Altitude, amplitude and integrity of Sichuan basin, Yunnan-Guizhou plateau, middle and lower reaches of Yangtze River and southeast hills

The main topographical areas are: the middle and lower reaches of the Yangtze River plain (Jianghan, Dongting Lake, Poyang Lake and Yangtze River Delta), the Pearl River Delta plain, the southern hills, the Sichuan Basin, the Yunnan-Guizhou Plateau, the Hengduan Mountains, the Nanling Mountains, the Wuyishan Mountains, the Qinba Mountains and the Taiwan Province Mountains.

Climate characteristics: tropical and subtropical monsoon climate is dominant, with accumulated temperature of 4500℃-8000℃, and the heat conditions are quite different between north and south. 1 The monthly average temperature is above 0℃, with warm winter and hot summer, and four distinct seasons (the monthly temperature in southern coastal areas and southern Yunnan is above 15℃, and there is no winter in long summer). The annual precipitation is more than 800 mm (the average annual precipitation in Huoshaoliao in the northeast of Taiwan Province Province is 6489 mm, which is the "rain pole" in China), mainly concentrated in the summer half year, and the rainy season becomes shorter from south to north. The climate in Hengduan mountain area varies greatly vertically. Yunnan-Guizhou Plateau is the intersection of the Pacific Ocean and Indian Ocean monsoon. In winter, the eastern part of Kunming Jingfeng is rainy and cold, and the western part is sunny and warm. The middle and lower reaches of the Yangtze River (east of Yichang, south of Huaihe River and north of Nanling Mountain) are affected by the static front of the Yangtze River and Huaihe River from June to July every year, with plum rains, and summer drought under the control of the Hawaiian high ridge from July to August. Cold wave in winter and typhoon in summer and autumn in coastal areas are the main disastrous weather.

Hydrological characteristics: abundant water, long flood season and small seasonal variation of water level (typhoon season is obvious in southern coastal rivers); The rivers in the hilly areas of the south of the Yangtze River, the southern coast, the Yunnan-Guizhou Plateau and the Sichuan Basin have a large drop and abundant water power. The Yangtze River system, the Pearl River system and the Beijing-Hangzhou Canal are of high shipping value. River sediment concentration is small; Ice-free period

Major lakes: The Yangtze River basin is the main distribution area of freshwater lakes in China, including Poyang Lake (the largest freshwater lake in China), Dongting Lake, Taihu Lake, Hongze Lake and Chaohu Lake; Sun Moon Lake.

Main rivers: Yangtze River and its tributaries, Hanjiang River, Dongting Lake, Poyang Lake and centripetal water system of Sichuan Basin (Minjiang River, Yalong River, Wujiang River and Jialing River); Pearl River and its tributaries Xijiang, Dongjiang and Beijiang; Qiantang River; Huaihe River; Minjiang river; Lancang River and Nujiang River in Hengduan Mountain Area; Turbid water flow

Vegetation: subtropical evergreen broad-leaved forest, tropical monsoon forest.

Soil: zonal soil is red, yellow and latosol, and non-zonal soil is purple soil in Sichuan basin and paddy soil in farmland area.

Dominant factors: the accumulated temperature in the east gradually increases from north to south, and the precipitation in the west gradually decreases from east to west.