What is the reason for the huge losses caused by frequent floods in our country?

The reporter learned from the Ministry of Water Resources: At present, floods have occurred in many areas, and the floods in the Yangtze River and Taihu Lake basins have entered the main flood season. According to **, some rivers in the north may flood in the future, and our country has entered the main flood season, and flood control has become the main goal in the near future.

According to the meteorological department** and analysis, the rainfall will increase significantly throughout the country in the coming months of this year, and there are rain areas in the north and south, mainly in the northern rain belt. The rainy areas in northern China are mainly distributed in Northeast China, North China, Huanghuai and most of the east-northwest, among which the rainfall in southern Shanxi, southern Hebei, Shandong, northeast Heilongjiang, western Inner Mongolia and southwestern Xinjiang may be 30% to 50% more than normal in the same period. Therefore, regional floods in the middle reaches of the Yellow River, Haihe River system, Songhua River, Liaohe River and other rivers are very likely, and mixed rainfall and snowmelt floods are likely to occur in some areas of Xinjiang.

The reporter learned from the emergency management department that until recent days, the floods have caused 19.38 million people in 26 provinces (autonomous regions and municipalities) including Guizhou, Sichuan, Hunan, Guangxi, Guangdong, and Hubei, and 10,000 people have been urgently resettled. 355,000 people in need of emergency life assistance this year; 17,000 houses collapsed and 218,000 were damaged to varying degrees; Up to 1.56 million hectares of crops were affected, of which 160,000 hectares were not harvested; Lost 100 million yuan of direct economy.

The relevant person in charge of the Ministry of National Defense said a few days ago that the total amount of local rainfall in recent days has been high in intensity. Since the flood season, the daily precipitation of 75 counties (cities) has exceeded the extreme value of the month nationwide, and the precipitation has exceeded the extreme value of the current quarter in 32 counties. In addition, the flood situation of major rivers is generally stable, and the flood of small and medium-sized rivers is relatively large. There are many dangers, for example, there are more and more flash floods and geological disasters.

The power of the typhoon is not so strong in the early stage, but it begins to strengthen in the later stage; The drought was generally mild, and some floods were more severe. The relevant responsible person of the Ministry of National Defense claimed that it is necessary to continue to implement responsibilities and further strengthen the responsibility system for flood prevention and disaster relief with the responsibility system of the chief executive as the core. Investigation and rectification of hidden dangers have been gradually strengthened, and then important flood control projects, key parts, and dangerous areas have been investigated and rectified.

There are two reasons for this, one is the weather, the rainy season comes too early but retreats very late, and the second is the economic reason, the expansion of the wheat sowing area, as soon as the floods come, it will be all in vain, which will cause huge losses.

There are natural disasters and man-made disasters, powerful weather, induced disasters, and defensive measures, which are old or not enough to reinforce, or people underestimate the disaster, and so on, which cause huge losses.

It is because of the imperfect sewer measures in our country that it will lead to frequent flood disasters, the imperfect hardware facilities of the sewers, and the imperfect drainage system.

May to August is the rainy season, especially in the southern region, when it is rainy, and at the same time it is affected by typhoons, and when the wind and rain are heavy, the momentum cannot be stopped.

There are two conditions that must be met for the formation of a disaster: natural conditions and socio-economic conditions.

1. Natural conditions:Floods are the direct cause of flood disasters. Disasters can only occur when the intensity of natural variation in floods reaches a certain standard. The main influencing factors are geographical location, climatic conditions and topography.

2. Socio-economic conditions:Floods can only be a disaster if they occur in a place where there is human activity. The areas most threatened by flooding tend to be in the middle and lower reaches of rivers, which are often economically developed due to their abundant water sources and flat land.

The threat of flood disasters will restrict social and economic development and affect the safety of people's lives and property.

Floods can be classified as river floods, lake floods, storm surge floods, etc. Among them, river floods are divided into the following types according to their causes:

1. Heavy rain flood: It is the most common and threatening flood. It is formed by heavy rainfall, also known as rainstorm.

2. Flash flood: It is a flood that swells and falls sharply in mountain streams and ravines after heavy rainfall. Mountain floods have the characteristics of suddenness, concentrated rainfall, and strong destructive power, and are often accompanied by disasters such as debris flows, landslides, and landslides.

3. Snowmelt floods: mainly occur in high-latitude snow-covered areas or alpine snow-covered areas.

4. Ice floods: often occur in northern rivers such as the Yellow River and the Songhua River. Because a certain section of the river flows from low latitude to high latitude, when the temperature rises, the upstream of the low latitude section thaws first, while the high latitude is still frozen, and the upstream water and ice accumulate on the downstream riverbed, forming an ice dam and causing flooding. In addition, ice flooding can occur when rivers freeze.

5. Dam failure flood: It is a flood caused by the sudden burst or collapse of a dam or reservoir.

In addition, waterlogging is divided into waterlogging and "door-to-door waterlogging". Waterlogging refers to the formation of waterlogging when excessive precipitation is not discharged from the river in time.

The direct cause of flood disasters in China is the strength of monsoon activity.

In years with strong summer monsoons, short stay in the south, little precipitation, and arid; The advance to the north is early, the stay time is long, and a large amount of precipitation is formed, often forming floods.

Flood disasters include flood disasters and rain and flood disasters, among which, due to heavy rainfall, ice and snow melting, ice cubes, dam bursts, storm surges and other reasons caused by the increase of water volume in rivers, lakes and coastal water, flooding and flash floods are called flood disasters; Disasters caused by heavy rain, heavy rainfall or long-term rainfall that produce a large amount of stagnant water and runoff, and the drainage is not timely, resulting in waterlogging and flooding of land and houses is called rain and flood disasters.

Natural disaster.

Natural disasters and floods are the direct cause of flood disasters.

Flood disasters include flood disasters and rain and flood disasters. Among them, the disasters caused by heavy rainfall, melting of ice and snow, ice and snow, ice storms, dam bursts, storm surges and other causes of increased water volume in rivers, lakes and coastal areas, flooding of water levels and flash floods are called flood disasters.

Flooding is heavily related to the monsoon climate.

Precipitation is concentrated in the summer.

During the flood season, the river water rises sharply, causing the river to drain poorly.

The vegetation in the basin area is destroyed, the soil erosion is serious, and the sediment content is large. The middle and lower reaches are generally plain areas, with slow flow rates and easy to form floods.

The strength and retreat of the summer monsoon are different.

<>1.Causes of flooding.

Under normal circumstances, water flows within river channels or is stored in lakes, soil, or oceans. But the amount of water flowing is not always the same. When there is a sudden increase in the flow of water, it is called a "flood".

If the river flood is too large and the river channel cannot hold all the water, the flood water will overflow the river and inundate the surrounding areas, causing flooding.

Rain is the most important thing for flooding**. When it rains, rainwater flows into the river and increases the water in the river, so if there is a lot of rainfall in one place and it lasts for a long time, flooding may occur. The accumulation of rainwater in cities is also known as waterlogging.

In addition, snow is the second most common cause of flooding**. In some places, the snow and ice in the mountains melt and flow into the river, greatly increasing the flow of the river.

In coastal areas, storms and waves at sea are also one of the most popular floods. In the summer, active typhoons bring a lot of rain to these areas. In some cases, strong winds can push seawater towards coastal areas, causing severe flooding.

2.The fundamental reasons for the frequent occurrence of flood disasters in China are as follows:

The area is vast, and when the summer enters the flood season, a large area rains at the same time, and the flood rises sharply, which is prone to flooding.

Large main streams, such as the Yangtze River and the Yellow River basins, have a large area and have been flowing into the sea for a long time, and the flood they carry is easy to reach their peak, then serious flooding has occurred.

Some rivers carry large amounts of sediment. When the sand and gravel in the river reaches downstream, it is deposited, causing the riverbed to be shallow, silting up the river channel and reducing its capacity. When heavy rain occurs, floodwaters overflow the river and cause flooding.

Global warming caused by the greenhouse effect: It is characterized by an increase in the frequency of heavy rainfall, or an instantaneous increase in rainfall brought by tropical depressions or typhoons. In addition, the rise in the global sea level caused by global climate change will also increase the water level datum, resulting in the impairment of the function of flood control facilities.

Human factors: indiscriminate reclamation, soil erosion, because trees can fix the water and soil, deforestation will lead to the weakening of the soil's water absorption capacity, and the soil surface will accelerate erosion due to the loss of vegetation protection, so every time it rains, rainwater and sand will quickly flow downhill and flow into the river, causing siltation, and the possibility of flooding will increase. In addition to deforestation, poor farming practices and overgrazing on hillsides have deprived the land of vegetation protection and accelerated soil erosion on slopes.