningtian Tang highest mountain, 1265 meters above sea level. Western mountains and more than 500 meters above sea level, the highest in Qidong Yunling Teng, elevation 1044 meters. In addition to the Mountain of the Northeast, the general ground elevation -500 m at an altitude of 300 meters. The highest point of the city throughout the Mountain Zhu Rongfeng, according to the latest national survey data, elevation 1300.2 m; lowest point east of Peng Heng Yi Hong Kong, only 39.2 m above sea level. HILLY-based landscape types. 21% of the total area of mountains and hills, 27%, Kong accounted for 27%, 21% plains, water 4%. Distribution of a large area in central Cretaceous and Tertiary red beds, an area of 3550 square kilometers, constitute the main body of Hengyang basin. 5 km within a river basin area of 10 km or more than 393 rivers and streams, the total 8355 km long border, river network density of 0.55 km per square kilometer. Originated in the Xiangjiang River in Guangxi Xing, Yang Zhen immigrants return from Qidong, Qidong County followed through, MIDDLE, Changning City, urban, Hengyang County, Hengshan County and Hengdong, within 226 kilometers long. Within the drainage area of 3,000 square kilometers there is a tributary of the Xiangjiang River Chung Lingshui, distilled water, Lei water, Mi water. Theoretical reserves of hydropower resources 876,100 kilowatts, the amount of 641,700 kilowatts for the development.
