The distinctive features of the terrain are low and flat terrain, criss-crossing rivers and canals, and dotted with lakes. Generally, the altitude is 5 ~ 100 meters, but most of them are below 50 meters. The central and coastal areas along the Yangtze River are flood plains and coastal plains.

2. The soil is fertile

The plain soil in the middle and lower reaches of the Yangtze River is mainly yellow brown soil or yellow cinnamon soil, with red soil in the southern margin and paddy soil in most of the flat land. The biological enrichment of red soil is very strong, and the content of soil organic matter under natural vegetation can reach 70 ~ 80 g/kg, but it is greatly affected by soil erosion and farming methods. The high content of soil organic matter is beneficial to form a good structure, enhance the cohesion of soil particles and improve the ability of water storage and soil conservation.

3. The climate is mild

Most of the plains in the middle and lower reaches of the Yangtze River belong to the north subtropical zone, and a few belong to the northern edge of the middle subtropical zone. The annual average temperature is 14 ~ 18℃, the most Leng Yue average temperature is 0 ~ 5.5℃, the absolute minimum temperature is-10 ~-20℃, the hottest month average temperature is 27 ~ 28℃, and the frost-free period is 2 10 ~ 270 days. Agriculture crops two or three times a year, and the annual precipitation is 1 0,000 ~10,500 mm. The seasonal distribution is relatively uniform, but there is a "summer drought".

4. Rich in mineral resources

The plain in the middle and lower reaches of the Yangtze River is rich in mineral resources, including fluorite, magnetite, talc, purple quartz, Qiu Shi, chlorite and nonferrous metals. Among them, non-ferrous metals occupy an important position in China. This is mainly due to the large-scale magmatic activity in the hilly areas of the south of the Yangtze River in geological history. In the process of condensation, various metal components contained in magma form non-ferrous metals such as tungsten, antimony, copper, lead and zinc at different temperatures.

Extended data:

Water supply system:

1, river

The Yangtze River natural water system and criss-crossing artificial canals in the plain area of the middle and lower reaches of the Yangtze River make this area the densest river network area in China. The most important river in this area is the Yangtze River and its tributary Hanjiang River, and most of the rivers in this area are alluvial rivers.

2. Lake

There are many freshwater lakes in the plain of the middle and lower reaches of the Yangtze River. The lake area is about 20,000 square kilometers, which is equivalent to 10% of the plain area. On the two lakes plain, there are 1300 large lakes, including small lakes, totaling more than 10000, with an area of 12000 square kilometers, which is the place with the largest number of lakes in China. In addition to Taihu Lake, there are 150 large lakes with an area of more than 1000 mu, and thousands of swings and berths with an area of less than 1000 mu.

? Baidu Encyclopedia-Plain in the Middle and Lower Reaches of Yangtze River