Why do floods still occur in the 21st century? The most practical survival safety skills →

On May 12, 2023, the Science Popularization China Starry Sky Forum, with the theme of "Scientific Disaster Prevention and Mitigation to Protect People's Safety", invited 5 experts from the field of disaster prevention, mitigation and relief to guide the public to improve their awareness of risk prevention and control through explaining scientific knowledge about disasters and popularizing common sense about emergency risk avoidance, push emergency management checkpoints forward, focus on preventing safety risks at the source, and fundamentally eliminate potential safety hazards.

Chen Wenjun, a flood control and drought relief expert from the State Flood Control and Drought Relief Headquarters, gave a speech: "If people don't give floods a way to flow, the floods won't give people a way to survive "

The following is an excerpt from Chen Wenjun’s speech:

Everyone may still remember the July 20 rainstorm disaster in Zhengzhou two years ago.

From July 17 to 23, 2021, Henan Province suffered from extremely heavy rainstorms and severe floods. The "July 20" rainstorm and flood disaster affected 14.786 million people in 150 counties (cities and districts) in Henan Province, with 398 people dead or missing and direct economic losses of 120.06 billion yuan.

Photo courtesy: Chen Wenjun

Why do such disasters still happen in the 21st century? Is there nothing we can do about floods?

01

Risk characteristics of flood disasters

Flood disasters include waterlogging disasters and rainwater flooding disasters. Flood disasters include mountain torrents disasters. Among them, mountain torrents disasters are the most serious disasters causing casualties and economic losses in my country.

Since flood disasters and rainstorm disasters often occur simultaneously or continuously in the same area, it is sometimes difficult to define them accurately, so they are collectively referred to as flood disasters.

Flood risks include:

First, the areas most threatened by floods are often the middle and lower reaches of rivers , which are often economically developed because of their abundant water resources and flat land.

Half of our country's population, one-third of cultivated land and three-quarters of total industrial and agricultural output are concentrated in the middle and lower reaches of the seven major rivers and coastal plains, which are also areas seriously threatened by floods and typhoons. Population concentration and high urbanization will inevitably compete with rivers and lakes for land, affecting the flood discharge capacity of natural water systems. In the face of flood disasters, the vulnerability is fully exposed, further aggravating the scale of flood disasters.

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Second, affected by the monsoon climate and my country's unique three-level terraced terrain features, about three-quarters of the country's land area suffers from flood disasters of different types and degrees.

From 206 BC to the founding of the People's Republic of China in 1949 AD, there were 1,029 major floods in 2,155 years, almost one every two years. Since the founding of New China, more than 50 major floods have occurred.

Third, against the backdrop of global climate change, extreme weather and climate events are becoming more frequent and intense , and will continue to break the predictions of the recurrence of traditional flood disasters. Flood disasters caused by extreme precipitation, typhoons and other meteorological factors will increase to varying degrees.

02

Good flood management

Flood prevention is a systematic project. If we do a good job in flood management, it will be possible for us to coexist harmoniously with floods.

First of all, people provide a "flow path" for floods . People are the main body of social and economic activities, and water is a basic and strategic natural resource for human survival and development.

Harmony between man and water refers to a virtuous cycle of mutual coordination between the human system and the water system. On the premise of continuously improving the self-sustaining and renewing capacity of the water system, water resources can provide rescue support and guarantee for human survival and the sustainable development of the economy and society.

Respect the laws of nature and adapt to the characteristics of floods. Under the reality that humans have excessively encroached on water areas and rivers, necessary concessions should be made to floods.

Make way for floods, return land to the river, and coordinate the relationship between people and water. People cannot compete with water for land, so give up water's territory.

Reasonable layout of projects, scientific flood control , and application of engineering measures such as interception, blocking, storage, treatment, sealing, and drainage to control floods. Traditional flood prevention and disaster reduction actions seek to minimize flood losses through engineering measures, including the construction of new reservoirs, weirs and ponds to regulate floods, the construction of embankments and dams to block floods, and the expansion of pipe networks and channels to drain floods, and other water management strategies to continuously improve the standards of flood control projects.

Not only is it impossible to completely eliminate flood risks, but the investment is too large and may lead to the transfer of flood risks to other areas and long-term adverse impacts on the ecological environment. If maintenance and management are not good, engineering measures also run the risk of failure.

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Flood management in the new era is based on the principle of sustainable development , with the purpose of coordinating the relationship between people and floods, rationally regulating flood control behaviors, enhancing their own adaptability, and appropriately bearing certain risks to rationally utilize flood resources and help improve the water environment. The objects of flood management are not only floods, but also people and land.

In addition to traditional engineering measures, flood management pays more attention to non-engineering measures for flood control, which are measures to reduce losses caused by flood disasters in floodplains through laws, policies, administration, economic management and technologies other than flood control engineering. They mainly include: flood control regulations, flood forecasting, flood dispatching, flood warnings, floodplain management, river channel clearance, super-standard flood defense measures, flood insurance, flood relief, etc.

03

Enhance self-safety awareness

The terrible thing about floods and waterlogging disasters is not only that they cause property losses, environmental damage and facility destruction, but more seriously, they may endanger life safety and bring about economic and social instability.

In addition to doing a good job of flood prevention at the system level, each of us can also master scientific skills to protect ourselves. Whether you are traveling, camping, participating in outdoor gatherings, or staying indoors to work and rest, there are some survival and safety skills that can be used.

Observing the sky, watching the clouds, measuring rainfall, avoiding water, avoiding mountains, and living in peace are the most basic knowledge for preventing natural disasters.

One is to observe the sky and watch weather changes.

Weather refers to the specific state of the atmosphere close to the surface of a region in a short period of time. Weather phenomena refer to the comprehensive expression of various natural phenomena occurring in the atmosphere and the spatial distribution of various meteorological elements in the atmosphere at a certain moment. Weather changes are the biggest threat to human survival and safety.

The second is to look at the clouds and observe the evolution of the cloud system.

A cloud system refers to a cloud area with a certain pattern and lasting for a certain period of time, and a system composed of various clouds that appear with the same weather system. The changes in cloud systems are helpful for weather forecasting.

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The third is to measure the rainfall and measure the amount of rain.

Rainfall refers to the weather phenomenon in which water vapor condensed in the atmosphere falls to the earth's surface in different ways. Precipitation is the main and most direct cause of flood disasters. In layman's terms, more rainfall means more runoff, which means the water level will rise, and when the water level rises, a flood peak will form.

Fourth, avoid water and stay away from ditches and depressions.

We must start with ourselves, establish safety awareness, strengthen self-protection, stay away from rivers, lakes, streams, river beaches, depressions, pools, ponds and other hidden dangers, and prevent drowning incidents.

The fifth is to avoid mountains and the foot of cliffs.

Generally, natural factors such as rainfall, river scouring, earthquake and snowmelt will cause hillside shelters or soil to slide down the slope. During the rainy season, you should avoid hiding in low-lying valleys and steep slopes.

Sixth, live in peace and gather in a safe environment.

The climate during the flood season is changeable and sudden, with frequent disastrous weather such as thunder, lightning, heavy rain, hail, and tornadoes. Natural disasters such as landslides, collapses, mud-rock flows, and flash floods are prone to occur. Priority should be given to public buildings and facilities such as parks, green spaces, squares, schools, and stadiums with relatively flat terrain, high elevation, good drainage, air circulation, and certain infrastructure. The surrounding areas should be disaster prevention and evacuation sites with unobstructed roads and convenient transportation.