Adjacent to the Yongxing River in southern Beijing, the second phase of the Daxing Airport flood detention basin is on the verge of completing its project inspection. Sitting across the river from the already operational first phase, these basins will transform into massive "water reservoirs" during intense storm seasons, safeguarding the adjacent Beijing Daxing International Airport, shielding nearby villages, and mitigating flood pressure on upstream and downstream river channels.

According to the Beijing Water Authority, following the Haihe River "23·7" basin-wide catastrophic flood, Beijing has newly constructed and upgraded eight flood storage and detention zones, adding roughly 35 million cubic meters of storage capacity. This initiative strengthens flood defense capabilities for the Yongding River and North Canal basins.

Dual Basins Guarding the Airport and Surrounding Areas

Located northwest of Daxing Airport, the flood detention basin is a critical line of defense. On the map, the Yongxing River stretches like a 30.8-kilometer ribbon, channeling upstream flows from Daxing New Town, Panggezhuang, and the airport economic zone southeastward along the airport's northern edge before merging into the Yongding River in Hebei Province. Consequently, the Daxing Airport detention basin serves as a vital shield, capturing floodwaters to protect both the airport and surrounding communities.

Wang Xuepeng, deputy director of the Nianyantan Water Affairs Institute under the Daxing District Water Authority, explained that the Daxing Airport detention basin is divided into two phases. Phase one sits on the southern bank of the Yongxing River, while phase two, located on the northern bank, is split into southern and northern sections connected by an underground culvert for water exchange. Phase one was completed in December 2020 with a storage capacity of 3.3 million cubic meters. Phase two, initiated in 2024 and finished in 2025, is scheduled for project inspection shortly. It adds 2.9 million cubic meters of storage, with the southern section holding 550,000 cubic meters and the northern section 2.35 million cubic meters. Combined, the two phases offer 6.2 million cubic meters of flood storage space, equivalent to the capacity of three Kunming Lakes.

"The Donglianggezhuang sluice is the pivotal control point, with downstream discharge capped at 110 cubic meters per second," Wang noted. Once upstream inflows surge and discharge exceeds this threshold, the detention basin activates. "Under extreme storm scenarios with heavy upstream inflow, phase one fills first. If it reaches capacity, the phase two flood diversion sluice opens." The southern and northern sections of phase two operate via gravity flow: floodwater enters the southern section through a three-gate diversion structure, and as water levels rise, it automatically flows through the northern connecting culvert into the larger northern section, requiring no manual gate operation. Once rainfall subsides and river flows stabilize, drainage gates open to release stored water back into the Yongxing River.

Phase One's Critical Role in the "23·7" Event

Both phases of the Daxing Airport detention basin resemble lush ecological parks, where wild ducks flap from the grass and aircraft from Daxing Airport soar overhead. During construction, existing vegetation such as oil pines and ginkgo trees was carefully relocated and later restored, complemented by new saplings to shape the current embankment landscape.

To ensure normal airport operations, the basins must remain dry year-round, preventing waterfowl congregations that could threaten flight safety. Before each flood season, they are kept completely empty. Although phase two has yet to be commissioned, phase one has already proven its worth in real-world conditions. During the Haihe "23·7" catastrophic flood, upstream waters surged into the Yongxing River, and the phase one sluice gates opened to retain floodwater, reaching a peak water level of 23 meters and securely holding the flood within the basin.

Now, with phase two nearing inspection completion, the two phases will work in tandem to detain floodwaters. Specifically, when all phase one diversion gates are fully open and water levels upstream of the Donglianggezhuang sluice continue to rise, phase two's diversion gates will open to stabilize levels at the Donglianggezhuang sluice. When phase one hits its maximum storage level of 24 meters, its diversion gates will close, and phase two's gates will progressively open fully to prevent river levels from rising. This coordinated approach ensures unobstructed flood passage through the Yongxing River and safe navigation of the flood season.

Enhanced Flood Defense for the Yongding River and North Canal Basins

Flood storage and detention zones are integral components of major river flood control systems, working alongside reservoirs, channels, and levees to manage floodwaters—often described as the "trump card" of watershed flood prevention. Their primary function is to temporarily accept and store excess floodwater from extreme storms, diverting surplus flows, reducing peak discharges, and minimizing overall flood damage.

The Beijing Water Authority reports that after the Haihe "23·7" catastrophic flood, the city constructed and upgraded eight flood storage zones, including the Beijing Daxing International Airport Flood Detention Project Phase Two, Mentougou Six-Water Connection Storage Project, Baoyangcheng Storage Project, Nankou and Shagou River Storage Zone, Beijing Wenyu River Park Shunyi Phase Two Storage Project, Bahekou Storage Construction Project, and Xiyuhe Storage Construction Project. These additions provide approximately 35 million cubic meters of new storage capacity, significantly bolstering flood defense across the Yongding River and North Canal basins.