The territory is surrounded by mountains, with rolling hills, few mountains and complex landforms. The hilly area accounts for 5 12.7%, the hilly area accounts for 10. 1%, and the flat area accounts for 28. 1%. The mountains and valleys in the territory are northwest-southeast, slightly higher in northwest and southwest, and inclined to the east. The middle part is cut by Zuojiang River, Youjiang River, Yujiang River and their tributaries, forming a misjudged hilly plain. Daming Mountain in the northeast is the highest peak in China, with an altitude of1760m. There are more than 10 main peaks 1000 meters above, such as Zhenlong Mountain in the east, Daming Mountain and Sichengling Mountain in the west, Daqing Mountain and Gongmu Mountain in the south.
Nanning has an ancient geological structure, which is based on Devonian, Permian and Triassic, mainly limestone, followed by shale and sandstone, and the surface is covered with Quaternary red soil. The rivers in China belong to Xijiang River system. Yujiang River, Zuojiang River and Youjiang River are the main streams, which are cut from southwest, northwest and east, and flow through the middle to form large and small river networks.
There are 1 13 rivers with rainfall collection area of more than 50 square kilometers in the whole region, with a river area of 92,400 square kilometers, of which the main stream of Zuojiang River is 539 kilometers long, the basin area is 3 1595 square kilometers, and the annual average flow is 174 billion cubic meters. The main stream of Youjiang River is 707 kilometers long, with a drainage area of 386 12 square kilometers and an average annual flow of14.5 billion cubic meters.
Nanning's topography is a basin shape centered on Yongjiang River Basin.
This basin is open to the east, surrounded by mountains in the south, north and west, with high peaks and low mountains in the north, high hills with seven slopes in the south and Phoenix Mountain (Dongshan Mountain in Daming Mountain in the west) in the west. Formed a long valley basin from Fenghuang Mountain in the west to Qingxiu Mountain in the east. The center of the basin has become a concentrated place of rivers, with Youjiang in the northwest, Zuojiang in the southwest, Liangfeng River in the south and Xinxu River in the north, forming a centripetal water system. In the middle of the basin, where the left and right rivers meet, the hills on the north and south sides cling to the river banks, forming a natural dividing line, which divides the long valley and the basin into two small basins, one is the Yongjiang valley basin with Nanning as the center; The second is the erosion-dissolution basin centered on Tanluo Town.
Nanning's landforms are divided into five types: flat land, low mountains, rocky mountains, hills and terraces.
Flat land is the largest landform type in Nanning, with an area of 1 0,037.33 square kilometers, accounting for 57.78% of the city's total area. It is distributed at the junction of the lower reaches of the left and right rivers and on both sides of the Yongjiang River.
The total area of low mountains is 82.64 square kilometers, accounting for 4.6% of the city's area. It is located in the Phoenix Mountain on the western edge of the city. It is a dome mountain with an altitude of 300-600 meters and a slope of 25-40 degrees. Gaofengling, located in the north of the city, is a series of folded low mountains, running northeast-southwest, with an elevation of 250-450 meters and a slope of 20-40 degrees.
Rocky Mountain covers an area of 46.7 square kilometers, accounting for 2.6 1% of the total area. Mainly distributed in the northwest edge and around Tanluo town, it is divided into two categories: peak forest stone mountain and solitary peak stone mountain. The peak forest Rocky Mountain is 300-400 meters above sea level and the valley is 120- 160 meters above sea level.
The Rocky Mountain in Gu Feng is generally 200-250m above sea level, and the flat land is 80-100m above sea level. The hilly area is 279.86 square kilometers, accounting for 15.59% of the city's area.
The platform is mostly a Tertiary erosion surface with slight cutting and gentle fluctuation. The elevation is below1.20m, which is a low-grade paleoerosion surface, generally with gentle slope fluctuation and flush top surface.