When Typhoon White Dolphin struck China's coast in August, it set multiple extreme weather records. As the storm moved northward, flood control strategies for Miyun Reservoir were already being tested in a digital environment. The newly developed digital twin platform, built as part of post-disaster reconstruction, processes real-time data from over a thousand sensors. The system completes flood simulations in minutes and generates more than a dozen forecast-based dispatch plans, providing critical support for balancing water storage and release while protecting downstream areas.

After the devastating rainfall in 2023, a large-scale reconstruction effort was launched across Beijing. The Municipal Development and Reform Commission collaborated with industry authorities and the hardest-hit districts of Fangshan, Mentougou, and Changping to quickly establish comprehensive recovery plans aligned with national requirements. The flood's destructive force damaged numerous reservoir structures, river embankments, sluice gates, hydrological monitoring equipment, and water supply facilities throughout the city.

The first priority was ensuring that damaged water conservancy and supply systems could recover to pre-flood standards before the 2024 flood season. The Municipal Water Authority prioritized 59 critical restoration projects. In heavily affected areas, construction continued around the clock as workers rushed to repair reservoirs, river channels, and monitoring stations along the Yongding River, whose embankments suffered severe damage during the July 2023 flood. A 100-meter section of the diversion dike downstream of Lugouqiao Barrage was destroyed, along with slope protections at flood detention reservoirs. By May 2024, repairs at the barrage were complete, and the river had resumed normal flood conveyance by June.

The "one-year basic recovery" initiative ultimately restored 12 reservoirs, 8 sluice gates, more than 500 kilometers of river channels, and 580 kilometers of mountain flood channels, while repairing 127 hydrological stations. Flood control capacity was elevated to at least pre-disaster levels. Water supply systems also returned to normal, with 130 pumping stations and over 1,100 kilometers of pipelines rebuilt in the first year. Drainage reconstruction included repairs to 8 urban sewage treatment plants and upgrades to 541 kilometers of pipelines.

While immediate recovery addressed urgent needs, the "three-year comprehensive improvement" plan focuses on long-term solutions. All 90 projects in this category broke ground in the first half of 2024, with 54 already completed. These include reinforcement of 10 reservoirs and sluice gates with updated automated monitoring systems. Beyond restoring original functions, the upgrades have moved flood control into an intelligent management phase.

This year, Miyun Reservoir unveiled its digital twin platform, making it possible to simulate flood scenarios before the water even arrives. On the night of August 11, as heavy rain battered the Miyun mountain area, dispatchers used the platform to navigate the delicate balance between reservoir safety and downstream pressure. "The platform integrates data from more than 1,000 monitoring sensors," explained Hao Hao, head of the Digital Twin Office. "Traditional manual calculations that took tens of minutes are now completed in minutes."

During the storm, the system received more than 40,000 data points daily. Over 200 high-definition cameras monitored the dam's upstream face, downstream slope, and spillway chambers, with AI algorithms automatically detecting anomalies such as floating debris. The platform generated more than ten flood forecasts under different rainfall scenarios and conducted hundreds of simulated dispatch runs. "It's like playing chess," said dispatcher Chu Xu. "For every move, we can see the potential risks in advance."

A similar digital twin system for the Yongding River collected rainfall data from five districts along its course, automatically generating multiple flood management plans and coordinating releases between upstream reservoirs and downstream sluice gates. The city has now completed comprehensive management of 550 kilometers of major river channels, widening flood sections by an average of 30% in the mountainous stretch and reducing channel resistance by 40%. A total of 59 new hydrological stations were built and 61 upgraded, with 336 monitoring facilities added or modernized.

Beijing has also begun planning five new mountain flood control reservoirs: the Guanting Mountain Gorge Flood Control Project, Zhangfang Flood Control Project on the Juma River, Erdaohe Reservoir, Zuanziling Reservoir, and Xifengshan Reservoir. Once complete, these will form a formidable flood defense network across the city's northern and western mountains, strengthening the entire Beijing-Tianjin-Hebei flood control system.

The capital's flood storage capacity has expanded significantly with eight new detention zones across key river basins, adding approximately 35 million cubic meters of storage — equivalent to 17.5 Kunming Lakes. These facilities embody a "dual-purpose" philosophy, serving as public parks during normal times and flood infrastructure during emergencies. The Wenyu River Park Detention Zone exemplifies this approach, functioning as a large urban park while capable of rapidly converting to flood storage. Its main control structure, the Wenyu South Weir, was completed before this year's flood season, completing the "Tongzhou Weir" system with total capacity of 12 million cubic meters.

The eight detention zones, distributed across southern, western, and eastern Beijing, incorporate river management, sluice construction, ecological restoration, and smart monitoring. Together with the 35 million cubic meters of new storage, they dramatically enhance the capital's flood buffering capacity. Urban waterlogging treatment has also improved, with drainage system upgrades at Baizhuangzi and Jinggangao Yancun, along with 54 kilometers of new or renovated stormwater pipelines.

Reconstruction has extended beyond flood defense to protect drinking water supplies. The Mencheng Water Plant in Mentougou District is now operational, while the Chengzi Water Plant has been upgraded. More than 170 mountain village water stations have undergone standardized renovations, with new disinfection equipment that precisely adjusts chemical dosing based on water flow. By the end of 2025, 300 such stations will be upgraded, working toward uniform water quality and service across urban and rural areas. Fifteen recycled water plants, including Fatou and Wulituo, have been built or renovated, with daily treatment capacity reaching 8.19 million cubic meters.

Addressing geological hazards, authorities have completed engineering treatments at more than 1,700 landslide and debris flow risk sites across 10 districts. The debris flow project at Sunhugou Village in Huairou District's Liulimiao Town involved constructing check dams, retaining walls, and drainage channels across six main gullies. During heavy rainfall, these structures diverted or contained 152,000 cubic meters of debris, preventing damage to homes and roads while ensuring no casualties from geological disasters.