Weather forecast for the next 30 days in Laizhou
We know that the general trend of precipitation in China is more in the east and less in the west, more in the south and less in the north, more in summer and less in winter. In the past, due to the uneven distribution of rainfall in time and space, local floods occurred in years with more rainfall and droughts occurred in years with less rainfall.
In addition, with the development of industrialization and the increase of world population, the demand for fresh water resources has soared, especially in some highly industrialized areas, so that some parts of China are short of fresh water resources.
If we can store the fresh water resources of the Yangtze River and the Yellow River, we can greatly alleviate the demand for fresh water in water-deficient areas, but why don't we do this and let the Yangtze River and the Yellow River flow into the sea in vain?
According to the statistics of the Ministry of Water Resources, 400 of the 669 cities in China are short of water, and 1 10 is seriously short of water, among which 9 cities such as Beijing, Tianjin, Qingdao and Dalian are the most seriously short of water.
The annual runoff of the Yangtze River is more than 960 billion cubic meters, and the annual runoff of the Yellow River is about 57.4 billion. So much water flows into the sea for nothing. Why can't it be stored to solve the urgent need?
In fact, the birth of human civilization is inseparable from water. In ancient times, limited by traffic and technology, people could only develop agriculture on both sides of the river. On the other hand, it is the great rivers that promote human civilization. Among the four earliest ancient countries, each country has a river, such as Ganges and Indus in ancient India; Tigris and Euphrates rivers in Babylon, Cuba; The Nile in ancient Egypt; The Yangtze River and Yellow River in China.
However, living around a big river has a disadvantage, that is, the river will overflow, so at the beginning of many civilizations, there are legends of great floods, such as Noah's Ark in western stories and Dayu in China's flood control.
Roughly speaking, the storage capacity of the Yangtze River is 2800+ 130 (South-to-North Water Transfer Project) = 293 billion cubic meters, which is close to 1/3 of the total runoff of the Yangtze River. About two-thirds of the water flows into the sea in vain. The main problem at present is how to store the water in the middle and lower reaches of the Yangtze River.
I have read the related materials of colored leaves. The previous com. The reason why the water resources of the Yangtze River are so large is related to the fact that its source is the Qinghai-Tibet Plateau. Many peaks here have reached an altitude of more than 6,000 meters, and perennial snow is the most typical geographical feature of this area. In addition, the 2000-meter-high alpine canyon in the Jinsha River section, the Tiger Leaping Gorge with a drop of 2 10 m and a total length of 17 km, contributed to the formation of rich water resources here.
The Yangtze River is the fourth largest river in the world, but it is better for us to be afraid of some. After all, this is a flow of more than 960 billion, and it cannot be swallowed at one gulp to achieve arbitrary regulation. This is good, and it can also retain the basic attributes of rivers, which plays an important role in maintaining the ecological balance of the Yangtze River basin.
In other words, in order to make full use of water resources, we have built many large-scale projects, which can be described as "squeezing out" the value of every drop of water.
However, the reason why the Yangtze River and the Yellow River still discharge more fresh water resources into the sea every year is actually because of the large amount of water in the Yangtze River and the Yellow River. If all of them are intercepted, most parts of China will be flooded, so the water that should flow to the sea will still flow.
Moreover, creatures in the water need to flow into the sea. If the waters of the Yangtze River and the Yellow River stop flowing into the sea, many creatures will not be able to reproduce or survive, or even become extinct.
Of course, even if we build more dams to completely control the flow of the Yangtze River and the Yellow River, it is theoretically difficult to realize the utilization of all water resources. Because reservoirs and lakes have many functions, such as prevention, drought resistance, navigation and sediment regulation, it is impossible to ignore other functions such as flood control, navigation and sediment regulation in order to store water resources. For the simplest example, the weather forecast suggests that there will be a continuous heavy rainfall in the upper reaches of the Yangtze River in the future, and the inflow will exceed the storage capacity of the Three Gorges Reservoir. Only the storage capacity can be vacated in advance to reduce the flood peak. After all, flood control is the biggest function of the Three Gorges Dam.
In addition, both the Yangtze River and the Yellow River actually contain a lot of sediment, but the Yangtze River is not so obvious. Water storage in rivers is not as simple as water tanks at home. Every time a river is intercepted and stored for a period of time, it will produce a lot of sediment at the bottom of the river. If it is not discharged in time, it will cause large-scale siltation. Dongting Lake is actually a living case, so artificial water storage is only temporary.