The Daqing Canal renovation started September in 2025 and was fully completed in April in 2026 “With traditional cast-in-place methods, we would have had to wait for the construction window until the end of August. Now, with prefabricated slabs assembled on site, efficiency has doubled,” He said.

　　The new canal also brought unexpected benefits. The rectangular canal takes up less land than a trapezoidal one, reducing the need to cut down trees on both sides. Reserved holes at the top of the canal can be fitted with steel railings, which are safer and more attractive than the old roadside wave barriers. The smooth inner wall of the concrete increases flow speed and stabilizes water movement.

　　“Look, the water is moving fast but there are no splashes, which means higher conveyance efficiency and less siltation,” He said, pointing at the canal. “Before, half the canal was mud. Now the bed is much cleaner.” If a single prefabricated slab is damaged, it can be replaced independently, reducing maintenance costs.

　　“Prefabricated assembly is especially suited to the next phase of the Qingtongxia Irrigation Area’s overall renovation,” Bai said, looking at the water surging through the new canal. “We upgraded the old canal in place, without changing the alignment or the distribution pattern. What changed was only the material and the construction method.”

　　Preserving heritages

　　The Hui Nong Canal was excavated 300 years ago and passes through six counties and districts. Longmen Bridge Headgate is the key control project downstream of the canal head.

　　Today, the headgate bottom slab and frame were built in the 1970s, but the lower structure remains relatively intact. At the inlet, the rough gate slots are clearly visible.