What are the causes of land desertification in the middle reaches of Heihe River Basin?

First, natural factors have long illumination time and abundant light and heat resources. The basic characteristics of climate are:

(1) It is hot in summer and cold in winter, and the daily range is greater than that in annual range. The precipitation is scarce, the air is dry and the evaporation is large;

(2) There are many sandstorms, which are mainly distributed from March to May in spring;

This is a typical dry and early morning area in China. Due to the long-term drought, the land in this area has no vegetation or little vegetation growth, and a large area of desert and Gobi has been formed in history.

2. Human factors (1) population growth. With the increase of population, people's ability to intervene in nature has increased, and the demand for various natural resources has also increased, and their ability to intervene and influence this environment has also increased. Human beings have both good and bad influences on nature. If the demand exceeds the compensation, it will naturally retaliate against human activities, thus forming various disasters.

(2) Overfarming and firewood burning. Indiscriminate planting of firewood forest refers to agricultural planting activities in arid, semi-arid and dry sub-humid areas, and excessive harvesting of natural vegetation in arid and semi-arid areas without reclamation conditions and protective measures.

According to the survey, the area of cultivated land has increased by nearly 30% after the contracting of five villages in Anyang Township, Ganzhou District, and now abandoned cultivated land can be seen everywhere. Reclamation of 1 hm grassland resulted in desertification of the surrounding 3 hm land. Due to excessive land reclamation and a large number of unreasonable firewood harvesting, vegetation has been obviously destroyed, which has aggravated land desertification.

(3) Overgrazing. Driven by market interests, herders blindly increase the number of livestock, leading to serious overgrazing of grasslands.

According to the investigation of grassland carrying capacity in Sunan county 1999, the available grassland area in winter and spring is 65 1000 hm2, and the total grass production is 625 million kg. According to the calculation of grazing for 8 months, the suitable stocking capacity is 973 1000 sheep, with an overload of 32 1900 sheep, with an overload of 49.44%. The grassland in summer and autumn is 420,000 hm2, with a total grass yield of 690 million kg, the suitable stocking capacity is 654.38+0.384 million sheep, and the actual stocking capacity is 654.38+0.998 6.5438+0.5547 million sheep, which is 654.38+0.233% overload.

The results are as follows: on the one hand, due to excessive eating of livestock, forage grass becomes short and scarce; On the other hand, due to the excessive trampling of livestock, the surface structure is destroyed, and the quality and coverage of grassland are reduced, which leads to wind erosion and desertification of many grasslands and becomes the main reason for grassland degradation.

(4) Unreasonable utilization of water resources. Reclamation from the sea destroyed the original surface vegetation, and also brought unlimited exploitation of groundwater.

Surface water itself cannot meet the needs of local industry and agriculture. Although pumping groundwater is a solution, due to the lack of understanding of natural laws, especially the formation and transformation of groundwater in inland river basins, effective measures have not been taken for groundwater exploitation, which has led to the uncontrolled exploitation of groundwater and the decline of groundwater level year by year, resulting in the death of large-scale artificial sand-fixing forests and the aggravation of saline-alkali land and secondary salinization.