Big dams. Love them or hate them, we have to live with them. Environmental campaigners contend that vast schemes such as the Three Gorges in China or Narmada in India are social and environmental catastrophes in the making. But their backers have a different view. Big dams provide non-polluting energy and control flooding. On the eve of the World Water Forum Earth Report presents the case for and against big dams.

For more on this programme, see the TVE Changing Currents page.