Fuzhou Xiyuan Reservoir (Image provided by the interviewed unit)

Southeast Network reported on November 20th (Fujian Daily reporter Chen Min)

Core Tip

In 2021, the Ministry of Water Resources issued the "Guiding Opinions on Vigorously Promoting Smart Water Conservancy Construction", which pointed out that by 2025, seven major river digital twin basins, including the Minjiang River, will be built nationwide.

As a pioneer in "Digital China" and water conservancy construction, Fujian has taken the lead in exploration. Two digital twin projects, the Xiyuan Creek Small Watershed (Xiyuan Reservoir) in Fuzhou and the Beixi in Jiulong River, were launched in 2022 and selected as pilot projects for the construction of digital twin watersheds by the Ministry of Water Resources. At present, both projects have been completed, and the mid-term evaluation by the Ministry of Water Resources has been excellent. The digital twin pilot project of Xiyuan Creek Small Watershed (Xiyuan Reservoir) has been selected as an excellent case by the Ministry of Water Resources.

Recently, reporters visited the Xiyuan River Basin and the Jiulong River North Creek Basin to experience how the digital twin basin project provides information technology support for flood control, water resource scheduling, and brings "visible, perceptible, and knowable" digital and visual applications to smart water conservancy.

Intelligent forecasting and timely flood prevention

Digital twin technology uses the powerful computing power of computers to more accurately calculate potential risks that may arise

What is the digital twin watershed? Recently, reporters walked into the comprehensive dispatch and command hall of Fuzhou Water Resources Bureau. On the big screen, a virtual simulation of Xiyuan Creek originated from Chi'an in Yongtai County, Fuzhou. It gathered Lei Tou Creek, Daqing Keng Creek, and Ke Creek along the way, passing through one embankment, one reservoir, three rivers, three stations, and five gates, and entered from Shangjie Town, Minhou County, and flowed into Nangang from Mapai Village in Shangjie Town. On the screen, real-time monitoring data on local rainfall, water conditions, meteorological forecasts, as well as cross-sectional water levels, meteorology, and surrounding economic and social information of various reservoirs and key nodes are clearly overlaid.

Xiyuan Creek, a small tributary of Nangang in the lower reaches of Minjiang River in Fuzhou City, is 43 kilometers long and has a drainage area of 208 square kilometers. It is the center of rainstorm in Fujian Province. The intensity of rainstorm is high, and the flood surges and falls, which is prone to flash floods. During the typhoons "Longwang" in 2005 and "Shengpa" in 2007, severe waterlogging occurred in the Xiyuan River basin. Afterwards, the flood control and drainage engineering system in the Xiyuan River Basin was gradually completed, laying a solid foundation for flood control and drainage in the basin. The Xiyuan River basin flows through Shangjie Town in Minhou and Fuzhou High tech Zone, collecting floodwater from Fuzhou University City along the way, "said Chen Yi, Deputy Director of Fuzhou Water Resources Bureau. The significance of flood control and disaster reduction in this basin is significant.

The system in front of us played a role in defending against the "Sea Anemone" typhoon in September this year. From September 5th to 7th, due to the severe impact of Typhoon Haikui, the 11th typhoon of this year, the Xiyuan Creek basin experienced heavy rainfall. Although the digital twin project is a trial, its power is beginning to show.

The forecast shows that the peak inflow of the Xiyuan Reservoir will reach 1290 cubic meters per second, with a high reservoir water level of 99.32 meters and an over flood limit water level of 14.12 meters. The 24-hour flood volume of the reservoir will be 22.08 million cubic meters, and the 48 hour flood volume will be 32.65 million cubic meters... reaching the standard of a once-in-a-century flood. "Chen Wei, the project leader of Sichuang Technology Co., Ltd., the construction unit of the digital twin project of Xiyuan Creek Small Watershed (Xiyuan Reservoir) in Fuzhou, recalled the situation at that time.

According to the rolling prediction, forecast and early warning of water and rain conditions, at 12:00 on September 4, Xiyuan Reservoir Management Office launched the Level III emergency response against typhoon and rainstorm. Based on the predicted trend of water and rain conditions, this digital twin system has generated a scheduling plan, suggesting early pre release of source water from the reservoir and gradually increasing the pre release flow rate. Based on the reference plan and actual water conditions, at midnight on September 5th, the reservoir increased the pre discharge flow to the maximum allowable overflow of the spillway tunnel -93.8 cubic meters per second.

At 5:00 on September 5th, the peak inflow of Xiyuan Reservoir reached 1290 cubic meters per second. Combined with the contingency plan generated by rolling, joint scheduling is carried out for the Xiyuan Reservoir and various gate stations in the downstream basin. Starting from 5:30 am, all five spillway gates of the reservoir were opened for flood discharge, successfully reducing the peak flow by 1135 cubic meters per second, with a peak reduction rate of 88%, greatly reducing downstream flood losses and ensuring the safety of people's lives and property.

Chen Wei said, "The system can provide strong support for flood control and disaster reduction." With further optimization in future practical operations, forecasting, early warning, rehearsal, and contingency plans will become increasingly accurate, comprehensively enhancing the ability to prevent mountain flood disasters in small watersheds such as Xiyuan Creek, and building a "digital barrier" for river safety.

"The main purpose of the digital twin project is to reduce the losses of flood disasters in Xiyuanxi small watershed caused by typhoon and rainstorm and ensure the safety of public life and property in Xiyuanxi small watershed," said Chen Yi.

What impact may a rain that falls from a tributary upstream have on urban areas tens of kilometers away? How did this' butterfly effect 'occur? In the past, it relied on manual on-site inspection and historical experience, which often had difficulties in reaching human resources; Digital twin technology, on the other hand, uses the powerful computing power of computers to more accurately calculate potential risks.

In the 2023 Fujian Province Flood and Drought Disaster Prevention Comprehensive Exercise held in May this year, the project used computing power to simulate the "Butterfly Effect" process.

"According to the forecast, in the next 24 hours, there will be a general rainstorm in the Xiyuanxi River basin and Minhou Shangjie area, with an average process rainfall of 300 mm, and some will exceed 450 mm. It is predicted that there will be flash floods in the upper reaches of the Xiyuanxi River basin, and the lower reaches will be backed up by the tide of the Minjiang River, and serious waterlogging may occur in the University New Area. It is suggested that the Xiyuanxi River basin reservoirs, lakes, gates, and stations should be jointly dispatched!" When the command and dispatching center receives the forecast, the digital twin "four forecasts" (forecast, early warning, rehearsal, and plan) of the Xiyuanxi Small Watershed (Xiyuan Reservoir) should respond immediately——

The automatic forecast of the reservoir shows that the current water level of Xiyuan Reservoir is 84.19 meters, with an inflow of 690 cubic meters per second and an outflow of 120 cubic meters per second. According to the forecast, the peak inflow at 5:00 in one hour will reach 900 cubic meters per second, exceeding the 10-year return period.

The system monitors the real-time water and rain situation, reservoir water level, and flood situation dynamics, and the early warning system rolls out flood forecasting and sends flash flood warning forms.

Based on the flood forecast results and the set warning threshold, the digital twin platform of Xiyuan Creek Basin will issue warnings for areas with disaster risk, such as hydrological stations that exceed the warning limit, reservoirs that exceed the flood control limit, and river sections that exceed the warning/protection limit.

Quick generation of reference plan: Adopting a combination of "spillway tunnel+dam crest overflow" for flood discharge, the design flow rate of the spillway tunnel is 120 cubic meters per second. Based on the safe flow capacity of the downstream river channel, the Xiyuan Reservoir will discharge 300 cubic meters per second, with staggered stacking of interval floods. It is expected that the water level of Rongqiao sluice will be 7.1 meters, and downstream flood discharge will be safe without overflowing the embankment.

The Xiyuan River Basin Digital Twin Project has achieved good results in the comprehensive exercise and trial application of water and drought disaster prevention by simulating scenarios such as mountain flood disaster monitoring and early warning, and joint dispatch of Xiyuan River Basin, "said Chen Yi, Deputy Director of Fuzhou Water Resources Bureau.

Automatic metering, more precise water adjustment

Fine tuned scheduling can ensure that downstream cities are not thirsty, nor waste water sources, and ensure water use during the dry season

Recently, the reporter visited the North Creek Sluice Dispatch Center in the Jiulong River Basin of Fujian Province. The dispatch center is located at Guozhoutou, at the mouth of the Beixi River in Jiulong River, at the junction of the Taiwan Business Investment Zone and Longhai District in Zhangzhou City. It manages the Beixi Sluice, the first level control water gate project behind the Beixi River in Jiulong River, and is the leader of the Beixi Water Diversion Project in Jiulong River. In late autumn, white egrets fly over the open water surface from time to time. The water quality here is excellent all year round, and it is the hub of Xiamen's raw water supply, responsible for 80% of Xiamen's raw water supply.

The distribution of precipitation in the basin is uneven throughout the year, and the runoff during the wet and dry seasons is vastly different, "said Lin Jianhong, Deputy Director of the Jiulong River Basin Center in Fujian Province." How to reasonably utilize water resources and ensure water supply safety during the dry season has become a key and difficult point in the work of the Jiulong River Basin.

In October 2022, the construction of the digital twin Jiulong River North Creek project was launched, which is the only pilot project in the first batch of digital twin watershed pilot projects in China that focuses on water resource allocation and scheduling management.

Yu Qicheng, Deputy Chief Engineer of the Jiulong River Basin Center, introduced that the project platform gathers data resources such as 82 water level monitoring, 52 rainfall monitoring, 6 water quality monitoring, 3 algae monitoring, 32 flow monitoring, 186 videos, and water engineering information. Factors to be considered also include the water storage situation of surrounding reservoirs such as Wan'an, Baisha, and Fangyang, as well as the water demand for daily life, industry, agriculture, and ecology in Xiamen, Zhangzhou, and Longyan City

How to achieve interconnectivity and system scheduling for a large number of water conservancy projects, which can not only ensure downstream cities are not thirsty, but also not waste water sources, and ensure water use during the dry season. This "brain burning" refined scheduling requires the assistance of information technology.

After half a year of construction, the digital twin Jiulong River Beixi project has gradually taken shape. In April of this year, the "Digital Twin Jiulong River Beixi" project successfully launched application scenarios such as watershed flood control, comprehensive water resource scheduling, and comprehensive engineering operation management.

On the large screen of the Beixi Sluice Dispatch Center, the "Water Resource Dispatch and Management System" not only displays real-time water volume from the left, middle, and right main canals of the Beixi Water Diversion Project, but also gathers more data and nodes - Jiangdong Pump Station, Jiangdong Sluice, Zhangzhou Second Water Plant, Longhai Water Plant, Jiaomei Water Plant... These are all downstream "massive" water users, including domestic water, production water, agricultural irrigation, ecological drainage, and other water needs.

The real-time data on the side keeps scrolling: the current water storage capacity of the Beixi Sluice, the increase or decrease in water volume in the future, the expected water supply in the next 10 days, and whether there is a water shortage based on the planned water consumption of the water users

In the application of water resource allocation, the 'four predictions' function can also be achieved. "Yu Qicheng opened the forecast section, which displayed real-time monitoring data of water and rainfall in the Beixi Basin. Combined with rainfall prediction, it automatically generated inflow forecasts for the basin. The water level changes in the upstream and downstream of the cascade hydropower stations in the entire basin are also monitored in real-time. By combining the water volume, planned water consumption, and water demand in different scenarios, the system can automatically analyze the supply-demand balance and calculate the water shortage.

Su Jinji, the contractor of the Digital Twin Jiulong River Beixi Project and the project leader of Sichuang Technology, simulated and demonstrated the water diversion process to reporters: if the forecasting system finds a water shortage of 1 million cubic meters in the next 10 days, open the rehearsal plan in the system, enter "emergency water diversion" in the settings for one day, replenish 1 million cubic meters of water to the Beixi Sluice Station, and select the "fast time" plan requirement. Click the "analyze" button, and in an instant, an emergency water diversion briefing will be generated. The measures are as follows: from upstream to downstream of Beixi, the daily small outflow of Wan'an Reservoir is 10 cubic meters per second, Baisha Reservoir maintains a daily small outflow of 20 cubic meters per second, Hexi Reservoir is 40 cubic meters per second, Xizai Reservoir maintains a daily small outflow of 20 cubic meters per second Kou Reservoir has a capacity of 60 cubic meters per second, while Huakou and Xiaoqi Reservoirs have a capacity of 80 cubic meters per second

When the dispatch center determines the optimal feasibility plan, the system automatically generates an "operation ticket" and issues it to the reservoir gates that need to be dispatched. Each reservoir can then open the gates to release water according to the order, without the need for manual data retrieval, meetings for analysis, and cross departmental coordination and notification as in the past.

Through the 'digital brain', we can achieve refined decision-making and scientific scheduling in flood control and water resource management, ensuring water supply safety and better serving the economic and social development of cities such as Xiamen and Zhangzhou, "said Lin Jianhong.

This summer's "Sea Anemone" and the following "Typhoon Sula" are the true touchstones of this digital twin technology. Yu Qicheng said that the "train effect" formed by the two typhoons resulted in floods exceeding 2000 cubic meters per second in the North Creek basin of the Jiulong River. With the parallel computing of the Jiulong River North Creek model platform, the node forecast plan was autonomously constructed every hour.

With the help of digital twins, we predicted the water levels and peak flow rates of nodes such as Punan, Changtai, and Beixi water gates one day in advance; predicted that the time when the flood peak of the Beixi main stream reached the Beixi water gate was close to the downstream tidal high tide time, and the discharge capacity of the gate may be weakened due to tidal uplift. "Yu Qicheng said that based on the three-dimensional scene simulation demonstration of the project, dispatch experts timely formulated and adjusted the dispatch plan, assisted the flood control headquarters in issuing the" fully open gate "flood discharge instruction in a timely manner, and issued the" lower gate water storage "instruction the next morning. Fully open the gate to release floodwaters for 12 hours, resisting over alert and over protected floods in the Beixi River basin of the Jiulong River

The integration of reality and virtuality opens the door to the "four predictions"

Realize dynamic and real-time information exchange and deep integration between physical and digital watersheds

Digitization is not only for 'beauty', but also for 'ease of use', "said Cai Haipeng from the Water and Drought Disaster Prevention and Hydrological Department of Fujian Provincial Water Resources Department. Traditional water conservancy is no longer able to meet the professional, refined, and intelligent management requirements of current economic and social development. Modern water conservancy requires a modern water conservancy infrastructure network platform that takes river basins as units, river systems as meridians, and water conservancy projects as nodes.

Providing intelligent support for the 'four predictions' (forecasting, early warning, rehearsal, and contingency plan) of disaster prevention and reduction is one of the applications of digital twin watersheds, "said Cai Haipeng. According to the local actual situation, there are many applications such as water resource allocation and water conservation. Our province has chosen to pilot the Xiyuan Creek small watershed and the Jiulong River North Creek watershed, which not only have a good foundation, but also meet practical needs. The application focus of the Xiyuan Creek small watershed is on flood control, while the digital twin of the Jiulong River North Creek watershed focuses on water resource allocation to serve downstream socio-economic development. I hope to activate the 'digital engine' for important tasks such as disaster prevention and reduction, water resource allocation, etc. in our province's modern water conservancy construction through the construction of digital twin watersheds

Digital twin watershed is a digital mapping of the entire process of physical watershed management and water conservancy governance, achieving dynamic and real-time information exchange and deep integration between physical and digital watersheds.

The foundation of a digital twin watershed is the 'data base' composed of the physical and hydraulic data of the watershed, which is also the 'data' of the system. Chen Wei introduced that the system can automatically calculate and analyze various water use applications based on the 'algorithms' of the hydraulic profession, relying on the' computing power ', to help science avoid risks, reduce losses or improve efficiency in advance.

Chen Wei opened the forecast section of the Xiyuan River digital twin basin and manually entered the forecast rainfall situation of Xiyuan Reservoir in the past 3 days. In an instant, the water volume forecast of the reservoir, water levels in various upstream and downstream areas, warning release, analysis of the impact of inundation in risk areas, water situation simulation, scheduling operation plan, and escape routes in the flooded areas were all automatically calculated and presented on the big screen one by one.

On the contrary, by inputting the set value at a certain section of flood control water level, the system quickly deduces when the upstream and downstream gates should be opened, how to control the inflow and outflow, and generates a simulation model, making the entire operation process and results clear at a glance.

In 2022, Sichuang Technology became the contractor of the Xiyuan River Small Watershed (Xiyuan Reservoir) Digital Twin Project.

Faced with this new topic, the project team has placed one of its focuses on the refinement of the data base. The strict requirements for the quantity and quality of data are the foundation of accurate calculation and a major challenge for the project, "said Chen Wei. He and his team braved the scorching sun of Fuzhou for two months, conducting field research along the Xiyuan River, at the Xiyuan Reservoir, every water gate along the way, and every village. They interviewed water management personnel, old water conservancy personnel, and villagers to understand which river section is prone to flooding, which village plot is prone to flooding, how to manage water conservancy projects in daily life, and historical flood data... On the map, more than 100 water level perception points were identified.

For example, the 055 section of Xiyuan Creek is located in Qiuyang River, which is one of the important points discovered during the visit. Chen Wei said that the river channel here is narrow and the terrain is low, which is prone to flooding risks; But it is also adjacent to the border between Shacheng Village and Hongfeng Village in Shangjie Town, and Hongfeng Primary School is nearby with a dense population. The team has set up a point here and established a safe cross-sectional water level. Based on this safe water level, in the event of heavy rainfall, the system can automatically deduce how to schedule the upstream reservoir and the two water gates of Houguan and Rongqiao, ensuring the safety of residents near the Qiuyang River.

With the assistance of water conservancy experts and multiple drone aerial photography, oblique photography, BIM modeling, and laser point cloud scanning, the team has finally created a highly simulated and intelligent hydrological mapping digital integrated analysis display for the entire basin. Every bend on the three-dimensional map, every village along the coast, every building and water conservancy facility, even the vegetation on the riverbank and the water quality of the river, all restore reality, "said Chen Wei.

Digital twin technology is like equipping a river with a 'strong brain'. Our province has further improved the construction of smart water conservancy from the top-level design, accelerated the formulation of the "Three Year Action Plan for the Construction of Fujian Digital Twin Water Conservancy (One Platform)", with the goal of gradually building a Fujian Digital Twin Water Conservancy Platform by 2025, which has the functions of information sharing, efficient management, high-quality service, and "four predictions", achieving "one screen water management" for the entire industry internally and "one screen water viewing" for the whole society externally, and promoting the high-quality development and governance capacity improvement of water conservancy.

Source: Southeast Bedroom