Second information
First, the fifth longest river in the world
The Yellow River, the fifth longest river in the world, is a 5464-kilometer-long river that meanders in the north of China. Viewed from the sky, it looks like a huge word "Ji", and it is also a unique totem of our nation.
2. Characterization of the Yellow River
It is not just a big river. Yellow River, yellow land, emperor, yellow skin, all these yellow representations sublimate this turbid stream flowing through the heart of China into a holy river. "Records of the ditch in the Han Dynasty" regards the Yellow River as the head of all rivers: "There are hundreds of Sichuan sources in China, not in Sidu, but in the river."
Third, the theory of loess weathering
In a long geological time, in the Gobi desert in the interior of Asia, the sand and gravel everywhere were decomposed and crushed in the harsh environment of sudden cooling and sudden heating until they formed powder. The northwest airflow prevailing in the inland has blown them to the east for years, and the coarse sand fell on the Mongolian Plateau, and the most delicate powder fell with the wind to today's six provinces of Gansu, Shaanxi, Shanxi, Qinghai, Ningxia and Henan. After millions of years of transportation and accumulation, a loess plateau has finally formed, which starts from the Great Wall in the north, reaches the Qinling Mountains in the south, reaches Sun Moon Mountain in the west and reaches Taihang Mountain in the east.
IV. Deep and broad loess layer
This is an unparalleled loess with an area of 41, square kilometers, and the thickness of loess cover is generally more than 1 meters. In Longdong, Shaanxi, Shanxi and other places, the loess is as deep as 1 to 2 meters, and the Lanzhou area is more than 3 meters thick.
Botanists in the Garden of Eden five or six thousand years ago
It was found that although the rainfall in the Loess Plateau was not as abundant as that in the south, there was less leaching loss of nutrients, which was very suitable for the growth of poplar, birch, oak, Chinese pine, spruce, sour jujube and Vitex negundo. At that time, lush vegetation nurtured a warm and rainy Eden. Today, Shanxi, Shaanxi, Gansu, Ningxia and other provinces, there are large areas of virgin forests. Henan province, located in Zhongyuan, is called "Yu" for short, which shows that it is still a place where elephants haunt in the era of Cangjie word-making.
VI. Foundation of historical prosperity
Geologists have found that loess has excellent understanding and is suitable for digging caves to live in; Agronomists have found that various minerals in loess are rich in nutrients and have high natural fertility. The ancestors gradually dug caves in this yellow land to live and planted grains for a living. More than 5, years ago, the tribes of the emperor and Emperor Yan flourished, and the footprints of Chinese ancestors traveled all over the yellow land. In the days that followed, Xia Xing, the first dynasty of China, flourished here, and Zhou Chaoyuan, the 8-year-old founding country, began here, and the Qin Empire, which swept Liuhe and unified the whole country, flourished here.
VII. Enlightenment of Ancient Civilization
In the site of human activities in Xihoudu, Ruicheng, Shanxi, more than 1.6 million years ago, people found burnt animal fossils and antler fossils, and in Lantian, Shanxi, 1 million years ago, people found many carbon deposits.
Since then, Lantian people, dali man people, Dingcun people and Hetao people have all thrived in the arms of the Yellow River. Until 6 years ago, matriarchal clan culture represented by Banpo civilization appeared on the yellow land.
Our ancestors hunted and gathered in such a green field and spent the golden childhood of Chinese civilization.
VIII. Historical account of the achievements in transforming nature
It is true that the light of civilization was first bathed here, and it is inevitable that it was the first to be touched by the fire of civilization. According to ancient legend, Shennong once taught people to cultivate crops. What is intriguing is that Shennong is Emperor Yan, that is, Vulcan, and what he teaches is actually burning forests and cultivating.
Mencius recorded the "achievements" of the three emperors and five emperors in burning forests: "When Yao was in power ... the vegetation was flourishing, the animals were breeding, the crops were not harvested, and the animals were threatening ... Yao was alone in worrying about it, and he took measures to deal with it smoothly. Shun makes good use of the fire. "When the mountain is burned, the animals escape."
In the Book of Songs, we heard the chanting of our ancestors when they cut down trees: "Kan Kan is cutting sandalwood, and the river is dry and the river is clear and rippling." "Logging tinkles and birds sing."
IX. The vegetation on the Loess Plateau suffered heavy losses for the first time
After the emperor unified the six countries, a large number of people entered Guanzhong, and the cultivated area increased greatly. At the same time, he built a large-scale building, built a palace mausoleum, and wantonly cut down the forest in Guanzhong Mountain. In the thirty-third year of the first emperor (214 BC), Meng Tian defeated the Xiongnu and acquired a large area of land in Hetao area. Later, he settled in the frontier and immigrated to the Ordos Plateau many times, with hundreds of thousands of people each time. The originally endless grassland became a farming area.
X. The forest on the Loess Plateau suffered heavy losses for the second time
During the Western Han Dynasty, the world was under great rule, and the population of China surged to 6 million. Exploiting migrants to the northwest has become the main means to solve the pressure of population expansion. During the period of Emperor Wu of the Han Dynasty alone, more than 7, people migrated to the northwest frontier fortress. The Western Han Dynasty drove the Xiongnu to the distant Mobei, turning a large forest and pastoral area into a farming area. The Yellow River diversion irrigation project developed in Hetao in the Western Han Dynasty was at the expense of the great destruction of Helanshan forest in Ningxia and Inner Mongolia and the forest in northern Shaanxi.
Xi. The forest on the Loess Plateau suffered heavy losses for the third time
At the beginning of the founding of the Tang Dynasty, efforts were made to govern and the economy recovered rapidly. Because the center of its economic, trade and diplomatic affairs is biased towards the northwest, the reclamation of farmland in the northwest region is very vivid. The forest and pastoral areas in the loess plateau have opened up large areas of farmland and cultivated hundreds of thousands of acres. There are 2-3 mu of cultivated land, and extensive planting and poor harvest have caused extensive damage to vegetation.
Chang 'an, the central city of the Yellow Land with its capital in the Tang Dynasty. In the prosperous Tang dynasty, the national strength reached its peak, and the scale of the capital was of course unprecedented, consuming countless wood. As far as Chang 'an is concerned, in the Tang Dynasty, in addition to logging in nearby mountains such as Baoji, Meixian, Zhouzhi and Huxian, it also went as far as Qishan, Longshan and then Lanzhou (now Lanxian) and Shengzhou (now Erdos Plateau in Inner Mongolia) for procurement.
XII. The forest on the Loess Plateau suffered heavy losses for the fourth time
Kaifeng, the capital of the Song Dynasty, had to go to Luliang Mountain for logging because the mountains in the north and south of the Yellow River near Luoyang had been cut down long ago. At that time, the forest area in the upper reaches of the Weihe River was also violently robbed. History records that just after the founding of the Northern Song Dynasty, it was heavily cut between Qin and Long. Qinling Mountains, Ziwuling Mountains and Luoshan Mountains in Shaanxi, Helan Mountain and Dapan Mountain in Ningxia, Zhaohe River and Longnan Mountain in Gansu, and forests have been destroyed successively. In the Song Dynasty, officials and merchants collected more than 1, large trees from Longshan Mountain between Shaanxi and Gansu every year, which made the good trees in Kaifeng city pile up like mountains at that time, and private merchants collected and sold countless wood.
XIII. The forest on the Loess Plateau suffered heavy losses for the fifth time
The Ming Dynasty regained the northwest, and paid attention to cultivating fields, so as to raise troops by stationing them and transfer troops to the people. At that time, "the field was all over the world" and "the northwest was the most". When I was stationed near Yanmen and Pianguan Great Wall in the early Ming Dynasty, there were steep hills and lush trees, so "people can't enter by bike". By the middle of the Ming Dynasty, high-ranking officials and dignitaries in Beijing, border soldiers and local residents had started to cut down trees. "Hundreds of families are in groups, and thousands of people are neighbors, so we can't drive them away, but we can't ban them." There are more than one million trees trafficked to Beijing every year alone.
XIV. The forest on the Loess Plateau suffered heavy losses for the sixth time
After entering the customs in Manchu, the population increased from 8 million to 2 million in just a few decades. North China and Jiangnan are overcrowded, so a large number of refugees spontaneously flock to the northwest. Once again, the Loess Plateau has become the hardest hit area. Before the Ming Dynasty, there were huge trees towering in Qilianshan and Liupanshan, and at this time it was completely a bare mountain.
Today, after fifteen or six thousand years, the forest has dropped from 69% to 6%
Today, after six thousand years, the forest has dropped from 69% to 6% and it has become a veritable loess. Loess itself is loose in soil, without any anti-scourability, and completely depends on the protection of ground vegetation and its roots. The role of plants in soil and water conservation is the most important, followed by grassland, and crops are almost zero. For thousands of years, we have been leveling natural vegetation with protective ability and replacing it with crops without protective ability.
sixteen, alas! Yellow River!
ouch! For thousands of years, we have destroyed the natural vegetation in the middle and lower reaches of the Yellow River with knives and axes and wars. Alas, countless magnificent temples built by trees have been cut down, but now they are safe?
Yellow land is deep and fragile. Because of its loose soil and fine particles, once the vegetation is destroyed, soil erosion is extremely serious. Soon we heard a sad sigh: "Initiate the river clearing, what is the life geometry?"
XVII. Depth of gully damaged by vegetation on the Loess Plateau
At present, there are more than 3, gullies with a length of more than 1 km on the plateau, and there are countless branch gullies and hair gullies with a length of less than 1 km. The final destination of gullies is the Yellow River, which keeps cutting the Loess Plateau and becomes the main source of sediment in the Yellow River.
18. The vegetation on the Loess Plateau is destroyed, and the ecological environment is not what it used to be.
Walking on what we call the Loess Plateau today, our eyes are full of rugged, cracked and fragmented loess, with no trees or even grass. How many people have deeply lamented: How can our ancestors give birth to such a splendid civilization in such a harsh natural environment?
what they don't realize is that green was the main color here until 6 years ago, when the forest coverage rate was as high as 69%.
XIX. A rainstorm changed dramatically
With the decrease of vegetation coverage, river gullies on the plateau cut down strongly, and at the same time they extended upward, both sides widened, and branch gullies developed, and branch gullies developed into hair gullies. Such a change often takes only a few years, months, days or even a rainstorm, so the Loess Plateau is also called the region with the fastest terrain change in the world.
2. 9% of the 1.6 billion tons of sediment dumped annually comes from the Loess Plateau
1.6 billion tons of sediment dumped annually, and 9% comes from these gullies on the Loess Plateau. The loss of 1.6 billion tons of soil every year is not just to dye a river shocking yellow. It went down with the water, silted up the lake, washed away the hills, raised the riverbed and washed away the plain.
Two breaches in twenty-one or three years, and a great diversion in a hundred years
The Yellow River has become increasingly tyrannical, and "two breaches in three years, a great diversion in a hundred years", and the mother river has finally become "the worry of China". Fighting against the Yellow River floods has become a top priority for life and death in the Central Plains.
twenty-two, guarding the Yellow River is short of water. Zhengzhou can be an example of the middle reaches.
Zhengzhou was originally prosperous because of water. It is close to the Yellow River, and Jia Luhe, Xiong 'er River and Jinshui River flow through the city. However, with the great development of industry and agriculture, the pollution is getting worse, the water diversion channels are criss-crossing, and the three rivers that once flowed endlessly have dried up. By the 197s, Zhengzhou had completely relied on the Yellow River for water supply.
23. Shandong is short of water, and the closer it is to the Yellow River, the more water is scarce.
Shandong's water resources situation is even more tense, with population and cultivated land accounting for 7.2% and 7.3% of the country respectively, while the total water resources only account for 1.2% of the country. The per capita water resources is only 3 cubic meters, which is 13.3% of the national average. Each hectare of cultivated land occupies 456 cubic meters of water, which is 17.3% of the whole country. However, the closer we get to the Yellow River, the more water resources are in short supply. The runoff in the Yellow River area drops to only 6 mm, and it is only 25 mm in Linqing and guanxian areas in northwest Shandong.