Summary of Key Points
In 2026, typhoon Meishak caused multiple reservoirs in Guangxi to be at risk, highlighting the current situation in China where there are a large number of small and medium-sized reservoirs, many old dams, numerous earth-rock dams, and dams with low heights. Extreme weather events have exceeded the design capacity of these reservoirs, necessitating substantial funds for reinforcement while also facing challenges such as local financial pressures and difficulties in coordinating engineering and management efforts. The approach to prevention is shifting from traditional dam repairs to the use of technological solutions like digital twins, aiming to balance safety and economic costs through a "graded and categorized" management strategy for more effective flood control.
Detailed Explanation
1. Reservoir Safety Issues in Guangxi: The Hidden Dangers of Old Dams
The incidents in Guangxi's reservoirs were ostensibly caused by the typhoon and heavy rainfall, but the root cause lies in the age and weak structural integrity of the dams themselves. Of the country's 98,000 reservoirs, 80% were built between the 1950s and 1970s; 99% are small to medium-sized, and 90% are earth-rock dams (which are less durable than concrete dams), with 92% having a height of less than 30 meters. These old dams, like elderly structures, have inherent vulnerabilities due to limited technical capabilities at the time of construction. After decades of operation, they have developed issues such as aging, leakage, and damage from pests. For example, the Liulan Reservoir in Guangxi, being an earth-rock dam, could not withstand the intense rainfall, leading to overfilling and leakage. The simultaneous saturation of multiple small reservoirs during the storm exacerbated the crisis due to a lack of adequate operational capacity.
2. Why Are Extreme Rainfalls Difficult to Prevent?
Reservoirs are not designed to withstand all possible extreme weather events. The flood control standards are determined based on factors such as the size of the project, the areas downstream that need protection, and available funding. For instance, if the downstream area includes a county town, the standards are higher. When extreme rainfall exceeds the "normal" conditions considered during design (referred to as "super-design scenarios"), even the strongest dams can be overwhelmed. Additionally, China's meteorological data is only available for about a hundred years, and some extreme events were previously unrecorded, meaning they were not taken into account during dam construction. Moreover, the population and economic activities downstream have increased over time, making potential damages much more severe.
3. The Cost of Reservoir Reinforcement: How Much Does It Take to Upgrade an Old Dam?
Take the Dongfeng Reservoir in Yuxi, Yunnan, as an example. Built in 1958, it was classified as a "dangerous dam" in 2007. The initial budget for reinforcement was 85.69 million yuan, which was later adjusted to 89.65 million yuan, and the actual cost was 85.68 million yuan. The funding came from various sources: the central government provided 68.55 million yuan (77%), and the provincial and municipal governments each contributed 8.57 million yuan (10%). Furthermore, an additional 225 million yuan was spent on a "road-dam integration" project (excluding nearly 100 million yuan for land acquisition), all of which was financed by local governments. The reinforcement improved the dam's resistance to earthquakes up to magnitude 8, and during the 2025 flood, precise water management resulted in an increased storage capacity of 24.58 million cubic meters compared to the previous year. This shows that upgrading old dams requires not only structural repairs but also additional infrastructure investments.
4. Where Does the Money Come From?
The funding for reservoir reinforcement comes from a variety of sources:
- Central Government Support: The central budget allocates different percentages (60%, 70%, 80%, and 80%) to reservoirs in the east, central, west, and northeast regions, respectively. Special government bonds support the construction of new large and medium-sized dams, and there are annual subsidies for the maintenance of small reservoirs.
- Local Governments: They raise funds through bonds and other means. For example, the Yuxi Reservoir received funding from both the provincial and municipal governments.
- Private Capital: Profitable projects (such as water supply reservoirs) can attract corporate investment.
However, local finances are under significant strain. Even with 80% of the funding coming from the central government, the remaining 20% can be a challenge for financially struggling areas. Some counties, with annual revenues in the tens of millions, may have to cut other expenses to fund dam reinforcement.
5. Balancing Safety and Cost: Avoid Excessive Spending on Low-Probability Events
Flood control cannot rely solely on spending money on new dams; a balanced approach is needed:
- Graded and Categorized Management: Priority should be given to reinforcing large and medium-sized reservoirs that serve densely populated areas with higher potential damages, while smaller reservoirs should be equipped with monitoring systems for early warnings and evacuation plans. Unusable old dams should be demolished or downgraded.
- Technological Solutions: The use of digital twins (virtual dam models) can help simulate floods in advance for precise management, and short-term forecasting systems can enable dam operators to respond promptly.
- Combining Engineering and Non-Engineering Approaches: Reinforcement is essential, but so are training personnel and clarifying responsibilities, such as who is responsible for evacuating residents during emergencies.
Experts suggest that it is unrealistic to upgrade all reservoirs to the highest standards due to limited funding. The focus should be on optimizing existing systems—more accurate forecasting, stricter management, and faster evacuation procedures—to achieve better flood control with fewer resources.
Conclusion
Upgrading old dams is a long-term effort that requires both financial investment in physical infrastructure and technological improvements. As technologies like digital twins become more widespread, flood control will become more efficient. The key is to ensure that every dollar spent is used effectively to protect reservoirs without wasting resources.