Case Study: Geosynthetics in the South-to-North Water Diversion Project

1. Project Challenge: The Seepage Imperative

The South-to-North Water Diversion Project, a critical infrastructure to alleviate water scarcity in northern China, required moving vast quantities of water over immense distances. A primary engineering challenge was minimizing water loss through seepage, especially in canal sections traversing porous soils or high water-table areas. Every drop saved was crucial for the project’s overall efficiency.

2. The Engineered Solution: Composite Geomembrane Liners

To address this, the project extensively utilized a composite liner system, with the “two cloths, one membrane” composite geosynthetic playing the starring role. This material consists of a central impermeable HDPE geomembrane, thermally bonded on both sides to a protective non-woven geotextile.

3. Strategic Application and Functionality

This composite liner was installed beneath the concrete panels lining the canals, where its multi-functional layers worked in synergy:

• Primary Containment (Geomembrane): The central geomembrane acted as a continuous, flexible, and high-performance hydraulic barrier, effectively eliminating the majority of potential seepage.

• Protection and Drainage (Upper Geotextile): The upper geotextile layer protected the sensitive geomembrane from puncture and abrasion during the placement of the overlying concrete lining. It also created a drainage plane, managing any incidental water that penetrated the concrete.

• Reinforcement and Filtration (Lower Geotextile): The lower geotextile, in direct contact with the subgrade, provided separation and reinforcement. Crucially, it acted as a filter, preventing fine soil particles from migrating into the drainage system or stressing the geomembrane, thereby preserving the integrity of the entire liner.

4. Project Outcomes

The deployment of the composite geomembrane liner resulted in:

• Dramatically reduced seepage losses, ensuring water delivery efficiency met strict design targets.

• Enhanced long-term structural stability of the canal slopes by preventing internal soil erosion.

• Superior durability thanks to the chemical and UV resistance of the HDPE geomembrane.

5. Conclusion

The success of the South-to-North Water Diversion Project underscores the vital role of advanced geosynthetics in modern water conservancy. The strategic use of the “two cloths, one membrane” composite liner provided a robust, integrated solution to the critical challenges of impermeabilization, protection, and filtration, setting a global benchmark for major water conveyance infrastructure.

“Hengyu’s geotextiles and geomembranes have been instrumental in our major water conservancy projects. Their consistent quality, technical expertise, and reliable performance make them our trusted partner for critical infrastructure development.”
GM Yu