Ancient drains save Chinese city

A 900-year-old drainage system has saved a city in south China from severe floods that have left over 100 people dead and a million homeless across the region.

The 100,000 residents of the ancient city of Ganzhou, in Jiangxi province, are safe and dry, thanks to two drains built during the Song dynasty (960-1279) which proved far more effective than modern systems at coping with the downpour.

Two long tunnels, built using bricks from the city walls, cross the city and channel floodwater into two ponds that function as reservoirs.

Wang Ronghong, head of the city's project management and maintenance office, said: "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."