Hunan Daily all-media reporter Feng Yongcheng correspondent Mao Zhouyu
On March 28, excavators and other large machinery drove into Eping Village, Tianmen Township, Xinhua County, to prepare for the opening of Meishan Irrigation District.
The Meishan Irrigation Project is located in the severe arid zone in the north of the "Hengshaolou Arid Corridor", and is an irrigation "thirst-quenching" project that the local people have been looking forward to for decades.
According to the plan, the construction of the Meishan Irrigation District Project will be completed in about 5 years. After completion, it will bring 137 million cubic meters of "living water" to 16 towns and towns in Xinhua County, as well as Xinhua High-tech Industrial Development Zone and Daxiong Mountain Forest Farm every year, and turn 649,900 mu of "Wangtian Field" into "Harvest Field".
(Renderings of Meishan Irrigation Area.) Courtesy of Provincial Hydropower Design Institute)
Crying thirst for many years, suffering from drought for a long time
The Meishan Irrigation District Project is a large (2) type comprehensive water conservancy project of the second type, with a total estimated investment of more than 7.3 billion yuan and a construction period of 62 months, and the main project is located in Xinhua County.
The irrigation area is dominated by limestone, red sandstone and karst karst rock, with poor soil water retention, large water leakage loss, and deep groundwater burial. Although there is a Zijiang River crossing, the controllable amount of water is small, resulting in "a small drought in three years and a major drought in five years".
The county's 18 townships (development zones, forest farms) are in the "Hengshao Lou Dry Corridor" severe drought zone, more than 6 percent of the farmland due to irrigation difficulties, grain yield is lower than the provincial average. The problem of "difficulty in water storage" has always been an important bottleneck restricting grain production in the county.
Trapped by the water, fighting for the water. Our province has always taken solving the problem of water shortage in the "Hengshaolou Arid Corridor" as the top priority in the development of water conservancy.
In 2022, Hunan suffered from a continuous drought, and small reservoirs, mountain ponds, and rivers in Xinhua County dried up. "We can only rely on fire trucks to deliver water, and use temporary port high-lift pumping and wells to supply water to 'quench thirst'. Cao Lisheng, director of the county water conservancy bureau, said.
(The Meishan Irrigation District Project alleviates the local drought problem by building a new Tuping Reservoir to divert water from the main stream of the Qujiang River.) Courtesy of Provincial Hydropower Design Institute)
Water diversion and water transfer, the best of the best
In April 2022, the Provincial Hydropower Design Institute received the task to carry out the feasibility study of the Meishan Irrigation Area project. Cheng Xiangyang, the general person in charge of the design, said that based on the situation in all aspects, the Meishan Irrigation District Project can only alleviate the problem of uneven distribution of water resources and achieve the purpose of fighting drought and quenching thirst by diverting water from the canal river, which is rich in water resources in the west of Xinhua County.
After completing surveying, geological survey, scale demonstration and other work, the design team initially prepared to divert water from the Yanwan River, a tributary of the Qujiang River. However, in the demonstration of water resources and other related technologies, it is found that the water source of the main stream of the Qujiang River is more abundant, and the rainfall collection area is nearly three times that of the Yanwan River.
After many rounds of comparison and selection, repeated demonstrations, and the best of the best, the final design plan was determined to build a new Tuping Reservoir in Tuping Town, Xinhua County, to divert water from the main stream of the Qujiang River, divert water across the Zijiang River, and divert water from the Zijiang River to divert abundant water for drought relief.
The difficulty of transferring water across the Zijiang River can be imagined. In order to ensure the smooth progress of the project, a number of new processes and new methods have been fully applied to the Meishan Irrigation Area Project.
"In the construction of the head tunnel, the design uses shield tunneling instead of traditional drilling and blasting construction, which can shorten the construction period by about 20 months. Yuan Feng, the general director of the initial design of the Provincial Hydropower Design Institute, said that this is also the first time that the province has applied shield tunneling construction technology to water conservancy engineering construction projects.
In order to fully quench the thirst of the severe arid zone in the northern part of the "Hengshaolou Arid Corridor", it is necessary to divert water from the west of the Zijiang River to the east of the Zijiang River to replenish the water source.
"We want to build a water bridge over the Zijiang River. Yuan Feng introduced that the main span of the bridge in the irrigation area is 280 meters, which is the largest bridge inverted siphon water pipeline in our province.
(Renderings of Meishan Irrigation Area.) Courtesy of Provincial Hydropower Design Institute)
"Long vines and melons" lead to abundance and drought
The Meishan Irrigation District Project is mainly based on irrigation, combined with township water supply, and takes into account the functions of improving the water ecological environment. According to the plan, the project is divided into two parts: the hub project and the irrigation area project. The total storage capacity of the Tuping Reservoir of the hub project is 96 million cubic meters, and the backbone project of the irrigation area includes one main trunk canal with a length of about 61 kilometers and four sub-trunk canals. After completion, it can add 137 million cubic meters of water to the severe drought in the northern part of the "Hengshaolou Drought Corridor".
"This is a typical 'long vine and melon' irrigation model. Cao Lisheng, director of the Xinhua County Water Conservancy Bureau, said. The Meishan Irrigation District Project takes the newly built Tuping Reservoir and the existing Chetianjiang Reservoir as the main water source and is the root; the new canal system is the main vine, and the canal line crosses the Zijiang River and the Youxi River, and is connected with the irrigation system of the Chetianjiang Reservoir to replenish water, and with the nutrient supply of roots and vines, the original Meihuadong Reservoir, Taiping Reservoir, Huadong Reservoir, Shanshan Reservoir and other small and medium-sized reservoirs in the territory will produce melons with "sufficient water" and give full play to the water supply role of the project.
The relevant person in charge of the Provincial Department of Water Resources said that our province is rich in water resources, but the distribution is extremely uneven. Taking the "Hengshaolou Drought Corridor" as an example, the annual rainfall in this area is less than 7% of the provincial average, but the evaporation is about 1.4 times that of the provincial average, and most of the rainfall occurs from April to June, so drought is very prone to occur. The irrigation mode of "long vine and melon" can effectively alleviate the dilemma of uneven distribution of water resources.
In recent years, our province has vigorously promoted the construction of major water conservancy projects. The water supply capacity of water conservancy projects has increased from 29.266 billion cubic meters in 2014 to 52.87 billion cubic meters in 2023.
This year, our province will continue to vigorously promote the construction of major water conservancy projects to provide strong support for ensuring water security, improving water ecology, and promoting sustainable economic and social development.