The ancients said that if oranges grow in Huainan, they will become tangerines, and if oranges grow in Huaibei, they will become tangerines. This sentence can certainly be used as a geographical symbol to distinguish the north-south dividing line, but if we want to clearly distinguish the north-south dividing line, this famous saying alone cannot solve the problem. This sentence is still too limited.

This is an issue that is often confused in physical geography. The Qinling Mountains and the Huaihe River are what we often call the geographical dividing line between the south and the north. In fact, this question still requires specific questions and specific analysis. After all, the north-south dividing line is not just a geographical concept. It is not only a geographical and climate issue, but also a humanistic custom issue, and it is also a civilization and cultural development issue! ?

There are significant differences between the areas north and south of the Qinling Mountains and the Huaihe River, both in terms of natural conditions and agricultural production. Therefore, the line between the Qinling Mountains and the Huaihe River is an important geographical dividing line in my country. .

From the perspective of precipitation distribution, except for the southern part of the Shandong hills, the 800 mm annual precipitation line is roughly equivalent to the Qinling-Huaihe River line. North of this line, the annual precipitation is mostly below 800 mm; south of this line, the annual precipitation is above 800 mm.

From the perspective of river hydrological characteristics, in the area north of the Qinling Mountains and the Huaihe River, the water volume of the river is small, the water level changes greatly, the flood season is short, the sand content is high, and it freezes in winter; in the area to the south, the river water volume is large, The water level changes little, the flood season is long, the sand content is small, and there is no ice in winter.

From the perspective of temperature, the 0°C isotherm in January is roughly distributed along the Qinling Mountains and the Huaihe River. North of this line, the average January temperature is below 0 degrees Celsius, and the river water freezes in winter; south of this line, the average January temperature is above 0 degrees Celsius, and the river water generally does not freeze.

From the perspective of thermal zones and dry and wet conditions, the area north of the Qinling Mountains and the Huaihe River is a warm temperate, semi-humid and semi-arid area; the south is a subtropical, humid area.

From the perspective of vegetation, in the area north of the Qinling Mountains and the Huaihe River, there are only deciduous broadleaf trees and coniferous trees such as pine and cypress; in the south, there are many evergreen broadleaf trees.

From the perspective of river hydrological characteristics, in the area north of the Qinling Mountains and the Huaihe River, the water volume of the river is small, the water level changes greatly, the flood season is short, the sand content is high, and it freezes in winter; in the area to the south, the river water volume is large, The water level changes little, the flood season is long, the sand content is small, and it does not freeze in winter.

From the perspective of agricultural production, north of the Qinling Mountains and the Huaihe River, the cultivated land is mainly dry land. The farming system is two crops a year or three crops every two years. Food crops are mainly wheat and miscellaneous grains. Among the economic crops, cotton and soybeans occupy an important position in the country; the cultivated land in the south is mainly paddy fields, with two to three crops a year. Food crops are mainly rice, wheat, sweet potato, corn, etc. Subtropical cash crops are widely distributed.

I guess what I introduced above is clear enough? The north-south dividing line is definitely not just a very simple concept. The content covered by this line is definitely very complex. So of course we have to use this dividing line and the various things included in the north and south to make a specific dividing line. .