The tidal basin formed by the two converging rivers was named "dubh linn" (meaning "black pool") by Celts, who had inhabited the area upstream as early as 500 BC.

BBC: Dublin's Viking heritage

The defences include a flood water storage area, upstream of the city, which can hold up to 1.5 million cubic metres of water.

BBC: Ripon's ?14.4m flood defence scheme completed

Farmers in the Jiaxing area of Zhejiang province, upstream from Shanghai, have denied dumping the pigs in rivers.

BBC: China pig deaths: Toll from Shanghai rivers nears 14,000