Summary of Key Points
Recently, several regions in the north (Liaoning, Jilin, Tianjin, Hebei, etc.) have experienced rare and extreme downpours, with some areas receiving rainfall equivalent to what occurs once every hundred years. This has led to severe flooding issues, such as submerged residential areas, interrupted transportation, and power outages. The underlying cause is a shift in northern China's rainfall patterns towards more frequent and intense episodes in recent years, highlighting the contradiction between climate trends and urban flood control systems. The existing drainage and flood prevention infrastructure in northern cities was designed based on historical climate data and is inadequate to handle such extreme weather events. Additionally, northern regions cannot simply adopt southern flood control strategies; instead, they need to make adjustments in areas such as system integration, improved understanding of the situation, and comprehensive management to adapt to this new normal of frequent extreme rainfall.
1. How Severe Were the Northern Rainstorms?
The intensity of these downpours exceeded many people's expectations:
- Dengta City, Liaoning: Residential areas were flooded for several days, with water depths exceeding one meter in some places. Despite efforts by property management to block the water with sandbags, it was ineffective, as the water from external rivers flowed back into the streets.
- Shenyang: In Chengdonghu Street, 310.6 millimeters of rain fell within 10 hours (equivalent to half a year's normal rainfall). Seventy-three areas were flooded, causing road closures, subway and bus service disruptions, and water and power outages in some old residential areas. Residents had to rely on camp stoves for lighting.
- Yanjiao, Hebei: Rainfall began in June, and residents had developed the habit of moving their vehicles when strong rain warnings were issued. On July 12th, a sudden downpour caused water to rise to knee height at the entrances of residential buildings, forcing residents to move their cars in the early hours of the morning.
In the past, northern residents viewed heavy rain as something similar to snowfall in the south; now, they are experiencing firsthand what it means for a city to become virtually submerged. Even Zhang Li, a resident from Shenyang who used to admire the southern humidity, remarked, "This year's weather in the north is nothing like we're used to."
2. Why Is It Raining More in the North?
The increase in rainfall is not due to a simple shift of the rain belt northward but rather a combination of various factors:
- Short-term Weather Conditions: Multiple weather systems collided, with the cold air from the Northeast interacting with warm and humid air moving northward, and the moisture from Typhoon Bavi contributing to the precipitation.
- Long-Term Trends: According to the China Meteorological Administration, average rainfall in the north has increased by 23.1% since the start of the rainy season this year, with the rainy season starting 8 days earlier than usual. Hebei and Tianjin have recorded record amounts of rainfall since 1961. More importantly, although the total amount of rain has increased, the number of rainy days has decreased, leading to more concentrated and intense downpours.
- Not All Areas in the North Are Affected: For example, the northwest region remains hot and dry, while southern Xinjiang has experienced heavy rainfall but overall drought. Experts point out that what is happening is a manifestation of northern regions exhibiting more characteristics typically associated with the south, rather than a complete change in climate type.
3. Why Can't the Floods Be Cured?
The reason why the floods persist even after the rain stops lies in the disconnection between different components of the flood control system:
- Inconsistent Standards: The systems responsible for drainage (managing rainfall), water removal, and flood prevention (managing river flow) are under the jurisdiction of different departments, leading to a lack of coordination. In Dengta City, the city's internal drainage capacity was adequate, but the higher water levels in external rivers caused the water to flow back into the streets.
- Infrastructure Inadequate for Extreme Weather: Urban drainage and flood prevention facilities were designed for historical climate patterns. A region that has historically experienced less rainfall cannot afford to build infrastructure for extreme events (the cost would be too high). However, this year's downpours exceeded the capacity of the existing systems.
4. Northern Flood Control Cannot Copy Southern Approaches
Northern regions cannot simply adopt southern flood control methods:
- Reasons for Differences: The frequency and intensity of rainfall vary between the north and south (the south experiences frequent light rain, while the north has occasional intense downpours), and the ground's ability to absorb water also differs (the north has more hardened surfaces, leading to faster runoff).
- Effective Solutions: Instead of focusing solely on drainage, a comprehensive approach is needed, including the creation of green spaces for water storage (such as wetlands and parks) to buffer rainfall before it enters the drainage system.
- Shift in Thinking: Governments need to incorporate the concept of extreme rainfall into urban planning (e.g., renovating low-lying areas and reserving space for water storage). The public should also become more aware of potential risks, taking precautions like moving their vehicles in advance when warnings are issued.
Experts emphasize that northern cities, which were used to dealing with droughts and cold waves, must now adapt to the new challenge of extreme downpours caused by climate change.
Conclusion
The northern downpours are not isolated incidents but reflect the normalization of extreme weather. To address flooding issues, it is necessary to improve the coordination between drainage and flood prevention systems and adopt a holistic approach to urban planning. Everyone, from governments to individuals, must recognize that the climate in the north has changed, and new strategies are required to manage these new risks.