What are the levels of flooding?

The flood classification is as follows:

1. Floods with a return period of less than 5 years are small floods;

2. The return period of flood elements is 5 years and 20 years of floods, which are medium floods;

3. The return period of flood elements is 20 years, and the flood of 50 years is a major flood.

4. A flood with a return period of more than 50 years is a catastrophic flood.

The flood element items in the estimated return period include the peak flood level (flow) or the maximum flood volume during the period, which can be selected according to the hydrological characteristics of the river (river section).

The causes of the formation of floods are:

Floods are torrential rains, sharp melting of ice and snow, and storm surges.

and other natural factors caused by the rapid increase in the water volume of rivers and lakes, or the rapid water level is a natural phenomenon.

It's a natural disaster.

Objectively speaking, the frequent occurrence of floods has its irresistible reasons, and it can be said that the "mandate of heaven" cannot be violated.

Compared with historical data, the frequency and severity of floods are quite consistent with the trend of population growth. We have to admit that China's rapid population growth, the expansion of cultivated land, the reclamation of lakes and fields, indiscriminate deforestation and other man-made destruction have constantly changed the state of the earth's surface, changed the conditions of confluence, and aggravated the degree of flooding.

In years with a lot of precipitation, whether floods cause disasters and the magnitude of flood disasters are inseparable from human factors. Long-term deforestation is an important cause of this. As the main body of terrestrial ecosystem, forests have various functions such as water conservation, soil and water conservation, and climate regulation, and have an irreplaceable role in reducing flood peaks.

There is not necessarily a flood, and a small flood can cause a large flood if the forest is destroyed.

Flood rating. Floods are very large runoffs that often overflow because the river channel cannot hold them. According to the water source and the time of occurrence of floods, floods can generally be divided into two categories: spring snowmelt floods and torrential floods.

According to the national standard "Specification for Hydrological Information Forecasting" [GB T 22482-2008], which came into effect on January 1, 2009, floods are divided into four grades: small floods, medium floods, major floods, and extra-large floods, according to the return period of flood elements less than 5 years, 5 20 years, 20 50 years, and more than 50 years.

The flood control level is divided into level 1 emergency response, level 2 emergency response, level 3 emergency response, and level 4 emergency response. A major flood occurs in a certain river basin or a major flood occurs in multiple river basins at the same time, and an embankment in an important section of the main stream of a major river bursts is a level 1 emergency response.

Flood Control Strategy: Since 1949, China's flood control has entered a new period of development. In the 50s of the 20 th century, efforts were concentrated on the cultivation and reinforcement of river embankments, and plans for the comprehensive utilization of major rivers were formulated, especially for flood control in the plain areas of major rivers.

The embankment project has grown from 10,000 km in 1949 to 170,000 km of embankments built and repaired across the country in 1985.

Dredging and renovating rivers at all levels, opening up new flood drainage channels for the Huai River and Haihe River, building flood diversion projects for major rivers such as the Jingjiang River Flood Diversion Project and the Dongping Lake Flood Diversion Project, and building water conservancy projects with greater flood control effects such as the Guanting Reservoir, the Sanmenxia Water Conservancy Hub, the Danjiangkou Water Conservancy Hub, and the Zhexi Hydropower Station, and the flood control system combining engineering measures and non-engineering measures for the lower reaches of the Yellow River, the middle and lower reaches of the Yangtze River, the Huai River, the Haihe River, and other rivers has taken shape. Ensuring the safety of flood control in key areas and cities plays an important role.

It defeated the flood of the Yangtze River in 1954 and the flood of the Yellow River in 1958, and achieved outstanding achievements in the 40 years of the Yellow River's Fuqiu flood without a breach. However, the flood protection standards of major rivers are still relatively low, and many rivers are generally only protected against floods once in 10 or 20 years. At present, the construction of flood prevention projects and non-engineering flood prevention measures is being continued, with a view to gradually improving the flood prevention systems on major rivers.

Legal analysis: According to the actual needs of China's flood control management, according to the return period of flood elements less than 5 years, 5 20 years, 20 50 years, and more than 50 years, floods are divided into four levels: small floods, medium floods, major floods, and extraordinarily large floods, as follows:

1. Floods with a return period of less than 5 years are small floods;

2. The return period of flood elements is 5 years and 20 years of floods, which are medium floods;

3. The return period of flood elements is 20 years, and the flood of 50 years is a major flood.

4. A flood with a return period of more than 50 years is a catastrophic flood.

Legal basis: Flood Control Law of the People's Republic of China

Article 1: This Law is enacted for the purpose of preventing and controlling floods, preventing and mitigating flood disasters, safeguarding the safety of people's lives and property, and ensuring the smooth progress of socialist modernization.

Article 2 The flood prevention work shall be carried out in accordance with the principles of comprehensive planning, overall planning, prevention first, comprehensive management, and subordination of local interests to overall interests.

Article 46 When the water level or flow of a river or lake reaches the flood distribution standards prescribed by the State and it is necessary to activate the flood storage and detention area, the national flood control command organization, the river basin flood control command organization, the people of the provinces, autonomous regions and municipalities directly under the Central Government, and the flood control command organization of the province, autonomous region or municipality directly under the Central Government shall decide to activate the flood storage and detention area in accordance with the conditions and approval procedures stipulated in the flood prevention plan approved in accordance with the law. The use of flood storage and detention areas in accordance with the law shall not be obstructed or delayed by any unit or individual; When obstruction or delay is encountered, it shall be enforced by the local people at or above the county level.

1. Floods with a return period of less than 5 years are small floods; 2. The return period of flood elements is 5 years and 20 years of floods, which are medium floods; 3. The return period of flood elements is 20 years, and the flood of 50 years is a major flood. 4. A flood with a return period of more than 50 years is a catastrophic flood.

Legal basis: Hydrological Information Forecasting Specification" The criteria for the classification of flood grades have been revised, and the flood is divided into four grades: small flood, medium flood, major flood and extra-large flood according to the return period of flood elements less than 5 years, 5 20 years, 20 50 years and more than 50 years, as follows: floods with a return period of less than 5 years are small floods; The return period of flood elements is 5 years and 20 years of floods, and the flood is a medium flood; The return period of flood elements is 20 years, and the flood of 50 years is a major flood; A flood with a return period of more than 50 years is a catastrophic flood.

<> floods are divided into four levels: small floods, medium floods, major floods, and extraordinarily large floods.

1. Floods with a return period of less than 5 years are small floods;

2. The return period of flood elements is 5 years and 20 years of floods, which are medium floods;

3. The return period of flood elements is 20 years, and the flood of 50 years is a major flood.

4. A flood with a return period of more than 50 years is a catastrophic flood.

Flood is a natural phenomenon caused by natural factors such as violent rain, rapid melting of ice and snow, storm surge, etc., or the rapid increase of water level in Xianqing, which is a natural disaster.

Floods are divided into four levels: small floods, medium floods, major floods, and extra-large floods.

1. Floods with a return period of less than 5 years are small floods;

2. The return period of flood elements is 5 years and 20 years of floods, which are medium floods;

3. The return period of flood elements is 20 years, and the flood of 50 years is a major flood.

4. A flood with a return period of more than 50 years is a catastrophic flood.

Flood is a natural phenomenon caused by natural factors such as heavy rainfall, rapid melting of ice and snow, storm surge, etc., or the rapid increase in water level, and is a natural disaster.

Legal Analysis: The levels are divided into: Level I Emergency Response, Level II Emergency Response, Level III Emergency Response, and Level IV Emergency Response.

Legal basis: "Regulations of the People's Republic of China on Flood Control" Article 7 The local people at or above the county level who have flood control tasks shall establish a flood control headquarters, which shall be composed of relevant departments, local garrisons, and people's armed forces responsible for rock search, and shall be commanded by the people's leaders at all levels. Under the leadership of the people's flood control headquarters at the higher level and the people at the same level, the people's flood control headquarters at all levels shall carry out the flood prevention instructions of the higher levels, formulate various flood prevention and flood control measures, and exercise unified command over the flood prevention and flood control work in their respective regions.

The offices of the people's flood control headquarters at all levels shall be set up in the water administrative departments at the same level; The office of the flood control headquarters in urban areas may also be set up in the department in charge of urban construction, which is responsible for the daily work of flood prevention within the area under its jurisdiction.