Two long tunnels, built using bricks from the city walls, cross the city and channel floodwater into two ponds that function as reservoirs. The designer of the system, Liu Yi, named the drains “Fu” or Fortune, and “Shou” or Longevity.
“The ancient residents of Ganzhou were very advanced in hydro-technology,” said Wang Ronghong, head of the city’s project management and maintenance office.
“They built 12 water gates at the mouth of the drain, which help block rising water during the rainy season. When the river level is lower than the gate, the water from the drainage system flows out, but if the water outside the city rises, the gates snap shut to prevent any of it coming in,” he explained.
The drainage system also uses the natural camber of the city to quickly channel water outwards. The original Song Dynasty system used hundreds of ponds across the city as reservoirs.