The geographical environment of Hengshan County

The terrain of the county is high on the inside and low on the outside, surrounding Zhurong Peak in the middle. The terrain gradually decreases to the northwest and southeast, forming two inclined planes. It is mainly composed of mountains, hills, and hills, with rivers and plains as well. Its landform combination has the characteristics of a belt-like stepped distribution. Hengshan County has mountains accounting for about 11.4%, hills accounting for about 42.3%, hills accounting for about 24.8%, and plains accounting for about 21.5%.

The main peaks in the territory include: Jinzifeng, Yanziyan, Goutou Peak, Tuwu Peak, etc. There are 64.85 kilometers of the main stream of Xiangjiang River in Hengshan County. There are 38 tributaries of the Xiangjiang River, with a total length of 444.8 kilometers. Among them, there are 10 first-level tributaries with a length of 177.5 kilometers; 17 second-level tributaries with a length of 186.2 kilometers; eight third-level tributaries with a length of 78.9 kilometers; and three streams with a length of 26.1 kilometers.

Hengshan County belongs to the Xiangjiang River system, with a total water area of ??48.6 square kilometers, accounting for 6.2% of the area of ??Hengshan County. There are 185 large and small tributaries of the Xiangjiang River, with a total length of more than 900 kilometers, of which 38 have a drainage area of ??more than 10 square kilometers, and a maximum length of 468.7 kilometers. The average annual rainfall in the territory is 1.181 billion cubic meters, the average annual runoff is 501 million cubic meters, the average annual flow of the Xiangjiang River is 50.54 billion cubic meters, Hengshan County's surface water resources are about 25.903 billion cubic meters, and the flood season is from April to July. The dry season generally occurs from November to January of the following year. During the Republic of China, the highest water level of the Xiangjiang River at Hengshan Station was 55.89 meters (1924), exceeding the warning level of 8.89 meters. After the founding of the People's Republic of China, the highest water level was 54.88 meters (1994).

The Xiangjiang River

Enter Caoyushi at the junction of Shigu District, Hengyang City, Hengnan County and Xuanzhou Town, Hengshan County, and flow from north to south through the counties of Xuanzhou, Yonghe, Shigu, There are six towns in Kaiyun and Changjiang, and they reach Yongfeng Village in Changjiang Town and enter Xiangtan Town. The territory is 64.85 kilometers long and the river is 300-1200 meters wide. The river can be navigable in all seasons. The Dayuandu navigation and power hub has been built, allowing direct navigation of 1,000-ton ships. The normal water level of the Xiangjiang River is 41.7 meters, the warning water level is 47 meters, and the normal water depth is 2.3 meters.

Trickle

The ancient name is Xingle River, also known as Baiguo River, which is a first-level tributary of Xiangjiang River. Originating from Changshan, Shuangfeng County, it enters from Xinqiaoshi Local Village, flows through five towns including Xinqiao, Guantang, Jiangdong, Ginguo and Changqing, and exits at Xiaolan Port, Xiaolan Village, Changqing Township, where it enters Xiangtan County. The territory is 26.8 kilometers long, the river catchment area is 490.4 square kilometers, and the average annual flow is 3.98 cubic meters/second. Before the 1950s, it was the second navigable river in Hengshan. Later, it became unnavigable due to high siltation of the river bed.

Jingpi River

Also known as Phnom Penh River, it is a first-level tributary of the Xiangjiang River. Originating from Futianpu Township on the east side of Zigai Peak in Hengshan Mountain, it flows through Shaquan, Kaiyun, Yangtze River and other towns before entering the Xiangjiang River, with a total length of 29 kilometers and a water collection area of ??112.2 square kilometers.

Wujiang

The first-level tributary of Xiangjiang River originates from the southeast side of Zigai Peak in Nanyue, flows through Shigu, Yonghe and other towns, and ends at Wushipu, Shigu Township, where it flows into the Xiangjiang River. 20 kilometers, with a water collection area of ??119.4 square kilometers.