How many years should flood control be considered in flood control engineering design?

Engineering measures and non-engineering measures

Engineering measures and non-engineering measures have conceptual meanings. Measures aimed at changing flood transport characteristics are called engineering measures, and measures that assist engineering measures to play a role, coordinate the relationship with floods and mitigate the impact of flood disasters are called non-engineering measures.

Non-engineering measures for flood control of flood control reservoirs, dikes, spillways and flood storage and detention areas; Linear structures such as subgrade and fence of high-grade highways (highways and railways) in flood risk areas are considered as engineering measures to some extent, although their original intention is to prevent flooding and obviously change flood transport characteristics.

Non-engineering measures focus on regulating flood control lines and issuing habitual auxiliary engineering measures in flood risk areas to alleviate or alleviate the impact of flood disasters. The formulation and implementation of non-engineering measures, techniques to bring benefits into play, flood characteristics, understanding flood disaster characteristics, flood forecasting techniques, flood risk maps and other means are generally included in the scope of non-engineering measures.

Non-engineering measures improve efficiency and attach importance to the limitations of original engineering measures.

Second, the limitations of engineering measures are facing difficulties.

With the rapid development of economy and science and technology, thousands of classes in flood control and disaster reduction are pursuing the same goal. With the rapid development of economy and technology, the class is full of confidence in their ability to transform themselves and conquer themselves. Countries all over the world have successively formulated the target scale of flood control and disaster reduction. With the understanding of engineering measures, floods and flood disasters are difficult to completely control and can be alleviated and eliminated to some extent.

My flood control practice began in the 1950s. Half a century has passed, and a series of problems faced by my family's flood control project have gradually become prominent.

1, the absolute loss of flood is still on the rise.

Although the flood control project has been interrupted for 50 years, the flood control project system has reduced the average flooded area of the river by 70%, and the absolute value of flood loss has increased, except for the increase of unit area loss caused by economic development and asset appreciation in the flooded area.

2. The dam site of the controlled flood control hub has been exhausted.

Recently, the Huang Helang Bottom Hub, the Pearl River Fei Xia Reservoir, the Three Gorges Hub and the Nenjiang Nierji Hub have been completed one after another, and the construction of flood control hubs to effectively control the flood in the main stream and protect dam sites in important areas has basically come to an end.

3. The economic, social and environmental problems faced by flood control reservoir construction are becoming more and more serious.

Although the main stream, tributaries and basins of Biehe River Basin are still under construction, the construction of Xu Reservoir has changed due to its economic, immigration, equity and environmental impact.

4. Dike construction is facing economic, technical and environmental constraints.

This paper mainly analyzes the flood control engineering system of about 260 thousand kilometers of dikes in China. At present, the average flood loss of rivers in China is 25 billion yuan, as shown in table 1.

For example, in order to prevent the flood of 1954, it is necessary to dig, press, plow and relocate one million people, which is about 7.6 billion m3. Rebuilding culverts, pumping stations and bridges 1 10,000, reducing the cost 100 billion yuan and losing about1200 million yuan, far below the average cost (about 8 billion yuan).

The river dikes in China, especially the main dikes, have always been very high, and there are many hidden dangers in the dike foundation and dike body. The water difference inside and outside the levee has been rescued. If the flood season is improved, the exposure of hidden dangers will be higher. It is difficult to ensure safety, that is, the so-called increase has not raised the standard.

Flood only shapes the floodplain, which has the functions of replenishing water, keeping moisture and maintaining materialization. At present, the humidity in major river basins in China has disappeared except Songhua River, and the water resources on the main front of dike construction are in serious shortage. The Haihe River Basin has improved its control, and the flood will be introduced into the plain area, so irrigation will suffer from continuous inundation losses and realize the function of flood resource utilization.

5. The application of flood storage and detention area is in a dilemma.

At present, there are 97 flood storage and detention areas in China with a total area of about 35,000 square kilometers and a total storage capacity of 97 billion cubic meters. The population of some flood storage and detention areas is about 2 million hm2,170,000 people, which causes two kinds of floods to bear the brunt and has high application frequency. Second, it is necessary to prevent catastrophic floods, protect important areas, and keep Jingjiang flood discharge area, Honghu flood storage area and Jindi flood discharge area on the north side of the Yellow River.

When the river water level reaches a certain height between dikes, it will burst or burst, which will reduce its efficiency or loss, so that some flood storage and detention areas have higher flood control standards. The social and economic development of unused or dozens of unused areas is even faster than that of ordinary people's dikes, and the corresponding management measures are still sound. Flood users are facing enormous socio-economic pressure (1998 adopts the flood control principle of "strictly guarding against death"); If it is difficult to arrange the excess water quantity of special flood, the flood storage and detention area will be in a dilemma.

Three. Legal basis for the construction of non-engineering measures

1, water

Article 10 The water administrative department shall be authorized to work out comprehensive river basin or regional planning jointly with the government, and the construction planning of non-engineering flood control measures shall be professional planning. Article 40 requires the Central Flood Control Headquarters to formulate flood control plans for major rivers and county-level governments. Article 40 stipulates that "flood storage and detention areas of flood control rivers and construction land in flood storage areas must meet the requirements of flood control".

2. Flood control

"Flood control" requires governments at all levels to use flood storage and detention areas for restoration, relief or compensation (Article 7); It is required that flood control planning should follow the principle of combining engineering measures with non-engineering measures, delimit flood areas and flood control protection areas, and apply the principle of flood storage and detention areas (Article 10); Requiring land development and utilization to avoid the threat of mountain torrents (Article 13); It is forbidden to reclaim land around the lake, and it is required to retreat the lake in a planned way (Article 23); Require governments at all levels to implement regional management according to flood control planning (Article 30); Require governments at all levels to strengthen the leadership exhibition of safety construction in flood control areas, popularize flood control knowledge, establish and improve flood control system, hydrology, meteorology, communication, early warning and flood disaster monitoring system according to flood control planning and flood control cases, and take flood control and flood avoidance measures; Require provincial governments to formulate safety construction plans for flood areas and flood storage and detention areas, and organize residents in flood storage and detention areas to move out after use; If the dam can be broken now, a plan for emergency rescue and temporary evacuation of residents should be made in advance (Article 36); In the event of a flood disaster, the government should organize disaster relief personnel to encourage and support flood insurance, such as disaster area supply, health and epidemic prevention, disaster relief materials supply, and school resumption to rebuild homes (Article 47).

Fourth, non-engineering measures construction constraints

1, legally binding

The flood control law and I, including "water" and "flood control", stipulate that the water administrative department and the government should formulate flood control plans including non-engineering flood control measures. Because the law does not clearly stipulate how the government participates in the planning, the scope of flood control planning formulated by the water administrative department can basically be limited to the flood storage and detention areas of rivers and lakes, which is subject to the existing laws or lacks corresponding operational regulations, and the conditions for coordinating the relationship with floods and standardizing flood disaster risks are not yet mature.

2. Social constraints

During the menstrual period, my basin was threatened by floods, and the economy in the flooded area developed. In densely populated areas, it is difficult to reduce flood disasters and benefit social and economic development by permanent flood avoidance measures such as rebuilding homes and restoring productivity without giving flood surplus and returning lakes.

The conflict of social values deeply restricts the demonstration process of the Three Gorges Project under the constraint of flood management. The same understanding of life value, ecological value, residents' right to choose in the reservoir area, regional equity, politics, economy and military issues leads to differences and even conflicts in values, and seeks the coordination and balance of non-engineering flood management tasks.

The effect of flood management affecting social system is especially difficult to predict. It is recognized that early warning of flood can reduce the loss of residents 1/5~ 1/3, and the benefit-cost ratio is 3. 1~7.5. If there is no equal preparation for preliminary research, organization and publicity, it will be difficult to achieve the interests of managers. Traditional customs need to be more cautious, and the response of some management measures often depends on "managers' expectation 1968+0973 that the mandatory provisions of flood insurance plan will take effect before the social response is extremely cold, which shows that flood management policies should adapt to specific social conditions and adjust with the response of social system.

3. Economic constraints

Basic principles that efficiency policy must follow. Using market mechanism to determine the efficiency of flood control engineering measures is easy to develop efficiency or failure in some fields. Although it is difficult to predict the response of non-engineering measures due to the randomness and certainty of floods, it is often difficult to determine their efficiency. Whether the policy economy such as flood risk area, flood storage and detention area, returning farmland to lakes and flood insurance is reasonable is still inconclusive.

4. Administrative restrictions

The implementation of all flood management measures is restricted by the characteristics, structure, quality, authority and financial resources of government departments at all levels. Based on the concept of engineering flood control, dozens of water administrative departments in China have formed a set of flood control engineering systems such as reservoirs, dikes, spillways and flood storage and detention areas, and implemented the pattern of "engineering water conservancy": "non-engineering" flood management measures are difficult to stabilize and have sufficient funds due to historical reasons.

The law gives the water administrative department management authority to limit the comprehensive flood management institutions. In the 1980s, it was suggested that flood management should extend from river courses to flooded areas, which was restricted by the "compartmentalization" of management authority. Up to now, the flood management policy in the flooded area is still under discussion.

Implement non-engineering measures such as flood management and flood insurance. American designers' comprehensive flood management plan and flood insurance federal flood insurance plan authorize the Federal Emergency Management Agency to manage non-engineering flood control measures, so that non-engineering measures can be guaranteed by administrative management.

Verb (abbreviation of verb) The present situation of non-engineering measures construction in China

Up to now, the planning of non-engineering measures in our system is scattered, and non-engineering measures mainly belong to the scope of auxiliary engineering measures that bring benefits into play, such as flood forecasting, gas situation judgment, flood control dispatching and flood control business.

My flood storage and detention areas are basically prepared for emergency flood avoidance. Even if I build a project to improve the water regime of the residents in the flooded area of Jingjiang River, the basic solution is 1998. At present, the organization of flood preparation and transfer is chaotic. The reason why flood storage and detention areas want to know shows that the public's understanding and propaganda of flood control knowledge in China is far from reaching the level where non-engineering measures can play their due role.

Standardizing the Release of Flood Risk Area & Taking You Jiang Flood as an Example 1998 The land development and utilization standard considering flood risk is still blank.

Urbanization of intransitive verbs and the trend of population migration

As a non-engineering measure-the main body of standardizing the construction of flood control and disaster reduction measures in flood risk areas, I am faced with two difficult problems: population and development.

The average area 1 mu of agricultural production mode in flooded areas only gives hope to the sustainable development of rural areas, which seriously restricts the implementation of flood control projects in some areas: it is difficult to change the recognition of flood storage (economic capacity limit), and social problems such as empty mining or wet restoration are serious.

Close to the development of urbanization, take the lead in abandoning land in the southern region, and implement the "32-character" post-disaster reconstruction policy in the main watershed of 1998 to solve the flood risk area and development problems, and provide conditions for non-engineering measures of flood management.

At present, I am in the rapid development stage of urbanization. It is predicted that in 20 1 12030, the urbanization rate will increase from the current 32% to about 40%, and the 50% population will decrease from the current 880 million to about 830 million and 720 million. Considering the two stages of population growth, the rural population will leave the soil and enter the town.

It is expected to develop large-scale agricultural management in line with the urbanization process-through adjustment-to implement non-engineering measures for water relations for 30 to 50 years-and the development model of floodplain with sustainable socio-economic impact on water coordination and flood disasters.

Seven, auxiliary non-engineering measures planning

Auxiliary non-engineering measures refer to auxiliary flood control engineering measures taken to give full play to flood control functions and improve flood control benefits, mainly including flood forecasting, flood control dispatching and flood control dispatching decision support system.

1, flood forecasting system planning

(1) Information acquisition system: Collect the information of cushion surface, Doppler radar, rainfall, actual river regime, etc.

(2) Database: Establish an information management database.

(3) Forecast model: Develop a hydrological and hydraulic forecast model adapted to the current situation of various water systems in Haihe River Basin.

2. Planning of flood control dispatching system

Haihe river basin has formed a relatively complete flood control engineering system, including reservoirs, dikes, flood storage and detention areas, spillways (rivers) and sluices. The establishment of flood control engineering dispatching system with multiple sources and the same type of floods has made the functions of the engineering system improve continuously.

(1) engineering practice GIS system: engineering design information, engineering dispatching principle and engineering practice.

(2) Develop the flood control project dispatching model and establish the actual flood control project dispatching system.

3, flood control dispatching decision support (business) system

Describe the basic considerations of forecasting system, dispatching system and establishing flood control decision support system.

(3) Flood risk analysis and case selection of the same flood control dispatching case.

(4) Expert flood control experience set

(5) flood control decision model

(6) Virtual reality system of flood control plan (or scheme)

Eight, flood risk area management planning

The focus of flood risk management is to standardize flood control lines, publish them in flood risk areas, and formulate management measures to mitigate or mitigate the impact of flood disasters. First of all, flood risk assessment is needed.

1, flood risk zoning

Flood risk zoning has three levels: frequency zoning and risk zoning, both of which are represented by risk schema.

(1) frequency division: the flood inundation calculation with the same frequency is basically divided into 5, 10, 20, 50, 100, 200 and 500 flood inundation ranges.

(2) Risk zoning: Risk zoning is carried out according to the characteristic frequency zoning basis such as flood depth and velocity interval.

(3) Risk zoning: Considering the socio-economic situation of the risk area, the expected loss of each risk unit (for example, per square kilometer) is calculated on the basis of zoning, and risk zoning is carried out.

2, dam-break flood risk zoning

3. Flood risk benefit assessment

(1) Establish a flood disaster risk assessment model at the same level of river basin, region and city, and evaluate the same historical period (to 10 period), current situation and non-(201,2020 and 2030) in recent 50 years (from/kloc)

(2) Evaluate the benefits of flood control measures and flood environmental benefits.

4. Reconstruction of flood storage and detention areas and resettlement of migrants

(1) History and Present Situation of Flood Storage and Detention Area

(2) socio-economic development trend of flood storage and detention areas

(3) The flood storage and detention area faces two problems-population and sustainable development.

(4) Basic mode of flood storage and detention area: sparse population intensive management with local wet recovery and main transformation.

(5) Reconstruction planning of flood storage and detention areas: demonstration and identification of wet restoration and intensive management of flood storage and detention areas; Prediction of socio-economic development and urbanization trend in the region and surrounding areas; Start resettlement and resettlement planning in flood storage and detention areas; Planning of wet restoration flood storage and detention area; Planning of large-scale operation flood storage and detention area; Reconstruction financing office; Reconstruction of virtual reality system in flood storage and detention area

5. Flood resource utilization risk dispatching system in the northern region.

(1) Risk Dispatching System for Reservoir Flood Resources Utilization

(2) Flood resource utilization risk dispatching system in flood storage and detention areas

(3) Flood resource utilization risk dispatching system in plain.

6, disaster simulation and planning

Catastrophe refers to the flood like 1954, or the flood disaster loss of reservoirs and key flood control areas, with the magnitude of 1000 billion yuan. Disaster simulation and planning includes contents.

(1) flood self-characteristic simulation

(2) Flood disaster simulation

(3) Emergency management and rescue simulation

(4) Alarm and refuge system shell and corresponding structure.

(5) Safety and epidemic prevention measures plan

(6) Cases of post-disaster recovery and reconstruction

(seven) preparations for raising disaster relief funds.

7, empty repair and wet repair plan

Analysis of flood characteristics, risks and migration trend of urbanization development: On this basis, a wet restoration scheme for flood risk areas suitable for the stage of social and economic development is formulated.

1998 Hongshui River Basin takes the lead in implementing the wet restoration measures of resettlement and air collection along the river according to the "32-character" needle. Problems such as insufficient demonstration in the early stage, large scale and hasty support of good measures can be seen.

According to the statistical data of floods in 1990s, the proportion of flood losses caused by waterlogging is increasing, especially in the cities in the plain area of southern basin. The flood area of the river basin is more than 90 million mu, and the flooded area of the river channel is about 3 million mu. The river flood loss is about five times as much as the river flood loss, which is 25.05 million mu less than the flood burst 1.545 million mu. Only the area affected by the flood disaster is 1.545 million mu.

The situation of waterlogging disaster tends to deteriorate mainly in two aspects: the water surface in the plain area is seriously shrinking, and the original water surface is reclaimed for low-lying and waterlogging-prone farming. In 1950s, the water surface area of lakes in the plain area of Daijiang River Basin accounted for about 19% of the dike area, but now it has shrunk by about 5%, and the waterlogging storage capacity has decreased by 75%. Although drainage facilities have been built, the increased waterlogging and accumulated waterlogging in plain areas are difficult to be discharged by themselves during the flood season when the river water level is high, and even can be forcibly closed on the other side of the sluice, thus reducing the flood control pressure of the river and forcing the situation of "closed flood discharge" to stop. The second situation is common in all river basins. With the rapid expansion of cities to surrounding areas in the process of urbanization, the increase of urban permeable area in some low-lying areas often leads to the increase of surface waterlogging, and the problem of waterlogging in urban development is often not well understood.

Due to the conflict between internal and external water, the contradiction between flood control and drainage is due to effective waterlogging control measures in agricultural areas. According to the analysis of the Basin Water Conservancy Commission, in order to effectively alleviate the waterlogging problem in You Jiang Plain, the net water surface area of the inner lake should be 10%, that is, the water surface needs to be restored by 3,000 ~ 4,000 km2, and the cities in the southern basin are also facing the same demand.

8, flood control knowledge propaganda, education and flood control exercise planning

The propaganda and display of flood control knowledge is suitable for flood characteristics and emergency education. Non-engineering measures in flood risk areas play an important role in flood control.