In late July 2025, Beijing faced severe flooding primarily caused by the release of water from multiple reservoirs. The high flow rate of the released water and short warning time, especially the discharge from the Miyun Reservoir, resulted in significant loss of life and property. The areas surrounding the Miyun Reservoir are where the troops defending Beijing are stationed, and the losses were likely substantial.
The Miyun Reservoir is a product of the Great Leap Forward, but its dam construction quality is poor. During the 1976 Tangshan earthquake, there was a landslide in the dam body, almost leading to its collapse. If the Baihe main dam of the Miyun Reservoir were to breach, the water would reach a depth of two meters at Tiananmen Square…
At the end of 2014, the Middle Route Project of the South-to-North Water Diversion (SNWD) Project was fully operational. Starting on September 11, 2015, the Miyun Reservoir’s associated project for the North-to-South Water Diversion commenced reverse water diversion, storing a portion of the “South Water” in the Miyun Reservoir. Subsequently, the reservoir’s water level and storage volume repeatedly broke records. By 2025, the Miyun Reservoir had reached its highest levels since its establishment in terms of storage volume at 35.81 billion cubic meters and a water level of 155.31 meters.
The flooding disaster at the Miyun Reservoir in July 2025 was rooted in years of accumulating excessive water from the Middle Route Project of the SNWD. The focus on large storage capacity and high water levels overlooked the risks to the reservoir dam’s safety when both were present. When heavy rains arrived, the Miyun Reservoir had limited spare capacity and could only resort to emergency high-flow releases to ensure dam safety, resulting in significant losses to downstream populations.
On July 29, 2025, Chinese authorities announced that the heavy rainfall in Beijing had led to at least 30 fatalities due to the disaster. Prior to this, much of northern China had experienced heavy rainfall leading to floods and landslides.
According to a report from “Beijing Daily” on July 28, due to the recent heavy rainfall, the upstream inflow volume at the Miyun Reservoir had significantly increased. By July 28, the accumulated inflow reached 630 million cubic meters, pushing the reservoir above its flood limit. In response to the incoming water, the reservoir initiated discharge on July 27 at 15:00, with an accumulated discharge of 56 million cubic meters by 17:00 on the 28th. With escalating rainfall, the reservoir increased discharge to 1,020 cubic meters per second by 17:40 on the 28th, reserving flood storage for potential heavy rain. Subsequent adjustments in discharge were made based on the reservoir’s inflow.
A report from “Jiemian News” on July 29, cited the Beijing Meteorological Observatory stating that from 20:00 before to 6:00 on the reporting day, the city had an average precipitation of 47.9 millimeters. Affected by heavy rain since the 23rd, the inflow to the Miyun Reservoir had notably increased, accumulating 730 million cubic meters by 6:00 on the 29th, causing the reservoir to operate above its flood limit. Continued downstream discharge amounted to 120 million cubic meters by 6:00 on the 29th. The reservoir was releasing at a rate of 1,120 cubic meters per second and would adjust discharge levels based on incoming water conditions.
With the ongoing increase in discharge, the rate had reached 1,120 cubic meters per second, equivalent to a total discharge of 97 million cubic meters per day.
In Beijing, it was not just the Miyun Reservoir releasing water but several reservoirs discharging concurrently. Apart from Miyun, other reservoirs such as Baihepu, Gucheng, Yudushan, Haizi, Xiyu, Huangsongyu, Huayu, Yangjiatai, Zhaotang, Zhuwo, Luopoling, and Sanjiadian sluice also opened for flood discharge.
The key objective according to the flood prevention plan is to ensure the reservoir dams do not collapse during flood seasons. Specifically in the Beijing-Tianjin-Hebei region, the focus is on protecting Beijing, Xiong’an New Area, and the Middle Route Project of the SNWD.
During the initial years of the Chinese Communist Party’s rule, the model for constructing reservoir dams was adopted from the Soviet Union. Reservoirs were proclaimed to serve flood control, drought resistance, and power generation purposes. The emphasis was on the flood control aspect when promoting dam construction using high dams to control flooding.
However, due to the poor quality of the dams constructed by the CCP, they often fail to meet the set flood control standards. Hence, during flood seasons, especially during heavy rains, emergency or unannounced discharges were initiated to safeguard the dam’s integrity, disregarding public safety concerns during dam construction.
In China, many people, including journalists, lack basic knowledge of reservoir dam flood control functions. For instance, interpreting the news reports mentioned earlier, the claim that reservoirs play a crucial role in flood interception means that the outflow must not exceed the inflow to fulfill the flood interception function, aiming to protect downstream areas. As the reservoir’s water level rises continuously, the remaining reservoir capacity diminishes, making it unable to cope with subsequent inflows, ultimately jeopardizing the dam’s safety. This calls for an increased discharge rate to reduce reservoir levels and enhance the available reservoir capacity, sacrificing the downstream population’s interests to improve the dam’s safety coefficient. These are two fundamentally different operational methods for reservoirs, each with distinct objectives that cannot be conflated.
Before commencing the construction of the Miyun Reservoir dam project, Miyun County belonged to Hebei Province. However, due to the construction of the Miyun Reservoir dam project, Miyun County was placed under Beijing’s jurisdiction. The reservoir is fed by two main rivers, the Chao River and the Bai River, which merge to form the Chaobai River, flowing into the Bohai Sea at Jiuhexias, Tianjin.
The construction of the Miyun Reservoir dam project served multiple purposes such as flood control, irrigation, power generation, and aquaculture. At that time, there was no water supply purpose envisioned, as sources like the Guanting Reservoir and shallow groundwater met Beijing’s water needs. The focus was on promoting agriculture and food production, with plans to increase irrigation by up to 6 million mu (a unit of area). Construction commenced on September 1, 1958, using a concurrent survey-design-construction approach with the command to “control floods in one year, complete construction in two years.”
The Miyun Reservoir dam project was designed by the Water Resources Department of Tsinghua University, with Professor Zhang Guangdou serving as the chief engineer. Due to this concurrent approach deviating from standard construction procedures, differences in dam design opinions emerged at the construction site. Legend has it that then-Premier Zhou Enlai personally visited the construction site of the Miyun Reservoir and issued three directives: 1. Have Mr. Zhang Guangdou permanently stationed at the construction site to promptly resolve various issues; 2. Technical decisions must respect Mr. Zhang’s opinions, avoiding forcing him to undertake tasks he disagrees with; 3. Critical design drawings must be reviewed and signed by Mr. Zhang to be considered valid, or else they would be deemed void.
Hebei, Tianjin, and Beijing organized 200,000 laborers who finished the project within two years, achieving a construction speed “miracle” in September 1960. The planned investment was 367 million yuan, but only 264 million yuan was used, saving 103 million yuan, fully aligning with the “rapid, good, and economical” spirit.
In Professor Zhang Guangdou’s career, four water resources and hydroelectric projects were notably mentioned: the Sichuan Changshou Longxi River Hydropower Project, the Taohuaxi Hydropower Station, the Yellow River People’s Victory Canal Headgate, and the Miyun Reservoir, with no mention of the Yellow River Sanmenxia and Yangtze River Three Gorges reservoir dam projects. This exemplifies the significance of the Miyun Reservoir dam project in Professor Zhang Guangdou’s life, reflecting his reluctance to associate himself closely with the Yellow River and Yangtze River dam projects.
Although the Miyun Reservoir dam project was completed within two years, showcasing the speed of the Great Leap Forward and saving 103 million yuan in investment, it continually faced issues post-completion, necessitating ongoing repair, reinforcement, and expansion projects for decades. Reports suggest that after repairs and reinforcements, the total investment in the Miyun Reservoir dam project amounted to 439 million yuan, overshooting the initial investment and ultimately increasing costs, expanding rather than reigning in expenses.
The following technical data aids in understanding the subsequent explanations:
Reservoir area: 188 square kilometers
Total capacity: 4.375 billion cubic meters
Dead storage capacity: 437 million cubic meters
Dead water level: 126 meters (above sea level)
Flood level: 150.0 meters (above sea level)
Normal water level: 152 meters (above sea level)
Flood limit level: 152 meters (above sea level)
Top dam elevation: 160.0 meters (above sea level)
In Miyun Reservoir’s history, there have been three instances of flood discharge, occurring in 1969, 1986, and 2025.
In March 1969, armed conflicts between Chinese and Soviet troops erupted on the Ussuri River at the Sino-Soviet border, leading to the capture of an advanced T-62 tank from the Soviet side. Over the following decades, China’s tank and antitank technology development was intertwined with the sacrifices made by hundreds of soldiers and militia for the T-62 tank.
After the Sino-Soviet Zhenbao Island military conflict, the harsh reaction from the Soviet leadership led by Marshal Grechko and Deputy Minister Traikov advocated for a complete elimination of the Chinese threat by deploying medium-range ballistic missiles stationed in the Far East, carrying nuclear warheads equivalent to several million tons, targeting Beijing and China’s nuclear weapons facilities for a devastating strike.
On September 20, 1969, the Chinese PLA held a nationwide combat readiness meeting involving commanders and political commissars of various military regions and branches (also known as the “Three North” War Preparation Meeting) to discuss countermeasures against the sudden Soviet attack. Over several days, the most common phrase heard in the meeting room was “Soviet attack imminent.”
As per a recollection by Lin Biao’s secretary Li Genqing, before any major battles, Lin Biao would meticulously study maps and terrains to memorize future battlefield conditions. In this particular war preparation, Lin Biao closely examined the maps of the “Three North” and personally selected several aerial spots, which were marked and remembered in detail.
“Before the National Day, during the ‘Three North’ war preparation meeting, Lin Biao studied the ‘Three North’ maps for several days. Lin Biao scrutinized the map for a while, asked me to report the scale, and started pointing out locations. For each place Lin Biao mentioned, I pointed out its location on the map and reported the approximate straight-line distance to Beijing, as he requested.
“‘Juyongguan,’ that was the first place Lin Biao indicated. I immediately pointed out Juyongguan’s location with a pool cue and reported, ‘Juyongguan.’ I then conveyed the distance from Juyongguan to Beijing.
“‘Nankou,’ Lin Biao pointed to the next location, and I promptly indicated Nankou’s position and reported the distance from Nankou to Beijing.
“‘Guanting Reservoir, Miyun Reservoir,’ Lin Biao continued pointing, and I continued reporting.
“Lin Biao was acquainted with the distances of these locations from Beijing. Twenty years earlier, during the Pingjin Campaign, he knew of them, yet I still reported them to him per his request. Nankou and Juyongguan are the northern gateway to Beijing and vital defensive points. Guanting Reservoir and Miyun Reservoir are essential to Beijing’s water supply, integral to daily life, and in the event of enemy raids causing dam breaches, would pose a severe threat to lives and properties.
“For this reason, the Chinese government took flood discharge measures at Guanting, Miyun, among other reservoirs, to prevent floodwaters from engulfing Beijing. Simultaneously, China’s top leaders and their families evacuated Beijing to ensure their safety.”
On July 28, 1976, a severe earthquake measuring 8 on the Richter scale struck Tangshan City, Hebei Province (some cite 7.8 magnitude). The earthquake devastated Tangshan and affected vast areas around it. The seismic intensity at the location of the Miyun Reservoir dam was 6.8 magnitude, with a seismic intensity between IIIV (8 degrees), seemingly within the dam’s fortification standards, suggesting no immediate concern. However, many of China’s reservoir dams, despite their high standards on paper, often fail practical tests, with the Miyun Reservoir dam being a prime example.
The White River main dam of the Miyun Reservoir suffered significant damage, with extensive landslides occurring below the dam’s upper part enhanced by storm surge and seawall collapse, creating an extremely perilous situation… A documented account of the damage caused to the White River main dam by the earthquake was found in the Beijing Water Authority’s archives: based on visual observations, within a 500-meter radius of the dam… a landslide occurred. The dam body had shifted, with some parts submerged, approximately 20 meters of the high dam body remained unshifted but lost structural support. Any substantial aftershocks could exacerbate the damage, leading to severe peril. At the time, national leaders including Hua Guofeng personally visited the impending breach area of the Miyun Reservoir, immediately ordering flood discharge and instructing the military to repair the dam to prevent a collapse.
To repair the reservoir dam, military and local leaders decided to blast a nearby mountain at the Zoumazhuang area to use the rocks for dam reinforcement, preventing a breach occurrence. A considerable amount of explosives were used, and upon detonation, a mushroom cloud rose resembling an atomic bomb explosion. To ease reservoir pressure, an emergency command was given to open the gates for water discharge, lasting for over half a month until all water was released.
This marked the second instance of flood discharge at the Miyun Reservoir.
Post-calculation revealed that in case the White River main dam of the Miyun Reservoir had significantly damaged, particularly the White River main dam from landslide or breaching, the entire Beijing, Tianjin, Baodi in Hebei, and other regions would be submerged. Reports even suggested that if the White River main dam breached, the water could reach a depth of two meters at Tiananmen Square…
The repercussions of a dam breach at the White River main dam traversating to Tiananmen Square could lead to a two-meter water depth…
Repeated three times for emphasis.
As previously mentioned, prior to the heavy rains and torrential downpour in late July 2025, if the Miyun Reservoir’s storage volume and water levels were equivalent to those on October 29, 2024, then during the torrential rainfall and flooding, the Miyun Reservoir failed to fulfill its flood mitigation function. Instead, it discharged all incoming runoff within a shorter timeframe, exacerbating flooding in certain Beijing areas. The primary cause of localized flooding was the discharge of water from the reservoir.
Assuming the storage volume and water level of the Miyun Reservoir were the same as in October 29, 2024, by 2:00 on July 29, 2025, the reservoir had accumulated 785 million cubic meters of inflow, with a water level of 155.52 meters and a storage volume of 3.617 billion cubic meters, surpassing the flood limit by 3.52 meters.
The report did not specify the total discharged volume by 2:00 on the 29th, but this discharged water constituted the main reason behind the flooding in certain areas of Beijing.
In conclusion, perpetually high water levels and expanding reservoir areas make for serene lake views at the Miyun Reservoir. However, the critical factor overlooked is that the Miyun Reservoir’s flood level is 150 meters, normal level at 152 meters, flood limit at 152 meters, with the top dam elevation reaching 160.0 meters. With the reservoir’s water level at 155.31 meters, surpassing both the flood limit and the normal levels, the reservoir operated in an extremely precarious state.
In line with the objectives of the CCP’s drought and flood prevention command center, the reservoir should lower its water level to the flood limit when flood season approaches. Specifically for the Miyun Reservoir, the water level should not exceed 152 meters. Evidently, the Miyun Reservoir did not adhere to this guideline.
According to a report titled “2025 Beijing Miyun Reservoir Discharge Progress” from a local source on July 29, 2025, by 14:00, the Miyun Reservoir had accumulated 7.85 billion cubic meters of inflow, reaching a water level of 155.52 meters and storage volume of 3.617 billion cubic meters, surpassing the flood limit by 3.52 meters.
This report underscores the importance of adhering to flood prevention measures to avoid disasters like the one witnessed at the Miyun Reservoir in July 2025. As Laozi stated in the Daodejing Chapter 8: “The best goodness is like water. Water is good at benefiting all beings without contention, dwelling in places people dislike, hence closest to the Tao… living in harmony with the land, having a kind heart, practicing benevolence, speaking the truth, governing well, managing tasks skillfully, acting appropriately. Only through non-contention can one be blameless.”
Water, at its best, possesses the remarkable quality of preferring lower positions, residing in humble places, and being unimposing and compliant to serve most living beings on earth, thereby embodying the essence of supreme virtue.