What are the hazards of the Yellow River? What is the harm of the above ground river of the Yellow

The main hazards of the Yellow River are flooding.

Most of the floods in the upper reaches of the Yellow River occurred in September, mainly from above Lanzhou, and the floods in Lanzhou mainly came from above Guide. Due to the long duration and low intensity of rainfall, coupled with the good vegetation above Lanzhou, the grassland and swamp have a strong effect on rainfall, resulting in a gentle flood rise and fall in the upper reaches of the Yellow River, with a long flood duration, low flood peak, and a short and fat flood process line.

A flood at Lanzhou station lasts an average of 40 days, the longest is 66 days, and the shortest is 22 days, and the measured peak flood flow is generally 4000 6000 cubic meters per second.

The upper reaches of the Yellow River are mostly canyon sections, regardless of the size of the flood, the general propagation time changes little, it takes about a few days from Guide to Lanzhou, and about a day from Lanzhou to Hekou Town. The flood in the upper reaches of the Yellow River and reaches the middle and lower reaches, which generally become the base flow.

The actual flood data of the upper reaches of the Yellow River began after the flood in 1933, when hydrological stations were set up in Lanzhou, Baotou and other places. The largest flood measured occurred in 1946, with a peak flow of 5,900 cubic meters per second at Lanzhou Station and a total flood of 6.5 billion cubic meters in 15 days.

In the 1981 flood, although the peak flow of Lanzhou Station was only 5,600 cubic meters per second, without the construction of the cofferdam of Longyangxia Reservoir and the storage of Liujiaxia Reservoir, the peak flow of Lanzhou Station could reach 7,090 cubic meters per second. According to the survey, the largest historical flood in the upstream area occurred in 1904, and the peak flood flow of Lanzhou station reached 8,600 cubic meters per second.

After the Yellow River enters the lower plains, the water flow is slow, and a large amount of sediment from the middle reaches is silted, and the riverbed continues to rise, and finally rises above the ground on both sides to form an "above-ground river".

For a long time, embankments have been built to contain flooding, resulting in an increasing difference in elevation between the riverbed and the ground on both sides. Historically, the lower reaches of the Yellow River have breached and flooded many times, bringing profound disasters to the people of the North China Plain. The areas on both sides of the river face the threat of flooding during the flood season, and once the levee bursts, it will bring immeasurable harm.

In addition, the "above-ground river" of the Yellow River causes no tributaries to flow in, so that the water volume of the Yellow River decreases as it goes downstream, and then the flow of the Yellow River is cut off. The amount and difficulty of building embankments for flood control are increasing year by year, and the input cost is also increasing year by year.

Soil erosion on the Loess Plateau has taken away a large amount of topsoil, resulting in thinner soil layers, loss of soil nutrients, and deterioration of cultivated land quality, resulting in a decrease in crop yield per unit area. At the same time, a large amount of sediment flows into the Yellow River, causing the sediment content of the Yellow River to increase dramatically, and silting up in the lower reaches, raising the riverbed and forming an above-ground river, seriously threatening the safety of people's lives and property in the areas on both sides of the river.

The main reason is that the flood storage capacity is poor, and it is easy to burst, resulting in large-scale flood disasters.

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Analysis: Water pollution in the Yellow River Basin seriously endangers the "Three Rural Areas".In late May, reporters visited the banks of the Yellow River in Gansu, Ningxia, Shaanxi and other provinces and regions, and witnessed first-hand the current situation of water pollution in the middle and upper reaches of the Yellow River and the increasing harm.

With the increase of urban industrialization, the pollution of the Yellow River Basin has formed a severe situation of coexistence of point source and non-point source pollution, superposition of domestic pollution and industrial emissions, and the combination of various new and old pollution and secondary pollution, and the pollution level of the Yellow River is far greater than that of the Huai River. The polluted Yellow River has afflicted 160 million urban and rural people in north-west and northern China, and the hardest hit are agriculture, rural areas and peasants.

1. The harm of water pollution in the Yellow River to people's health.

2. The frequent interruptions of the lower reaches of the Yellow River have directly affected the water used for urban and rural life and industrial and agricultural production that depend on the Yellow River's water supply.

3. The Yellow River has reduced biodiversity and lost biological populations and genetic diversity.

4. The imbalance of the water environment of the delta wetland seriously threatens thousands of aquatic organisms in the wetland reserve.

5. Cause the number of biological populations to decrease, and the structure tends to be simple.

There are many reasons for the water pollution in the Yellow River Basin, which can be summarized as follows. (1) Some large and medium-sized cities in the basin are located near the river, and some large industrial and mining enterprises are also distributed along the river. At the beginning of the 90s, there were 20 million people in cities and towns in the basin, of which more than 2 3 were concentrated in these cities and industrial and mining areas.

Advantage. 1. The Yellow River has shaped the Ningxia Plain and the Hetao Plain, which are known as the "Plugging the Yangtze River", and is also one of the main shapers of the North China Plain, one of the three major plains in China.

2. The Yellow River contains abundant water energy resources, which provide abundant water energy for the development of industry and agriculture in the upper and middle reaches of the Yellow River.

3. The Yellow River flows through arid and semi-arid areas, most of which lack precipitation, and the Yellow River water provides abundant irrigation water sources, which makes the land here vibrant.

Harm. The main disaster brought to us by the Yellow River is that the downstream is prone to breach and divert its course. The reason for this is that the downstream riverbed is higher than the ground, forming an "above-ground river".

Because the middle reaches of the Yellow River flow through the Loess Plateau, where soil erosion is very serious, the Yellow River has become the river with the largest sediment content in the world. The lower reaches of the Yellow River flow through the plains, and the water flow is slow, and a large amount of sediment carried by the river water is deposited, making the riverbed silt up and become an "above-ground river".The embankments on both sides of the river are in danger of bursting anytime and anywhere during heavy rainfall, making it the most difficult river in the world to manage.