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The Yellow River cut-off problem

The Yellow River originates from the northern foot of bayan har on the Qinghai-Tibet Plateau and is the second longest river in China, with a total length of 5,464 kilometers.

Qinghai, Sichuan, Gansu, Ningxia, Inner Mongolia, Shaanxi, Shanxi, Henan and Shandong provinces are injected into the Bohai Sea.

. The Yellow River nourishes people on both sides of the strait, and people on both sides of the strait cannot do without it. So, how much water resources does the Yellow River have?

And then what? According to the national water distribution plan of the Yellow River, the annual runoff of the Yellow River is 58 billion cubic meters, of which 37 billion cubic meters.

Rice is used for agricultural irrigation, industrial production and urban life in the provinces along the Yellow River, and 2 1 100 million cubic meters is used to scour the downstream rivers.

Sediments in the river bed. However, the actual water consumption of the former greatly exceeds 37 billion cubic meters, second only to more than 50 cities along the Yellow River.

The city's industrial and agricultural production and urban and rural residents use more than 30 billion cubic meters of water, but the amount of sand washing water can not be guaranteed, which aggravates this situation.

Sediment deposition in the downstream is reduced, and flood discharge capacity is weakened.

In order to fight drought, various water conservancy facilities are aimed at the Yellow River. Mr. Wang Hao, China Institute of Water Resources Science (1999)

Said: "The Yellow River cut off is the result of the interaction between natural factors and human factors. The root cause of disconnection,

Or a large increase in water use outside the river, disorderly water diversion. Measured average runoff since Huayuankou 1990.

It is about 850 cubic meters per second, but the water diversion capacity of the downstream embankment is as high as 4000 cubic meters per second, resulting in a large number of disorderly diversions.

Water can be cut off at any time. "

More and more water resources are consumed by human activities in the Yellow River Basin, which moistens the largest river in this basin-the Yellow River Road.

The traffic is drying up. The average cut-off length of the Yellow River was 242 kilometers in the 1970s and 256 kilometers in the 1980s.

It reached 392 kilometers in the 1990s. Before the 1990s, the cut-off mainly occurred in the estuary area. 1992 ~ 1994, broken

The flow direction extends to the vicinity of Jinan, Shandong; The cut line at 1995 extends above Jiahe beach in Henan, with a length of 683 kilometers; 199

In 7 years, it extended to Kaifeng, Henan, with a total length of 704 kilometers, accounting for more than 90% of the length of the main stream in the lower reaches of the Yellow River. According to profit

According to the measured data of Tianjin Hydrological Station, water was cut off for 70 times in 20 years, ***908 days, with an average of 45 days, including 199.

7 years separated by 226 days. At the same time, the discharge of the Yellow River into the sea is decreasing, with an average annual rate of 1990 ~ 1994.

The volume is only 65.438+084 billion cubic meters, which is equivalent to the average annual inflow of 28.6 billion cubic meters in the 1980s and 64% of the average in the 1970s.

They all entered 59% of the huge 37 1 100 million cubic meters and 47% of the annual average of 49.2 billion cubic meters in the 1960s. Some experts

It is predicted that if calculated in five years, the lower reaches of the Yellow River will be cut off every year by 2000, which will reach 2.

In 2020, the lower reaches of the Yellow River will dry up all the year round, and the Yellow River will become an inland river.

The more dangerous signal is that in the past, the Yellow River was only cut off in the downstream, and now the upstream source area is also beginning to flow out.

Now cut it off One of the 1999 "Top Ten Environmental News in China" awarded by China Environment News is: "Qinghai Province.

The main stream of the source of the Yellow River in maduo county has been cut off for nearly 8 months, which is the first time in the history of the source of the Yellow River.

The first cross-year deadline appeared. "Zhaling Lake (covering an area of 526 square kilometers) and Eling Lake are located at the source of the Yellow River in maduo county.

The lake (with an area of 6 10.7 square kilometers) is the source of the Yellow River,199810 February 2-1999 June 3,

Since the interruption of 1997, there has been a second interruption. The water yield of Erling Lake 1993 is 7.80m3/s,

1995 dropped to 2.7 1 m3/s, the third largest lake in maduo county-Donggetona River and Lake, and the water level has dropped vertically.

2 ~ 3 meters, the lake is reduced by 30 meters. According to the latest statistics of maduo county, there are more than 2,000 4,077 lakes in the county.

A small lake has dried up, and the new highway can go directly through the center of the dried-up lake. Wind erosion activities in the territory have been strengthened, and Xingxingxia

The original semi-fixed sand dunes in this area have become mobile sand dunes. The deterioration of ecological environment in the source area of the Yellow River is increasingly threatening animal husbandry.

The survival of the people also makes the runoff in the source area of the Yellow River smaller and smaller.

(4) Desertification

Drought and desertification have become one of the most serious problems threatening the living environment of China. Covers an area of 40%

% of the northern region is dry, which is mainly manifested in the decrease of rainfall, the drying up of river networks, the shrinking of lakes, and the rise of snow lines and soil.

Desertification and ecosystem degradation. According to the observation data obtained in recent years, a large number of lakes on the Qinghai-Tibet Plateau have been degraded.

More than 30% of lakes have dried up into salt lakes, and the cumulative water shortage has reached 654.38+048 billion cubic meters. Lake surface in Xinjiang

Compared with the 1950s, this product has shrunk by 4,952 square kilometers.

Glaciers are valuable fresh water resources. From 1979 to 1998, the national snow area decreased by 1 1%.

From 1956 to 1976, the average retreating speed of mountain glaciers is16.8m/year in the east and 2.2m/year in the west.

Far more than the general retreat of ocean glaciers. According to the analysis of remote sensing measurement, Gangjia Quba Glacier at the source of the Yangtze River

In the past 30 years, glaciers have retreated by 600 meters, with an average annual retreat of 20 meters.

Drought promotes desertification, and desertification intensifies drought. Song Zongyi, Institute of Rural Development, China Academy of Social Sciences

The researcher (1999) wrote that desertification in China is large in area, widely distributed and seriously harmful.

One of the most important countries The area of desertified land in China is 2.622 million square kilometers, accounting for 27.3% of the total area of the country.

Covering 13 provinces, autonomous regions and municipalities, including 90 in Shaxian County and 508 in Pianshan County, with nearly 400 million people affected.

. According to estimates, the direct economic loss caused by desertification in China reaches 54 1 100 million yuan every year, and the indirect loss is even greater.

Due to deforestation, climate change, population explosion, over-cultivation and grazing, desertification is advancing from south to east.

Desertification reduces species and biodiversity, creates "environmental refugees" and forces people to leave their homes to look for them.

New living environment. The area of desertification in China has exceeded the total area of cultivated land in China, with an annual area of 2460.

The speed of square kilometers is expanding, forcing some rare and sensitive species to survive. For example, desertification in Xinjiang

In the grassland area, when the wind blows, sand and stones fly, and sand and stones flow with the wind, which is more than 0.270 square kilometers per hour.

The speed of advancing to the grassland is shocking.

About 200 million mu of farmland in the "Three North" area of China is often harmed by sandstorms; There are 65.438+0.5 billion mu of grassland desertification and grassland.

Degradation, the carrying capacity of livestock decreased; Thousands of reservoirs and a large number of irrigation canals were blocked by sandstorms; There are 80

Railways over 0 kilometers and highways over thousands of kilometers are often threatened by sandstorms. According to 1999+ 15, People's Political Consultative Conference reported in February.

Report: A windbreak and sand-fixing forest with a length of 154 km and a width of 50 meters in Bayannaoer League section of Wulanbuhe Desert in Inner Mongolia.

Belt, now basically has become a barrier to wither. Yellow sand is threatening the Yellow River and baotou-lanzhou railway at a speed of 5-8 meters per year.

And 1 10 national highway. Many floodgates in the main canal of Dengkou County were destroyed, and quicksand overflowed the levee, devouring nearly 10,000 mu of fertile land. river

Road siltation is more than 4 meters higher than the county seat. 1993 sandstorms occurred many times, which increased the amount of sediment discharge and led to the deformation of the river bank.

It has become an 80-square-kilometer yellow flood plain.

The situation of desertification control in China is still that the speed of control can't keep up with the speed of destruction. Desertification land also has the ability of self-recovery.

Function, but man-made destruction often makes it difficult for desertification land to restore vegetation on its own, taking Qinghai as an example. Qinghai province

Located at the source of the Yellow River, the natural conditions are harsh, the ecological environment is fragile, it is difficult to protect the ecological environment, and it is naturally balanced.

Once destroyed, it is difficult to recover. At present, Qinghai is facing more and more serious disasters (including natural disasters and man-made disasters).

Problems: First, grassland degradation. At present, there are 410.3 million hectares of degraded grassland in the Yellow River basin of the province, accounting for the total of the province.

1/4 of grassland. Among them, the desertification area is1130,000 hectares, and it is increasing by 40,000 hectares every year.

It's huge. In 1980s, due to the influx of gold diggers into Qinghai, they engaged in illegal plunder at the expense of the environment.

Grab mining leads to the fragile ecological environment deteriorating again and again. Most of the grasslands at the source of the Yellow River are alpine grasslands.

And 1 hectare of grassland can feed a sheep, and once it is destroyed, it will be very pitiful.

It is difficult to recover. After the grassland becomes bare soil, it will go through a hundred or even a thousand years of natural recovery. The source of grassland destruction

, leading to desertification and water conservation function decline, so that the Yellow River runoff has a decreasing trend; Second, grasslands and vegetation retreat.

, leading to serious soil erosion. The area of soil erosion in the Yellow River basin in the province is 7.5 million hectares, accounting for the whole flow of the Yellow River.

17.5% of the soil erosion area, the sloping farmland in the eastern arid mountainous area loses 30 ~ 40 tons of topsoil per hectare every year.

Therefore, the sediment concentration of the Yellow River is increasing year by year. The cultivated land in Huangshui River Basin is reduced by nearly 10,000 mu every year due to soil erosion, and it flows every year.

The loss of nitrogen, phosphorus and potassium is more than 230 thousand tons, which is more than twice that of agricultural chemical fertilizer in Qinghai Province from 65438 to 0985. Shizo

Drought causes snow line to rise, snow to decrease, and lakes to shrink or dry up. 1997 Qinghai Lake is lower than 1908.

After11.12m, the average flow of Huangshui, the main tributary of the Yellow River, decreased from 65438+20.5m3 per second before 0990.

26.3%. 1997, the inflow from the upper reaches of the Yellow River also fell to the lowest point in history, and large-scale inflow such as Longyangxia and Lijiaxia appeared.

Compared with 1995, Kubu stores 2.49 billion cubic meters less water.

Recently, the national key basic scientific research project "Evolution of Human Settlements in China and Prediction of Drought Trend in Northern China"

The research has achieved phased results (see Science Times, February 65438+February 65438, 2000). Researcher Fu Yunbin pointed out

: "The drought in northern China, which accounts for 40% of China's land area, is an abnormal change of the whole environmental system, which is probably,

It is a comprehensive expression of that influence of global war on local living environment. Academician An Zhisheng pointed out: "Preliminary analysis

The results show that there has been an obvious trend of drought in northern China in the last hundred years, especially in the last 30 years. ...

According to the data, since the 1960s, the drought index in Northeast China and North China has obviously increased. Soil moisture in recent 50 years

The data shows that the drought is the most serious in the North China Plain and the western part of the northwest. The Ice Core of Rongbu Glacier in the Far East of Mount Everest

Records show that the glaciers on the north slope have been retreating since the 1960s. Drought statistics show that 60.

Since 1990s, the arid areas in Northeast China and North China have been increasing continuously. On-the-spot investigation in western Northeast China and eastern Inner Mongolia

It is confirmed that drought and desertification are intensifying. "One of the main factors causing this grim situation is people.

Unreasonable activities destroy the ecological environment, focusing on the unreasonable use of water resources and land. Is unreasonable.

Under the action of human activities, drought and the deterioration of ecological environment promote each other and form a vicious circle.

At the beginning of 200 1, the State Environmental Protection Administration and China Academy of Sciences jointly organized a scientific investigation activity of "Exploring Sandstorms".

The survey results show that "sandstorm has nothing to do with native desert, and human activities should bear the main responsibility". so-called

Sandstorm: "The real sand does not come from the original desert Gobi, but from human activities on the surface."

Desertification areas after disturbance and vegetation destruction. The Gobi Desert in China was 2 million years ago.

After the uplift of the Qinghai-Tibet Plateau, it was formed due to the arid climate in the west, and the fine materials on its surface passed through a long land.

The geological period has long been blown away by the wind, leaving the gravel on the Gobi and the coarse sand on the desert surface. place

Therefore, in human history, especially in the past 50 years, the sand source areas of sandstorms mainly come from the process of land degradation.

It causes desertified land. ""Sandstorm is the product of the interaction between weather process and ground process. It mainly

It occurs in desertification and prone areas with drought and water shortage, sparse vegetation and serious interference from human activities. China building

The area around Kelamagan Desert and the area west of Helan Mountain are controlled by continental climate, and lack of rainfall all the year round is beneficial to the land.

Oasis irrigated agriculture; The main factors and manifestations of desertification are improper allocation of water resources in the middle and upper reaches and improper allocation of water resources in the lower reaches.

Wandering farmland is due to water shortage or blind reclamation in the transition zone between desert and oasis, or grassland is exhausted by surface water.

The groundwater level drops, natural plants die and wind erosion increases; The east is affected by the East Asian monsoon, with summer and autumn.

A certain amount of precipitation, desertification mainly occurs in the ecotone between agriculture and animal husbandry, winter and spring dry season, deforestation, strict grassland.

Overloading, etc. , mainly manifested in soil desertification, gravel, shrub desertification and sand activation.

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